[Ingest manager] Namespace should not accept empty string.

[ph]

it's possible to enter an empty string for the namespace box when adding or modifiying a datasource.
We should:

• Not allow an empty string.
• Use "default' as the default value.

Having an empty string will cause issues in Elasticsearch.

 FATAL  [illegal_argument_exception] The provided expression [logs-redis.log-] matches a data stream, specify the corresponding concrete indices instead. :: {"path":"/_alias/.kibana_k8s","query":{},"statusCode":400,"response":"{\"error\":{\"root_cause\":[{\"type\":\"illegal_argument_exception\",\"reason\":\"The provided expression [logs-redis.log-] matches a data stream, specify the corresponding concrete indices instead.\"}],\"type\":\"illegal_argument_exception\",\"reason\":\"The provided expression [logs-redis.log-] matches a data stream, specify the corresponding concrete indices instead.\"},\"status\":400}"}

[elasticmachine]

Pinging @elastic/ingest-management (Team:Ingest Management)

[ph]

We have a guard in 7.8 for the agent, elastic/beats#18769 but we should have the same guard in the UI to generate valid configuration.

In 7.8 we will massage the configuration to make it valid but 7.9 we will fail hard.

[nchaulet]

@ph how different this is from #65666 ?

[ph]

@nchaulet I think the main difference is to make sure we have a value for 7.8, #65666 seems to be more complicated to implement ?

[nchaulet]

I think it's probably not going to be more complicated to do #65666 directly @jen-huang correct me if I am wrong here

[ph]

@nchaulet Well, I think its more a matter of risk here for 7.8, which one appear to be less risky?

[nchaulet]

Yes let do the fix to not accept empty string and modify the UI in an another step for 7.9 👍Going to work on the fix this morning