Allow flutter attach to discover flutter engine running on Custom Device #170635

dannyvalentesonos · 2025-06-14T16:29:20Z

Summary

A Custom Device's log reader doesn't do anything, and thus flutter attach will fail to ever find the flutter engine's VM service.

This change adds a new readLogs command to the CustomDeviceConfig, and which allows a custom device to read the logs from the running flutter app on the actual custom device, and then allow flutter attach to work.

Fixes #170634

Testing

Created a custom device, and added the following readLogs command in the custom_devices.json file:

"readLogs": [
        "sshpass",
        "-f",
        "/home/dvalente/player.txt",
        "ssh",
        "[email protected]",
        "tail -Fn +1 /opt/log/flutter.log"
      ]

Then, running flutter attach works every time.

Tested the following scenarios:

Launched flutter attach before app is running on device, and once app runs, flutter attach succeeds
Launched flutter attach after app is already running on device, and flutter attach succeeds.
Used flutter attach in Android Studio, and hot reload works just like any Android device.

flutter-dashboard · 2025-06-14T16:29:23Z

It looks like this pull request may not have tests. Please make sure to add tests or get an explicit test exemption before merging.

If you are not sure if you need tests, consider this rule of thumb: the purpose of a test is to make sure someone doesn't accidentally revert the fix. Ask yourself, is there anything in your PR that you feel it is important we not accidentally revert back to how it was before your fix?

Reviewers: Read the Tree Hygiene page and make sure this patch meets those guidelines before LGTMing.If you believe this PR qualifies for a test exemption, contact "@test-exemption-reviewer" in the #hackers channel in Discord (don't just cc them here, they won't see it!). The test exemption team is a small volunteer group, so all reviewers should feel empowered to ask for tests, without delegating that responsibility entirely to the test exemption group.

bkonyi

I like this! I do think we'll need some more thorough tests that actually exercise the behavior of the log reader before I can approve this. This could be as simple as setting the readLogs command to echo some message and then verifying we're actually able to see it.

packages/flutter_tools/lib/src/custom_devices/custom_device.dart

dannyvalentesonos · 2025-06-30T18:47:19Z

I like this! I do think we'll need some more thorough tests that actually exercise the behavior of the log reader before I can approve this. This could be as simple as setting the readLogs command to echo some message and then verifying we're actually able to see it.

Thanks for the comment @bkonyi! Can you point me to where this test should live? I have not been able to find where the other commands from the custom device are unit tested anywhere. Thanks!

bkonyi · 2025-07-02T14:54:15Z

Thanks for the comment @bkonyi! Can you point me to where this test should live? I have not been able to find where the other commands from the custom device are unit tested anywhere. Thanks!

I think they can live in packages/flutter_tools/test/commands.shard/hermetic/custom_devices_test.dart

dannyvalentesonos · 2025-07-07T23:26:36Z

Thanks for the comment @bkonyi! Can you point me to where this test should live? I have not been able to find where the other commands from the custom device are unit tested anywhere. Thanks!

I think they can live in packages/flutter_tools/test/commands.shard/hermetic/custom_devices_test.dart

@bkonyi I've added the unit test. Thanks!

bkonyi

LGTM overall! Thanks for adding the test!

packages/flutter_tools/lib/src/custom_devices/custom_device.dart

A Custom Device's log reader doesn't do anything, and thus `flutter attach` will fail to ever find the flutter engine's VM service. This change adds a new `readLogs` command to the CustomDeviceConfig, and which allows a custom device to read the logs from the running flutter app on the actual custom device, and then allow flutter attach to work.

dannyvalentesonos · 2025-07-09T19:06:55Z

@bkonyi I do not have access to merge this PR. Would you do it for me please? Thanks!

matanlurey · 2025-07-09T19:23:30Z

I got it.

auto-submit · 2025-07-09T19:25:20Z

autosubmit label was removed for flutter/flutter/170635, because This PR has not met approval requirements for merging. The PR author is not a member of flutter-hackers and needs 1 more review(s) in order to merge this PR.

Merge guidelines: A PR needs at least one approved review if the author is already part of flutter-hackers or two member reviews if the author is not a flutter-hacker before re-applying the autosubmit label. Reviewers: If you left a comment approving, please use the "approve" review action instead.

dannyvalentesonos · 2025-07-10T14:34:40Z

@bkonyi From code inspection, I noticed that the desktop implementations also have the same issue. If so, I feel it could be beneficial to add the same type of thing for those platforms too...

…Custom Device (flutter/flutter#170635)

flutter/flutter@ac12f66...43657f3 2025-07-10 [email protected] [web] Add frame number support. (flutter/flutter#171592) 2025-07-10 [email protected] Fix the hitTest issue of reversed SliverMainAxisGroup. (flutter/flutter#171073) 2025-07-10 [email protected] Roll Fuchsia Linux SDK from 0-xqmXWc4cXzw3tfe... to lO64ePNEGrGzs-MFC... (flutter/flutter#171937) 2025-07-10 [email protected] Refactor compositor classes (flutter/flutter#171414) 2025-07-10 [email protected] Give an actionable error to `flutter_test.*tap` of a `RenderSliver` (flutter/flutter#171930) 2025-07-10 [email protected] Fix the issue with `SliverMainAxisGroups` growing in the reverse direction during layout. (flutter/flutter#171005) 2025-07-09 [email protected] Adds a MCP server for working with the engine (flutter/flutter#171738) 2025-07-09 [email protected] Use Async SurfaceHolder Callback to remove need for setting alpha workaround (flutter/flutter#171398) 2025-07-09 [email protected] Update `CHANGELOG` for 3.32.5, 3.32.6 stable hotfix releases (flutter/flutter#171891) 2025-07-09 [email protected] Add `flutter config --enable-omit-legacy-version-file` (flutter/flutter#171903) 2025-07-09 [email protected] Allow flutter attach to discover flutter engine running on Custom Device (flutter/flutter#170635) 2025-07-09 [email protected] Hide the rarely direct used `--sample` argument by default (flutter/flutter#171898) 2025-07-09 [email protected] Support `NO_COLOR` to opt-out of `flutter` tool ANSI colors (flutter/flutter#171892) 2025-07-09 [email protected] [Android 16] Added Docs to Warn Users that SystemChrome.setPreferredOrientations will Not Work (flutter/flutter#171089) 2025-07-09 [email protected] Add analytics events for wasm dry runs on web builds (flutter/flutter#171818) 2025-07-09 [email protected] feat: new builders for size experiment (flutter/flutter#171886) 2025-07-09 [email protected] Update `.gitignore`s (flutter/flutter#171907) 2025-07-09 [email protected] Add total execution time to the flutter upgrade command (flutter/flutter#171475) 2025-07-09 [email protected] Simplify the template for infrastructure requests (flutter/flutter#171905) 2025-07-09 [email protected] Add detailed error message for BorderRadiusDirectional (flutter/flutter#171805) 2025-07-09 [email protected] Add public postmortem of the 3.32.3 release. (flutter/flutter#171904) 2025-07-09 [email protected] Make `labels` field an array (flutter/flutter#171906) 2025-07-09 98614782+auto-submit[bot]@users.noreply.github.com Reverts "Reverts "Roll Packages from cba2e90 to 4a231ae (5 revisions) (#171879)" (#171897)" (flutter/flutter#171910) 2025-07-09 98614782+auto-submit[bot]@users.noreply.github.com Reverts "Roll Packages from cba2e90 to 4a231ae (5 revisions) (#171879)" (flutter/flutter#171897) 2025-07-09 [email protected] [skia] Fix flag fiddling for Fuchsia, FreeType, & friends (flutter/flutter#171874) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages Please CC [email protected],[email protected] on the revert to ensure that a human is aware of the problem. To file a bug in Packages: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

…ice (flutter#170635) ## Summary A Custom Device's log reader doesn't do anything, and thus `flutter attach` will fail to ever find the flutter engine's VM service. This change adds a new `readLogs` command to the CustomDeviceConfig, and which allows a custom device to read the logs from the running flutter app on the actual custom device, and then allow flutter attach to work. Fixes flutter#170634 ## Testing Created a custom device, and added the following readLogs command in the `custom_devices.json` file: ``` "readLogs": [ "sshpass", "-f", "/home/dvalente/player.txt", "ssh", "[email protected]", "tail -Fn +1 /opt/log/flutter.log" ] ``` Then, running `flutter attach` works every time. **Tested the following scenarios:** * Launched `flutter attach` before app is running on device, and once app runs, flutter attach succeeds * Launched `flutter attach` after app is already running on device, and flutter attach succeeds. * Used `flutter attach` in Android Studio, and hot reload works just like any Android device.

…r#9589) flutter/flutter@ac12f66...43657f3 2025-07-10 [email protected] [web] Add frame number support. (flutter/flutter#171592) 2025-07-10 [email protected] Fix the hitTest issue of reversed SliverMainAxisGroup. (flutter/flutter#171073) 2025-07-10 [email protected] Roll Fuchsia Linux SDK from 0-xqmXWc4cXzw3tfe... to lO64ePNEGrGzs-MFC... (flutter/flutter#171937) 2025-07-10 [email protected] Refactor compositor classes (flutter/flutter#171414) 2025-07-10 [email protected] Give an actionable error to `flutter_test.*tap` of a `RenderSliver` (flutter/flutter#171930) 2025-07-10 [email protected] Fix the issue with `SliverMainAxisGroups` growing in the reverse direction during layout. (flutter/flutter#171005) 2025-07-09 [email protected] Adds a MCP server for working with the engine (flutter/flutter#171738) 2025-07-09 [email protected] Use Async SurfaceHolder Callback to remove need for setting alpha workaround (flutter/flutter#171398) 2025-07-09 [email protected] Update `CHANGELOG` for 3.32.5, 3.32.6 stable hotfix releases (flutter/flutter#171891) 2025-07-09 [email protected] Add `flutter config --enable-omit-legacy-version-file` (flutter/flutter#171903) 2025-07-09 [email protected] Allow flutter attach to discover flutter engine running on Custom Device (flutter/flutter#170635) 2025-07-09 [email protected] Hide the rarely direct used `--sample` argument by default (flutter/flutter#171898) 2025-07-09 [email protected] Support `NO_COLOR` to opt-out of `flutter` tool ANSI colors (flutter/flutter#171892) 2025-07-09 [email protected] [Android 16] Added Docs to Warn Users that SystemChrome.setPreferredOrientations will Not Work (flutter/flutter#171089) 2025-07-09 [email protected] Add analytics events for wasm dry runs on web builds (flutter/flutter#171818) 2025-07-09 [email protected] feat: new builders for size experiment (flutter/flutter#171886) 2025-07-09 [email protected] Update `.gitignore`s (flutter/flutter#171907) 2025-07-09 [email protected] Add total execution time to the flutter upgrade command (flutter/flutter#171475) 2025-07-09 [email protected] Simplify the template for infrastructure requests (flutter/flutter#171905) 2025-07-09 [email protected] Add detailed error message for BorderRadiusDirectional (flutter/flutter#171805) 2025-07-09 [email protected] Add public postmortem of the 3.32.3 release. (flutter/flutter#171904) 2025-07-09 [email protected] Make `labels` field an array (flutter/flutter#171906) 2025-07-09 98614782+auto-submit[bot]@users.noreply.github.com Reverts "Reverts "Roll Packages from cba2e90 to 4a231ae (5 revisions) (#171879)" (#171897)" (flutter/flutter#171910) 2025-07-09 98614782+auto-submit[bot]@users.noreply.github.com Reverts "Roll Packages from cba2e90 to 4a231ae (5 revisions) (#171879)" (flutter/flutter#171897) 2025-07-09 [email protected] [skia] Fix flag fiddling for Fuchsia, FreeType, & friends (flutter/flutter#171874) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages Please CC [email protected],[email protected] on the revert to ensure that a human is aware of the problem. To file a bug in Packages: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

…Custom Device (flutter/flutter#170635)

…ice (flutter#170635) ## Summary A Custom Device's log reader doesn't do anything, and thus `flutter attach` will fail to ever find the flutter engine's VM service. This change adds a new `readLogs` command to the CustomDeviceConfig, and which allows a custom device to read the logs from the running flutter app on the actual custom device, and then allow flutter attach to work. Fixes flutter#170634 ## Testing Created a custom device, and added the following readLogs command in the `custom_devices.json` file: ``` "readLogs": [ "sshpass", "-f", "/home/dvalente/player.txt", "ssh", "[email protected]", "tail -Fn +1 /opt/log/flutter.log" ] ``` Then, running `flutter attach` works every time. **Tested the following scenarios:** * Launched `flutter attach` before app is running on device, and once app runs, flutter attach succeeds * Launched `flutter attach` after app is already running on device, and flutter attach succeeds. * Used `flutter attach` in Android Studio, and hot reload works just like any Android device.

github-actions bot added the tool Affects the "flutter" command-line tool. See also t: labels. label Jun 14, 2025

dannyvalentesonos mentioned this pull request Jun 16, 2025

Flutter attach never finds the running app on a custom device #170634

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dannyvalentesonos force-pushed the topic/fix_vm_discovery_custom_device branch 2 times, most recently from e11f162 to 7b1d1c7 Compare June 16, 2025 18:19

bkonyi reviewed Jun 23, 2025

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dannyvalentesonos force-pushed the topic/fix_vm_discovery_custom_device branch 5 times, most recently from 0b4c094 to 79ea8ff Compare July 7, 2025 21:57

bkonyi approved these changes Jul 8, 2025

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packages/flutter_tools/lib/src/custom_devices/custom_device.dart Outdated Show resolved Hide resolved

dannyvalentesonos added 13 commits July 8, 2025 10:33

Added 'readLogs' to expected custom device config for unit tests

4a93bd7

Fixed analyze error

b3ad830

Formatting

67eaa4d

Use async/await

90077c0

Fix build break

341c288

Formatted dart file

1a702c9

Add readLogsCommand unit test

80de253

Fix analyzer errors

ba502c4

Using the config directly

ad01371

Run formatter again

bd9375f

Fix new analyzer errors with new dart version

bb2c1c5

Fix more analysis issues

1b17abb

Remove redundant return statement

9672a8d

dannyvalentesonos force-pushed the topic/fix_vm_discovery_custom_device branch from 128dc92 to 9672a8d Compare July 8, 2025 14:33

Merge branch 'master' into topic/fix_vm_discovery_custom_device

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Merged via the queue into flutter:master with commit 953b6e4 Jul 9, 2025
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engine-flutter-autoroll mentioned this pull request Jul 10, 2025

Roll Flutter from ac12f66681f1 to 43657f3baa17 (25 revisions) flutter/packages#9589

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…Custom Device (flutter/flutter#170635)

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engine-flutter-autoroll added a commit to engine-flutter-autoroll/packages that referenced this pull request Aug 14, 2025

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…Custom Device (flutter/flutter#170635)

engine-flutter-autoroll added a commit to engine-flutter-autoroll/packages that referenced this pull request Aug 15, 2025

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engine-flutter-autoroll added a commit to engine-flutter-autoroll/packages that referenced this pull request Aug 15, 2025

953b6e4a2 Allow flutter attach to discover flutter engine running on …

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…Custom Device (flutter/flutter#170635)

engine-flutter-autoroll added a commit to engine-flutter-autoroll/packages that referenced this pull request Aug 16, 2025

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