fix: don't mark volume as external in bind-mount workspaces

The `devcontainer-volume` volume alias must be `external: false` for bind-mount workspaces, otherwise Docker Compose errors, complaining that it doesn't exist (even though it's not referenced).

Author: h4l

.devcontainer/docker-compose.yml

@@ -24,7 +24,9 @@ services:
  - ${WORKSPACE_SOURCE:?}:${WORKSPACE_TARGET:?}
 
 volumes:
- # $WORKSPACE_SOURCE is "devcontainer-volume" when the workspace is in a volume
+ # $WORKSPACE_SOURCE is "devcontainer-volume" when the workspace is in a
+ # volume, and devcontainer-volume is an alias for the actual external volume.
+ # In bind-mount workspaces, it's an empty, unused volume created by compose.
  devcontainer-volume:
- name: ${WORKSPACE_CONTAINER_VOLUME_SOURCE}
- external: true
+ name: ${WORKSPACE_CONTAINER_VOLUME_SOURCE:-not-used-in-bind-mount-workspace}
+ external: ${WORKSPACE_IS_CONTAINER_VOLUME:?}

.devcontainer/gen-docker-compose-workspace-env.sh

@@ -128,8 +128,8 @@ and including references to the envars it generates in your docker-compose.yaml:
 
  volumes:
  devcontainer-volume:
- name: ${WORKSPACE_CONTAINER_VOLUME_SOURCE:?-devcontainer-volume_not-used-in-bind-mount-workspace}
- external: ${WORKSPACE_IS_CONTAINER_VOLUME}
+ name: ${WORKSPACE_CONTAINER_VOLUME_SOURCE:-not-used-in-bind-mount-workspace}
+ external: ${WORKSPACE_IS_CONTAINER_VOLUME:?}
 EOF
 )"
 

README.md

@@ -59,8 +59,8 @@ The key parts are:
  ```yaml
  volumes:
  devcontainer-volume:
- name: ${WORKSPACE_CONTAINER_VOLUME_SOURCE}
- external: true
+ name: ${WORKSPACE_CONTAINER_VOLUME_SOURCE:-not-used-in-bind-mount-workspace}
+ external: ${WORKSPACE_IS_CONTAINER_VOLUME:?}
  ```
 
 ## Compatibility