[collector] Fix: Enable external configmap checksum

[bixu]

Fixes "[collector] No collector reload when using external configmap" (#1194)

This PR ships a new config option, configMap.existingPath, which is unset by default. When enabled, it takes a relative path to a custom ConfigMap that can be bundled in a wrapper chart. A new helper template calculates a checksum annotation from the custom ConfigMap file.

[TylerHelmuth]

It looks like the demo examples got removed. If you only want to generate the collector examples you can do make generate-examples CHARTS=opentlemetry-collector.

[bixu]

It looks like the demo examples got removed. If you only want to generate the collector examples you can do make generate-examples CHARTS=opentlemetry-collector.

I've re-run the example generator for the Collector after reverting the previous generation (which seemed to be the cause of deleted files). The diff is much smaller now.

I'm not sure how to best handle merge conflicts from upstream around generated examples, though -- tried a few merge flows locally but was not happy with the results.

[TylerHelmuth]

@bixu the best way to handle merging the examples is to take mains, bump the chart version to the appropriate value, and regenerate.

[onematchfox]

Hey @bixu,

Are you actively using this feature and if so, how? I am trying to deploy this chart as a subchart whilst using existingPath but can't seem to find a working configuration and keep getting an error like:

foo/charts/opentelemetry-collector/templates/_helpers.tpl:234:22: executing "opentelemetry-collector.configTemplateChecksumAnnotation" at <include (print $.Template.BasePath "/" .Values.configMap.existingPath) .>: error calling include: template: no template "foo/charts/opentelemetry-collector/templates/../../../../otel/config.yaml" associated with template "gotpl"

According to the docs

Files outside of a Helm application subchart, including those of the parent, cannot be accessed

so it doesn't look like what I'm trying to do is possible.

I noticed that in the description you mentioned "can be bundled in a wrapper chart". What exactly is a "wrapper chart". Perhaps I'm approaching this wrong?

[bixu]

Hey @bixu,

Are you actively using this feature and if so, how? I am trying to deploy this chart as a subchart whilst using existingPath but can't seem to find a working configuration and keep getting an error like:

foo/charts/opentelemetry-collector/templates/_helpers.tpl:234:22: executing "opentelemetry-collector.configTemplateChecksumAnnotation" at <include (print $.Template.BasePath "/" .Values.configMap.existingPath) .>: error calling include: template: no template "foo/charts/opentelemetry-collector/templates/../../../../otel/config.yaml" associated with template "gotpl"

According to the docs

Files outside of a Helm application subchart, including those of the parent, cannot be accessed

so it doesn't look like what I'm trying to do is possible.

I noticed that in the description you mentioned "can be bundled in a wrapper chart". What exactly is a "wrapper chart". Perhaps I'm approaching this wrong?

@onematchfox, I actually ran in to the same issue the other day, but hadn't gotten around to thinking about a fix. I'm afraid this config option is broken and I'd like to remove it, or do you have a better idea?

[onematchfox]

or do you have a better idea?

Nope, sorry, I don't. I was hoping that I was just approaching it wrong.

[bixu]

or do you have a better idea?

Nope, sorry, I don't. I was hoping that I was just approaching it wrong.

@onematchfox, are you in the CNCF slack for the Collector? I'm @bixu there; would love to chat more about your use-case and what our options are.

[onematchfox]

@onematchfox, are you in the CNCF slack for the Collector? I'm @bixu there; would love to chat more about your use-case and what our options are.

I am. Will drop you a msg a bit later this afternoon when I have some spare time.