Remove redundant chart and image tags when building (i.e. what should have a `v` prefix)

[bokysan]

I found #216 reporting an issue resulting from this, where helm search repo can get confusing as well.

Looking at your comment from back then in that issue, the reasoning seems to have been related to the fact that Helm expects X.Y.Z SemVer format, without the v prefix.
But I'm not sure if you didn't refer to a different issue, since #216 alone doesn't explain why the Helm chart with vX.Y.Z is then still being released.

Judging from other charts I use, from projects that release v-prefixed tags, releasing the Chart as X.Y.Z, with an AppVersion like vX.Y.Z is a common approach.

If I'm not mistaken, releasing Charts to OCI registries instead of Helm HTTP Repositories (which would be a nice addition at some point) would not only expect a non-prefixed version, but actually blocks prefixed versions from being pushed - but could have been another tool in our pipeline complaining about this as well, not sure anymore.

I'll see if this still feels icky later in the day and if I didn't forget about it already, and open an issue for further discussions :)

Originally posted by @outofrange in #268 (comment)

[bokysan]

I generally am not against removing v in helm charts. I'm making a separate issue for this so we can continue the discussion here.

[outofrange]

Found it: #141

Originally posted by @bokysan in #268 (comment)

[outofrange]

From your comment there:

Thank you for this commit. I am well aware that semver is without the v prefix. However, based on my experience, having only numbers in version causes more issues than it brings benefits.

Can you remember what issues you were thinking about?
I know only of historical issues that aren't relevant anymore today.

But from my point of view, this MR can be merged - for this change, I'm for using both tag variants for postfix-exporter anyway to keep it consistent with postfix, but I'll create a follow up issue for further discussions about versioning - I think it's only going to be relevant when implementing #270.

Originally posted by @outofrange in #268 (comment)

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(no we should have all the context here :))

[outofrange]

I generally am not against removing v in helm charts. I'm making a separate issue for this so we can continue the discussion here.

Judging from other charts I use, from projects that release v-prefixed tags, releasing the Chart as X.Y.Z, with an AppVersion like vX.Y.Z is a common approach.

What do you think about this - removing the prefixed Helm chart release, as well as the non-prefixed image tag?

I would assume that very few would notice when no new prefixed chart versions would be released anymore - your README doesn't use the version at all in the example, and ArtifactHub only knows about the non-prefixed Chart.

Adding more assumptions:
Most users using the Docker image without Helm (like with Docker Swarm) either try the prefixed version number they see in your Release name or git tags when pulling the image, latest, or none at all (mostly when copying from the docker swarm example I guess).
I tried to get a quick sample from reported issues - couldn't find anyone using non-prefixed tags directly, but I also only found very few indicating use of prefixed versions in their reports.
So it could be fair to say that most uses of the non-prefixed tag by far might be coming from from people using the Helm chart with the default AppVersion / no tag override.

But I wouldn't be surprised if people show up after CI stops publishing those artifacts, reporting that they actually rely on the prefixed Helm charts, and non-prefixed image tags :D

Do you happen to have more insights into image and chart usage?
But as far as I can tell, Docker Image Insights are not available for "normal" community accounts, and GitHub pages hosting the chart doesn't support metrics at all?

My recommended approach would be, from most to least recommended:

1. deprecate the non-prefixed image and prefixed Chart; use prefixed version for .Chart.AppVersion, and non-prefixed version as .Chart.Version
2. Just deprecate the prefixed Chart, so no one is confused when seeing two different-but-same charts in the Helm repository, but only one chart in the registry
3. keep both images and charts, realizing confusion about eventual OCI helm chart versions shouldn't be disastrous

...

(10. change everything to non-prefixed versions, including your git tags and Release names, so everything feels like I'm personally used to)

[bokysan]

Frankly, I'm a bit lost now. :)

Can we put it in an example -- what is your proposal? E.g., if I understand correctly

Property	Value
git tags	6.0.0
github releases	6.0.0
.Chart.AppVersion	v6.0.0
.Chart.Version	6.0.0
Docker image tag	6.0.0

(did I miss anything?)

[outofrange]

I'd actually try to end up with something like this - so a more fitting title of this issue would be "Remove redundant charts and images".

Property	Value	Note
git tags	v6.0.0	Format should not change
github releases	Release v6.0.0	Should contain git tag / Format should not change
.Chart.AppVersion	v6.0.0	Should match image tag
.Chart.Version	6.0.0	Shouldn't have v prefix
Docker image tag	v6.0.0	Should match git tag

The v-prefixed chart, as well as the non-prefixed image tag wouldn't be built anymore.

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For new projects, I wouldn't use the v prefix anywhere but only the semver version. I'd also just use the semver version directly as release name, without the Release string prefixing it, to make it a bit more comfortable to work with tools like Renovate without requiring custom regex expressions. But I don't think breaking consistency here is worth it for established projects.

[bokysan]

Frankly, for me -- the above is even more confusing. There's no strict rule what has a v prefix and what not. Does not follow the Principle of least astonishment.

Even if we change this, it wouldn't be a "breaking" breaking change. I believe consistency, in the long term, is more important than backwards compatibility in this case. If we do this for 6.0.0 and document it properly, upgrade path should be trivial.

Going through some of the more popular docker images:

Image	Note
stakater/reloader	uses v prefix
nginx	no v prefix
buysbox	no v prefix
postgres	no v prefix
istio/proxyv2	no v prefix
redis	no v prefix
ubuntu	no v prefix
python	no v prefix

Seems to me that general consensus leans towards not having v in the Docker image tag name.

Given that as of Helm v3.5.0 (released Jan 13, 2021), helm create wraps the default appVersion field in quotes, a question opens if it really does make sense to use v for .Chart.AppVersion.

On a side note, Helm went from naming releases without version prefix (see 3.5.0) to naming them with v (see v4.1.1). Their git tags have v prefix.

In other words, i'm thinking of the following:

Property	Value	Note
git tags	v6.0.0	Keep as-is
github releases	Release v6.0.0	Keep as-is
.Chart.AppVersion	6.0.0	No version prefix
.Chart.Version	6.0.0	No version prefix
Docker image tag	6.0.0	No version prefix