Running Azurite inside a Dev Container

I recently worked on an improvement to the flask-admin extension to upgrade the Azure Blob Storage SDK from v2 (an old legacy SDK) to v12 (the latest). To make it easy for me to test out the change without touching a production Blob storage account, I used the Azurite server, the official local emulator. I could have installed that emulator on my Mac, but I was already working in GitHub Codespaces, so I wanted Azurite to be automatically set up inside that environment, for me and any future developers. I decided to create a dev container definition for the flask-admin repository, and used that to bring in Azurite.

To make it easy for *anyone* to make a dev container with Azurite, I've created a GitHub repository whose sole purpose is to set up Azurite:
https://github.com/pamelafox/azurite-python-playground

You can open that up in a GitHub Codespace or VS Code Dev Container immediately and start playing with it, or continue reading to learn how it works.

devcontainer.json

The entry point for a dev container is .devcontainer/devcontainer.json, which tells the IDE how to set up the containerized environment.

For a container with Azurite, here's the devcontainer.json:

{
  "name": "azurite-python-playground",
  "dockerComposeFile": "docker-compose.yaml",
  "service": "app",
  "workspaceFolder": "/workspace",
  "forwardPorts": [10000, 10001],
  "portsAttributes": {
    "10000": {"label": "Azurite Blob Storage Emulator", "onAutoForward": "silent"},
    "10001": {"label": "Azurite Blob Storage Emulator HTTPS", "onAutoForward": "silent"}
  },
  "customizations": {
    "vscode": {
      "settings": {
        "python.defaultInterpreterPath": "/usr/local/bin/python"
      }
    }
  },
  "remoteUser": "vscode"
}

That dev container tells the IDE to build a container using docker-compose.yaml and to treat the "app" service as the main container for the editor to open. It also tells the IDE to forward the two ports exposed by Azurite (10000 for HTTP, 10001 for HTTPS) and to label them in the "Ports" tab. That's not strictly necessary, but it's a nice way to see that the server is running.

docker-compose.yaml

The docker-compose.yaml file needs to describe first the "app" container that will be used for the IDE's editing environment, and then define the "azurite" container for the local Azurite server.

version: '3'

services:
  app:
    build:
      context: .
      dockerfile: Dockerfile

    volumes:
      - ..:/workspace:cached

    # Overrides default command so things don't shut down after the process ends.
    command: sleep infinity
    environment:
      AZURE_STORAGE_CONNECTION_STRING: DefaultEndpointsProtocol=http;AccountName=devstoreaccount1;AccountKey=Eby8vdM02xNOcqFlqUwJPLlmEtlCDXJ1OUzFT50uSRZ6IFsuFq2UVErCz4I6tq/K1SZFPTOtr/KBHBeksoGMGw==;BlobEndpoint=http://127.0.0.1:10000/devstoreaccount1;

  azurite:
    container_name: azurite
    image: mcr.microsoft.com/azure-storage/azurite:latest
    restart: unless-stopped
    volumes:
      - azurite-data:/data
    network_mode: service:app

volumes:
  azurite-data:

A few things to note:

• The "app" service is based on a local Dockerfile with a base Python image. It also sets the AZURE_STORAGE_CONNECTION_STRING for connecting with the local server.
• The "azurite" service is based off the official azurite image and uses a volume for data persistance.
• The "azurite" service uses network_mode: service:app so that it is on the same network as the "app" service. This means that the app can access them at a localhost URL. The other approach is to use network_mode: bridge, the default, which would mean the Azurite service was only available at its service name, like "http://azurite:10000". Either approach works, as long as the connection string is set correctly.

Dockerfile

The Dockerfile defines the environment for the code editing experience. In this case, I am bringing in a devcontainer-optimized Python image. You could adapt it for other languages, like Java, .NET, JavaScript, Go, etc.

FROM mcr.microsoft.com/devcontainers/python:3.12

pip install -r requirements.txt