Avoid stripping yaml comments? about kbld HOT 5 CLOSED

i see. may be following is useful kbld -f ... --lock-output /tmp/lock.yml (which will record resolved/built images and save them as ImageOverrides in lock.yml) and then use it later via ytt ... | kbld -f - -f /tmp/lock.yml (to use those overrides).

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there are two challenges with that even if kbld would preserve comments -- (1) kbld returns combined output which would "break" any non-trivial ytt template since loads would not be able to find files (2) there is no guarantee that kbld can find image references since they might be in format like this: image: #@ data.values.image (or some variation).

because of issues above i typically recommend to run kbld on the templating results or some kind of more deterministic input to the templates (eg data values files that are setting image references).

what are your thoughts on challenges above?

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I better understand the challenges. I have a use case where spawn a lot of jobs from the same template and kbld execution, even when cached, is adding up to a long time.

In addition, kbld requires docker while ytt, kubectl does not. A system with docker could build the image and update the templated yaml. That updated template could then be used by another system without docker.

It's not something I desperately need, but I was slightly surprised to discover it wasn't possible.

Perhaps, the Sources object could have a default tag. We could invoke kbld -f build.yaml > build.yaml to build and update the default tag (build.yaml containing only Sources and ImageDestinations). Then invoke kbld with a --noop that would only transfer the default tag kbld --noop -f build.yaml -f temaplte.yaml > rendered.yaml. I don't know, I am thinking out loud..

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Thanks @cppforlife. I didn't know about --lock-output. Makes a lot of sense. Now I almost feel embarrassed.

In case it helps others, here is what I did in a Makefile:

workflow.build.lock.yaml: workflow.yaml  workflow.build.yaml Dockerfile
	kbld -f workflow.yaml -f workflow.build.yaml --lock-output workflow.build.lock.yaml

/tmp/rendered-workflow.yaml: metadata.yaml workflow.yaml workflow.build.lock.yaml
	ytt -f metadata.yaml -f workflow.yaml | kbld -f workflow.build.lock.yaml -f - > /tmp/rendered-workflow.yaml

submit: /tmp/rendered-workflow.yaml
	argo submit /tmp/rendered-workflow.yaml

workflow.yaml in an argo workflow I want to run many time. metadata.yaml configures the workflow. workflow.build.yaml contains the image sources and destinations. workflow.build.lock.yaml is the ImageOverrides resulting for the build, it can be checked-in for teammates to use.

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@jpambrun glad it solves your problem!

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