Docker Wormhole configuration

[JackFrostStudios]

I am attempting to set up a DevContainer so that I can use a container as a dev environment using visual studio code, however I am running into issues with TestContainer not finding the docker host.
I have followed the documentation here: https://dotnet.testcontainers.org/dind/ which lays out that you have to mount the volume to allow a connection to docker, however when I run the tests I get this error:
Cannot detect the Docker endpoint. Use either the environment variables or the ~/.testcontainers.properties file to customize your configuration

My repository can be seen here:
https://github.com/JackFrostStudios/summer-born-info/tree/init-repo
And specifically my docker compose file that mounts the volumes and sets the TESTCONTAINERS_HOST_OVERRIDE environment variable:
https://github.com/JackFrostStudios/summer-born-info/blob/init-repo/.devcontainer/docker-compose.yml

Am I missing something obvious?
Thanks in advance!

[JackFrostStudios]

I think ive been a fool, I did review other answers but think ive possibly found it here:
#492 (comment)
My container base image wont have the Docker daemon running, so I need to ensure that is added to my Docker file and try again?

I will give it a go tomorrow 🤞

[HofmeisterAn]

How do you provide the Docker daemon to the Dev Container? Here is a working configuration.

[JackFrostStudios]

So I was actually trying to use docker outside of docker so I had to make a slightly different change than just following your example.

You are correct though, I needed to provide the Docker daemon to the Dev Container (by adding the docker-outside-of-docker feature of dev containers).

For my dev container I was actually using docker compose so this ended up being my full set up:
devcontainer.json:

{
    "name": "C# (.NET) and PostgreSQL",
    "dockerComposeFile": "docker-compose.yml",
    "service": "app",
    "workspaceFolder": "/workspaces/${localWorkspaceFolderBasename}",
	"features": {
		"ghcr.io/devcontainers/features/docker-outside-of-docker:1": {}
	},
	"customizations": {
		"vscode": {
			"extensions": [
				"ms-dotnettools.csharp",
				"ms-dotnettools.csdevkit",
				"saoudrizwan.claude-dev"
			]
		}
	},
	"forwardPorts": [5119]
}

docker-compose:

version: '3.8'
services:
  app:
    build:
      context: .
      dockerfile: Dockerfile
    volumes:
      - ../..:/workspaces:cached
      - /var/run/docker.sock:/var/run/docker.sock
    environment:
      - TESTCONTAINERS_HOST_OVERRIDE=host.docker.internal
    command: sleep infinity
    network_mode: service:db
  db:
    image: postgres:14.3
    restart: unless-stopped
    volumes:
      - postgres-data:/var/lib/postgresql/data
    environment:
      POSTGRES_PASSWORD: postgres
      POSTGRES_USER: postgres
      POSTGRES_DB: postgres
volumes:
  postgres-data:

Dockerfile

FROM mcr.microsoft.com/devcontainers/dotnet:10.0-noble

Now that I look back it seems blindingly obvious that I had to enable docker on the actual container I was using but following the documentation it doesn't specifically state that:
https://dotnet.testcontainers.org/dind/

I am embarressed I made this mistake but if I made it others possibly will. Do you think it's worth me raising a pull request to update that doc with a note that docker daemon must be available in the container instance or is it spoon feeding something that is really obvious and I just made a mistake?

Thanks for the help either way, I appreciate you offering the example 👍

[HofmeisterAn]

Do you think it's worth me raising a pull request to update that doc with a note that docker daemon must be available in the container instance or is it spoon feeding something that is really obvious and I just made a mistake?

I believe a quick note can be easily overlooked. It might be better to have a section dedicated to configuring Dev Containers, explaining the different configurations and requirements, like docker-outside-of-docker vs. docker-in-docker. WDYT? Would you be interested in contributing to this?