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holos-run / holos

Holos - The Holistic platform manager
https://holos.run
Apache License 2.0
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Helm Capabilities #330

Closed jeffmccune closed 14 hours ago

jeffmccune commented 1 day ago

Add the ability to configure the helm template --api-versions flag.

We have prior art with how we handle Helm hooks with the EnableHooks field of core.Helm

See https://helm.sh/docs/chart_template_guide/builtin_objects/

Discussion

The native ArgoCD helm tool calls helm template with --api-versions that are also retrieved from the API server, so the rendered manifests are consistent with what helm install would do.

Proceed with adding new fields to core.Helm.

jeffmccune commented 1 day ago

Watch out for if we need to provide an escape hatch to allow the user to execute an user defined helm. This might be a generic Execute generator that executes any command that produces data on standard output.

msteinhoff commented 1 day ago

Watch out for if we need to provide an escape hatch to allow the user to execute an user defined helm. This might be a generic Execute generator that executes any command that produces data on standard output.

I like the idea of a generic executor, because that would also open the possibility to use our existing kustomizations as generators in holos. We have a mono repo with a lot of kustomizations (200+) and doing a big bang move to holos is not feasible, but having a kustomize generator would give us a nice incremental adoption path. It would also enable other rendering tools like jsonnet very easily.

Right now the helm generator is a bit special because it downloads the helm chart into the repo and adds logic to pass a values file. IMHO both features are not a good fit for a generic executor, but they would be required for helm template to work.

The helm generator needs to pass a values file to helm template which current is implemented by writing a temporary values file to disk and passing --values path/to/tempfile.yaml to helm template. Instead of using a temp file for values, you could pass values to helm template via stdin. Passing in data via stdin in a generic executor makes sense and is something that other rendering tools like jsonnet could benefit from.

For the generic executor to run helm template, it would need to know the local path to the chart. In our repo we already use https://github.com/Qovery/helm-freeze and the experience has been quite good. I already built a prototype to generate helm-freeze.yaml from cuelang and its probably very easy to integrate this with holos as well. But maybe its a good idea to integrate such functionality directly in holos, improving the overall UX and developer flow.

jeffmccune commented 14 hours ago

@msteinhoff FYI, added the KubeVersion and APIVersions fields in #338 and released in v0.99.0