pubsub/gcppubsub: Upgrade cloud.google.com/go/pubsub/v2

[tyrone-anz]

Is your feature request related to a problem? Please describe.

cloud.google.com/go/pubsub is deprecated. there is a new cloud.google.com/go/pubsub/v2

it is not possible to upgrade other libraries to v2 when some are still using v1.
this is due to loading of protos with same name

Describe the solution you'd like

Upgrade pubsub/gcppubsub to use cloud.google.com/go/pubsub/v2

Describe alternatives you've considered

N/A

Additional context

N/A

[vangent]

FYI, I am considering whether to update pubsub/gcppubsub to use v2 in place (which would be a breaking change, at least for some users), or to create a new pubsub/gcppubsubv2 package that uses v2 (which would require changes like updating imports and URL paths). Feedback welcome.

[tyrone-anz]

My personal preference is pubsub/gcppubsubv2. This is the less intrusive change. I am unsure however whether consumers will not run into the proto registration conflict issue, pubsub/v1 will still be a dependency.

If the breaking changes are minimal, updating pubsub/gcppubsub is probably not that bad.

No issue to me as well if you end up tagging a whole new gocloud.dev/v2, obviously overkill.

[vangent]

I am unsure however whether consumers will not run into the proto registration conflict issue, pubsub/v1 will still be a dependency

Hmm -- if that's the case then I'm not sure if there's a point in creating a separate v2. I don't think it's the case though. Any chance you can check? I.e., can you run your app normally and use, say, mempubsub without the panic? (I think yes, I think the panic happens only if you try to use pubsub/gcppubsub, so if I create a separate v2 it will be fine).

[tyrone-anz]

@vangent I debugged the issue.

It seems actually that only cloud.google.com/go/pubsub v1.49.0 is causing the proto conflict issue. When upgraded to v1.50.0, both cloud.google.com/go/pubsub and cloud.google.com/go/pubsub/v2 can coexist.

Let me test using mempubsub and not import gcppubsub and see if I'll get the proto conflict issue.
UPDATE: ^ This is working okay. As I am not importing gcppubsub, the init() func to register protos does not execute. So having pubsub/gcppubsubv2 should be fine.