Starting local HTTP server in background causes GoCD to be stuck

Martin Burger

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Jan 13, 2022, 2:33:56 PM1/13/22

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Hello:

I am using GoCD for continuously deploying some websites and web applications, respectively. Those websites and web apps are build with Snowpack, a frontend build tool which uses Node.js / npm.

As part of the whole build and deployment process, I run a local HTTP server using npm package http-server. That server serves the built app from the local project folder. Then, using that local web server, a series of playwright tests is run to conduct various end-to-end tests in different rendering engines like Chromium. That way, I can run some quick smoke tests locally before the whole app will be deployed to a remote server. There, more elaborate tests are run.

On my local machine, that works like a charm. However, when GoCD executes the built process, it gets stuck when launching the web server.

Basically, the web server is launched in package.json via "http-server ./build -a 127.0.0.1 -p 8181 &". Then, the playwright tests are run. At the end, I use "kill $(lsof -t -i:8181)" to stop the server.

However, GoCD gets stuck when trying to launch the web server. I assume that has something to do with trying to run the web server in the background (note the ampersand at the end of the command).

How can I run that build process using GoCD?

Best wishes,

Martin

Chad Wilson

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Jan 14, 2022, 11:05:43 AM1/14/22

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Are these individual steps in separate GoCD "command" tasks within a single job? Can you share what your job definition looks like?

-Chad

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Martin Burger

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Jan 15, 2022, 2:51:11 PM1/15/22

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Hey Chad:

Thanks for your help. To run the smoke tests is an individual step and task, respectively. More precisely, it's a custom command that runs `npm run test:smoke:build`:

That's the expected output as captured on the console at my local machine:

❯ DEPLOY_TARGET=preview npm run test:smoke:build

> test:smoke:build
> run-s --continue-on-error test:smoke:build:startserver test:smoke:build:run test:smoke:build:stopserver

> test:smoke:build:startserver

> http-server ./build -a 127.0.0.1 -p 8181 &

Starting up http-server, serving ./build

http-server version: 14.0.0

http-server settings:
CORS: disabled
Cache: 3600 seconds
Connection Timeout: 120 seconds
Directory Listings: visible
AutoIndex: visible
Serve GZIP Files: false
Serve Brotli Files: false
Default File Extension: none

Available on:
http://127.0.0.1:8181
Hit CTRL-C to stop the server

> test:smoke:build:run
> DEPLOY_TARGET=build run-s test:smoke

> test:smoke
> playwright test --config=test/smoke.config.ts --project=firefox

Using config at [...]/test/smoke.config.ts

Running 1 test using 1 worker

[...]

1 passed (3s)

To open last HTML report run:

npx playwright show-report

> test:smoke:build:stopserver

> kill $(lsof -t -i:8181)

http-server stopped.

As you can see, the http-server is started, the playwright tests are run successfully, and eventually the http-server is stopped.

When running with GoCD, the job gets stuck as soon as the http-server has been started:

GoCD warns about the possibility that the job may be hung:

It is hung indeed. So, I cancelled it manually as you can see in above raw output where I marked it in red text color.

Best wishes,

Martin

Chad Wilson

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Jan 16, 2022, 12:37:08 AM1/16/22

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Hi Martin

I get rather confused as to how npm does its thing when interaction with shells, but it's most likely because when you launch something via an automated process such as GoCD you don't have any shell (or the right type, interactive with tty etc) when you launch a process with `npm` as the originating point, so my guess is that the & is being ignored, or not working as you might expect due to lack of interactive shell/stdin.

You could try with a wrapping shell, e.g

Command: bash

Arg[1]: -c

Arg[2] npm run test:smoke:build

Don't have the time to test via npm and npm scripts, but it works fine with raw commands and npx:

If none of that works, you might be better to look for something that can be daemonized more easily, or plays nicely with some other process manager like pm2/supervisor etc rather than relying on shell jobs. In my experience often these simpler local dev tools on NodeJS aren't all particularly well suited for automation, but YMMV.

-Chad

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Martin Burger

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Jan 16, 2022, 7:50:03 AM1/16/22

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Chad, thank you very much for your quick and competent help. Switching to PM2 did the trick within minutes. Best wishes, Martin

Chad Wilson

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Jan 16, 2022, 9:10:26 AM1/16/22

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No problem Martin - appreciate the confirmation!

On Sun, Jan 16, 2022 at 8:50 PM Martin Burger <mburg...@gmail.com> wrote:

Chad, thank you very much for your quick and competent help. Switching to PM2 did the trick within minutes. Best wishes, Martin

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