Build strategy that is Dockerfile (for simple use cases)

[aslom]

That was mentioned during today WG call.

If I understand it correctly that would be simpler build strategy when buildpacks or s2i is not needed? @lance

[lance]

I think a reasonable option would be to add a docker package here: https://github.com/knative/func/tree/main/pkg/builders and when specified in func.yaml or on the command line as func build --builder=docker the CLI looks for a Dockerfile and builds using the docker/podman APIs. @matejvasek wdyt?

[zroubalik]

Are we going to provide Dockerfiles with the language templates or do we keep it on users?

[lance]

Good question! We could start with templates in knative-sandbox/func-tastic, perhaps?

[lkingland]

This is now a planned feature, and will likely be implemented as a so-called "Base Image". The necessary Functions middleware is injected by func itself, so building with Buildpack, S2I, or directly on the host (outside of a container) are all very similar. What is needed is a way to easily specify that the final runtime image be a given base image built from, for example, a Dockerfile; a feature currently only available via a custom buildpack with a Dockerfile for the "run" image.

Currently the plan is to make this available via the flag --base-image=[myimage]. The base image itself could be built any way the user sees fit, either within the Function's build pipeline or externally.