sources: Allow configuring a custom AWS region

[brancz]

This can be useful when using an s3 compatible service, such as minio or
Ceph.

This takes a slightly simpler approach than initially suggested in #447, since rusoto already supports parsing custom regions from tuples, I decided not to introduce yet-another-representation.

Tested with this configuration:

sources:
- id: minio
  type: s3
  bucket: symbolicator
  region: ['minio', 'http://minio.minio.svc.cluster.local:9000']
  access_key: minio
  secret_key: minio123
  layout: { type: "unified" }
  is_public: true

Closes #447

@jan-auer

[Swatinem]

lgtm, unless @jan-auer has objections?

[flub]

Any chance we could add some unit tests for these various functionalities?

[brancz]

I'm afraid that would exceed my rust abilities, I'm somewhat surprised that I managed to get this to work 😅

(I'm probably missing them entirely, I think I would have been able to add a single additional test case, but I can't find tests for deserializing at all, so creating entirely new tests probably exceeds my current rust abilities)

[flub]

heh, fair enough. Sad we don't have an existing test, I'm just a bit concerned that changes like this could easily break existing valid configs and we should have some way of avoiding this.

Could you maybe update https://github.com/getsentry/symbolicator/blob/master/docs/api/index.md#amazon-s3-bucket to represent the current state though. People shouldn't have to read the source to figure this out.

[flub]

Also, adding a changelog entry in the same style as existing ones will make the CI happier too :)

[brancz]

Updated documentation and added a changelog entry.

[flub]

I took the liberty of pushing a simple test, hope you don't mind.

It might be simple but sadly it already shows that your change breaks the previous functionality, so all existing configurations will break. Could investigate this?

[brancz]

Thank you! No problem at all, this will help me investigate alternative solutions such as the initially proposed string-or-struct type of construct.

[brancz]

Ok, I tried, but it seems that this is out of my breadth 😅 ... does anyone think they might be able to take this over the finish line?

[relaxolotl]

I've pushed a few changes that should make this change compatible with old configs in addition to supporting custom AWS regions; @flub @Swatinem could I trouble the both of you to take a look at the changes? They're a little bit more involved now but it's honestly just a heavily modified version of https://serde.rs/string-or-struct.html.

@brancz sorry it's taken so long to get to this. Hopefully this is the last push needed to get support for this into symbolicator proper 🤞

[flub]

nice! 👍