Fix addon devcontainer not being able to build addons

[felipecrs]

Coming from the warning?

If you came here because of a warning like this:

Then all you need to do is add these two lines to your devcontainer.json:

  "workspaceFolder": "/mnt/supervisor/addons/local/${localWorkspaceFolderBasename}",
  "workspaceMount": "source=${localWorkspaceFolder},target=${containerWorkspaceFolder},type=bind,consistency=cached",

PR description

After home-assistant/supervisor#5974 was merged, the add-on devcontainer was not able to build addons.

Now that Supervisor delegates the build to a container, we need to ensure that the add-on directory is within Supervisor's data directory on the host, so that Supervisor can properly mount it within the builder container.

Note that this PR is backwards compatible, i.e. it will work even against Supervisor versions prior to home-assistant/supervisor#5974.

I tested this and confirmed it works.

Closes home-assistant/supervisor#5991

/cc @agners

[ggravlingen]

@felipecrs is it possible to take this for a spin while waiting for the PR to be reviewed and merged?

[felipecrs]

@felipecrs is it possible to take this for a spin while waiting for the PR to be reviewed and merged?

Yes, swap your devcontainer image with ghcr.io/felipecrs/homeassistant-addons-devcontainer.

[ggravlingen]

@felipecrs is it possible to take this for a spin while waiting for the PR to be reviewed and merged?

Yes, swap your devcontainer image with ghcr.io/felipecrs/homeassistant-addons-devcontainer.

Thank you! Can confirm it works on my Apple M2.

2025-07-07 18:27:34.721 INFO (MainThread) [supervisor.docker.addon] Starting build for local/amd64-addon-pypmanager-hass:1.0.0
2025-07-07 18:27:34.725 INFO (SyncWorker_3) [supervisor.docker.manager] Runing command '['docker', 'buildx', 'build', '.', '--tag', 'local/amd64-addon-pypmanager-hass:1.0.0', '--file', 'Dockerfile', '--platform', 'linux/amd64', '--pull', '--label', 'io.hass.version=1.0.0', '--label', 'io.hass.arch=amd64', '--label', 'io.hass.type=addon', '--label', 'io.hass.name=Pypmanager', '--label', 'io.hass.description=Local portfolio management and transaction analysis tool', '--build-arg', 'BUILD_FROM=ghcr.io/home-assistant/amd64-base:latest', '--build-arg', 'BUILD_VERSION=1.0.0', '--build-arg', 'BUILD_ARCH=amd64']' on docker.io/library/docker:28.3.1-cli
2025-07-07 18:27:34.745 DEBUG (MainThread) [supervisor.hardware.monitor] Hardware monitor: remove - Device('/sys/fs/nfs/net/nfs_client')
2025-07-07 18:27:34.992 DEBUG (MainThread) [supervisor.hardware.monitor] Hardware monitor: add - Device('/sys/fs/nfs/net/nfs_client')
2025-07-07 18:27:36.542 DEBUG (MainThread) [supervisor.docker.addon] Build local/amd64-addon-pypmanager-hass:1.0.0 done: #0 building with "default" instance using docker driver

#1 [internal] load build definition from Dockerfile
#1 transferring dockerfile: 201B 0.0s done
#1 WARN: InvalidDefaultArgInFrom: Default value for ARG $BUILD_FROM results in empty or invalid base image name (line 2)
#1 DONE 0.0s

#2 [internal] load metadata for ghcr.io/home-assistant/amd64-base:latest
#2 DONE 0.3s

#3 [internal] load .dockerignore
#3 transferring context: 2B done
#3 DONE 0.0s

#4 [1/1] FROM ghcr.io/home-assistant/amd64-base:latest@sha256:4bb7a73f643f07416573cb892396a76e2663bc7ac127d475f1f3a0b950a58e15
#4 CACHED

#5 exporting to image
#5 exporting layers done
#5 writing image sha256:ef2c98f95ae5021df423d1305edd9ac0bf41c34b1674ce0f97b1adf8676c2596 done
#5 naming to docker.io/local/amd64-addon-pypmanager-hass:1.0.0 done
#5 DONE 0.0s

 1 warning found (use docker --debug to expand):
 - InvalidDefaultArgInFrom: Default value for ARG $BUILD_FROM results in empty or invalid base image name (line 2)

2025-07-07 18:27:36.542 INFO (MainThread) [supervisor.docker.addon] Build local/amd64-addon-pypmanager-hass:1.0.0 done

[agners]

LGTM, thanks!

[dunxd]

I'm currently getting this when I try to install a local addon:

I have the lines mentioned above in my devcontainer.json

  "workspaceFolder": "/mnt/supervisor/addons/local/${localWorkspaceFolderBasename}",
  "workspaceMount": "source=${localWorkspaceFolder},target=${containerWorkspaceFolder},type=bind,consistency=cached",

What else is needed to get this devcontainer working again?

[felipecrs]

Yeah, I have been getting that in the
Supervisor devcontainer as well recently.

It's not related to this PR though.

[dunxd]

I can't see avenues to raising issues about the devcontainers. Issues isn't enabled on this repo. I'm not having much luck with discord. HA community just gets a few "me too" comments. How to get attention of people behind this part of HA?

[felipecrs]

I'd open an issue in Supervisor repository, after all that devcontainer is borked too.

[felipecrs]

@agners are issues intentionally disabled for this repository? Just checking, maybe it was just a miss.

[agners]

@agners are issues intentionally disabled for this repository? Just checking, maybe it was just a miss.

I don't think so. I can't enable it, but I'll check with the team.

[agners]

Speaking of this PR, should we maybe add these two lines to the template in this repository (addons/devcontainer.json)?

[felipecrs]

@agners, but I did, right?

62292e3

[agners]

@felipecrs uh right, I did not update my local devcontainer repo 🙈 . Sorry for the noise!