npx signal forwarding isn't working as expected in Kubernetes

[madhusudancs]

We launch our Nodejs services as Kubernetes. We have an ENTRYPOINT command in our Dockerfile that looks like this:

ENTRYPOINT ["npx", "cross-env", "NODE_ENV=production", "node",  "--import", "./build/common/instrumentation.js", "./build/service/src/index.js"]

When the pod that runs this container is killed, service process launched as ./build/service/src/index.js never gets called on its process.on('SIGTERM', ... )

Using [killsoop](https://github.com/iovisor/bcc/blob/master/tools/killsnoop.py) from bcc-tools it is clear that SIGTERM never gets forwarded beyond a sh -c process that's spawned. Here is the process tree for our pod

npm exec cross-,1
  |-sh,17 -c cross-env NODE_ENV=production node --import ./build/common/instrumentation.js ./build/service/src/index.js
  |   `-node,18 /myapp/node_modules/.bin/cross-env NODE_ENV=production node --import ./build/common/instrumentation.js ./build/service/src/index.js
  |       |-node,25 --import ./build/common/instrumentation.js ./build/service/src/index.js
  |       |   |-{node},26
  |       |   |-{node},27
  |       |   |-{node},28

Here is the killsnoop output:

$ ./killsnoop
TIME      PID    COMM             SIG  TPID   RESULT
...
19:06:08  588834 runc             15   521532 0
19:06:08  521532 npm exec cross-  15   17     0
19:06:08  521532 npm exec cross-  15   1      0
19:06:09  588869 runc             9    521323 0

Does npm exec create a wrapper shell process (with sh -c)? How does this work? Any idea why signal forwarding wouldn't work with our setup?

[LiteBrite82]

Thanks for posting in the GitHub Community, @madhusudancs !

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[madhusudancs]

Thanks! Made a copy of this as the original post that was moved was closed.

[gmile]

@madhusudancs did the discussion continue elsewhere? Were you able to find a solution to this? I suspect this could be npx issue 🤔