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[BUG] webServer.reuseExistingServer is broken on node 18 #24101
Description
System info
- Playwright Version: [v1.35.1]
- Operating System: [All]
- Browser: [All]
Source code
- I provided exact source code that allows reproducing the issue locally.
Link to the GitHub repository with the repro
Steps
- Clone this repo and using your shell of choice navigate to the root of the repo.
- Execute
npm start. This will build and run an angular app. - Once the angular app is running, execute
npm test
When running with node 16.19.1 the output after step 3 is:
> [email protected] test
> npx playwright test
Running 1 test using 1 worker
✓ 1 [chromium] › example.spec.ts:3:5 › dummy test (1.8s)
1 passed (2.6s)
When running with node 18.16.0 the output after step 3 is:
> [email protected] test
> npx playwright test
[WebServer] ? Port 4200 is already in use.
Would you like to use a different port? (Y/n) [WebServer]
Error: Timed out waiting 30000ms from config.webServer.
As you can see, it tries to execute the webServer.command and then eventually times out because the port is already taken.
Expected
When running on node 18.16.0 it should NOT try to execute the webServer.command when webServer.reuseExistingServer is set to true.
Actual
When running on node 18.16.0 it executes the webServer.command when webServer.reuseExistingServer is set to true.
Other
I used nvm to swap between node versions whilst testing this.
Activity
pavelfeldman commentedon Jul 7, 2023
Here is what I get on Node 18:
edumserrano commentedon Jul 7, 2023
Since you're running with node
18.6.1, I've installed that version but I still get the same problem:I'm running on Windows build
10.0.19045.0and through powershell7.3.5. Any thoughts?pavelfeldman commentedon Jul 7, 2023
I would guess that the problem is due to the ipv4 vs ipv6 mismatch, Node migrated to ipv6 in Node 18. So if you are already running ng on ipv4 elsewhere, it could probably manifest this way. But I'm trying this on Linux and it works fine. I ran
npx ng serve --port 4200on Node 16 and then ran tests on Node 18.edumserrano commentedon Jul 7, 2023
Hum... On my windows machine if I try to use the demo repo I provided on this issue and from the root of the repo I run:
docker run -it --rm --ipc=host --workdir=/app -v "$(Get-Location):/app" mcr.microsoft.com/playwright:v1.35.1-jammy npx playwright testI still get an error that indicates that Playwright is trying to execute the
webServer.command:P.S: I do know that I didn't start anything on port 4000 inside the container so it would always timeout eventually, but I shouldn't see the message from the WebServer trying to execute the
commandinstruction with will dong serveand is where thatGenerating browser application bundles (phase: setup)...message comes from.edumserrano commentedon Jul 7, 2023
Well, there's something weird going on.
It does seem that Playwright tries to execute the
webServer.commandif I run this docker command from Windows:docker run -it --rm --ipc=host --workdir=/app -v "$(Get-Location):/app" mcr.microsoft.com/playwright:v1.35.1-jammy npx playwright test.I'm saying it seems to because otherwise I can't explain that
WebServerlog message which comes fromng serve.However, if I do:
docker run -it --rm --ipc=host --workdir=/app -v "$(Get-Location):/app" mcr.microsoft.com/playwright:v1.35.1-jammynpx ng serve --port 4200 &which outputs:wgetto see that the app is running finewget http://localhost:4200:npx playwright testand it works as expected, it didn't try to execute thewebServer.command:edumserrano commentedon Jul 7, 2023
I'm so confused right now as to what might be causing this 😵 . So here's what I did:
webServer.commandON THE DOCKER CONTAINER.Here's some images:
Working fine with Node 16:
A) Run the app
B) Run the tests via Docker that will connect to the app running on the host. All works as expected.
Fails in Node 18:
A) Run the app
B) Run the tests via Docker that will connect to the app running on the host. Tests fail because tries to execute the
webServer.command.P.S. - the commit I did to allow this docker connectivity from inside docker container to the app running on docker's host doesn't impact the reproducibility of the bug using the demo repo when running without docker. Following the steps initially describe on this issue still result in error for me when running on Windows.
pavelfeldman commentedon Jul 7, 2023
I did not realize there was docker involved in your setup. To re-iterate, the main thing that happened in Node 18 which is different from Node 16 is that the ports are now bound using ipv6 by default. So when you bind :4000, it is [:1]:4000, not 127.0.0.1:4000 anymore. Those are different ports, even though the port number is the same. Browsers (and Playwright) are using technology called Happy Eyeballs to mitigate that, but I'm not sure how this goes through the docker boundary.
edumserrano commentedon Jul 7, 2023
Pavel Feldman (@pavelfeldman) note that on the original description of the issue there is no Docker involved. For me the issue happens without Docker and running on Windows just by swapping from node 16 to 18.
I did further testing using Docker after you pointed out you couldn't replicate the issue on linux.
EDIT:
Can you replicate what I saw in this comment for instance? I don't understand why it seems Playwright seems to execute the
webServer.command.edumserrano commentedon Jul 7, 2023
Pavel Feldman (@pavelfeldman) I think part of the issue was that I didn't understand that
webServer.reuseExistingServerwill fallback to execute thewebServer.commandif it can't get to the specifiedwebServer.url. As noted in thewebServer.reuseExistingServerdocumentation:The other part of this issue is very likely related to the change you've mentioned about the fact that Node migrated to ipv6 in Node 18. Somehow that is affecting the way Playwright tries to check if the
webServer.urlis up and running and then falls back to executing thewebServer.command.edumserrano commentedon Jul 7, 2023
And you were absolutely right regarding the root cause Pavel Feldman (@pavelfeldman) . Thank you very much for pointing me in the right direction.
On the
package.jsonI changed thenpm startcommand so that it would bind specifically to127.0.0.1by passing a--hostflag to theng servecommand:And then running
npm testor via docker withdocker run -it --rm --ipc=host --add-host=host.docker.internal:host-gateway --env USE_DOCKER_HOST_WEBSERVER=true --workdir=/app -v "$(Get-Location):/app" mcr.microsoft.com/playwright:v1.35.1-jammy npx playwright test, everything works as expected.Feel free to close this issue.
pavelfeldman commentedon Jul 7, 2023
I just noticed that you were using 127.0.0.1 explicitly in your config. Switching it to
localhostwould trigger all those happy eyeballs paths. But I would recommend keeping it as you have it as it makes everything simpler for both browser and Playwright.