Part7.md

Building applications with Docker

Intro to problem

One i

Installing node and Yeoman

Node Yeoman

Build api and app

or clone this repo insert

Api

    yo aspnet

Pick api

    dotnet retsotore
    dotnet run

test on localhost:5000/api/values

App

    yo aspnet

Pick basic web app

    dotnet retsotore
    dotnet run

test on localhost:5000/api/values

Modify web app to call api

First update the HomeController.cs to call the api

    insert code here

Modify Views/Home/Index and by insertign the following;

    Insert some view updates

Change the port of the web app to 5001 in the Program.cs file

.UseUrls("http://localhost:5001/")

Start both apps to test (two terminals, VS Code terminal etc.).

    Insert command(s)

Make url's configurable

In both projects delete the Program.cs and insert the following in the Startup.cs instead of the xxx method

    public static void Main(string[] args)

        {

           Configuration = new ConfigurationBuilder()
                .SetBasePath(Directory.GetCurrentDirectory())
                .AddJsonFile("appsetings.json", optional: true, reloadOnChange: true)
                .AddEnvironmentVariables()
                .Build();

            var hostUrl = Configuration.GetValue<Uri>("HostUrl").ToString();

            var host = new WebHostBuilder()
                .UseConfiguration(Configuration)
                .UseKestrel()
                .UseContentRoot(Directory.GetCurrentDirectory())
                .UseIISIntegration()
                .UseStartup<Startup>()
                .UseUrls(hostUrl)
                .Build();

            host.Run();
        }

        public static IConfigurationRoot Configuration { get; set; }

In the HomeController update the hardcoded url with this:

    ViewData["Message"] = await new HttpClient().GetStringAsync(
                Startup.Configuration.GetValue<string>("ApiBaseUrl") + "/api/values");

###Adding the configuration settings

In the app project add config for the HostUrl in the appSettings.json like this:

    "HostUrl" : "http://localhost:5000"

For the app project add this;

    "HostUrl" : "http://localhost:5001",
    "ApiBaseUrl" : "http://localhost:5000"

Dockorizing

First of all let's have look at the dockerfile that the yeoman scaffoldign added for the api project:

FROM microsoft/dotnet:latest

COPY . /app

WORKDIR /app

RUN ["dotnet", "restore"]

RUN ["dotnet", "build"]

EXPOSE 5000/tcp

ENTRYPOINT ["dotnet", "run", "--server.urls", "http://0.0.0.0:5000"]

Lets try to build and run that:

docker build -t myapi .

Let's run the api container

    docker run -itd -p 5000:5000 --name=myapi myapi

Test your api on the host machine

Now do the same for the app

Build the image

docker build -t myapp .

Let's run the app container

    docker run -itd -p 5001:5001 --name=myapp myapp

Test your app on the host machine

Linking

That didn't work... The reason is that the two containers are not able to see each other. Let's fix that. THe easiest way is by linking.

    docker run -itd -p 5001:5001 --link myapi --name=myapp myapp

Networking

Well linking is just so last yeah, and the new way is to create shared networks. So let's do that.

Create backend network:

And then start the two containers

Compose

Docker compose is a tool for stitching together docker containers in a declaraive way. Composer runs confifurations specifies in docker-compose.yaml files. For our example app we need a docker-compose file like this.

version: '2'
services:
    api:
        build: ./myapi
        container_name: myapi
        ports:
            - "5000:5000"
        networks:
            - backend

    app:
        build: ./myapp
        container_name: myapp
        ports:
            - "5001:5001"
        depends_on:
            - api
        networks:
            - backend

networks:
    backend:
        driver: bridge

Distrubuted

Swarm

Ensure containers run on startup

• Upstart
• Systemd
• ?

Reference to Wolfy's repo