Is it possible to use distroless image?

[gregjotau]

When I use a distroless image (deploying java/kotlin apps) Kamal fails due to health check not working, probably because the containers do not have curl available.

Would it be possible for curl locally on my machine to be used to check for availability instead or allow to ignore the health check (make it optional)?

[acidtib]

is installing curl not possible?

[gregjotau]

installing additional packages such as curl is not super easy. Distroless images do not have package managers and does not include a shell. Also defeats a bit the purpose with distroless I guess :)

[pschmitt-tc]

@gregjotau

I read that you can try to run the deploy without health check:

kamal deploy --skip-hooks

This command will deploy your application to the servers without running the healthcheck or any other custom scripts you have set up in the hooks.

[gregjotau]

Ensure app can pass healthcheck...
INFO [0491581f] Running docker run --detach --name healthcheck-ecomtools-3f0223e609839c9f7a264e55fde0caaeaa4c0dfc_uncommitted_58eee533750cc1ef --publish 3999:8080 --label service=healthcheck-ecomtools -e KAMAL_CONTAINER_NAME="healthcheck-ecomtools" --env-file .kamal/env/roles/ecomtools-web.env --health-cmd "ls -l > /dev/null" --health-interval "1s" gregtau/ecomtools:3f0223e609839c9f7a264e55fde0caaeaa4c0dfc_uncommitted_58eee533750cc1ef on oslo2
INFO [0491581f] Finished in 0.791 seconds with exit status 0 (successful).
INFO [bb191bd2] Running docker container ls --all --filter name=^healthcheck-ecomtools-3f0223e609839c9f7a264e55fde0caaeaa4c0dfc_uncommitted_58eee533750cc1ef$ --quiet | xargs docker inspect --format '{{if .State.Health}}{{.State.Health.Status}}{{else}}{{.State.Status}}{{end}}' on oslo2
INFO [bb191bd2] Finished in 0.127 seconds with exit status 0 (successful).
INFO container not ready (starting), retrying in 1s (attempt 1/7)...
INFO [1fda577c] Running docker container ls --all --filter name=^healthcheck-ecomtools-3f0223e609839c9f7a264e55fde0caaeaa4c0dfc_uncommitted_58eee533750cc1ef$ --quiet | xargs docker inspect --format '{{if .State.Health}}{{.State.Health.Status}}{{else}}{{.State.Status}}{{end}}' on oslo2
INFO [1fda577c] Finished in 0.086 seconds with exit status 0 (successful).
INFO container not ready (starting), retrying in 2s (attempt 2/7)...

ERROR (Kamal::Cli::Healthcheck::Poller::HealthcheckError): Exception while executing on host oslo2: container not ready (unhealthy)

  "Output": "OCI runtime exec failed: exec failed: unable to start container process: exec: \"/bin/sh\": stat /bin/sh: no such file or directory: unknown"

Did you test this on a distroless image? Doesn't seem to work :(

[pschmitt-tc]

Not a distroless...
And this error makes sense - I just googled:

"Distroless" images contain only your application and its runtime dependencies. They do not contain package managers, shells or any other programs

Without a shell we cant send any command like this ls to there...

[acidtib]

--skip-hooks prevent hook scripts from running, it has nothing to do with healthcheck

if you want to fake helathcheck success add a simple .sh file that returns true and call it using the healthcheck config

 healthcheck:
   cmd: ./bin/good_check.sh

[Sija]

Wouldn't simply using cmd: true be enough?

[acidtib]

you can try it, i dont think it will work, the value of cmd: is passed to docker run param --health-cmd you can see some examples here in the healcheck test

kamal/test/commands/healthcheck_test.rb

Line 37 in aea5548

"docker run --detach --name healthcheck-app-123 --publish 3999:3000 --label service=healthcheck-app -e KAMAL_CONTAINER_NAME=\"healthcheck-app\" --env-file .kamal/env/roles/app-web.env --health-cmd \"/bin/up\" --health-interval \"1s\" dhh/app:123",