fix(agent): start devcontainers through agentcontainers package #18471

DanielleMaywood · 2025-06-20T14:49:54Z

Context for the implementation here
coder/internal#706 (comment)

Synchronously starts dev containers defined in terraform with our DevcontainerCLI abstraction, instead of piggybacking off of our agentscripts package. This gives us more control over logs, instead of being reliant on packages which may or may not exist in the user-provided image.

Fixes coder/internal#706 Context for the implementation here coder/internal#706 (comment) Synchronously starts dev containers defined in terraform with our `DevcontainerCLI` abstraction, instead of piggybacking off of our `agentscripts` package. This gives us more control over logs, instead of being reliant on packages which may or may not exist in the user-provided image.

Copilot

Pull Request Overview

This PR refactors how devcontainers are started by splitting out the devcontainer CLI functionality from the agentscripts package. Key changes include removing post start scripts from agentscripts, updating tests to reference new expected outputs and behavior, and updating the API to synchronously trigger devcontainer creation via a new CreateDevcontainer method.

Reviewed Changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
agent/agentscripts/agentscripts_test.go	Removed tests for post-start scripts and updated expectations.
agent/agentscripts/agentscripts.go	Refactored to remove runnerScript and post start script logic.
agent/agentcontainers/testdata/devcontainercli/parse/up.expected	Updated expected log output for devcontainer CLI.
agent/agentcontainers/devcontainercli_test.go	Updated test file references to expected log output file.
agent/agentcontainers/devcontainercli.go	Updated option defaults and logging writer behavior.
agent/agentcontainers/devcontainer_test.go	Entire file removed, reflecting changes in devcontainer handling.
agent/agentcontainers/devcontainer.go	Removed devcontainer script extraction helper functions.
agent/agentcontainers/api.go	Modified recreateDevcontainer to return errors and added CreateDevcontainer.
agent/agent.go	Removed legacy handling of experimental devcontainers and added calls to containerAPI.CreateDevcontainer.

Comments suppressed due to low confidence (1)

Copilot · 2025-06-20T15:35:14Z

agent/agentcontainers/devcontainercli.go

@@ -401,6 +408,7 @@ func (l *devcontainerCLILogWriter) Write(p []byte) (n int, err error) {
 		}
 		if logLine.Level >= 3 {
 			l.logger.Info(l.ctx, "@devcontainer/cli", slog.F("line", string(line)))
+			_, _ = l.writer.Write([]byte(logLine.Text + "\n"))


It might be beneficial to check the error returned by l.writer.Write rather than ignoring it. Handling any potential write failure could improve the reliability of the logging.

Suggested change

_, _ = l.writer.Write([]byte(logLine.Text + "\n"))

if _, err := l.writer.Write([]byte(logLine.Text + "\n")); err != nil {

l.logger.Error(l.ctx, "failed to write to log writer", slog.Error(err), slog.F("text", logLine.Text))

}

mafredri

Cursory glance looks good! 👍🏻

Couple of notes (in addition to inline comments):

Testing, this could be done in agent_test.go for e.g. autostart integration test
A api_test.go to test CreateDevcontainer behavior
(Re-introduce agent script timing for autostart of devcontainer, not critical for GA, but perhaps track via ticket or if simple a follow-up PR.)

mafredri · 2025-06-24T12:51:20Z

agent/agent.go

+
+				if cAPI := a.containerAPI.Load(); cAPI != nil {
+					for _, dc := range manifest.Devcontainers {
+						err = errors.Join(err, cAPI.CreateDevcontainer(dc))


I think it's a good idea to do these sync so we avoid potential Docker concurrency races, it'd be nice if it was asynchronous but let's go with this!

mafredri · 2025-06-24T12:52:59Z

agent/agentcontainers/api.go

+	api.asyncWg.Add(1)
+	api.mu.Unlock()
+
+	return api.recreateDevcontainer(dc, dc.ConfigPath)


How about we rename this createDevcontainer and make recreate an argument? I'm thinking that iff users use a docker volume for Docker, it might be nice if we didn't delete/recreate the existing container that was persisted across workspace restart. 🤔

I'd like to bump this idea, not critical to get this merged though.

I'm not entirely sure I understand what the difference would be? What would the recreate argument make it do differently?

It would decide whether or not to pass WithRemoveExistingContainer to the up command. If not given and the container exists but is stopped, it would simply be started rather than removed and a new created in its place. May allow users to persist fs changes in their devcontainer across workspace restarts.

mafredri · 2025-06-24T12:53:15Z

agent/agentcontainers/devcontainer.go

-	// have not been enabled, a warning will be surfaced in the agent logs.
-	script.RunOnStart = false
-	return script
-}


mafredri · 2025-06-24T12:57:56Z

agent/agentscripts/agentscripts.go

-			})
-		}
-	}
-}


Good bye my beautiful hack! 👋🏻

agent/agentcontainers/devcontainercli_test.go

agent/agentcontainers/api.go

mafredri

Largely looks good, but I still have some concerns with initialization order of the containers API (see comment). Ideally it would be initialized early, like e.g. SSH server, then the race could be avoided.

agent/agent.go

mafredri · 2025-06-24T21:08:43Z

agent/api.go

-					agentcontainers.WithDevcontainers(manifest.Devcontainers, manifest.Scripts),
-				)
-			}
+		if cAPI := a.containerAPI.Load(); cAPI != nil {


I imagine there could be a race here? And since this method will only be called once, we would then never correctly set the routes if that happens. Just considering since we saw the race the other way today, but this seems to have worked as intended before.

It would also be good to verify that cAPI.UpdateSubAgentClient still gets called in an appropriate location/order considering the refactor.

Quite possibly. I'll need to address updating the WithManifestInfo call as we won't have the manifest information yet.

I've given it a go, let me know if I've done anything obviously wrong.

I think it can work! It's a bit different than what I had in mind but yours is probably better tbh 😄

mafredri · 2025-06-24T21:14:11Z

agent/agentcontainers/api.go

+	api.asyncWg.Add(1)
+	api.mu.Unlock()
+
+	return api.recreateDevcontainer(dc, dc.ConfigPath)


I'd like to bump this idea, not critical to get this merged though.

mafredri · 2025-06-24T22:10:35Z

agent/agentcontainers/api.go


 	return api
 }

+func (api *API) Init(opts ...Option) {


Suggestion: Document purpose and also special behavior (like must only be called once).

~~An option is also to move watcher/updater start here, which would remove the need for the waiting goroutine in NewAPI, but either works.~~ Perhaps better if kept as-is, but just amend the channel closing.

mafredri · 2025-06-24T22:16:31Z

agent/agentcontainers/api.go

+			break
+		case <-api.initialized:
+			go api.watcherLoop()
+			go api.updaterLoop()


An important consideration here is that Close is dependent on these functions closing their channels.

mafredri · 2025-06-24T22:17:55Z

agent/api.go

-					agentcontainers.WithDevcontainers(manifest.Devcontainers, manifest.Scripts),
-				)
-			}
+		if cAPI := a.containerAPI.Load(); cAPI != nil {


I think it can work! It's a bit different than what I had in mind but yours is probably better tbh 😄

github-actions bot assigned DanielleMaywood Jun 20, 2025

DanielleMaywood added 2 commits June 20, 2025 14:52

chore: appease formatter

fe99bd6

chore: fix test, appease linter

aeae6e2

DanielleMaywood requested a review from Copilot June 20, 2025 15:34

Copilot AI reviewed Jun 20, 2025

View reviewed changes

mafredri reviewed Jun 24, 2025

View reviewed changes

DanielleMaywood added 10 commits June 24, 2025 13:43

chore: feedback

916f7e8

Merge branch 'main' into dm-devcontainer-log-spam

53e256b

chore: re-add script timings

91bb43a

fix: change how containerAPI is stored

81fe11d

Merge branch 'main' into dm-devcontainer-log-spam

5c70a8c

chore: appease linter

8437ca4

chore: ensure the last log line is printed

2c6a2b1

chore: fix typo

a512ad4

chore: OOPS

c50dc6e

chore: 1 -> 2

4d40ef2

DanielleMaywood marked this pull request as ready for review June 24, 2025 20:40

DanielleMaywood requested review from mafredri and johnstcn June 24, 2025 20:40

mafredri reviewed Jun 24, 2025

View reviewed changes

DanielleMaywood added 3 commits June 24, 2025 21:22

chore: add a status to the timings

ce32e2e

chore: initialize containerapi even earlier

32ac48a

chore: only enable when devcontainers are enabled

738b755

mafredri reviewed Jun 24, 2025

View reviewed changes

-			_, _ = l.writer.Write([]byte(logLine.Text + "\n"))
+			if _, err := l.writer.Write([]byte(logLine.Text + "\n")); err != nil {
+				l.logger.Error(l.ctx, "failed to write to log writer", slog.Error(err), slog.F("text", logLine.Text))
+			}

fix(agent): start devcontainers through agentcontainers package #18471

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fix(agent): start devcontainers through agentcontainers package #18471

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DanielleMaywood commented Jun 20, 2025 •

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mafredri Jun 24, 2025 •

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