`.Release.Revision` not working correctly in diff

[aianus]

Hi, we have a pod label as follows that includes the helm revision number as a value:

tags.datadoghq.com/version: {{ .Release.Revision | default 0 | quote }}

This seems to work fine with helm, but with helm diff, the value is always displayed as "1" in the diff:

Observed output in diff:

-     tags.datadoghq.com/version: "5"
+     tags.datadoghq.com/version: "1"

Expected output in diff:

-     tags.datadoghq.com/version: "5"
+     tags.datadoghq.com/version: "6"

[david92rl]

I just had a quick look and it seems that the issue isn't really related to the plugin itself.
helm-diff relies on the template function from helm (see this)

I ran a quick test and I was able to reproduce. All helm template commands are returning 1 where .Release.Revision is defined

Helm versions I used for this test: 3.4.1 and 3.5.0

[david92rl]

And.... this is why:

The template command uses the install method to generate the templates. This method sets the revision to 1 as it thinks it's the first deployment of the release

[david92rl]

Ok, so apparently helm template works as intended.
One way to fix this could be replacing the command used to render templates, so we use upgrade --dry-run instead of template

[aianus]

Any update on whether helm-diff will switch to upgrade --dry-run?

[strainovic]

It is very annoying behavior. We have one-time jobs for database migrations and it is triggered each time, no matter if we changed something on not.

As far as I can see, helm-diff is not maintained actively?

[mumoshu]

As far as I can see, helm-diff is not maintained actively?

@strainovic Hey! What is the point to calling it not maintained actively? Are you willing to contribute?

[mumoshu]

I've never realized upgrade --dry-run can be used for the replacement to helm template!

As we need to handle diffing on first install too, probably we'd need to use helm upgrade --install --dry-run?

[mumoshu]

I was blindly beliving helm template --is-upgrade we're currently using would magically handle the revision number as well, but apparently not.

      --is-upgrade                   set .Release.IsUpgrade instead of .Release.IsInstall

helm-diff/cmd/helm3.go

Line 134 in 0882d8c

flags = append(flags, "--is-upgrade")

I'm not fully sure if it's safe to fully migrate helm-diff to use helm upgrade --dry-run instead of helm template.

Should we add some envvar to toggle helm-diff to use upgrade --dry-run in

helm-diff/cmd/helm3.go

Line 141 in 0882d8c

args := []string{"template", d.release, d.chart}

?

[strainovic]

As far as I can see, helm-diff is not maintained actively?

@strainovic Hey! What is the point to calling it not maintained actively? Are you willing to contribute?

Hi @mumoshu, I told you that as I haven't seen any commit almost for a year, while a lot of things have been changed since then.

My knowledge in Golang is very limited, but if I find any spot where I can contribute, I would do it :)

Thank you @mumoshu for your amazing work!

[mumoshu]

@strainovic Thanks! Gotcha. I was rather in an impression that that kind of inactivity means maturity of the project :)

I use helm-diff and helmfile and haven't seen big blockers for a year or so.

I occasionally review issues and pull requests but most of the time (1) they look like not necessities but nice-to-haves, good workarounds exist, or (2)no preceding issues are written to clarify the goals of the changes so I'm unsure if I should merge it or (3)have no tests or manual test report so I'm not sure if I can safely merge it or (4) I responded/asked question(s) but no one answers, or (5)many people talk about big dreams but no one actually contributes code 😢

Regarding this issue, I already took some time to test helm upgrade --dry-run myself, wrote my thought and concern in #253 (comment), and I'm now awaiting replies and feedbacks.

And I thought it's reasonable and forgivable to wait a few weeks until anyone tries to contribute, as this is annoying but not critical as you can just omit .Release.Revision from the chart template... I actually don't understand why one wants to have it in k8s resource labels.

a lot of things have been changed since then.

If you've specific/critical things helm-diff needs to address, please feel free to raise issues.

I can't promise to do everyone's all works myself, but I'll try keeping my best to maintain the project!

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.