.Net Foundation On .NET, 7 Nov 2019

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From YouTube: Working with Entity Framework & Docker

Description

EF Core in a Docker Containerized App
https://msdn.microsoft.com/magazine/mt833405?WT.mc_id=ondotnet-c9-cephilli

EF Core in a Docker Containerized App, Part 2
https://msdn.microsoft.com/magazine/mt833438?WT.mc_id=ondotnet-c9-cephilli

EF Core in a Docker Containerized App, Part 3
https://msdn.microsoft.com/magazine/mt833457?WT.mc_id=ondotnet-c9-cephilli

Use Docker Tools in Visual Studio 2017 on Windows
https://docs.microsoft.com/en-us/dotnet/architecture/containerized-lifecycle/design-develop-containerized-apps/visual-studio-tools-for-docker?WT.mc_id=ondotnet-c9-cephilli

In this episode, Julie Lerman comes on the show to share some insight and great tips for working with Entity Framework in Docker. You will see thing tips for working with the SQL Server Docker image, using environment variables for passports, using the Docker tools for Visual Studio and so much more!

[T04:02] - Overview of containers versus virtual machines
[T07:04] - Developing in Docker
[T12:34] - Setting up ASP.NET Core
[T17:31] - Working with Docker in Visual Studio
[T25:10] - Point to databases from your container
[T38:08] - Using SQL Server Docker image

A

Today, on on.net show, we're going to be learning about containerized database applications,, docker, entity, framework,, sql, server,, linux.,.

A

All that stuff. come watch it.

A

Hello. welcome to another episode of on.net.

A

Today we have, julie, lerman, who's, going to talk to us about docker and entity. Framework. welcome,, julie., hey,, rich.

B

Yeah., how about you tell us a little bit about.

A

Yourself and then we'll get into the topic?

A

sure. well,. A lot of people might know.

B

I've done some work with the entity framework,.

A

Over the years, few books.

B

I also write a column for msdn magazine called data points.

B

I'm an mvp., I just got my 17th award.

B

Oh, my god., it makes me feel so old. or so appreciated.

A

B

Microsoft, regional director and you've probably heard this one before,. I don't work for microsoft,, I don't have a region, and I don't direct anything. docker captain. oh,, I didn't know you were a docker captain.

B

yeah., but that's all my volunteer work.

B

Then what I do for a living, is,.

B

I do software coaching and mentoring.. I do a lot of work with domain. Different design., so,, yeah.

A

It makes sense. so do you have like a shirt somewhere.

A

That's got like all these badges on it with all-.

A

B

A

I remember when I was small, my mother had this hoodie, before hoodies we're cool, with all my like swim, badges on it.

A

Anyway, yeah., I actually wish I still have them.

B

Brownies girl scout badges.

B

yeah,. I remember this, long time, ago.

B

for sure.. So before we really get talking,.

A

You and I have something in common which is,.

A

You're near a little bit ahead of me on this, but we've both been buying gravel bikes.

A

Well,, I only bought one.

A

sorry. bikes,, plural between the two of us..

A

I understand what you mean., so we shouldn't dwell on this topic, but like 30 seconds,.

A

What is a gravel bike, and why would someone want one?.

A

Well, I've always been on a hardcore road bike.

B

I'm not a racer, but I've always been asphalt. Road bike.

B

Where I live, there's so many dirt roads and I have to work really hard.

B

To make sure that when I plan routes, that there's dirt.

B

I don't want it to be too many miles on it or.

B

Real rocks or anything, and so this bike, is,.

B

It's just designed a little more comfortably.

B

Compliance is the word, right?

B

compliant? yeah., that's the word I use.

B

well,. The other interesting thing about it is that it's disc brakes now, which leaves more room for the tire width..

B

So, instead of being on 23 millimeter tires,.

B

Now, I'm on 28., I can throw in 32s. If I want., I live on a steep dirt road..

B

I live in vermont and I can just fly down that road now and it's easier to go up. It, too.

A

Yeah. we actually,, I think, ride on more, like 40s up here.

A

So next time you are in town.

B

So you are doing more like mountain bike, riding?.

A

Yeah. next time, you're in town,, we have this ride called thriller, which has this hill on it. Called. pardon me?,.

B

Thriller in seattle.

A

Something like that. so next time, you're in town,, we'll have to do that and with some other folks that we'll bring along for the ride., so it'll be awesome..

B

Okay,, just as long as I don't end up with scratches, and bumps, and bruises.

A

Okay,, we'll just try and avoid broken bones.

A

Okay. okay., so let's get back to the .net and database stuff.

B

All right. yeah, that.

A

Yeah, that.. So what specifically, are you going to be talking to us about today?.

A

Well,, I always.

B

Like to put together the things that I'm learning., so I had been doing a lot of work with.

B

Docker and databases like sql server and docker.

B

But I'd never really thought about what, if I'm using entity framework and doing things in containers?.

B

So I actually went through that process and, like we always do,.

B

Bumped my head a whole bunch of times, just because there were some concepts that I didn't understand,.

B

Which is how you learn, right? yeah., I think docker really is our containerized applications,.

A

Really is a different form of computing.

A

It's this kind of like single, isolated process, model,.

A

Is the way that I choose to think about it.?

A

That's not the way we think about desktop or even really server. Computing.

A

no, and I used to.

B

Really just be confused by the whole container thing and just thought, "oh,. It's for like rocket scientists, kind of people.".

B

I actually, it was when sql server.

B

Became sql server for linux that created that and then put it in a container..

B

It was the first time I finally played with it.

B

And had to just get over some, well,.

B

A little bit of fear, a little bit of miscomprehension.

B

Because you start trying to compare it to what you already know. the biggest thing I think people compare it to is virtual machines.

A

Huge difference is virtual machine has an operating system in it.

B

Yeah,, maybe containers and virtual machines.

A

Are a poor analogy for one another, because I.

A

Think of containers as being an alternative to what.

A

People have used virtual machines for and with quite different characteristics.

B

Yeah,, I totally agree..

B

I think the analogy starts because it's the closest thing.

B

That people have to try to comprehend it.

B

They start there,, but then, if they get stuck there,.

B

It's a problem, but at least it gives.

B

there's so many times when I've seen these introductions to docker and I've done the same thing.

B

It's not a virtual machine and kind of comparing what the virtual machine.

B

so it gives context where people can.

B

Start at least because they've already been there.

B

It's like a virtual machine, but it's just that people come into it. Thinking, that.

B

Anyway,, I bet you've done a whole bunch of shows on interests to docker and everything.

A

Yes,, so we don't need to do that. Thing.

B

Yeah, cool., so what I wanted to do was take that little bit of experience.

B

I have with docker for sql server and really start making it a little more real..

B

I wanted to build an app,.

B

Not just spin up a sql server in a container and go,.

B

"Oh,, that's cool and now,. I can connect to it from this" and trying to understand. What's going on.

B

But actually to start writing some code and also,.

B

I focus so much on working on my mac.

B

I was in visual studio code,. I was at the command line,.

B

And I knew there were these great tools for docker and visual studio also, and I wanted to give them a try.

B

So I actually went through this whole process of starting from scratch, creating projects,, creating apis, using docker,.

B

Worrying about protecting passwords,.

B

And even deploying it to azure,.

B

Deploying it to azure containers or to.

B

A linux container that is hosted on azure.

B

And just really understanding how all those things work.

B

So it was really great experience.

A

I'm sure,: let's go for you.

B

A

Sorry, I interrupt that., it's okay.. I just said it was a lot of fun. yeah,, but I'm sure that's good for your consulting practice.

A

To have all of that experience and competence in that space.

A

B

Well,, it certainly works.

A

So far it's been writing articles.

B

But I've been having a lot of fun doing a variety of new conference sessions too.

B

With all these new skills,, so it's kind of fun., yeah.

A

So you told me- and I think I actually saw this on twitter- that you have an msdn magazine article on all this same stuff, that you-.

B

Three. yeah., could you tell us about that?, show us.

A

Okay,, so this is the article.

A

so april 2019,. So it's only a couple of months: old.

B

Yeah, but it's three., I had so much that I learned and so much I was writing about not.

B

Only are there the three articles, but there's also, I did a huge,.

B

A big blog post about deploying one of these examples.

B

To azure, because not just doing the development on.

B

My machine, but really deploying it and running it.

B

Deploying it for test, on production.

B

Then,, I wrote another really long, one.

B

I wrote it for docker., it's not on their blog, yet though.

B

that one was taking a fully containerized solution and putting it.

B

Into a linux container, on azure and just going through.

B

All those steps, because all of it was learning experience,.

B

Learning curves for me,, so it was really, really important to share that.

A

Which azure service did you use for the container hosting?.

B

Well, one scenario was.

B

My api was in a container pointing to an azure sql database,.

B

So I only had one container,, so I used azure container services.

B

Did that change it's name months, ago?.

A

So there's several kind of option.

A

there's container hosting option and app service.

A

There's is azure kubernetes, service, aks.

A

Yeah,, it was this and that.

B

Yeah. then, there's azure container service.

A

Which, I believe is no longer the one that people point to,.

A

And then there's azure container instance, which is kind of-.

B

That's it., so what I did was,. I push the image up to.

B

Aci and then, if you've just got one container to run,.

B

You're not doing composition,, then you can literally just run that.

B

That's actually what I did in my blog post.

B

So let me just.

A

Yeah. so when I've used aci as well,.

A

It's an awesome testing tool in exactly the same way that you've used it.

A

Super easy to be productive with it.

B

So there's the blog post.

B

it's from may second on,, but you can see it's really really really really really long.

B

But that's the one where I did that.

B

I just had the single image, because my database was then azure sql.

B

So I didn't have the database in a container in this example.

B

Right., that is a more straightforward, scenario.

A

B

For sure., then, the second one was for the more complicated setup.

B

Not complicated,, it's just a more composed,.

B

Orchestrated setup where I had sql server in a container and apis in a container.

B

okay., so those I deployed into a linux container,.

B

And then that was the host for those anyway.

A

Makes sense. yeah., so do you want to show us some code? yeah.? So what I wanted to do is first share.

B

That initial experience, because I.

B

Ran into something that was confusing to me,.

B

Because I still was learning and understanding docker.

B

So what I've done? Is, I've just set up a simple asp.net core api,.

B

Like a web api., this has nothing to do with docker yet.

B

Even though it says, docker in here, that's because I unwound it.

B

It uses entity framework to interact with a localdb.

B

So just a start I'll go into my app settings.

B

It's show you,, I'm using this is my connection. String.

B

Just a localdb on my computer,.

B

And I have an entity framework core context.

B

One of the things that's doing is seeding some data.

B

So it is so simple.. This is the only class in their magazine, id and name,.

B

Because it's not about building a model like this.

B

Just needed the simplest thing I could find.

B

So I'm taking advantage of one of the ways to see to the database.

B

So it's self seeding, and what else?.

B

I have got asp.net core startup,.

B

And in there it's adding the dbcontext.

B

So just basic ef core use inside of an api.

B

The other thing that I'm doing in this,.

B

And just want to point out: this is a demo,.

B

Is that I'm triggering entity framework core to migrate? My database.

B

When the application starts up, and I'm just doing that,, I've got that inside the app because it's a demo.

B

So, given that we are eventually talking about having this in.

B

Docker, you might have it in multiple containers running at the same time..

B

You don't want all of those containers migrating the same database at the same time.

B

right.. It could be a problem.. So that's demo, aware.

A

Just for context,, how would you normally do database migration?.

B

In this environment, where.

B

I would have my application in multiple containers.

B

I don't want the application responsible for the database.

B

If it's sql server, you've got all kinds of tools.

B

For running scripts and creating the databases there.

B

I've been also playing with flyway, which is one of them migrating apps.

B

One of my conference sessions- I've got a demo.

B

Where I have an api in one container,.

B

Database in another container, and then I have another container, that's a flyway.

B

from a flyway image,. This application- and I run it.

B

So that it does the database migration and then it shuts down.

B

So it does that. it's just like a one shot. Deal.

A

Makes sense., so I just think, though, that the way you would.

A

Do this normally as part of a more orchestrated, deployments.

A

Yeah. yes, definitely. okay.

B

So I just think it's important to make sure I state that this is demo aware, okay.

B

Got it. this migrate database? That's not built in.!

B

That's just some custom stuff that I built based on.

B

Some ideas that maybe I think it was price lampson,.

B

And somebody on the ef team had in there showing in a docker issue,, so there's code behind that., but that's essentially calling entity framework's migrate command to do the migration.

B

Perfect., so that's how that's happening., then I have a controller. That's just stupid, simple default controller created by the template.

B

That's really all that I have. so remember,. This is not in a container,.

B

This is just running on metal and it's using localdb,.

B

And I'll go ahead and run that,.

B

I just have some breakpoints, but I'm just going to fly through them,.

B

And then now it's just going to go to webhost,.

B

And there it's running, right?.

B

Okay., so the key here is that I'm using localdb,- and I think it's pretty typical when we're starting development.

B

Starting development and we plan to use sql server,.

B

Like so many of us use localdb when we're doing development and working against it..

B

So now what I don't want to do, is, the steps that I went, through,. Okay, let's see, if I take this and then make it be in a container.

A

Can I just burden for just one second?.

B

We could have created a new project, and I'm just going to show you from the template.

B

You've probably shown this before..

B

If I was starting a new project,.

B

okay., you can create a new project. That's already got docker support.

B

That's one of the options here, enable docker support., so you could start a new project and have the docker support already baked in.

B

A

But I created something that didn't have that.

B

So I'm going to use the docker, and all of that's available, because I've got the docker tools. Extension installed in visual studio.

B

So they're in here somewhere.

A

You have a lot of things: installed.

A

well,, a lot of this stuff at the top is from the productivity.

A

Understood., so I had one question.

B

It's here, somewhere. yeah,. I had one question on what you showed before.

A

I was actually confused at first with your terminal window,.

A

It seems to be in like crazy, high contrast mode or something like that.

A

I actually thought it was: a windows forms app at first., so the thing that was gray.

B

Wait,, oh, that popped up at console?.

A

Yeah,, that was just the terminal: window.

A

command, prompt, yeah.

B

And that was just asp.net core doing its thing.

A

Yeah, I just never seen that color scheme before.

A

oh, sorry.. I could imagine some folks at home. Being like, "what is going on here?" yeah, and it was just relaying,.

B

Like it's startup and stuff- and I have not seen this before.

B

Maybe it's some new default with visual studio or something or some setting, I just don't know and I'm sure there'll be like million people will want to tell me what I did wrong. There.

B

Yeah, but it was just asp.net core, just going,.

B

Doing this, doing that. http routing, blah blah blah., I got it.

A

So no, it wasn't, a windows forms app.

A

So all it was doing was running a controller.

A

Okay,, so that will work. because it got the tools,.

B

I can also add docker after the fact, and it is hiding somewhere.

B

Here we go, "add", "docker support".

B

Okay? so I'll click that and I have the option of choosing "windows" or "linux", and I do want to point out that on my machine,.

B

Can you see this where it says "switched to windows, containers"?.

B

Yes. okay, when you're running the docker client application on windows,. So I'm on windows,.

B

I installed docker, the docker client,.

B

The docker engine, and by default in windows,.

B

It'll be set to run windows containers.

B

Windows containers are different than linux containers and you can,.

B

Just because I'm on windows, doesn't mean I have to use windows containers.

B

that just means, windows containers is good for hosting certain kinds of things, right?

B

and linux containers are good for hosting lots of other kinds of things., so I'm doing cross platform development.

B

Here and linux containers are a lot easier to work. With.

B

So I've got my docker engine set to use linux containers,.

B

Which is why this option is switched to windows, right?.

B

And then, when I create this, docker file,.

B

I'm going to make sure that it's targeting linux, not windows.

A

Yeah,, so one pro tip that I do is, I have the docker.

B

You know, another thing: when you're on windows is,, you have to have hyper-v running for docker.

A

Yeah,, otherwise it doesn't work., but one pro tip.

B

And I have to go back and forth, because I use virtualbox to do.

B

My visual basic six and foxpro 2.6. work that I still do for a client,.

B

A 25 year old, stuff., so yeah,. I have to go back and forth all the time.

B

anyway,, so there.

B

it added this docker file, and that docker file that added, there's a lot going on here., but essentially what it is,. It's called a multi stage build..

B

So it's able to build you know,.

B

It creates different images to do whatever it needs,.

B

So the image it needs in order to be able to.

B

Build to actually build the app needs. The sdk in there.

B

But the image it needs to just run the app,.

B

It only needs the runtime., so it creates an image for building,. These different ones.

B

So that's what that is.!

B

What's nice about this is,, it already knew everything it needed to and it just created it perfectly for me..

B

So I don't have to worry about making any modifications to it.

B

So I can now just run this, right?.

B

But now, notice up here, the debug options.

B

Before it was data, api, no docker.

B

So that was going to run my api inside of kestrel, right?.

B

It could also run it inside of iis express., but this is running using the kestrel server,.

B

But now I also have this option to run it in docker,.

B

So what that means is, it's going to take this whole application and.

B

Create using the instructions inside the docker file,.

B

It's going to build up an image and then the debugger,.

B

This is thanks to the tools, visual studio, in debug mode, which is really really cool.

B

You can debug in this scenario..

B

It will run the image as a container inside of a container, right?.

B

I mean the application will be inside the container,, so it'll run the container of my web api,.

B

My api application and it's really cool because again,.

B

I'm assuming you've had people demoing the stuff.

B

Even though it's in the container, I can put breakpoints and everything.

B

it all works. really amazing., so I'm just going to run it.

B

Containerized and then there will be information.

B

Some of this output you're, seeing in the build,.

B

That was outputting some of the steps related to what was in the docker file.

B

The docker file had like a whole bunch of steps,, so it's like I'm doing this step, I'm doing that step., but it's still hitting my breakpoints,, which is really cool..

B

So you can debug and still hitting.

B

I should just get rid of all my breakpoints., it's nice to see them working.

B

Now this is opening up another screen.

B

Now I could be really embarrassed, "oh, my god.. Something went wrong.

B

what to do?", but I knew this was going to happen,.

B

But this is what happened to me. The first time I went through that process. Of, "okay.

B

What happens when I turn this into a containerized api?".

B

So, what's going on, is it says that localdb isn't supported on this platform.

B

So I am on my windows: machine, right?.

B

Like localdb is perfectly fine.

B

but what's happening, and I really had to get my head around this,.

B

The api is inside the docker container.

B

It's looking for localdb at local host and.

B

Local host is inside the docker container, right?.

B

I don't have localdb,, I don't have sql server installed inside that container.

B

All that's in there is .net, runtime and my code for running the api.

B

right,. You might as well be on saturn.

B

Right. exactly, and I didn't bring the database with me.

B

So one thing I did, and again, I went through all this in the article was just to help me comprehend. It.

B

I switched from using localdb over to using sqlite.

B

We don't have to do that., but I switched the app to use sqlite, and then the result of that was sqlite became inside,.

B

Went inside of the container, inside of the image, along with everything else.

B

So it runs right there., so this works. If I was using sqlite because sqlite's.

B

Inside the image, when the image is run as a container.

B

It's inside of there, so it's able to find it, right?.

A

Makes sense. yeah. it's a little bit like going on a trip to europe..

A

You need to make sure you've got everything in your suitcase that you need before you go.

A

Because once you're in europe,, you can't put something in your suitcase. That's back at your house in vermont., so containers are like that. everything you need has to be provisioned in some way,.

A

Otherwise, it's not going to work out.

A

unless,! I have the internet.

A

Oh,, the internet.

B

Right? not sure.

B

I know of a scenario where I would actually just use sqlite inside the container,, but completely self-contained app, actually, that makes sense, right? completely self-contained,.

B

Even the database is contained in the docker image.

B

Then you can have as many as you want.

B

People just aren't, sharing the database. go ahead.

A

Well, one comment on that: though., so with sqlite or any database for that matter,.

A

For you to use in the container, now you're going to get into a volume mounting presumably,.

A

Otherwise, the data will be deleted.

A

Every time you stop their container.

B

Yeah. I mean, it's not persistent. yeah.

A

Yes., I don't want to get into that.

B

With the kind of little hack of the sqlite.

B

Totally., I'm just saying.

A

Yeah,, it's just kind of one-time thing.. That is what you would have to do, right?.

B

Yeah., that's the part, you would have to go. Down. yeah.! That's another really big thing to understand about a containers..

B

We have an image, and then the running instance of the image is the container.

B

So if I have a database in the database,.

B

I create the database inside that container.

B

when that container goes away,, so does the database.

A

Yeah. then there are other options,.

B

But there's this concept of a data volume.

B

Which is separate from the container, separate from the image, so that you can have something persistent as long as that volume is not deleted.

B

The volume needs to always be running in order for that.

B

Right. so yeah., so that was another interesting thing..

B

I actually showed that in some of these other demos.

B

So what I did was the next step of this,.

B

Again, in these articles,, so there was the part two.

B

In the part, two, what I did was,, I said, "okay.

B

What I really need is to have an external data source.".

B

So my first stage of that was to say,.

B

"Hey,, why don't I just use an azure sql database?"!

B

That's always going to be available, no matter where I'm running this app.

B

I can just point to that.: it's always going to be the same. Connection.

A

Right., let's use the internet option.

A

right. exactly., let's say,.

B

I got all these windows open., you see?. I got all these windows open.. Oh my god.

B

So I can be sure to show the right one with you.

B

That's the no docker one.

A

Yeah, that looks like the same as the one we have before.

B

Yeah, I haven't switched yet.

B

Yeah,, so this is the one where, instead of using localdb,.

B

I'm using azure sql.

B

however,. This is really cool.

B

So in my app settings, development,.

B

And for local development,, when I'm running this in debug mode,.

B

If I was running it, as,.

B

I'd have to have this, be the startup project.

B

So if I was just going to run this in kestrel,.

B

Run my api on metal and I'm in debug mode,.

B

It's going to read this.

B

I've got it set up so that it's going to read my connection string from here and it's going to use localdb., I'm just on metal on windows.

B

docker is not involved in this scenario. When I'm running in kestrel.

B

But I'm going to just set the startup project now to docker compose., I'm taking advantage of docker compose for other reasons. As I step up to this.

B

But notice in this docker file, here,.

B

In addition to the stuff we saw before,.

B

I'm creating an environment, variable.

B

notice, the environment variable is no longer my localdb.

B

My environment variable is my azure sql database connection, string.

B

But not all of it.

B

we scroll to the right.

B

see,. This is the problem..

B

I don't want to put my user id and password.

B

Hard-Coded into the docker file,.

B

Share it on github, or have it inside [inaudible].

A

Or on this channel, 9 video.

B

Yeah., I don't want it in there.

B

So what I did was I've got.

B

The connection string and I've got these placeholders for id and password.

B

Placeholder variables.

B

I mean, I could create environment variables on my computer,.

B

But then I have to recreate them every single time., so I wanted to have a way to have.

B

Environment variables that were not on my computer,.

B

But I didn't have to worry about them being inside of my source. Control.

B

So I took advantage of the orchestration, docker compose.

B

Now, normally,, you use docker compose to orchestrate multiple containers.

B

Not using multiple containers, yet, I've just got the api container and it's going to talk to this azure sql database.

B

But what I'm doing is in my docker compose,.

B

I'm letting it know that these environment variables exist,.

B

And then I'm using docker environment, variables.

B

So docker also has its way of reading environment variables.

B

I'm taking advantage of that and that's where I'm storing my environment, variables.

B

now, notice. I have a .env file and a .env.fake file.

B

Because I'm not going to show you my real sql, azure password.

B

Right. but docker compose will read .env and find the values for these variables.

B

Right. one of the ways I think of docker compose is.

A

It's doing docker from the outside,.

A

Like with the original scenario that you showed us., that was very much docker being fundamentally integrated with that particular project..

A

I see you still do have a docker file in your api docker.

B

Yeah., I need the docker file, because the docker file is the instructions of how to build the image.

A

Totally. yeah., but with docker compose,, all of the steps,.

A

As opposed to the recipe, are all done from the outside., the data api docker is unaware of all this.

A

So it brings,, I guess, a level of external formalism to the whole thing.

A

Yeah., when we go to the next step,.

B

It'll be more obvious because we're orchestrating multiple containers.

B

But notice that this is saying,.

B

"Yes,, I'm going to have to build this.

B

Here's one of the images.: it's the only one that we're working with..

B

It's called data api docker.

B

I want you to name that image data api, docker.".

B

By the way, you're going to have to build it.

B

yeah., it doesn't exist yet., so look for a file called docker.

B

File inside of the data api, docker folder.

A

Directory, yeah.

B

That's going to give you the instructions how to build the image. also,. The image is going to need some environment variables.

B

So we're going to pass them into the image., so the environment variable values are not going to be built into the image.

B

They're coming in from the outside.

B

what this will do,, it's not going to put them into the image.

B

It's when the container gets run,.

B

It's then going to use them.

B

This knows that they exist, but normally,.

B

You could just put the password secret.

B

You could set the value of the environment variables right, here,.

B

But what I'm doing is using yet another,.

B

There's many, many ways of using docker environment variables.

B

So I'm using the path that says, "I'm just going to declare them and then you're going to.

B

Have to find them in one of the ways that you know how to find them." the way it's doing when you do it is by looking inside my .env file,, which looks just like this,, except it has. My real password.

B

makes sense. okay., so I mean, it's a lot.

B

again, in my article,.

B

I go through it. More-.

A

Step by step., -details. yes., so for people like me,.

B

I'm trying to explain, because I went through all of this.

B

So this will all work,.

B

I could show it to you or not..

B

We should probably advance to the next one.

A

Because I think we have the basic idea: now.

B

Yeah., but the one thing I do want to show is that.

B

I am reading the configuration,.

B

The connection string, right?

B

asp.net core is really smart..

B

It looks for configuration information in various places.

B

So it knows that there might be configuration in app settings.

B

It knows to look on the computer's environment, variables,.

B

But it also will get fed the docker environment variables.

B

So those will be there.. So if I was running this in kestrel,.

B

It won't know about the docker compose environment, variables.

B

The only one it's going to find is the app settings,.

B

And that's the localdb., but it uses the last one. In, right?.

B

So if I'm running this from docker compose,, the last one in is going to be the environment variables that are coming out of this file..

B

So that's what it's going to read, and then I'm just doing a replace, right..

B

My connection string, remember had the placeholders.

B

yeah., so I'm just replacing with the placeholders, and then passing that connection string in..

B

So that uses my azure sql.

B

Looks pretty straightforward to me.

A

All right. so there's one more.

B

How are we doing for time? like,? You want to see any of that?.

A

Yeah, we can do one more, and then- yeah,, we'll call it a night.. -We can be done., okay. yeah.

B

Look, they all look alike., which ones?

B

okay.. That's the one., I'm just going to pick one and see.

A

Eeny, meeny, miny, moe.

B

Let's see if it's this one. it's this one.

B

Okay. so same exact, application., all right.

B

Only difference is that if you look in docker file,.

B

Now, I'm not using that base connection string for my sql azure.

B

I got a new connection string in here, and it still has a placeholder for my password, right?.

B

I'm not exposing the password.. This is because now I'm going to use sql server inside a docker container., but inside a different one.

B

Yes., so there is a sql server for linux.

B

Sql server for linux exists as an image,.

B

And you can run that,.

B

And there's also regular sql server is inside a windows, container.

B

So you could also run it that way if you want,, but I'm using sql server for linux,.

B

And here's how I'm doing it.

B

In my docker compose,.

B

This will help, I'm going to go back in, and we're going to look at the connection string, again.

B

now,. I still have this data api, docker, service,, right.,.

B

Each service describes a different image, slash container.

B

Like container that we're going to end up with.

B

So there's the same one, there's a few differences, there.

B

now,. I have another container described, I've named it db,.

B

And it's based on microsoft's sql server, image.

B

There's different flavors of this and microsoft now,.

B

Most of their images,, you probably know this,.

B

Most of their images are hosted on microsoft, container, repository,, mcr.

A

Registry. registry. thank you, instead of on-.

A

B

-Docker hub., so I don't have to build this image or create it, it already exists..

B

So I'm just saying you're going to use this image., so there's no build instructions right up. Here,.

B

I've got some build instructions to create the image of my api,.

B

But here I don't have to do that.. I am in this case, defining a volume, right?.

B

We talked about volumes., so this is where I'm going to have persisted data.

B

It's outside of the container, outside of the image,, it's a separate place,, but because I'm describing it and compose,.

B

It will know how to find all of it based on the syntax. I've been using.

A

Right, and just one point on that, is those on the right-hand side of the volume mount there,.

A

And some folks might think well, that looks like a pretty crazy path,, but basically what that is, I suppose for one,, it's a linux file, system,.

A

And the second one is,, I assume that's the prescriptive location.

B

It's actually a file path.

A

Yes,, but I mean it's the one you have to use.

A

I assume that's the one where sql server chooses to put the data.

A

You don't have any choice on that particular location..

A

I believe you. I didn't know that.. That sounds right.

A

Yes, I was guessing., it sounds right. yeah.

B

It might not be, right?.

B

Maybe because I'm defining it here,, maybe it's going to be wherever I wanted it to be.

A

B

I'm not sure. yeah,. I don't think that's how it works. okay. yeah,, I believe, you..

B

So this is just a name,. My name that I gave it.

A

Absolutely. notice that I'm defining the volume here.

B

So ci of services- and I volumes, so they're separate.

B

So I'm saying, by the way I want to have a volume, and this is the name I want it to have,, and this is saying my database container should use.

B

That volume- and this is where to find it.

A

Can you tell us about the right-hand side where there's the two curly brackets in the volume section?.

A

At the very bottom, yeah.

A

no., what's that all mean?.

B

No,, I don't remember.

A

B

That's just how, a whole lot of what I learned was from trying.

B

Things and copying things as opposed to deeply understanding every little thing.

A

Okay., that's this scenario: working example.

B

Yes,, that is this scenario: working example.

A

B

But I think yeah,, the curly braces related to using,.

B

Word that I've known for 30 years just went out of.

B

My head,, an evaluating, right.

B

So if we look up here,.

B

Notice that for the accept_eula I'm saying.

B

The value of that environment variable is y.

B

No matter what. right?.

A

Just literal term.

B

Here I'm saying,, I'm not telling you the password here.

B

you're, going to have to evaluate it,, right?.

B

Here's, the environment, variable, you're, going to know the environment, variable, and you're going to find its actual value inside the .env file.

A

Yeah., I would think, though,.

A

If no specific location is specified,.

A

Then it has to be specified somewhere, else.

A

Anyway, we shouldn't drill on this particular thing.

B

You should show us this working.

A

I was hoping you were going to say,. Do you know?.

B

Oh, you don't? well,. I can tell you.

A

I haven't used that particular syntax before.

B

So I don't know the answer to that.: it's just what happened to work in this case when I was desperately trying to get all the pieces coming. Together.

B

So this last bit is, do I need to hide the connection string in this case?.

B

I don't know, because I mean the password.

B

I'm defining the password for the sake of creating and running this, right?.

B

So it's going to get shared all the way through,, but I am defining it.

B

in .env like I was defining it before.

B

So a couple other things I want to point out,.

B

Notice that this says depends on db., so this won't start doing.

B

Its thing until it knows db, is up and running.

A

Right., it's going to erect that container image first and then it'll erect the other one.

A

Yeah. now db up and running;.

B

There's two different definitions of that.

B

When you start sql server in.

B

A container the container starts right, up,, right?.

B

But then there's startup stuff that.

B

Has to happen afterwards, that's defined in the docker file,.

B

In the sql servers, docker file., it runs a whole bunch of sql, right?, there's some scripts that it will run.

B

so the container's up right away, but it's still another 20 or 30 seconds until it's really ready to use. When all the system, databases and things are all set up.

B

Right,, I think that's sometimes referred to as liveness.

B

Okay,, that's cool., okay., that's a new one for me.

B

All right, and then the other thing, now notice. I've named this db;.

B

I can name it foo,. I can name it whatever. I want, it's my name., but I'm using the name here., but I'm using it one other place..

B

This is where I go back to the connection. String.

B

Notice that the server name is db.

A

I was wondering about that.

B

That's only going to work when you're doing docker compose.

B

Because with the orchestration, they're aware of each other and they're aware of their service names and that's how it's going to find it.

B

Otherwise,, how will it ever know?.

A

I feel like this particular pieces, the part that's worth the price of entry.

A

yes. as matter of fact,.

B

A friend on twitter was asking about that.

B

What I mentioned that we were doing this and he said,.

B

"I've been trying to do with mysql,", but I think what he was asking, can't totally remember,, but something like, "how. Do I get my api to find my sql when it's in a container?".

B

It's the orchestration that enables all that to happen.

B

Sweet, I love it. right.. Now, if I go back to docker compose,.

B

I want to point out something else about when I'm running the database container.

B

notice the ports here. one is what port is it going to be.

B

Exposed externally on metal to my windows, machine.

B

What?, so I can still interact with this database.

B

Even though it's inside of a container as long as I go, local host, comma 1433,,.

B

Or 1600, or 1784 whatever.

A

Right,, they don't have to match.

B

Right., that's what it's exposed on the host.

B

But 1433 is the port that it's exposed on internally and that's.

B

The classic port for first sql server, 1433.

B

So I'm doing that., so I can have this be whatever I want it to be.

B

That's just for external access..

B

It has nothing to do with my api container accessing it.

B

So, do you want me to go ahead and run this?.

A

Sure. is that still going to work with that number changed?.

A

You just change that to 1783,.

A

I kind of have a bad feeling about that.

A

shouldn't. You change it back to how it was.

B

Yeah,, maybe not in the middle of a demo. yeah.. I think it ought to work. but yeah,. Let's just make it..

B

This is how it was working., but I frequently use various ports because.

B

The other nice thing about docker containers is, you can have multiple instances. Running.

B

So I have different instances of sql server running on.

B

The same machine that are all hosted and managed by docker engine.

B

So I have 1600, and 1620, and 1783.

B

A

So you can definitely do that,.

B

So I'm going to go ahead and run it and cross. My fingers.

B

Because you never know what goes on with these things.

B

Okay, so now it's going through the docker file, steps.

B

Something's going on.

B

oh, here we go into the startup.

B

And it's built the connection string.

B

And so it's going to push that into the db context.

B

it's going to migrate, we're hoping it won't hit that exception. Breakpoint.

B

Oh yeah,, I think the docker tools will also spin up.

B

The web page here. yeah, here it comes.

B

Same thing. so now before you close this,.

A

Can we go back to the vs code tools or to.

A

The command line, whichever one you prefer and we can show which containers are actually loaded?.

B

B

actually,: let's just do both for kicks.

A

Yeah, but this doesn't have a huge amount of information.

A

B

But so this is what is interesting,.

B

This was what the tools did. the tools named the container on the fly.

B

It's tagged and then the name I requested in docker compose; data, api, docker.

B

I guess I've done it a few times, so it did underscore one,.

B

And here's the sql server container- that's running.

B

again,. It gave the container.

B

The name of this running debug, session, right?.

B

Then db and then again underscore one and it's been up for two seconds.

A

So, let's look at the command line, yeah.

B

We should have the volume, docker volume ls.

B

So there's actually two docker volumes.

B

Running because of different things, I've been doing.

B

yeah.. So this data one, again with this there's that preface, right?.

B

Then the name that I defined in docker compose;.

B

Ms sql server, julie, data, and then docker ps.

B

Right there are my two dockers.

B

totally, and is there a docker def compose ls?.

B

Right. they're my two containers., so yeah.

A

Is there a docker-compose ls??

A

Is that a thing?? Can we try it?.

A

I have actually never tried that. docker-compose,, let's see what docker-compose.

B

Okay, is there an ls? list containers. there isn't an ls.

A

Or we could do ps. the ps list, containers.

B

I wonder how that's different,.

B

Can't find the sql container.

A

Oh,, it's because you're in the wrong location,, never mind.

A

yeah,. You would have to be in the place where your docker compose file lives., let's skip that. okay. okay. well,. This was awesome., so I think we pretty much covered everything.

A

B

An enormous amount of learning going through all that.

B

And getting stuck for hours on one problem and.

B

Hours on another thing and reading a million things.

B

Because I have to spend many, many hours on a problem.

B

Before I humble myself and ask for help.

B

So stupid., do you find you do the same? Thing? [inaudible].

A

Well,, the only advantage I have is I sit in a team room with basically geniuses.

A

So I've actually become quite lazy.

A

So I spend like 10 seconds thinking about something.

A

I actually I could do this, but it's too hard.

A

I'm just going to ask jared.

A

That's awesome.

B

Yeah. okay. well,, where else should people be looking at?.

A

Right, you've showed that your website,, the data farm, and your msdn magazine articles.

A

So we'll put both of those links in the show notes.

A

B

So I know you're on twitter. yeah, a little too much.

B

Okay, awesome. well,, thanks for being.

A

On the show today., we learned a lot.

B

Yeah,, it was really fun..

B

It's really fun to be able to share this stuff..

B

You know, writing it as an article is one way of expressing it, but actually showing somebody and go,.

B

"Oh look, this is cool." yeah,. So I really appreciate the opportunity. thanks.

A

For sure. okay,, this has been another episode of the on.net show.

A

And hope you learned something about containerized database-oriented applications., thanks for watching.