VMware TGI Kubernetes, 5 Feb 2021

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From YouTube: TGI Kubernetes 145: Duck Typing in Kubernetes

Description

Come hang out with Scott Nichols (@n3wscott) as we explore the wild world of duck typing in Kubernetes! We will look around the ecosystem to find duck type examples and learn how to leverage duck typing to do novel control plane tricks!

Show notes available at https://github.com/vmware-tanzu/tgik/blob/master/episodes/145/README.md

A

Hello and welcome to tgi kate's, it is episode. 145. today is february 5th and then here's. My very first show.

A

So what a week right, I see, we got some people in the stream ready to learn about duck typing and interfaces and kubernetes, and somebody from israel, howdy, netherlands,.

B

North texas, helsinki.

A

Well, go kick our other finnish friend to get on the stream he's apparently in bed. Mr velay.

A

Boy: okay: okay, are we ready to start actually uh week in review right.

A

I pushed a button. I'm sorry, I'm new at this.

B

A

All right, so what happened this week?

A

uh Well in core kubernetes, we got an announcement that uh v1 beta 1 for crds and admission web hook. Configurations are heading out. Well, I won't miss you a v1 beta 1, but if you happen to still be using those you're going to be real sad in uh in 0 22., so you've got some you've got some time, but you know get on that video! Better! You better update!

A

I see kind. Zero 10 is out that that's from two weeks ago. uh That's that's good news, good news, I'm still running kind! Nine because you know, but maybe I should update it, but not right now and uh heads up if you're thinking about writing a cap and it's not already in the system. The freeze is the ninth, which is in a few days. So you know you have the weekend to go. Write your.

A

A

uh Yes, we're talking about api removal in 121, not deprecation. It's already been deprecated for a while in I think, maybe a release or two ago. So they are, they are ready to be hoisted out. Kenny asks. Am I nervous yeah, you know what it's a weird thing actually to to be broadcasting to the internet and talking to yourself, so you know it's something to get used to.

A

Okay, actually let me tell you a funny story uh side note here, while you watch me struggle reading the news here uh for about three weeks, I was a radio dj at in college, and it really it didn't go well because I I couldn't read the cards and not, and I was just too nervous to read the advertising cards and you had to read like I don't know, five every 15 minutes- and I just I couldn't do that job at that time, and I was I so I I said, I'm sorry.

A

I really want to be this like night dj, but I can't read your advertisement for like life insurance or whatever it was so you know, everybody's everybody has things that are hard for them. This happens to be mine,.

B

A

What's radio yeah it was, I mean it's kind of fun, although so here's here was the one bummer. It was a college radio station and I could play anything I wanted as long as it was one of the cds that they had.

A

I didn't really know any of the music and because it was all this like indie interesting stuff, so didn't go well. I was like basically randomly picking cds and sticking them like.

B

I hope this is good.

A

Okay, back to the back to the news focus, so uh our our good friend tiffany is going to be uh occasional, tgi host she's written up a blog about valero. If you want to back up your cluster, take a look here: ah it'll get you going just in case you you know, want some persistence.

A

Oh boy pinned up. I didn't! Oh okay! So let's see it kind of looks like pineapple right matt.

A

I don't know what this is. I didn't click this yet uh some toys. That's neat! uh Batteries included authentication system; okay, I'm I'm in I'm in um okay. So I'm not sure what that is, but it sounds interesting uh at first pass. Maybe it's oauth for apps in kubernetes.

A

And if that's the case, uh that's cool, because there's not really a great solution for that scottsdale.

A

Nice we got mark in the chat yeah. I I got the uh amazing opportunity to to make these hoodies. This is actually embroidered. How fancy is that.

A

Okay, uh good news, contour 112, is out it's pretty good, uh also some nice q native integration. If you go to net contour, that's what I use not to toot my own horn, but you know what it just kind of works.

A

So it's a controversy of health. Somebody added this.

A

This is an interesting read if, if you have a minute to go over it- and I I kind of agree with what they're talking about, I think the basic premise is that well helm is. Is this ball of opinions? And if you want to make a change, that's not already baked into that template. You really have to fork the chart.

A

Okay, which kind of also feels backwards to me if we're talking about uh temporalization of stuff, so I I'm not a big helm user I'll I'll touch it. If I need to, but not not not a big thing for me.

A

Some in and some interesting news you know so docker's having some, uh maybe some mid-life drama right, so they're looking for ways to keep keep all this core tech going, because you know honestly, a lot of people depend on what docker has provided and they have gone and donated the docker distribution to the cncf, which is interesting. So maybe we would get some more registries out there. That'd be nice.

A

Let me check on the chat. Are we doing.

A

Anybody anybody in the uh the rambly, so you can speak trash, talk and kibbits me.

A

Ctrl plus, what if I do, one better.

B

A

Better: hey, it's old scott! What's up buddy thanks for tuning in uh so I don't know if you, my my nickname, is new scott super hack, a tastic with the w or an e uh it's because of scott stout. Here, it's not one of my friends long-term friend. uh He was the first scott, so we we call him scott classic and I am new scott and that's so, if you've ever wondered. Why? My name is that it's it's right there, okay, all right back to this!

A

uh Okay, so that I found this this uh blog post. That's talking about the kubernetes operator pattern and if you're confused or have some questions, it's pretty good and there's a bunch of fun pictures and there's even some animated ones, which I thought was pretty awesome.

A

So I think it's a good, succinct, uh long-form, post of operators and kubernetes worth the read if you're. If you have questions, then maybe use it as a jumping off point to go and look at other things or read, documentation or read a couple of books.

A

Speaking of books, we'll jump one, uh so canadian action is hitting the presses right now. So that's you. If you want a physical copy of the k native in action book, which I'll show you a little picture, you could get yours today, for uh you know, 50 bucks, what a deal.

A

There was a so there's this other blog post around demystifying the container tool jib. If you don't know what jib is it's a imaging library for java things?

A

And I I think this is on the right direction and I point this out because someone needs to pick up jib and turn it into co, because that would be sweet. So I point to co. Joe did a a co episode. uh I have to look up the episode.

A

I am a huge, huge co-fan. uh Basically well, I have the luxury of staying in the go. Land go world, and so I basically just use co all the time all day.

A

Yeah that's right. Evan points out, jib is fast docker or fast container images without needing docker, like the cli docker locally.

A

I guess there's a there's: a new kpac release that that just showed up that's cool, okay, okay, okay, so we're here to talk about ducks and uh let's see if I can see a uh see, a raise of hand of who understands what in the world we're talking about. When we talk about duct types in kubernetes, we could start with what is a duct type.

A

The name gets um it's it's, okay, so in in programming languages right like in java, you would say something like uh foo class implements and then it would list all of the interfaces that it has opted into right, and that's that's a very explicit. I am this thing. A duct type is more like something in python. It was made popular, but go.

A

Does this too, where you say, I know that I would like to interact with this object in this certain way, because it has you know this method and this method I'm going to find an instance of an implementation and attempt to overlay that interface on top of the implementation.

A

So I'm going to basically probe the the instance of that thing to say: do you have these methods? Do you have this shape? Do you do these things and if it passes the duck test, then it's that duct type and we can do stuff with it?

A

The interesting thing about duct typing is that the implementer of that target class never knew they were being targeted as a duck type.

A

Yes, there there's a cute phrase if it walks like a duck and it talks like a duck, it's a duck. So what that really means is you know it? It has a certain shape, it does. A certain thing must be a duct type.

A

So I have. I have set up um a semi-contrived thing that we can walk through and then add to it as a as a duct type.

B

Let's see that's a.

A

Yes, uh javascript also does duck typing. If you want um I've mostly used it inside of python, go so okay. Here's the scenario. Let me switch to this one.

A

Oh, uh the hack, I o link is k native or no uh tgik dot, io, slash notes.

B

B

Notes, yeah.

A

Thank you, okay. Okay, here we go so um what do we got? So I built this uh thing. Actually, sorry we're gonna we're just gonna jump in and then I'm gonna hopefully answer some questions and then we're gonna jump into some actual live coding, stuffs uh and and see where we end up so first off what we're gonna do is uh I'm gonna copy and paste this little kind, cluster creation thing. Basically, I'm going to set up a kind cluster with some extra things so that it lets me build images and push to it.

A

So here we go we're going to wait for that it has the font by the way, is it readable?

A

Can I send someone a bigger, monitor.

A

How is duct typing implemented under the hood in the compiler? You know what I'm not I'm, not totally sure. um I have some guesses, but I just use it if only there were some compiler nerds in the audience.

A

Okay, here we go getting some nodes. You know what you know, take a lesson from the kind tool uh cute emojis and check marks it. Just it kind of makes me feel like I'm doing something super important by using it.

A

So you know if you have an opportunity, add an emoji or some like scrolly thing or whatever, because it makes me feel good and we're just gonna make sure that so I'm going to export the kind cluster name. I called this one tgik and then I'm going to point my local co instance to to push to the local registry there. So I do have docker running and installed, but I don't actually like writing doc files. So I I didn't um there's no docker file here we can.

A

We can look at this code, so I'm going to cheat a little bit and we'll get into this more a little bit later.

A

Let's see, I guess I'll show you the config, so I'm going to do some secret magic, co stuff, so we're gonna, deploy this operator and then I'll explain what in the world it is in a second. So.

A

uh So I'm going to apply the config directory, I don't have any images or docker files, I'm going to use code to kind of build up this stuff, but that's not really what we're talking about it's just kind of an efficiency that I I've.

A

Short-Circuited my little dev loop, okay, cool.

B

A

See so let's get the namespaces and I can show you ah cool so there's this new math namespace in this new cluster.

A

And in there is, you know it's a bunch of stuff. uh The important parts are the controller and the web hook. This this project has uh oh, actually, I can show you this. So I've made up two crds and I didn't put the schema in here, because uh this is a silly silly silly demo, please don't do anything like this and for reals uh it's a contrived thing uh that I'm trying to show. What's.

C

A

An example, and so okay, so we'll we'll make we'll make an instance of the add resource, okay. So the concept here is that we're making opera operators as crds and part of the spec is going to be what the that operator does.

A

The the operand in mathematic terms, so good good I'll get and then we'll they're in this uh category called math. So we can get them and I have made an add one right: the expression is one, and the answer is one.

A

Okay, that's that's boring. So, let's add some some more numbers.

A

Right so what the spec says here is uh you know it's a kind ad add a few. The bottom of the screen, oh.

C

A

Thanks for the tip, okay, so we're going to make another one. And if you read this, you know it's going to say, add up these values, one two three four and and we'll take a look and in fact my silly silly silly reconciler has gone and looked and said: yep, I'm gonna. I developed this expression that represents this crd and the result is this, so we can edit that it's an add, object and view.

A

So here's where the duct typing comes in in the status of these resources, I've defined expression, so status.expression is a string. That represents something right like whatever the the equation: that's required to produce the result in spec or the in the status, and so the duct type doesn't actually know what is in the spec or what this. What any of the pieces mean? All it understands is status.expression and status.result mean these certain things. So now we can kind of look at other objects in the cluster and uh figure something out about them.

A

And of course you know we can change stuff.

A

So we've added edited add a few uh look at the math again cool, so we can see that expression has updated, but we can do fancier things in the implementation detail of the ad resource.

A

The reason why I added value is because I also have this thing called ref ref is an object reference to a doctype that implements this results duck if that makes sense, and we might have to talk about duct types and partial schema when we look at the code of how this works, but for now we'll keep on charging on with this silly silly.

A

Demo, okay, so what's happened. This is interesting, so I've um here's the schema up here for the ad refs and in its spec. I I give a static value and then I give two object. References to the two things that we just created uh and what's happened is the controller.

A

It's it's just set to basically take the expression and add it together and then add up the result, because it's add okay, all right, so we can do the same thing for subtract, we'll just make some of these and where it gets fun- and this is where the duct type stuff comes in is I can mix the resources.

A

So now I have this really more interesting, so it's it's real pipe is an add object and I've made the mixed expression, one plus an object. Ref plus an object. Ref and the first object ref in the mixed. uh Add co is a subtraction object.

B

A

Demo over show done, everybody understand no just kidding so okay. So what the demo is and.

A

If we have, I think, if we have the patience and the time to do it, we can make another resource that implements the duck that will mix in with this controller without me having to redeploy anything or change anything about what we installed for the maths bit.

A

Should we charge ahead or should we step back and talk about how this is happening? Let me give me a, I don't know, put a duck in the chat if you think we should take a pause and and uh ask some more questions.

A

Does the math crd recurse it it will recurse um it will recurse it will not detect loops because I wrote this in a couple hours yesterday you get what you pay for all right, okay, so we're going to we're going to pause for a second and we're going to take a little look at the controller here to see what's going on, so I have two reconcilers there's an add and the subtract so we'll take a look at add.

C

A

The reconciler function uh method and let's make this a little bigger, it's kind of what you would expect. So we have some magic in k native that helps us generate a bunch of all of the preamble pieces for reconciliation and the end result is. I just have to implement this reconcile kind in the next demo. We're going to try to do it in not k native land. It's because duct typing isn't dependent on k native, but I implemented this quickly yesterday by using our frameworks.

A

So so, basically, I just say for every operand inside the spec, so we could sorry I'll show you that object. First,.

A

So I here's an add type it. It looks like a standard. Kubernetes object. It's going to use client gen in its here's, it here's its spec right, it's spec! I I have one object. It's a slice of operands, that's labeled, add right so inside of json and an operand is defined.

A

Oh here, sorry, so it's just what we were showed in the the yaml. It's either a ref or a value. I made them pointers just to determine if it's null or not yeah, don't feed the ducks.

A

Popcorn, so, okay, so that's what the ad looks like and then the reconciler again is: I'm I'm just looping through them, because it's a very simple example to kind of describe duct types. I I just checked to see if you know like length at night, so here's where the recursion happens right. I don't actually look at what's down. I rely on the reconciliation of the object below like that. I'm pointing to to come up with a result, so it will recurse, but it doesn't actually like traverse the recurse.

A

That makes sense, try to say that five times fast.

A

So the magic, though I glaze over this right, what I'm doing here is I'm going to get a result, get results that says if the reference that I'm pointing to is not null go and get the results and right. This is a big hand. Wavy thing I I made this thing called a results type, that's part of the duck package. It's in this project we can. We can take a look there and it's kind of what you'd expect too.

A

It uses client gen, but I don't actually generate a client because there's no api endpoint that you could actually go in and fetch this thing it's gonna, it's gonna sit in front of well, it's just a definition of an object that you could cast any other runtime object into and interact with it. Remember: okay, yeah! So so it looks like a normal type right. It has a type meta, it has object meta, it doesn't have a spec, because I don't care right, I'm only interested in the results in this duct type.

A

So I only map in the status, which means when all the the tooling and the libraries take whatever I'm wondering is a duck and it converts it to that thing. Spec gets stripped off because I don't care and inside here is a an inline results. I don't yeah, and this is the duct type here.

A

It's expression and result just the same exact thing that I showed in inside the uh the add resource the duct type matches the shape, because results is the partial schema of the spec of the duct type that I'm interested in a bunch of tooling note. This fancy gen duck thing. The tooling expects some of the other object meta to help me deal with dynamic clients, so I don't have to so there's a bunch of tooling and wrappers that.

A

That help help right. So, okay, so we'll go back to here.

A

So the the get results thing we're using some tooling that comes out of a k native given a gvk and a name and a namespace go and fetch an object tracker or we're going to track that object, which means that we get updates for for changes for these things that uh occur, and so we can get re-enqueued and re-reconcile as our object, refs update, which is interesting, because I can watch things. I don't actually know about ahead of time, which.

A

A

What did I miss? Oh just duck types, it's no big deal.

A

Okay, okay, all right! So uh basically there's the there's a. I can ask the informer factory for a lister given a gvr, so you know under the hood here, there's like a bunch of dynamic clients and some other stuff and some caches that's based on a gvr. I can give it the the lister interface, which is exactly what you would expect for typed clients, so like a typed lister and then I can go and list that object.

A

I can you know because go doesn't have generics yet, but maybe wait a release or two.

A

Oh come on mark. I have an id I'm going to pop it out in one second, uh so we cast and cast that thing to a results type if it's, if it is and then we return it so up here get results, returns back an object, that's known by the gvk, that's defined by the object, ref and reminder that object graph looks like this.

A

So in this case, as the ad reconciler is running, it finds a ref. That's not null. It says: okay cool, I guess, you're a subtract whatever. That is from the same api version, which is maybe cheating. If you you want to be a purist and then it goes and basically converts that to the duck type and then I can operate them. I can. I can operate on the duct types as if I know what they are, but I don't actually know what they are. They don't really need to care.

A

A

Carlos asks do I want the expression or the result out of the ref. I actually want both, because I don't want to calculate the here's. Here's my micro optimization for the demo, and this is stupid, details in it. This is why I didn't actually pick a real thing. um I'm just concatenating concatenating the expressions wrapped up in parentheses right.

A

So if, if the result type, you know I so I grab the status of the expression or sorry the result, status, expression and I just concatenate that inside of parentheses and the reconciler adds in a plus and then whatever the whatever the result is. I add it in and so subtract actually looks very identical. I think I changed a couple things. It turns out that you can't assume you can subtract 0 like 0.

A

Plus a number is a positive number, but 0 minus a number is not what you expect so subtract subtract had to understand some more state. So I I stuck that in there and then, aside from that change, the only real code change between the two reconcilers is the minus sign there there, okay, okay, here we go so um chime check, okay, 130., so here is where we get real nervous, we're going to try to add the square crt, okay, but we're gonna use controller runtime.

C

A

uh Oh multiply: well we're gonna we're gonna, make it square okay. So we have a a good start of the project here we gotta read me in a license, so I've already installed controller runtime and I hope it's still all connected and I'm going to follow along in the quick start guide with some modifications.

A

So this isn't really about like how to use controller runtime. But I wanted to show that, like this stuff just connects, if, if you connect it okay, so I'm gonna knit that project with tgi kate sat io, please don't sue me, tg, kates, dot, io and then we're going to make.

A

We can make it well, let's, let's do fun we're going to make a kind square so inside this group tgik we're going to make a a kind square and yolo straight to v1.

A

So that's going to do its stuff.

A

And now now here's the interesting part. I I honestly haven't used controller runtime in over in over. uh I don't know a couple: it's been a year, it's it's been at least a.

A

A

And so, okay, so the docs tell me I have to do a make install and I don't totally understand what that is, because I don't also use make files so make install. What does it do? I don't know it makes manifest, so we're not going to do that um in fact, so for for just for mark.

B

Please work come on.

B

One second one: second technical, oh, come on.

A

A

Okay, uh I use goland- I I kind of like this ide. It has all the key bindings that my fingers know. I spent several years, maybe more than that doing a java stuff intellij, and I really liked it, and so when golan came out, I was I was big into it.

A

Okay, um now I don't I don't so like I said I don't really like make files, and uh I also don't really like docker files, so we're gonna make a couple modifications to the base installation here and uh I just need to okay right reviewing, okay, so in the config inside of the web hook. What is this thing.

B

A

So they have this concept called the manager. The manager has an image controller latest. Well, I'm not going to make one of those so.

A

This is going to be part of new scot multiply right, so I'm going to codify it. If I can, co creates manifest correctly, so we don't need to tell the pod what the executable is.

A

So we save that and then I'm kind of done with the everything else is fine. Actually I don't know what their their crd is. Where does where's my where's, my stuff.

A

Well, that'll be interesting.

B

We'll see what happens.

A

uh And then I can okay. So now I can go back to this one.

A

And I'm gonna take that yaml and get an error cool.

B

A

Oh because we're targeting the default oh come on, maybe I maybe I do have to do a make install.

A

Maybe that does some generation stuff that I need. First, okay, okay, it did. I don't know. I just I just work here all right like.

A

So I'm gonna pull out my favorite fast idea.

A

And so, okay, so let's, let's look in here: did it okay, so it has that co directory. Now it's out of customize, it's now just straight yaml. I can deal with this, so you know for fun. Let's just let's just apply that.

B

A

So it's going to do the build it's going to well, it's so, okay! So here's the quick version of what co is doing. It's looking for that, basically the same thing that has the main function in this case: it's at the root of the project and it's compiling it and putting it into a container that we know works well with go, which is distroless because you don't need anything else.

A

Yeah, so co is the containerization magic. So if we look here, there's this new multiply system.

A

So if we look at the pods in.

A

A

And we look at the container the container that is mine. It's this, so co has done a build. It's replaced the outbound, yaml and and taken that new yaml and pushed it to coop cuddle apply right. So now I don't have to think about doing. Docker builds or anything like that. I can just push it through co, co, containerizes it and there's a bunch of optimizations there that work really well for go workloads which a lot of controllers and kubernetes are built and go. So it's a great great flow okay.

A

So we have a running controller and I think, there's like an example. We cuddle.

B

B

Config samples.

A

Okay, we made a square function or a square resource.

B

Oh boy, oh boy,.

A

Does it have a spec it does? It doesn't have a status though so this is where it might get interesting.

A

Okay. So let's go back to go land.

A

And we are now we're in hacky land right, we're gonna, we're gonna, get it done.

A

Well, it's not the uh layout. I would have picked, but all right we're going to leave the fu string in there because I've already applied one, and I don't want there to be problem, so we're just going to leave that alone. What we're going to do now is, I I don't know.

B

A

So bass is an int, we're gonna, you know it's gonna, be a bass.

B

A

The two- maybe that's a bad number- I don't know what do people call that number.

A

All right, yolo, well we're gonna call it bass, wait! Don't edit this, oh edit, this file, that's a really scary warning: how do people, okay, scaffolding, for you, okay, got it okay, I I owned it. I changed it, I'm a little nervous that there's no status, though in that object up there. Aha, because there's nothing in this.

A

So if we right so what's the contract, we know that we need a result.

A

And result was an int. Let's pretend, like only inc exists right now, because it's a silly demo.

A

And an expression.

A

Okay, so now we're back to the duct type shape right.

A

Do I have to do more things, or is that gonna just work well, we'll find out we'll find out.

A

I heard uh coup builder doesn't have to you: don't have to generate stuff anymore, so I'm curious what that's like? Okay, oh hey! I found the square controller so in here what I want to do. Oh look at that. uh Oh I have to.

B

Okay, all right.

B

A

B

It's a time what okay.

A

That's like how do I get?

A

How do we get the object hold on? Okay, all right so abort we we're gonna we're gonna.

B

A

Chrome window and we're going to learn about how to do.

C

A

Yeah, you see deep copy. I think that they there's some.

A

There's some code generation that has to happen, but they don't generate the client. I think they filter things through the dynamic client. So it's all kind of runtime.

A

All right, how do I get the object? uh Next steps, cron job tutorial, that looks like a good plan. Oh my goodness,.

A

What I want to know is how to get the object from uh this. The control request.

B

Oh, oh here we go.

A

No now we can implement our controller, okay, cool cool, sorry.

B

B

A

Oh, our client get oh okay, ben's ben's in here for the save. Let's see if that get.

A

I don't ever talk about that, I'm sure I'm sure they'll get there.

B

A

Let's, let's try it and.

C

B

A

But I don't have a context, but maybe that comes from the request.

A

A

Here we go what's object.

C

A

Still learning like I said, I'm sorry, it's been a really long time, since I've actually done anything outside the canada blend. So we are in a fun duck type. Adventure.

A

So we're looking at the docs right now.

B

Writing ted no.

A

I want what implementing yes this this should this should say something about getting.

A

Now we can implement our controller. Would what.

B

Are you talking.

A

A

Then an empty version of the object, you're retrieving, so I assume that means my square type. What is this thing called? It's called a square.

C

A

Where how do you get used interesting.

A

hmm Okay, here we go. I found one.

A

A

A

I'm assuming it's probably going to be a pointer type and we're going to get.

A

A

A result I now I recall some stuff about this- we're gonna. I bet there's a.

A

Switch windows we're good we're good we're in the go.

C

B

A

So one of my favorite features- I don't know something I just do one of those.

A

Okay, so now I guess we have an object and it came back clean and we're going to take a look at its spec and we're looking at base.

A

And we're going to say, object status.

A

Result equals and then just multiply two of these thingies.

A

Why line 41?

A

Oh I don't. I have no idea here evan. That is a weird thing.

A

I don't know why you do that, maybe to remind people, ah you know what I bet they're doing is making sure that the imports pull in context so that when I typed contact step background, everything was.

A

A

Okay, so now we have a result right, it's base times base which is base squared and then we're going to make our cute little value here.

A

The expression is- and I hope victor is not on the call- because I'm going to use an s print.

B

A

We can make this fancier, but that's not really my point here right. It's okay,.

A

Oh, of course, okay, so that that defaults to false we're just going to return that we're never going to try again, because we can math.

A

Cool okay, we're good we're good.

A

So, let's try deploying one I'm not totally sure. If I I need to recompile or rebuild anything, I don't think so.

A

So I'm just going to attempt to apply that same release. Don't forget to update what I don't I have to man. What okay matt is reminding me that I might have to ask this thing to update this status. Is that true? Oh, my goodness,.

B

hmm You're right.

A

It's been a long time since I've had to think about that.

A

What are the update options applied? Okay, we're fine, so boom and then boop.

A

A

Ben asks: what kind of magic controllers have I been using, so in k native we've been building a thin wrapper that sits on top of the the reconcile key idea. We started with what's what's inside, of api machinery, as example api and we built from there, and so we I showed you that actually, okay, tangent, this is fun. um This is the this reconcile kind function is the the what gets invoked from a bunch of uh generated code, so we do generated code because there's no there's. No.

A

uh We want strongly typed right, like it's kind of a bad experience. If you pass in like a a runtime object here that it happens to be a type, but we don't know it because we can't tell you so there's I'm actually importing the right. The client injection, reconciler, math, subtraction reconciler, and that's the thing that does all of the common tasks that you need to do to do.

A

Reconciliation like update the status or hydrate the thing or make sure you don't mutate, the spec or update conditions, and that that kind of stuff right, like retries, on apply uh because sometimes, if you mutate the status and you want to go push it back, but it's mutated, because the spec changed or whatever. But you still want to store that status.

A

We can do retries where you you bump up the resource number, and things like that. So maybe like do a merge of things that don't matter all that stuff is handled by this generated layer above this layer. All I'm responsible for is taking this object. Note that I don't have to do any deep copies or anything which might get me in trouble in the other side in the controller one-time code.

A

A

So yeah I I forgot because I I was able to forget so that's nice, let's see if it did it all right. So, uh let's, oh! Let's update our example so that we can actually apply.

A

Something and so we'll leave that leave that.

B

There I don't know um how about five.

A

And then we come up here and.

B

B

But okay, what did it.

B

A

New keyboard fingers are still trying to figure it out. No spec no status.

A

I mean it could be that I'm misunderstanding some of the.

B

A

A

A

Was saying? Oh it, it did a thing.

A

It thinks it did it cool.

A

So it could be well. Okay, sorry! This is now turning into me trying to learn how to use controller runtime, but I do I have to re-generate some stuff to make this. The crd have the right pieces, maybe we'll just try it I'll, just try it.

A

I think it was make install.

A

And then we're gonna get out of the all that stuff and and run the customized piece.

A

My notes have the wrong command.

A

Okay, so where maybe that thing built some new stuff, I'm not.

B

A

A

Let's just check out stern, everyone know what stern is there's a couple. Other tools like it, but it basically it lets me watch any logs of anything that matches some regular expression, which is super nice and it does active watches for like new as new pods come in and out.

A

So I'm gonna from a different window. I'm gonna just cuddle, delete those pods because you know what I don't. I don't trust it. Let's see. What's going.

B

B

A

It's getting the lease go, go, go. It got a lease, it reconciled. Okay, so it thinks it did it. Maybe my maybe my update status isn't happening.

A

Let's just get it one more time to make sure.

A

There's no status.

B

A

Well now I am confused.

C

A

I've defined some stuff here that looks good.

B

That looks good.

A

Important run make to generate yeah, so I think we did.

A

B

A

So, let's see bin manager, I think, is probably what gets wrapped up in the docker file, but we don't actually use that. Maybe that's something we needed to do or it's maybe.

B

A

Not formatted, we need to enable the status of resource that could be, uh I think, there's an annotation for that for coup builder, so I should switch to chrome.

B

B

A

We were talking about the in the k native version. We kind of assume that everything has to have a status so that gets pre-baked.

B

A

There was no annotation here, we don't need any other path, so all right we'll try it again.

A

I guess we run make.

A

B

Don't think that's gonna do.

B

A

What we want is the controller gen, so.

B

A

Let's, let's just check out the crd, just real.

A

A

Okay, now it has a status object, but maybe it was there before aha cool, but it has the two things. So I think that now the open api is it understands what I'm talking about, and maybe the controller has done the right thing, because the crd is updated.

B

If we touch it.

A

So sorry bam so we'll start up a watch and I just killed the pods. Maybe it in another window, I'm gonna, try editing it.

B

B

What's it called.

A

What's your name sample.

A

A

I don't know if you don't know this trick, you just add. If you want to get a something to re-reconcile or re-reconcile, you, just maybe like add an annotation, and that should poke the reconciler to uh to do something, but it didn't so maybe there's some extra stuff that needs to get built.

A

So let's just try after that make and the annotation.

A

We are going to apply the release yaml again.

A

A

Multiply system.

A

Okay, we've reconciled once did it.

B

A

May need our back.

A

Yes, you're, probably right. Why would that just not be there? Okay, whatever square editor squares status, ah we're good.

B

A

B

A

But you know what we're just going to do this if you're an editor, you're good to go.

B

I want that formatting.

A

You know one thing go, land is kind of bad at is.

A

Yaml, it doesn't do it and every time I copy and paste it just it's like wow.

A

It has a bad day.

A

So, okay, we're going to customize one more time to get back to our release and then we can co-apply. I know I don't have to build a container, but it's just the process goes really fast. If that's like your loop right all right, so we're back and let's run a watch on the object, and hopefully this thing gets the status as soon as it gets reconciled.

A

I don't yeah controller, so carlos is saying the controller without a status. I don't at that point. Is it really a resource or is it just a data.

A

I haven't found a lot of uses for just pure data, except for like config. Maybe it says structured, config map.

C

A

Okay, it's getting the lease.

A

It reconciled it's not there.

C

A

I wonder if there's like a cube builder command that I'm supposed to have run instead of trying to do this by hand well, um plan b, I don't know.

A

I just this is like simple stuff. I expected this to just kind of work.

A

Yeah they don't have spec. They just have data. That's right.

C

A

A

Maybe I'm getting an error from the update.

A

I'm hoping it what's this, what.

B

A

A

Can't see can't see my weight matted. Can you still not see the editor? I have go land on.

A

Screen and for fun, if we get past.

B

B

A

Well, that makes me really uncomfortable, but okay, do I.

A

Do I have to no, maybe it's weird. What I want to do is okay. Well, I don't know here. I guess we have to wrap it with this.

A

Because I don't know what it's going to.

A

A

And we want the object that we created.

A

Okay, so maybe some arrow things for fun.

A

And reapply oop.

A

So we're looking for an arrow come on arrow.

B

A

Odd number of arguments- oh yeah, okay,.

A

I'm betting: it's because keys and values.

A

Is not what I would expect and it's not typed, so it's uh not helped me a lot keys and values.

A

All right so we're gonna apply again.

A

And we're gonna come back.

A

Here is it zap? Is it delegating to zap.

A

I normally use zap, but I I tend to pass in zap objects.

B

A

Got another stack.

C

A

Sample square not found.

A

That's weird because you just reconciled it right.

B

B

A

Do I need a namespace, uh oh you're, thinking.

B

A

A

A

It could be, let's see, let's, let's poke at the client interface real, quick, oh status, client status, writer update it's stuff; no, maybe we patch, I don't think so, where's the resource deployed it should be in default.

A

No, no, no, no maths only has the other.

A

A

A

Oh, it didn't add it to all, so this sample square right, cube, cuddle, get this.

B

A

It has a namespace, but the update is not using the namespace.

A

What is um what's inside, the multi multiply, namespace can do it get.

A

All so just normal stuff, and not very old pod, because we just shipped it a deployment, that's slightly older as we've been fumbling around so sorry and then a bunch of replicas because that's how it works.

A

So that looks right, but we're still getting we're still getting that.

B

A

B

We'll just take.

A

Look at this pod log.

B

A

I wonder if this is actually the cash is out of.

A

Date, I wonder if we can go and touch this little resource and see if it wakes up.

A

So in a different window, I'm going to keep cuddle edit.

B

A

A cone, it's a square and its name is square sample. I'm going to delete that. Please.

A

B

What in the world.

A

B

A

No it's so it has the right namespace and it has the right name and it has the right kind. I wonder if it's an.

B

A

Do we need to do something?

A

Update is missing the namespace. There isn't an obvious place to put the status update.

A

We already updated the r back and we would get some other error if it was not found, is really weird.

A

I mean we could try just doing an update and it'll. Do the right thing.

A

We could try that I thought that's not allowed, but let me try it.

B

A

Other pro tip always use a generation. It's really difficult to understand what a reconciler is doing if it doesn't propagate the generation into an observed generation instead of status.

A

Yeah, I just did that.

A

A

Not on the type structure, let.

B

Me check let's.

B

A

Sub resource status is not on the type.

B

A

That's, I think, that's where it said it should go. Oh you're right the docs say.

A

It goes on the object that has everything else. So it's it's on this thing.

B

A

Okay, sorry for that detour, let's try again so we're gonna make.

B

A

And then we're gonna spit out the yaml, so we can use co.

A

And then we're gonna go apply.

A

Oh, our back might get broke because I edited the actually it found out that there was a different thing so inside of the the roll it has the right stuff. So that should be okay.

A

I don't know what the editor role is and it looks like my changes are still there. So that's.

B

A

Okay, so it launched- let's just hope for the best here, just take a look.

A

Oh, my goodness, we have okay, all right, we're back on business.

A

So, okay cool! So now we have a thing that is a custom, silly resource that implements our duct type, okay, but that's only a little bit of the problem because of our back, so we need to go and create a custom, rbac role that assembles.

A

So over here in the maths department, the controller can only do what it can do, because it has. This results, viewer, cluster role, and so what this is is a cluster role that goes and collects all other cluster roles with uh duck.tableflip.div results, okay and then down here, because this particular controller implements the maths resource and it adds add and subtract.

A

We want to be able to get lists on those things, so we can copy this and.

A

Make some minor modifications and then we'll we should have a good to go multiply that we can use as reference in the original project with without actually touching it again. Okay, so here we go back.

B

A

We'll make a new.

B

File here we'll call this the.

A

So we want to make a cluster role, that is a.

B

The I don't know we'll call it the.

A

The multiviewer.

A

The important bit is this label.

A

That's going to let the the cluster role that has been defined in the maths project actually use the role, and then this stuff is wrong right and I think, let's see, make sure we get this right for whatever reason it added at tgik.tgik, and maybe I messed that up. I doubt that I'm supposed to just say: dot io, but okay, that's cool uh the resource right. It's it's they're squares, but with a little.

B

A

A

So now, what's supposed to have happened, is the controller of of the maths department has picked that thing up and reapplied now it has the rights to go and read the the new types that we've installed. So let let's go up here and we can make a new make a new example of a mixture. Actually we could maybe probably edit this thing.

A

So, let's add another ref and I'm really sorry about how slow it it was to get the uh controller runtime bit going because I just haven't touched it.

B

A

Right so here's our example.

A

Let's give it a cool name like demo,.

A

We don't need bar.

A

Anymore and then over here we're going to use demo in it's a square and it comes from.

A

Tgik, okay, so I'm going to apply this, but for.

B

For your sake, maybe we'll do.

B

No, the other way other way.

C

C

A

I think we didn't add custom columns to square. So it's not actually that interesting to watch, but we can go over here. We can make a new square.

A

Oh gonna make it so it's pasta.

A

Somebody evan says: coop cuddle get minus w. The the bummer with cube cuddle get minus w is that it appends lines to changes, and you get this stream of stuff and it's not exactly clear what it what it's doing. I prefer watching the cube cuddle call.

A

I do have to wait two seconds, but I get a more crisp result. Okay and just to confirm right, we'll get a little bit. Let's see if our math is well, I'm sure it worked.

A

B

Doesn't have us what.

B

B

A

No, I'm actually really confused. I. Why is that.

A

This one has a status, maybe just takes a while. Maybe you have to wait for the uh re-list.

A

Okay well plan b, we'll figure it out that later so back over here. Let's, let's use the one that works so that we can move on.

A

uh The eight yeah, the api's version, looks.

A

A

So we're going to update.

A

A

Okay, so our back is not quite yet ready.

A

Double check the it's actually right. That's.

B

A

On so, the expression didn't get updated because we're unable to go and fetch the mixed object, which means either our back, didn't assemble in the way that we thought or the api group is wrong.

A

But you know we got this and this looks right.

A

Add a v1, oh thank you.

A

Because I copied and pasted yeah it's api groups, not api versions. Okay, that makes sense before we go and touch anything we'll just go and reapply that.

A

Okay, here we go so we're not.

A

Our back results.

A

Now changing our back doesn't actually cause re-reconciliation. So let's poke.

A

B

A

Yeah, uh okay, all right, you know what okay, let's, let's just, let's be real for a minute.

A

This is the the single dumbest thing that kubernetes ever did the single versus plural resource names.

A

Bane of my existence, the unsafe guess to resource. I hate that method, the worst. If you're, not aware of this, I think you know it's like a a good re. Rest pattern was a single square means the resource squares means to list all the resources. So what happens?

A

Is uh you never know what the thing is? Gonna be.

B

A

So you have to guess or you have to look it up and it's it's non-trivial. Let's remove poke.

A

Sometimes our back aggregation takes a minute to actually collect.

A

The kind is right sample, that's the.

A

A

Yeah, okay, so our back has not yet collected. So that's okay,.

A

If we're impatient, we can kill the pod and we'll reload. Maybe we'll do that.

A

So because I'm doing a multi resource watch, the re, the resource kind here is added to the name. I think so. The api group is this: the name of the resource is this:.

A

Okay, we got another squares, tgik dgik is forbidden.

B

B

A

How do I fetch the aggregated cluster role like? Does it have a status and.

C

A

Me what's what's.

A

B

Let's just double check what it's.

B

B

A

No, my my demo has a.

A

B

A

Stupid but okay, I'm sorry about that.

A

It shouldn't change the.

A

A

Look at that, okay, so I didn't have to kill the pod it just I had a small typo when I was copying pasting the cluster roles, so I I defined the aggregate cluster role and then I accidentally didn't rename the the local cluster role that gets aggregated. So it worked in the demo because you know it, it has the right rights, but it didn't have that aggregate role. So we added we switched out use the same name as the role binding uses, which is here the cluster roll binding.

A

So this is where it's collecting the results viewer, that's how it knows the other duct types we had a typo there we fixed it. We we also have the correct cluster role here in for our multi-viewer, which is this multiply class and the result go back here. Is we get our our cute little text inside of the ad? So now we have this. This full thing where we we provide a the add resource gets a fixed value. It gets a subtraction, an addition, and now this.

C

A

Multiplication or square function; okay, all right, so sorry that that was a long, long haul. Thank you for sticking with me. uh Okay, so.

B

A

So, let's go: let's talk about duct typing a little bit so like what would you do with this stuff? What I'm trying to show is the what I've done is made this ecosystem of things that you could come participate in right like if you would like to be a a resource that produced a result by providing an equation, you could participate by adding the r back for your resource and having the right shape so that my controllers can go and without understanding anything about you.

A

Change what we square- oh yeah, okay, so matt wants me to do an active watch.

A

That's the other neat thing, so, okay, this is a.

B

Got distracted.

A

So if we change the the base number to 10, which is a more bigger number.

A

Well, the funny thing is, I don't know if the controller is still working because, like the controller runtime stuff seems to be a little.

B

A

So, let's see, if that, even so it this is still on the old thing, and I don't know how to kick it. Let's cheat.

A

Where did this stuff live? It lives in.

A

The multiply system, of course, so let's just bounce controller runtime and see what's up, and hopefully we get a reconciliation.

A

B

Do it buddy you got this.

A

I you know what um so the issue is that I think that there's, but I just I just killed all the pots, so it really should just.

A

A

But I don't really see a place where I can set up watches. I guess that's what this is and I think when I'm watching these resources, that's what that is supposed to do. It's managed by that. It's that type. I don't know what complete does. Maybe that's the builder.

B

A

I don't think you need to set up a watch.

B

Let's, let's just make.

B

B

A

Okay, that that's cool that they're showing me the raw patch. That's that's nice, updated status. What did you update it to.

A

You're looking at the wrong thing there, you never got the update. Oh hey, there's there's our new one.

B

A

Oh, we never switched back to the old status update. That is a good.

A

B

A

Client.Steps I got it.

A

Release oh wrong.

A

A

So we have to wait the uh the lease expiration time.

A

Yeah, to be honest, it's super hard to watch the youtube channel chat and try to talk and try to type the same time. I you know kudos to joe for doing this and making it look easy. It's.

B

It's good okay come on. Do your thing, go, go, go, go! Do it, you can do it.

A

I think this is an old log. We haven't seen anything new yet.

A

hmm Getting the image pull air cool.

B

A

I wonder I wonder if uh I got helped.

B

Let's just double check.

A

I know we didn't get helped image pull air. That's interesting.

B

Should totally.

B

A

I wonder which image it's trying to pull.

A

Oh, ha it's because I'm in a new terminal and it doesn't have the kind config. Let's just try this one. Last.

A

Time so now we're going to push the kind there's a local kind registry that yeah there we go. That's that looks better, and so, if we, if we go up here, I'm sure yeah it was pushing to my azure cluster, so never push a new tab.

A

Okay, now we're running and we should be reconciling you got this: hey, okay, cool. Did you see the mixed signal got updated and so there's a bit of magic there in the reconciler that I haven't really shown you inside of package reconciler, take the add controller.

A

When I set up the instance of the reconciler, I'm I set up all this uh watches on the re. Basically remember I was doing tracking for objects. The tracker has a delegate, the delegate re-enqueues the uh the thing that I would like to reconcile.

A

So when I, when I'm doing the real reconciliation- and I I ask the tracker for the reference it registers- the I'm interested in this thing, every time it changes- please re-enqueue me and so without changing anything or even being aware of the real kind, the when we're reconciling ads- and this thing points to an object reference of something like a square, it changed. So, oh, oh, oh sorry,.

A

uh So let me go back so there's there's this. The delegate is watching on the factory for the, so the tracker calls the delegate and says like yeah, something I attract got updated and then it re, uh so it recalls reconcile kind, yeah yeah. It's also delayed it's the problem, so, okay, so magic, that's magic.

A

The demo worked right so now now we can at will change this thing and and not be so embarrassed.

A

You know fumble fumble, fumble, that's fine!.

A

I don't know: let's do 42, because that's a nice fun number and we see that the result instantly gets updated in the ad, because that's how you know edge based reconciliation works, so okay cool, so so back to back to the duct type top right like.

A

If I think that there's kind of two people that are thinking about providing uh like you can either provide duct types to play in an ecosystem, so that others can come in and add their whatever thing and so like. How would you use this in the real world in k native? We use it to figure out the address of some object. That represents something that has an internet address.

A

A

Through the the same technique that I've shown, you can look in the status of any subscriber object in some of our resources and you can pull out its uri and invoke it over http.

A

The we also do this by we make crds that represent protocol choices for channels, they're strongly typed crds with all all sorts of stuff, and then there's there's a duck type contract that actually lets us mutate them generically. So I can operate on these like channelable objects, and I can inject subscribers into their specs and they can reconcile it in whatever way they need to and we never have to.

A

But we can provide that same well, I'm going to do a single job and I'm going to inject the subscribers into your spec for you as a specific role, so that lets us have a very extendable system in this duct type ecosystem. So the you know we could also do. um I don't know if, if your resource has a backup, maybe there's like a you- can add something to the spec. That says like do a backup and then that valero stuff can, you know, do its thing so.

A

The what I want to shout out to here is, uh I am asking inside of the api machinery to come and.

A

It would be really cool if we could upstream a lot of this work right now. um There there's several so the list of uh right. So there's this giant list of current implementers of duct type concepts. Some things call it duct types. Some like example, like cross playing totally understands they're producing duct types.

A

Service bindings, they call them duct types. Cluster api is actually doing exactly the same thing with aggregate roles and some other stuff.

A

In their case, you want to have you know, an object that represents configuration on some remote cluster and then they want to be able to have you provide instances of those cluster objects and, and then it their controllers can operate on some generic pieces or view the status in some generic way based on duct types right so based on some partial schema that we've uh we understand, so we are going to meet and we're going to talk uh it in more detail and hopefully show a better quicker demo during the meeting to talk about duct types and where we could get some common tooling inside of upstream kubernetes, so that everyone can pull from that or build from that, and I don't know what the world will look like kind of in a year.

A

uh It's gonna be really interesting, because I could provide a big platform where I you know, my real contract is an assembly of duct types all like so I have a runtime contract.

A

That's this dock that duck and the other duck, and then I can plug into these systems that maybe only care about one aspect of that duct type, but I can make choices when I'm authoring the my crds for later, so that I can target those other ecosystems that I'm aware of, but right now, there's not a real good way to describe or even agree with those shapes should be, and kubernetes kind of already has a couple.

A

Doug types right like if you think of owner refable, every resource can be owned by another resource because of garbage collection and things tools like octant, take advantage of this by building up object, graphs and viewing what things are and that tool just works even for crds that it doesn't know because every resource has that common shape. So the proposal is, you know some common tooling for being able to make reconcilers that can operate on a duct type and.

A

Maybe a discovery api which I'll demo in the workgroup meeting next, I think it's next thursday or wednesday. I think it's, I think it's thursday.

B

A

Check the twitters- I I don't know um with that- I think I'm gonna wrap it up. I think we're kind of over time. Thanks for sticking with me. uh I hope it was interesting, I'm so sorry for fumbling with the controller runtime it. Maybe I should have tried a little harder but uh yeah, that's that's the show. I think what do you think any questions? I'm yeah I've been answering stuff as we go, but maybe there's some more direct questions that I could try.

A

Okay, awesome well I'll, see you on the internet. uh This is super fun, see you next.

A