Add health-checker buildpack to stack?

[herder]

Describe the Enhancement

The image produced by this pack is very trimmed down and lean, which is great for reducing the attack surface and risk of CVE:s.
However, there is no way to support internal health checks like docker health checks or the k8s equivalent where a command is spawned in the pod without either:

• Using the full builder and utilizing curl as health check
• Setting the buildpacks param to java and health-checker, and using the thc binary to do the health check.

Both of these options work, but the first option makes the image a lot larger and adds a lot of packages that should not be needed for a Java app.
And the second option requires some manual selection of contributing buildpacks, which is certainly possible but makes it harder to create a streamlined app pipeline.

Possible Solution

Add the health-checker buildpack to this pack.

Motivation

Adding this pack would allow defining Docker healthchecks on platforms that use it (ECS, for example), while causing no impact on platforms that don't need it.

Since the buildpack only contributes if the BP_HEALTH_CHECKER_ENABLED environment variable is set, it would be an opt-in and not activated by default.

[dmikusa]

@paketo-buildpacks/java-maintainers - Thoughts?

Primarily, we haven't added this to the builders because of the layer limit issues. Now that we have a Java specific builder, that issue goes away. The only other thought is that it would be ideal if we added it to the Java composite buildpack, but then it would go into all the builders and then we have layer limit issues again.

I can PR this directly into the builder, if there are no objections.

[anthonydahanne]

I don't have any objections to include https://github.com/paketo-buildpacks/health-checker into the builder directly, and make it specific to this builder (although I think people switching between java-tiny and base could be wondering why a base builder could loose content vs a tiny builder...)

Now, I'm surprised not all container orchestrators come with an HTTP health check like k8s; but I understand that could be the case and this buildpack could come in handy...

So I don't have a strong opposition to this inclusion, nor a strong desire to have it added.

[herder]

I don't have any objections to include https://github.com/paketo-buildpacks/health-checker into the builder directly, and make it specific to this builder (although I think people switching between java-tiny and base could be wondering why a base builder could loose content vs a tiny builder...)

Now, I'm surprised not all container orchestrators come with an HTTP health check like k8s; but I understand that could be the case and this buildpack could come in handy...

So I don't have a strong opposition to this inclusion, nor a strong desire to have it added.

I agree that it's surprising that ECS doesn't have a built-in http check, but when running a service that doesn't have an internal load balancer it's seems to be the only way to get ECS to check the service. Quite annoying...

So adding this to the default pack would simplify things until ECS provides this, or we move to a platform that works a bit more like you would expect :)

[anthonydahanne]

or we move to a platform that works a bit more like you would expect :)

haha, I don't think you'll move platform just for that.

I'm okay adding it, cc @dmikusa - let it be clear that if people switch to base, they could come back to this issue wondering why base does not have health-checker included.

That's my only concern, and it's not a red flag to me.

[herder]

or we move to a platform that works a bit more like you would expect :)

haha, I don't think you'll move platform just for that.

I'm okay adding it, cc @dmikusa - let it be clear that if people switch to base, they could come back to this issue wondering why base does not have health-checker included.

That's my only concern, and it's not a red flag to me.

Sorry, I was unclear - by 'like you would expect' I meant the general 'you', not you specifically
Should have phrased it 'like most expect' :D

[anthonydahanne]

@dmikusa with #134 , maybe we should move this issue to https://github.com/paketo-buildpacks/ubuntu-noble-builder ?