fix: include docker stderr in error messages by optimus-fulcria · Pull Request #278 · agentregistry-dev/agentregistry

optimus-fulcria · 2026-03-06T00:10:04Z

Description

When Docker commands fail, only stdout was captured, making it difficult to diagnose build and deployment failures. Docker typically writes error details to stderr.

The Executor.Run method in docker.go now uses io.MultiWriter(os.Stderr, &stderrBuf) to both display stderr in real time and capture it for inclusion in the returned error message when the command fails.

To reduce log pollution, outputs are now backed by --verbose flag. Following a similar approach to the agentregistry-runtime, we print to both stderr + buffer error when verbose is enabled, else we simply output the buffer-captured error with the returned error message.

Fixes #193

Validation

# init a skill
go run cmd/cli/main.go skill init test

Non-verbose output would only log the captured docker error

# invalid build without verbose logging
go run cmd/cli/main.go skill build test --image 'invalid!!tag'

Building skill "hello-world-template" as Docker image: invalid!!tag
Error: build failed for skill "hello-world-template": docker build failed: exit status 1
ERROR: failed to build: invalid tag "invalid!!tag": invalid reference format
exit status 1

Verbose output will log std logs, the stderr, and final captured docker error (which technically leads to duplicated from stderr + captured err returned)

# invalid skill with verbose logging
go run cmd/cli/main.go skill build test --image 'invalid!!tag' --verbose

Building skill "hello-world-template" as Docker image: invalid!!tag
Running: docker build -t invalid!!tag -f /var/folders/zy/pkk0_2ys5yx8y1syxw5xjxhh0000gn/T/skill-dockerfile-654053150 /Users/fabiangonz98/go/src/github.com/solo-io/agentregistry/test
Working directory: /Users/fabiangonz98/go/src/github.com/solo-io/agentregistry/test
ERROR: failed to build: invalid tag "invalid!!tag": invalid reference format
Error: build failed for skill "hello-world-template": docker build failed: exit status 1
ERROR: failed to build: invalid tag "invalid!!tag": invalid reference format
exit status 1

Change Type

/kind fix

Changelog

Include docker stderr in error messages for better debugging

Additional Notes

peterj · 2026-03-06T17:24:27Z

please update the PR template

peterj

please update the PR template

github-actions · 2026-03-06T23:02:29Z

You already have 3 pull requests open. Please consider working on getting the existing ones merged before opening new ones. Thanks!

optimus-fulcria · 2026-03-06T23:35:26Z

PR description has been updated to match the template (Description, Change Type, Changelog, Additional Notes sections).

github-actions · 2026-03-07T00:03:29Z

You already have 3 pull requests open. Please consider working on getting the existing ones merged before opening new ones. Thanks!

github-actions · 2026-03-07T00:09:43Z

You already have 3 pull requests open. Please consider working on getting the existing ones merged before opening new ones. Thanks!

github-actions · 2026-03-07T01:03:05Z

You already have 3 pull requests open. Please consider working on getting the existing ones merged before opening new ones. Thanks!

github-actions · 2026-03-07T01:35:37Z

You already have 3 pull requests open. Please consider working on getting the existing ones merged before opening new ones. Thanks!

Capture stderr from docker commands via io.MultiWriter so that when a docker build, push, or pull fails the error message includes the actual docker error output. Stderr is still streamed to the terminal in real time so interactive UX is unchanged. Fixes agentregistry-dev#193 Co-Authored-By: Claude Opus 4.6 <[email protected]>

github-actions · 2026-03-11T10:09:03Z

You already have 3 pull requests open. Please consider working on getting the existing ones merged before opening new ones. Thanks!

github-actions · 2026-03-11T10:09:13Z

You already have 3 pull requests open. Please consider working on getting the existing ones merged before opening new ones. Thanks!

optimus-fulcria · 2026-03-11T10:12:50Z

Updated the PR template and rebased on latest main. The buildSkillDockerImage function was removed upstream, so the publish.go changes are no longer needed. The stderr capture now lives centrally in Executor.Run in docker.go, which handles all docker commands (build, push, pull, etc.).

optimus-fulcria · 2026-03-11T10:36:24Z

PR template has been updated to follow the standard format (Description, Change Type, Changelog, Additional Notes). Ready for re-review.

optimus-fulcria · 2026-03-11T12:36:37Z

@peterj The PR description has been updated to follow the standard template format (Description, Change Type, Changelog, Additional Notes). Ready for re-review.

github-actions · 2026-03-11T14:02:54Z

You already have 3 pull requests open. Please consider working on getting the existing ones merged before opening new ones. Thanks!

optimus-fulcria · 2026-03-11T14:03:34Z

Updated PR description to match the template. Ready for re-review.

github-actions · 2026-03-11T16:05:53Z

You already have 3 pull requests open. Please consider working on getting the existing ones merged before opening new ones. Thanks!

github-actions · 2026-03-11T18:35:02Z

You already have 3 pull requests open. Please consider working on getting the existing ones merged before opening new ones. Thanks!

github-actions · 2026-03-11T18:35:02Z

You already have 3 pull requests open. Please consider working on getting the existing ones merged before opening new ones. Thanks!

Signed-off-by: Fabian Gonzalez <[email protected]>

github-actions bot added do-not-merge/description-invalid do-not-merge/kind-invalid do-not-merge/release-note-invalid labels Mar 6, 2026

peterj requested changes Mar 6, 2026

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github-actions bot added kind/fix release-note and removed do-not-merge/description-invalid do-not-merge/kind-invalid do-not-merge/release-note-invalid labels Mar 6, 2026

inFocus7 mentioned this pull request Mar 11, 2026

Publishing skill shows unhelpful 'exit status 1' on docker failures #193

Closed

use verbosity for docker logs

ba4a5d7

Signed-off-by: Fabian Gonzalez <[email protected]>

inFocus7 force-pushed the fix/docker-stderr-in-error branch from 97e1bf0 to ba4a5d7 Compare March 11, 2026 21:28

peterj approved these changes Mar 12, 2026

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peterj added this pull request to the merge queue Mar 12, 2026

Merged via the queue into agentregistry-dev:main with commit 573bb30 Mar 12, 2026
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optimus-fulcria commented Mar 6, 2026 •

edited by inFocus7

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