HELM_DIFF_USE_UPGRADE_DRY_RUN=true crashes helm when no deployment exists in target namespace

[davidgubler]

We use helm diff like this:

HELM_DIFF_USE_UPGRADE_DRY_RUN=true helm diff upgrade "${DEPLOYMENT}" . --namespace "${NAMESPACE}" --values "values.yaml" --values "env.yaml" --values "values/foo/values.bar.yaml" --values "values/baz/values.bum.yaml" --allow-unreleased

This works fine IF the target namespace already contains a Helm deployment. However if there isn't one then this fails with

********************
	Release was not present in Helm.  Diff will show entire contents as new.
********************
panic: runtime error: slice bounds out of range [-1:]
goroutine 1 [running]:
github.com/databus23/helm-diff/v3/cmd.extractManifestFromHelmUpgradeDryRunOutput({0xc00062c400, 0x3e, 0x400}, 0x0)
	github.com/databus23/helm-diff/v3/cmd/helm3.go:359 +0x3aa
github.com/databus23/helm-diff/v3/cmd.(*diffCmd).template.func3({0xc00062c400?, 0x4?, 0xc0001ec4b0?})
	github.com/databus23/helm-diff/v3/cmd/helm3.go:263 +0x25
github.com/databus23/helm-diff/v3/cmd.(*diffCmd).template(0xc000003c00, 0x0)
	github.com/databus23/helm-diff/v3/cmd/helm3.go:336 +0x1ad7
github.com/databus23/helm-diff/v3/cmd.(*diffCmd).runHelm3(0xc000003c00)
	github.com/databus23/helm-diff/v3/cmd/upgrade.go:299 +0x30c
github.com/databus23/helm-diff/v3/cmd.newChartCommand.func2(0xc000146c08, {0xc0001482c0, 0x2, 0x224bc12?})
	github.com/databus23/helm-diff/v3/cmd/upgrade.go:211 +0x379
github.com/spf13/cobra.(*Command).execute(0xc000146c08, {0xc000148210, 0xb, 0xb})
	github.com/spf13/cobra@v1.9.1/command.go:1015 +0xa94
github.com/spf13/cobra.(*Command).ExecuteC(0xc000146f08)
	github.com/spf13/cobra@v1.9.1/command.go:1148 +0x40c
github.com/spf13/cobra.(*Command).Execute(0x0?)
	github.com/spf13/cobra@v1.9.1/command.go:1071 +0x13
main.main()
	github.com/databus23/helm-diff/v3/main.go:16 +0x18
Error: plugin "diff" exited with error

Removing the HELM_DIFF_USE_UPGRADE_DRY_RUN=true makes this work.

We want to use HELM_DIFF_USE_UPGRADE_DRY_RUN=true because without this environment variable set helm diff can display bogus changes that don't actually happen.

Would be nice if this could be fixed. Thanks!

Software versions:

• helm diff runs in the container image from https://github.com/appuio/container-helm : ghcr.io/appuio/helm:latest
• Versions can be found here: https://github.com/appuio/container-helm/blob/main/Dockerfile
• Last build was may 17 using Helm v3.17.3 and the then latest version of helm-diff

[yxxhero]

@davidgubler could you give an demo in order to debug?

[davidgubler]

Hi @yxxhero,

Sure, here you go: https://github.com/davidgubler/helmdiff/

Since you may not be able to see the action output here's a screenshot: https://github.com/davidgubler/helmdiff/blob/main/helmdiff-fail.png

Note: The problem only appeared after I added the secret.yaml in the template dir, it worked without what. So it must have something to do with the functions used in that template.

Best regards,

David

[yxxhero]

@davidgubler please try my branch. and give me some feedback. you can install helm-diff by running make install

[yxxhero]

@davidgubler https://github.com/databus23/helm-diff?tab=readme-ov-file#build

[davidgubler]

Hi @yxxhero , Thank you very much for fixing this, that's of great help!

I've tested both my toy example from above and some way more involved non-public cases and both now work without issues. Our Helm/helm-diff etc. Docker image is now updated as well.