Cannot export using otlp with basic auth

[politician]

Describe the bug
I would like to export traces to a Tempo instance hosted on Grafana Cloud. This requires authentication with basic auth, but I cannot make it work using the basicauth extension, it seems only supported when receiving traces via otlp but not exporting.

It works when using basic auth headers.

Steps to reproduce

receivers:
  jaeger:
    protocols:
      grpc:
      thrift_http:

processors:
  batch:

exporters:
  logging:
    logLevel: debug

  otlp:
    endpoint: tempo-eu-west-0.grafana.net:443
    auth:
      authenticator: basicauth

extensions:
  basicauth:
    htpasswd:
      inline: |
        user:pass

service:
  extensions:
    - basicauth

  pipelines:
    traces:
      receivers:
        - jaeger
      processors:
        - batch
      exporters:
        - logging
        - otlp

What did you expect to see?

Traces sent to Tempo

What did you see instead?

cannot start exporters: requested authenticator is not a client authenticator

Workaround using headers

receivers:
  jaeger:
    protocols:
      grpc:
      thrift_http:

processors:
  batch:

exporters:
  logging:
    logLevel: debug

  otlp:
    endpoint: tempo-eu-west-0.grafana.net:443
    headers:
      authorization: Basic {{ "user:pass" | b64enc }}

service:
  pipelines:
    traces:
      receivers:
        - jaeger
      processors:
        - batch
      exporters:
        - logging
        - otlp

What version did you use?
Version: 0.48.0

Environment
Kubernetes

[jpkrohling]

The basic auth extension is only for incoming requests, not for outgoing. There's a plan to add support for basic auth on the client side, but it hasn't been merged yet (see #8847). As such, I'm closing this, as work is being tracked there.