Download remote chart to Archive dir

[codenio]

Downloading remote chart to Archive dir (~/.helm/cache/archive) would keep the current dir clean.

[elemental-lf]

Sounds like a good idea to prevent clutter. Could there be any issues when running multiple helm instances in parallel? I haven't looked into DownloadTo to see if it does any locking or so.

[codenio]

I just made it to mimics the way, Helm works. It works fine to me (as am using them often)
BTW what do you mean by running multiple helm instances in parallel? could you be brief?

[elemental-lf]

@aananthraj I mean multiple instances of helm running under the same user account at the same time and so using the same archive directory. I haven't looked into the Helm source code if it does anything to prevent races between different processes when both try to download the same chart to the archive directory at the same time and so possibly corrupting the file or leading to failed verifications of the chart. If locking is done in downloadTo we'd be fine. If this isn't the case then we'd need to mimic the locking logic in helm diff, too, when writing to the shared archive directory.

[codenio]

@elemental-lf , That was nice. Thanks..!!.

I have a query.

when both try to download the same chart to the archive directory at the same time and so possibly corrupting the file or leading to failed verifications of the chart.

This could happen in PWD as well right..?, I mean when charts are downloaded to current working directory.

upon inspection codes of helm and helm diff plugin, I would like to share the following infrence.

helm diff plugin uses DownloadTo func from Helm's official k8s.io/helm/pkg/downloader package.

If this isn't the case then we'd need to mimic the locking logic in helm diff, too, when writing to the shared archive directory

so logic would be exactly the same.

[elemental-lf]

This would also happen with the download to the cwd. But if there is a locking problem (at all), then it would be confined. I took a quick look at Helm now and I don't see any looking, so we're probably fine (or not worse than Helm itself).

[codenio]

ya, exactly 😄 , can this be merged..? now.

[databus23]

Thanks!

[codenio]

Thanks @databus23 and @elemental-lf .
It would be helpful , If we could work together on PR #22 and #24 as well.