Kubernetes Kubernetes Gathering (Feb, 2015), 20 Mar 2015

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From YouTube: Upgrading Kubernetes - Kelsey Hightower & Brian Walden

Description

Recorded on Feburary 25th, 2015 at the Kubernetes Gathering in San Francisco, CA, USA

A

Next presentation, I'm kelsey hightower again from coreos, and this is an engineer formerly known as walden. He doesn't like us to use his government name, I'm not sure why, um and what we're going to do is demo upgrading the full kubernetes stack right. So once you get kubernetes deployed out in your cluster, how can you upgrade it to the next version of kubernetes right? So this is one of the discussion topics we have within the team is how do you manage kubernetes itself so core os by design?

A

We have no package manager right, so we were built for containers from the very beginning and we also ship a very simple scheduler called fleet and fleet also serves as our package manager and our simple scheduler for deploying things.

A

So what we're going to see today is we're going to use we've actually packaged up all the kubernetes components using rocket so rocket is our container runtime engine and we have all the components in rocket and we're going to use fleet to deploy kubernetes on top of rocket and we're going to walk through using the omaha protocol through core update to refresh the stack. So I'm going to turn it over to walden and he's going to walk us through that process.

B

Thanks kelsey, so as kelsey said, and we have kubernetes deployed here with rocket and fleet, um I mean, if you don't know what fleet is it's a distributed internet system just like it says up there we're not going to dig into it too far. It runs system to unit files.

B

I know systemd is kind of a dirty word, but it's coming so get over it. So everybody's run kubernetes before we've all run the guestbook apps. Just something simple that I can set up an ssh tunnel into my local cluster and then then hit some silly port and get hello there version 1.0. So there's something running somewhere on my laptop. Can you see that okay yeah sort of um anywho, so we've got kubernetes cluster running? If you believe me, it's there um to prove it uh cube. Ctl list. Minions, oh get minions there.

B

It is so we've got three node cluster um got stuff running in it. We've got replication controllers, we've got pods, we've got services, things are there so going back to what this little app was. um You can clearly see there's this thing called hello.

B

I've just got an ssh tunnel set up, so I can hit this service port and see something happening so, as kelsey kelsey said earlier, we're actually more interested in the the upgrade strategy for kubernetes. I know there's been a lot of discussion around this as far as how upgrades should work. Should it be turtles all the way down. Should it be two separate tools?

B

Should somebody have to walk up to the machine and push a button or something and we'll figure it out, but for now we've started to get our approach together, which is built on fleet built on rocket built on all these tools, but we actually have a commercial product that we've built to drive our operating system.

B

If you don't know we're core os, we build an operating system, it's really small, it's great! It keeps you secure from poodle heartbleed, whatever the next vulnerability is going to be, but we've built this tool to help manage our entire deployment deployment of coreos. So core update is using sorry. The product is called core update. It uses something called the omaha protocol. Omaha protocol is what I don't know.

B

If it came out of google, but google chrome uses it to keep browsers up to date across the world, we use the same approach to keep core os up to date across the world. So it's simple enough to apply the same sort of heuristics to keeping kubernetes up to date at the cluster level.

B

So going back to this dashboard here, this is not a kubernetes dashboard. This is a core update, dashboard, so you're not going to see pods you're not going to see services you're going to see three important things: there's core os the operating system, there's kubernetes the the thing we're all here to talk about, and then there's this thing called hello world and if you haven't connected the dots yet there's something saying hello to me right here.

B

So if we take omaha which allows individual deployments to say I'm at this version, what version should I be running and then do something with that information?

B

We should be able to see statistics about what versions are running out in the world. We should have some level of control over what's running in the world right here, see I'm sorry. This is kind of hard to see. You see this little number right here. Oh wow, it's 0.10.1, that's the it's two tags back in the kubernetes tree, so we've got a cluster running version. 0.10.1 like I said this is an update dashboard. So you should be able to update something I'm going to first prove this is actually running.

B

0.10.1 run my little cube, ctl version tool and there it is server version, major, zero, minor 10.. So there's something happening here. I go in and actually run my upgrade it's as simple as again sorry for the resolution clicking 0.11.0, which is the next version, saving it and then something happens. I don't know what. um So, if we dig into it a little bit further right now, we still have it says 10.

B

This is dumb data from before, when I was trying to get this demo working hiding in the room over there, we see 0.10.1 uh cube ctl version like well. The api server isn't up, apparently there's nothing serving my requests. So if we sit here long enough, we'll actually come back up with version 0.10., I'm sorry 0.11.0.

B

We can apply the same approach to applications running on top of kubernetes, so this hello world application here you see just one of them and that's the one that I've got running on my laptop.

B

It's probably not in a super healthy state right now, because kubernetes just got pulled out from under it, but we should be able to upgrade this just like we did kubernetes so using the same super high resolution, modal. We can upgrade it and let's go see if kubernetes is back actually back up.

B

So if we hit kubernetes view all graphs, no, it's still.

B

B

Well, there we go cube, ctl is reporting version 11 now, so we got kubernetes to officially upgrade.

B

And if we go look at our reporting.

B

In classic demo fashion, it doesn't work.

B

Well, it'll work here in just a second.

B

Wait for it: okay! Well, let's not prolong this it'll show 0.11.0 as soon as I walk over there, but I think that's all I have for.

B