ECS-W1: We Need to Talk About Windows Containers

This episode introduces Docker on Windows, talks about how containers are different on Windows and Linux and shows you some typical Windows workloads you can run in containers.

Here it is on YouTube - ECS-W1: We Need to Talk About Windows Containers

Links

• Windows support in Kubernetes

• Docker for .NET Apps - which is a Udemy course, coming soon :)

• Episode 15 of DIAMOL which covered multi-architecture Docker images

• Modernizing .NET Apps with Docker - on Pluralsight

• Docker on Windows - the book

• Learn Docker in a Month of Lunches - the other book

Pre-reqs

You can follow along with the first demo using Vagrant - the setup provisions Linux and Windows VMs with Docker installed. You’ll need Hyper-V on Windows or VirtualBox on Linux/Mac/Windows to run the VMs.

The rest of the demos use Docker Desktop on Windows 10.

Setup

From the root of this repo, switch to the Vagrant folder and provision the VMs:

cd episodes/ecs-w1/vagrant

vagrant up linux

vagrant up windows

The Linux setup script and the Windows setup script install Docker so the machines are ready to use.

Demo 1 - Comparing Linux and Windows containers

Open two terminal sessions, connecting to the Linux and Windows VMs:

vagrant ssh linux

vagrant ssh windows

Check the Docker setup in each:

docker version

Run a simple web server in a Linux container:

docker run -d -p 8080:80 diamol/apache:linux-amd64

ps aux

Browse to the VM IP address at port 8080

Try to run the Windows variant:

docker run -d -p 8081:80 diamol/apache:windows-amd64

docker pull diamol/apache:windows-amd64

It fails because the runtime OS doesn’t match the image OS - see https://hub.docker.com/r/diamol/apache/tags

Switch to the Windows VM and run the Windows variant:

docker run -d -p 8080:80 diamol/apache:windows-amd64

Get-Process

Browse to the VM IP address at port 8080

Try to run the Linux variant:

docker run -d -p 8081:80 diamol/apache:linux-amd64

docker pull diamol/apache:linux-amd64

Demo 2 - Container modes on Docker Desktop

Docker Desktop runs Windows containers, and it also manages a Linux OS to run Linux containers.

Run a Windows container:

docker run -d -p 8080:80 sixeyed/tweet-app

Switch to Linux container mode to run the Linux version:

docker run -d -p 8081:80 sixeyed/tweet-app:linux

Browse to http://localhost:8080 and http://localhost:8081

Check the running containers:

docker ps

Demo 3 - Windows workloads

Windows containers based on Windows Server Core can run pretty much any Windows app. The huge image size is the price of backwards compatibility.

Switch to Windows containers and run SQL Server:

docker container run -d -p 1433:1433 --name sql `
  --env sa_password=DockerCon!!! `
  docker4dotnet/sql-server:2017

And another SQL Server:

docker container run -d -p 1434:1433 --name sql2 `
  --env sa_password=DockerCon!!! `
  docker4dotnet/sql-server:2017

docker ps

Connect with a SQL client (like Sqlectron) and run some CREATE DATABASE commands

docker exec -it sql powershell

cd 'C:\Program Files\Microsoft SQL Server'

ls .\MSSQL14.SQLEXPRESS\MSSQL\data

Run a distributed app from a Docker Compose manifest:

cd episodes/ecs-w1/

docker-compose up -d

Browse to http://localhost:8030 and add an item

Then connect to Postgres on port 5433 and query the todo database

Coming next

ECS-W2: Building and running Windows apps in Docker containers