Verify message format to publish on the bus

[simonswine]

The message format (cf. https://github.com/grafana/prometheus-pulsar-remote-write/blob/7d5901bb9d0ac60313a50b85a309949ccbeb2a10/pulsar/serializers_test.go) how metrics are represented is based on the provided implementation from https://github.com/liangyuanpeng/prometheus-pulsar-adapter.

I think we should review this going forward and think about those conditions:

• We need to make sure we have a lossless marshal and unmarshaling of the payload (esp. for phase 2 when we trying to read back the messages from the bus)
• Potentially the customer has some custom requirements or other legacy format that we need to match
• We might need to store more information (e.g) tenant ID
• We should also consider using the properties fields and/or the EventTime of pulsar Messages (not for now)

[simonswine]

@jtlisi I think this is the next step for this adapter. Let me know what you think and if we have any idea in which format the customer expect the messages to be sent

[jtlisi]

I agree, we are going to need to store the tenant ID. The ideal format for these messages will be JSON initially, if another format is requested we can add support for it later.

[simonswine]

We should remove AVRO from the CLI and publish the tenant ID in JSON format

[simonswine]

An important point to remember is that the tenant ID should be acquired through basic auth