Can't create topics after #12818 using Pulsar master client and 2.9.x (or prior) broker (v3/persistent NOT FOUND)

[nicoloboschi]

Describe the bug
After #12818, a client (built starting from the master branch) get not found while trying to create a topic, if the server doesn't support admin v3 topic endpoint (currently only the master branch has this endpoint).

To Reproduce

• Run Pulsar standalone 2.9.x (or prior)
• Run command (from master branch) bin/pulsar-admin topics create-partitioned-topic test -p 1
  You get:

2022-02-03T12:26:16,790+0000 [AsyncHttpClient-7-1] WARN  org.apache.pulsar.client.admin.internal.BaseResource - [http://172.17.0.2:8080/admin/v3/persistent/public/default/test/partitions?createLocalTopicOnly=false] Failed to perform http put request: javax.ws.rs.NotFoundException: HTTP 404 Not Found
HTTP 404 Not Found

Reason: HTTP 404 Not Found

Expected behavior
The client should be send the request to v2 rest api endpoint

[eolivelli]

@nicoloboschi good catch!

We should discuss about this on dev@ and we must fix this somehow

[eolivelli]

So this comment is not correct
#12818 (comment)

[lhotari]

This was discussed in the Pulsar community meeting. Some notes from the discussion:

• PR PIP 110: Support Topic metadata - PART-1 create topic with properties #12818 changes should be reverted so that API could be kept backwards compatible.
• It’s possible to have the current v2 API for creating persistent topics to handle multiple different payload types
  The challenge seems to be that in the old method, the number of partitions was passed in the payload as a single integer without having a JSON object at all. This makes it harder to extend the existing API, but doesn’t make it impossible.
• One possible solution is based on request’s “Content Type”
  Content-Type: application/vnd.some-custom-identifier+json on request, @Consumes("application/vnd.some-custom-identifier+json") on method that handles the new payload type. It also needs an annotation that the newer payload uses the custom mime type.

[lhotari]

The custom content type could be set here:

pulsar/pulsar-client-admin/src/main/java/org/apache/pulsar/client/admin/internal/TopicsImpl.java

Lines 353 to 358 in 10036d5

	if (properties != null) {
	PartitionedTopicMetadata metadata = new PartitionedTopicMetadata(numPartitions, properties);
	entity = Entity.entity(metadata, MediaType.APPLICATION_JSON);
	} else {
	entity = Entity.entity(numPartitions, MediaType.APPLICATION_JSON);
	}

Would be MediaType.valueOf("application/vnd.some-custom-identifier+json")

[eolivelli]

@lhotari would you please the PR with the revert?
This way we will unblock downstream consumers of the master branch

[lhotari]

@lhotari would you please the PR with the revert? This way we will unblock downstream consumers of the master branch

It might be simpler to create a PR to fix the issue. I can do that.

[lhotari]

I pushed #14117 as a fix that uses the custom JSON media type solution.

[lhotari]

I noticed that this is needed to fix the issue too: 02a3201

That alone would fix the issue. However I think it's better to not add a new API version in this way since it's not even consistent. For all other methods, the support for PIP-110 was added directly to the existing v2 API.