.devcontainer: why is the host's docker.sock mounted into the container?

tholewebgods · April 26, 2024, 1:04pm

In the .devcontainer configs the host’s docker.sock is mounted into the container and docker is installed within the container.

github.com

nextcloud/server/blob/296c9beff6faee4b93160ffd093dfbbc7d55c180/.devcontainer/docker-compose.yml#L7


      
          version: '3'
          services:
            nextclouddev:
              build: .
              volumes:
                - .:/workspace:cached
                - /var/run/docker.sock:/var/run/docker-host.sock
                - ..:/var/www/html
              command: /var/www/html/.devcontainer/entrypoint.sh
              ports:
                - 80:80
                - 8080:8080
                - 8025:8025
          
            db:
              image: postgres
              restart: always

github.com

nextcloud/server/blob/296c9beff6faee4b93160ffd093dfbbc7d55c180/.devcontainer/Dockerfile#L69


      
              curl \
              gnupg-agent \
              software-properties-common && \
              curl -fsSL https://download.docker.com/linux/ubuntu/gpg | apt-key add - && \
              add-apt-repository \
             "deb [arch=amd64] https://download.docker.com/linux/ubuntu \
             $(lsb_release -cs) \
             stable" && \
              apt-get update -y && \
              apt-get install -y docker-ce docker-ce-cli containerd.io && \
              ln -s /var/run/docker-host.sock /var/run/docker.sock
          
          # Dedicated DevContainer user runs Apache
          ENV APACHE_RUN_USER=devcontainer
          ENV APACHE_RUN_GROUP=devcontainer
          RUN useradd -ms /bin/bash ${APACHE_RUN_USER} && \
          	adduser ${APACHE_RUN_USER} sudo && \
          	echo '%sudo ALL=(ALL) NOPASSWD:ALL' >> /etc/sudoers && \
          	sed -ri "s/^export APACHE_RUN_USER=.*$/export APACHE_RUN_USER=${APACHE_RUN_USER}/" "/etc/apache2/envvars" && \
              sed -ri "s/^export APACHE_RUN_GROUP=.*$/export APACHE_RUN_GROUP=${APACHE_RUN_GROUP}/" "/etc/apache2/envvars"

(The blobs refer to the current master)

What’s the reasoning behind this?

This was introduced with the initial commit and currently I see no use case for Docker within the container environment.

kesselb · April 27, 2024, 10:11am

cc @R0Wi do you know?