Support backtraces for crashing Swift binaries by Joannis · Pull Request #290 · wendylabsinc/wendy-agent

Joannis · 2026-01-31T19:51:01Z

Depends on a PR for swift-container-plugin.

codecov · 2026-01-31T20:09:25Z

Codecov Report

❌ Patch coverage is 0% with 149 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
Sources/Wendy/cli/commands/BuildCommand.swift	0.00%	66 Missing ⚠️
Sources/Wendy/SwiftPM.swift	0.00%	57 Missing ⚠️
...es/WendyAgent/Services/WendyContainerService.swift	0.00%	17 Missing ⚠️
Sources/Wendy/cli/commands/PackageCache.swift	0.00%	6 Missing ⚠️
Sources/Imager/DownloadSupport.swift	0.00%	3 Missing ⚠️

@@            Coverage Diff             @@
##             main     #290      +/-   ##
==========================================
- Coverage   13.11%   13.04%   -0.07%     
==========================================
  Files         137      137              
  Lines       25461    25603     +142     
==========================================
+ Hits         3338     3340       +2     
- Misses      22123    22263     +140

Flag	Coverage Δ
Linux	`11.23% <0.00%> (-0.06%)`	⬇️
macOS	`13.67% <0.00%> (-0.09%)`	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
Sources/Imager/DownloadSupport.swift	`0.00% <0.00%> (ø)`
Sources/Wendy/cli/commands/PackageCache.swift	`0.00% <0.00%> (ø)`
...es/WendyAgent/Services/WendyContainerService.swift	`0.00% <0.00%> (ø)`
Sources/Wendy/SwiftPM.swift	`0.00% <0.00%> (ø)`
Sources/Wendy/cli/commands/BuildCommand.swift	`0.00% <0.00%> (ø)`

... and 2 files with indirect coverage changes

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

…171) This is needed for swift-backtrace #154 . Following PR should be able to address that once we figure out https://forums.swift.org/t/where-to-source-swift-backtrace-binaries/84499 Motivation ---------- #154 ability to see backtraces for swift binaries. But generally it's also useful to set environment variables in containers for certain use cases. Modifications ------------- Allow passing in `--env`, so you can direct `SWIFT_BACKTRACE`. Result ------ Swift backtrace is possible on the end-user side. Example: wendylabsinc/wendy-agent#290 Test Plan --------- I did manual testing already in wendy-agent. You can trivially test this by passing `--env` and reading it out in a swift app with the following code: ```swift import Foundation print(ProcessInfo.processInfo.environment) ```

Joannis · 2026-02-02T11:56:52Z

PR upstream is merged

Joannis · 2026-02-03T08:31:20Z

Just recalled something, we'll want to add a check for the adopted swift-container-plugin version. Needs to be 1.3.0 or higher

Add warning if too low, and omit swift-backtrace

PR updated

Copilot

Pull request overview

Adds support for Swift crash backtraces when running/building Swift apps in Wendy-built containers, gated behind a newer swift-container-plugin version, and adds a small example app to validate crash behavior.

Changes:

Preserve image-provided environment variables in the agent by merging image config env with Wendy’s base env.
Detect swift-container-plugin version (cache it) and pass extra --env / --resources to swift package build-container-image to enable swift-backtrace.
Bump example dependency version and add a new “HelloCrash” example package for validating backtraces.

Reviewed changes

Copilot reviewed 8 out of 9 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
Sources/WendyAgent/Services/WendyContainerService.swift	Merge image config env with Wendy base env when generating OCI spec.
Sources/Wendy/cli/commands/RunCommand.swift	Detect plugin version (cached) and attempt to include swift-backtrace + env during `wendy run`.
Sources/Wendy/cli/commands/PackageCache.swift	Cache container plugin version alongside previous package analysis results.
Sources/Wendy/cli/commands/BuildCommand.swift	Enforce/upgrade plugin version and attempt to include swift-backtrace + env during `wendy build`.
Sources/Wendy/SwiftPM.swift	Add `--env` passthrough to container build; add dependency search + semver compare helper; add `updateDependencies()`.
Examples/HelloHTTP/Package.swift	Bump `swift-container-plugin` minimum version to 1.3.0.
Examples/HelloCrash/Sources/main.swift	New crash-on-launch sample to validate backtrace behavior.
Examples/HelloCrash/Package.swift	New minimal Swift package for the crash example.

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

Copilot

Pull request overview

Copilot reviewed 10 out of 11 changed files in this pull request and generated 3 comments.

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 11 out of 12 changed files in this pull request and generated 3 comments.

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

# Conflicts: # Sources/Wendy/cli/commands/BuildCommand.swift # Sources/Wendy/cli/commands/RunCommand.swift

Copilot

Pull request overview

Copilot reviewed 10 out of 11 changed files in this pull request and generated 4 comments.

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

Copilot · 2026-02-11T08:47:54Z

+                // Add swift-backtrace binaries for crash reporting
+                findBacktrace: for binaryName in [
+                    "swift-backtrace-static-linux-arm64",
+                    "swift-backtrace-linux-arm64",
+                ] where backtraceAvailable {
+                    let destination = "/swift-backtrace"
+                    if let backtraceUrl = Bundle.module.url(
+                        forResource: binaryName,
+                        withExtension: nil
+                    ) {
+                        resources.append((source: backtraceUrl.path(), destination: destination))
+                        additionalEnv.append(
+                            "SWIFT_BACKTRACE=enable=yes,sanitize=yes,threads=all,images=all,interactive=no,swift-backtrace=/swift-backtrace"
+                        )
+                        break findBacktrace
+                    }
+                    let backtraceUrl = URL(fileURLWithPath: CommandLine.arguments[0])
+                        .deletingLastPathComponent()
+                        .appending(path: "wendy-agent_wendy.bundle")
+                        .appending(path: "Contents")
+                        .appending(path: "Resources")
+                        .appending(path: "Resources")
+                        .appending(component: binaryName)
+
+                    if FileManager.default.fileExists(atPath: backtraceUrl.path()) {
+                        resources.append(
+                            (source: backtraceUrl.path(), destination: destination)
+                        )
+                        additionalEnv.append(
+                            "SWIFT_BACKTRACE=enable=yes,sanitize=yes,threads=all,images=all,interactive=no,swift-backtrace=/swift-backtrace"
+                        )
+                        break findBacktrace
+                    }
+                }


When backtraceAvailable is true but neither backtrace binary is found, the build proceeds silently without backtraces. Consider emitting a warning in that case (similar to the ds2 handling below) to make missing resources diagnosable.

Copilot

Pull request overview

Copilot reviewed 10 out of 11 changed files in this pull request and generated 5 comments.

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

Copilot · 2026-02-15T14:35:10Z

+                        entry[entry.index(after: separatorIndex)...]
+                    )
+                }
+                let env = envDict.map { "\($0.key)=\($0.value)" }


The environment variable dictionary is converted to an array using .map, which does not guarantee a stable ordering. This could lead to non-deterministic behavior when comparing environment variables or debugging. Consider sorting the output for deterministic results: let env = envDict.map { "\($0.key)=\($0.value)" }.sorted()

Suggested change

let env = envDict.map { "\($0.key)=\($0.value)" }

let env = envDict.map { "\($0.key)=\($0.value)" }.sorted()

Joannis mentioned this pull request Jan 31, 2026

Allow providing custom --env variables to be used in the container apple/swift-container-plugin#171

Merged

Support backtraces for crashing Swift binaries

68e0e09

Joannis force-pushed the jo/swift-backtrace branch from 3d6178b to 68e0e09 Compare January 31, 2026 19:56

Joannis marked this pull request as ready for review February 2, 2026 11:56

Joannis requested a review from a team as a code owner February 2, 2026 11:56

Joannis enabled auto-merge February 2, 2026 13:43

zamderax previously approved these changes Feb 3, 2026

View reviewed changes

Check the swift-container-plugin version

2f3d60c

Add warning if too low, and omit swift-backtrace

Joannis requested a review from zamderax February 3, 2026 08:58

Formatting

9844716

Joannis requested review from mihai-chiorean February 5, 2026 20:14

Merge branch 'main' into jo/swift-backtrace

0237ecb

Copilot AI review requested due to automatic review settings February 8, 2026 21:54

Copilot started reviewing on behalf of Joannis February 8, 2026 21:55 View session

Copilot AI reviewed Feb 8, 2026

View reviewed changes

Comment thread Sources/Wendy/cli/commands/BuildCommand.swift

Comment thread Sources/Wendy/cli/commands/RunCommand.swift Outdated

Comment thread Sources/Wendy/SwiftPM.swift Outdated

Comment thread Sources/Wendy/SwiftPM.swift

Comment thread Sources/Wendy/SwiftPM.swift Outdated

Joannis added 3 commits February 9, 2026 08:22

Fix Noora usage

3f09e79

Add backtrace env in hotpath

62f5011

Remove dead code

166a732

Copilot AI review requested due to automatic review settings February 9, 2026 07:24

Copilot started reviewing on behalf of Joannis February 9, 2026 07:24 View session

Copilot AI reviewed Feb 9, 2026

View reviewed changes

Comment thread Sources/Wendy/cli/commands/RunCommand.swift Outdated

Comment thread Sources/Imager/DownloadSupport.swift

Comment thread Sources/Wendy/SwiftPM.swift Outdated

Update Sources/Wendy/cli/commands/BuildCommand.swift

14eb8b1

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Copilot AI review requested due to automatic review settings February 9, 2026 20:41

Copilot started reviewing on behalf of Joannis February 9, 2026 20:41 View session

Joannis and others added 2 commits February 9, 2026 21:42

Update Sources/Wendy/SwiftPM.swift

3828929

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Address feedback

7942f3f

Copilot AI reviewed Feb 9, 2026

View reviewed changes

Comment thread Sources/Wendy/SwiftPM.swift

Comment thread Sources/Wendy/cli/commands/RunCommand.swift Outdated

Comment thread Sources/Wendy/cli/commands/RunCommand.swift Outdated

Joannis added 2 commits February 10, 2026 18:28

Cleanup findBacktrace and applying it

138cd00

Merge remote-tracking branch 'origin/main' into jo/swift-backtrace

670577f

# Conflicts: # Sources/Wendy/cli/commands/BuildCommand.swift # Sources/Wendy/cli/commands/RunCommand.swift

Copilot AI review requested due to automatic review settings February 11, 2026 08:39

Copilot started reviewing on behalf of Joannis February 11, 2026 08:39 View session

Copilot AI reviewed Feb 11, 2026

View reviewed changes

Joannis added 2 commits February 15, 2026 15:25

Merge the env while deduplicating keys

e02e270

Add warning Swift backtracing is missing

e8eff90

Copilot AI review requested due to automatic review settings February 15, 2026 14:26

Joannis force-pushed the jo/swift-backtrace branch from d557da3 to e8eff90 Compare February 15, 2026 14:26

Copilot started reviewing on behalf of Joannis February 15, 2026 14:27 View session

Copilot AI reviewed Feb 15, 2026

View reviewed changes

Implement github copilot nits

eedb111

mihai-chiorean approved these changes Feb 19, 2026

View reviewed changes

Comment thread Sources/Wendy/Resources/swift-backtrace-linux-arm64

Comment thread Sources/WendyAgent/Services/WendyContainerService.swift

Joannis disabled auto-merge February 19, 2026 14:11

Joannis merged commit 7dce643 into main Feb 19, 2026
8 of 9 checks passed

Joannis deleted the jo/swift-backtrace branch February 19, 2026 14:11

	let env = envDict.map { "\($0.key)=\($0.value)" }
	let env = envDict.map { "\($0.key)=\($0.value)" }.sorted()

Conversation

Joannis commented Jan 31, 2026

Uh oh!

codecov bot commented Jan 31, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Codecov Report

Uh oh!

Joannis commented Feb 2, 2026

Uh oh!

Joannis commented Feb 3, 2026

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Reviewed changes

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

Uh oh!

Copilot AI Feb 11, 2026

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

Copilot AI Feb 15, 2026

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

4 participants

codecov bot commented Jan 31, 2026 •

edited

Loading