How Do I Set and Retrieve an Environment Variable with Docker and .NET 7 in VS Code

I created a .NET 7 Web API App and created the Docker configuration files using the command Docker: Add Docker Files to Workspace. When prompted, I also add the Docker compose files. I've added environment variables to my tasks.json and docker-compose.debug.yml .

I then start my application using the generated launch configuration Docker .NET Launch.

None of the environment variables are populated when I call Environment.GetEnvironmentVariable("MY_VARIABLE") in my Program.cs.

Note that they are populated when I use .NET Core Launch configuration with an env object.

How do I properly set and retrieve environment variables when using my docker image + container?

Code Examples:

# docker-compose.debug.yml
services:
  myservice:
    image: myservice
    build:
      context: .
      dockerfile: ./Dockerfile
    ports:
      - 5000:5000
    environment:
      - ASPNETCORE_ENVIRONMENT=Development
      - FOO=foo
    volumes:
      - ~/.vsdbg:/remote_debugger:rw

// tasks.json

        {
            "type": "docker-run",
            "label": "docker-run: release",
            "dependsOn": [
                "docker-build: release"
            ],
            "dockerRun": {
                "env": {
                    "foo": "bar"
                }
            },
            "netCore": {
                "appProject": "${workspaceFolder}/Kno2.WebSockets.csproj"
            }
        }

// Program.cs

var foo = Environment.GetEnvironmentVariable("FOO");
Console.Write(foo); // null

I tried setting environment variables in any file that would take them.

From the documentation for Environment.GetEnvironmentVariable...

> Environment variable names are case-sensitive on non-Windows systems but are not case-sensitive on Windows.

Your Docker platform is no doubt using one of the official Linux images so you need to match the text case...

"dockerRun": {
  "env": {
    "FOO": "bar"
  }
},

If you've taken the time to create a Docker Compose configuration, you could instead use a Docker Compose task

{
  "version": "2.0.0",
  "tasks": [
    {
      "label": "Run docker-compose up",
      "type": "docker-compose",
      "dockerCompose": {
        "up": {
          "detached": true,
          "build": true,
          "services": ["myservice"]
        },
        "files": [
          "${workspaceFolder}/docker-compose.yml",
          "${workspaceFolder}/docker-compose.debug.yml"
        ]
      }
    }
  ]
}