obtuse and confusing error with local feature under WSL

[dotysan]

My mistake was putting "myfeature" inside devcontainer.json instead of "./myfeature". However the error message was horribly misleading.

To reproduce, create .devcontainer/myfeature/devcontainer-feature.json and add this to .devcontainer/devcontainer.json:

"features": { "myfeature": {} }

You will get this error:

[1013 ms] @devcontainers/cli 0.59.1. Node.js v18.18.2. linux 5.15.146.1-microsoft-standard-WSL2 x64.
[1013 ms] Start: Run: docker buildx version
[1072 ms] github.com/docker/buildx v0.14.0-desktop.1 7b0470cffd54ccbf42976d2f75febc4532c85073
[1072 ms] 
[1072 ms] Start: Run: docker -v
[1100 ms] Start: Resolving Remote
[1103 ms] Start: Run: git rev-parse --show-cdup
[1347 ms] Start: Run: docker ps -q -a --filter label=devcontainer.local_folder=\\wsl.localhost\Ubuntu\home\curtis\src\mydevcon --filter label=devcontainer.config_file=/home/curtis/src/mydevcon/.devcontainer/devcontainer.json
[1387 ms] Start: Run: docker inspect --type image ubuntu:24.04
[1426 ms] Resolving Feature dependencies for 'myfeature'...
[1426 ms] * Processing feature: myfeature
[1426 ms] Legacy feature 'myfeature' not supported. Please check https://containers.dev/features for replacements.
[1422 ms] Error: Legacy feature 'myfeature' not supported. Please check https://containers.dev/features for replacements.
...
[1428 ms] Exit code 1

After changing .devcontainer/devcontainer.json:

"features": { "./myfeature": {} }

The error is gone:

[884 ms] @devcontainers/cli 0.59.1. Node.js v18.18.2. linux 5.15.146.1-microsoft-standard-WSL2 x64.
[884 ms] Start: Run: docker buildx version
[941 ms] github.com/docker/buildx v0.14.0-desktop.1 7b0470cffd54ccbf42976d2f75febc4532c85073
[941 ms] 
[941 ms] Start: Run: docker -v
[968 ms] Start: Resolving Remote
[971 ms] Start: Run: git rev-parse --show-cdup
[975 ms] Start: Run: docker ps -q -a --filter label=devcontainer.local_folder=\\wsl.localhost\Ubuntu\home\curtis\src\mydevcon --filter label=devcontainer.config_file=/home/curtis/src/mydevcon/.devcontainer/devcontainer.json
[1013 ms] Start: Run: docker inspect --type container 1323df1e4d14
[1054 ms] Start: Removing Existing Container
[1054 ms] Start: Run: docker rm -f 1323df1e4d1482cdd184d9ac503c3179a880cb05372474405c8f7527d25557aa
[1113 ms] Start: Run: docker inspect --type image ubuntu:24.04
[1156 ms] Resolving Feature dependencies for './myfeature'...
[1156 ms] * Processing feature: ./myfeature
[1156 ms] Local disk feature.

Can we fix https://github.com/devcontainers/cli/blob/main/src/spec-configuration/containerFeaturesConfiguration.ts#L700 so the next poor schmuck that makes the same mistake I did doesn't waste hours tracking this down?

A simple "you forgot to prepend './' to your feature" would have really helped.

Or better yet, allow the WSL syntax with relative subdir without the leading './' would be nice!

[samruddhikhandale]

Hi 👋

"features": { "myfeature": {} }

^ was an older and deprecated approach for using Feature (even before the concept of dev container Features). Hence, the error message seems correct given the prior context.

However, I can understand how this might be confusing to you. Apologies for the inconvenience!

We can update the error message as 👇 Let us know if that will be helpful, thanks

Legacy feature '${userFeatureId}' not supported. Please check https://containers.dev/features for replacements. \n
If you were hoping to use local Features, remember to prepend your Feature name with "./". Please check https://containers.dev/implementors/features-distribution/#addendum-locally-referenced for more information."

[dotysan]

Legacy feature '${userFeatureId}' not supported. Please check https://containers.dev/features for replacements. \n
If you were hoping to use local Features, remember to prepend your Feature name with "./". Please check https://containers.dev/implementors/features-distribution/#addendum-locally-referenced for more information."

Yes, I presumed there was some history in that code. And that error message looks great!

[samruddhikhandale]

@prathameshzarkar9 / @gauravsaini04 Can either of you pick this up next? All it needs is an update to the logging & error message. See #834 (comment)

[prathameshzarkar9]

Hi @samruddhikhandale ,

I have created a PR for this fix. Modified the confusing error message displayed to the user as recommended.
#838