Allow to use HTTPS protocol in URLs

[sonjek]

This change allows clients to download Helm charts over HTTPS while retaining the ability to upload Helm charts via S3.

[hypnoglow]

Hi,

http(s) is already supported, see: https://helm-s3.hypnoglow.io/docs/advanced-features/#serving-charts-via-http

What is the motivation of the proposed change?

[sonjek]

Hi, we are using the relative param as an alternative option for now.
But relative paths are not convenient when parsing the file index.
Therefore, this change allows to write an absolute path with the https protocol (like helm repo index).

[hypnoglow]

@sonjek

Therefore, this change allows to write an absolute path with the https protocol (like helm repo index).

I see the effect, but I don't understand the need yet.

But relative paths are not convenient when parsing the file index.

Could you please elaborate on this and provide more details on your use case? I'm asking because some time ago we had a similar discussion. There was a proposal similar to your change request. In the end we concluded that --relative option solves the problem and we don't need anything more complex.

[sonjek]

The relative path does not cause problems if interact with this index only through helm.

But when using a relative path, the index file loses information about the location of the chart.
Therefore, the relative path breaks the essence of repository metadata logic. The file does not contain all the necessary information.

So, this makes it impossible to use the index file outside the directory with the chart files.
The index file saved locally or on the server does not allow to find out where the chart files are located.
If you need to download and parse the index file, you need to additionally set helm files path.

Therefore, it is necessary that the index file has absolute paths + does not differ from the structure created by the official helm repo index.

I expect that this PR will allow to use this plugin for manage charts and automatically rebuild index and in same time will allow users to download charts via https while keeping the index structure as it is when generating through the helm itself.