Make S3 endpoint configurable

[tongmingleee]

We would like to use commuter as a way to share notebooks on S3, but we are not using AWS S3 and there is no way to configure S3 endpoint.
Can you make S3 endpoint configurable as environment variables?
The change is easy and straightforward, would like to contribute to it.

[brunowego]

I have a similar issue, my infrastructure have MinIO, currently we have a mount point with NFS to the data folder.

[captainsafia]

Hello @tongminglee! Thanks for opening this issue.

Are you looking for S3 configuration options beyond those that exist currently? If so, happy to take a look at an example implementation you can provide in a PR.

[withsmilo]

@tongmingleee @brunowego @captainsafia
I implemented it!

[dazzag24]

Hi, Any plans to support other storage backends such as Azure blob storage?

Thanks
Darren

[captainsafia]

@dazzag24 No implementation plans at the moment but PRs adding support for other storage backends are welcome!