[Docker] Default to running as root

Previous setups will already contain folders created as root. Making a different user the default
will break these setups. So just make it opt-in instead.

.devcontainer/docker-compose.extend.yml

@@ -5,6 +5,7 @@ services:
   # https://github.com/microsoft/vscode-remote-release/issues/8734
   dev-container:
     image: e621
+    user: ${DOCKER_USER:-root}
     environment:
       RAILS_ENV: development
     volumes:

.env.sample

@@ -38,12 +38,13 @@
 #
 
 #
-# When using the Dev Container in Linux, you must set these variables to avoid file permission errors.
-# If not set the container will default to the root user and modified files will only be accesible to
-# root on your host as well. Use `id -u` to print the UID and `id -g` for the GID.
+# When wanting to run as the non-root user, you must set these variables to
+# avoid file permission errors. If not set the container will default
+# to the root user. Use `id -u` to print the UID and `id -g` for the GID.
 #
 # HOST_UID=
 # HOST_GID=
+# DOCKER_USER=e621ng
 
 # discord: Starts the discord integration to join users to a discord server.
 #          The application must have its OAuth2 redirect URI set to ${JOINER_BASE_URL}/callback.

.github/prepare-docker-image/action.yml

@@ -15,5 +15,5 @@ runs:
         tags: e621
 
     - name: Set docker run command
-      run: echo "DOCKER_RUN=docker-compose run --user 0:0 -e CI=true" >> "$GITHUB_ENV"
+      run: echo "DOCKER_RUN=docker-compose run -e CI=true" >> "$GITHUB_ENV"
       shell: bash

Dockerfile

@@ -32,6 +32,8 @@ COPY --from=node-builder /usr/local/share /usr/local/share
 COPY --from=node-builder /usr/local/lib /usr/local/lib
 COPY --from=node-builder /usr/local/include /usr/local/include
 COPY --from=node-builder /usr/local/bin /usr/local/bin
+# Copy yarn to both root and the user created below to support running as both
+COPY --from=node-builder /root/.cache/node /root/.cache/node
 COPY --from=node-builder /root/.cache/node /home/e621ng/.cache/node
 
 # Copy gems and js packages
@@ -45,9 +47,8 @@ RUN addgroup --gid ${HOST_GID} e621ng && \
   adduser -S --shell /bin/sh --uid ${HOST_UID} e621ng && \
   addgroup e621ng wheel && \
   echo "e621ng ALL=(ALL) NOPASSWD:ALL" >> /etc/sudoers
-USER e621ng
 
-# Ignore warnings from git about .git permission differences
+# Ignore warnings from git about .git permission differences when running as root
 RUN git config --global --add safe.directory $(pwd)
 
 CMD ["foreman", "start"]

docker-compose.yml

@@ -35,6 +35,7 @@ services:
       args:
         HOST_UID: ${HOST_UID:-1000}
         HOST_GID: ${HOST_GID:-1000}
+    user: ${DOCKER_USER:-root}
     image: e621
     volumes:
       - .:/app