feat: add UBI image support

[Victoremepunto]

based on the spirit of #5 and since I thought it may be really useful to have UBI based images for caddy.

[francislavoie]

I think this needs a Dockerfile.ubi.tmpl similar to https://github.com/caddyserver/caddy-docker/blob/master/Dockerfile.tmpl so that the codegen produces the files correctly.

[Victoremepunto]

I think this needs a Dockerfile.ubi.tmpl similar to https://github.com/caddyserver/caddy-docker/blob/master/Dockerfile.tmpl so that the codegen produces the files correctly.

Thanks @francislavoie , I just submitted it!

[Victoremepunto]

@francislavoie ping! Hello , what is required for this to move forward ? do I need to do anything else ?

Also, would it be better to set it to UBI-8 instead (more stable) ?

I also saw #369 and thought it might be really helpful indeed, esp. for running in Openshift clusters, I can incorporate those changes in this PR as well.

[francislavoie]

This is still incomplete, the make script doesn't produce the correct output. We would need to reorganize the folders to be like alpine, alpine-builder, ubi and ubi-builder, and make sure the correct templates are used for each. Right now make is using the alpine template for ubi which isn't correct.

[francislavoie]

Any interest in finishing this off @Victoremepunto?

I don't have any issue with this in principle, adding a ubi variant is fine, but at the same time I don't particularly see much benefit since alpine serves 99% of people just fine anyway. I'd like a stronger argument for it other than "just cause we also use other UBI images" especially since the base alpine image is so small, hardly matters.

[polarathene]

There's been little engagement of interest expressed at the associated issues or this PR. I doubt there's the demand to warrant official image support?

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If there was a desire to have a slimmed down image that is effectively a distroless variant, it would seem more fitting to go with an image built with Canonical's chisel, but that's still not quite at a stage yet where I feel comfortable advocating it strongly 😅

If a Google distroless image variant meets the needs for Caddy, that'd be quite simple for anyone to just copy the Caddy binary from the official Alpine image and go from there?

Sometimes there is merit for preferring glibc over musl, but quite a few of the historical issues have since been resolved (including one that was specific to Go built apps IIRC).

[francislavoie]

ubi is supported as a base image in the DOI program, the other options you mentioned are not. So that's immediately a no-go.

[polarathene]

So that's immediately a no-go.

Technically that only applies to DockerHub. When introducing GHCR as an alternative you would have the option for such :)

[francislavoie]

I have no interest in maintaining more than necessary.

[francislavoie]

I'll close this for now. It's not a "no never", but more "maybe with more reason"