About Docker HEALTHCHECK again

[alex-arana]

Following up on Issue #183 regarding implementation of Docker HEALTHCHECK within a distroless image, the accepted solution no longer appears to work.

As per one of the closing comments back in March, adding wget to a distroless image could be used to implement Docker HEALTHCHECK like so:

COPY --from=busybox:1.36.0-musl /bin/wget /usr/bin/wget

However, this does not appear to work with the following distroless container images I have tested:

• gcr.io/distroless/base:latest
• gcr.io/distroless/base:nonroot

Has anyone else encountered this issue?

[loosebazooka]

I think more information is needed here. What doesn't work? Is it not putting the wget binary in the container? or is your healthcheck failing for some other reason?

[alex-arana]

Sure. I've created a small Java/Kotlin application to demonstrate the issue:

https://github.com/alex-arana/demo

The project creates a Docker image out of a Kotlin Spring Boot app using a distroless base and packages wget executable to implement Docker HEALTHCHECK as discussed. Creating and running a local container using docker-compose usually becomes unhealthy after a couple of minutes.

[alex-arana]

I've added a branch called openjdk17-base-working to the demo repository which implements a working version of the Docker HEALTHCHECK.

The only difference with the non-working version of the same project is using an openjdk:17 based image instead of a distroless image.

[jbergstroem]

What I've seen in very minimal images for healtchecks is invoking the language runtime for doing a http request. Check this supabase container for instance:

https://github.com/supabase/supabase/blob/fde963b239d4fb8cc014d710ebb82641876609db/docker/docker-compose.yml#L14-L22

[gblandinkingland]

I've also come across this issue. I ran with a debug image to try and get a better idea of what was going on, and it seems that wget gives a "Bad system call" response.

[eifinger]

Based on @jbergstroem comment I succesfully implemented that for Java/Kotlin:
https://github.com/eifinger/distroless-healthcheck