gnmic supports exporting subscription updates to multiple NATS Streaming (STAN) servers/clusters simultaneously

A STAN output can be defined using the below format in gnmic config file under outputs section:

    - type: stan # required
      address: localhost:4223 # comma separated STAN servers
      subject: telemetry # stan subject
      subject-prefix: telemetry # stan subject prefix, the subject prefix is built the same way as for NATS output
      username: # STAN username
      password: # STAN password
      name: # client name
      cluster-name: test-cluster # cluster name
      timeout: # connection timeout
      ping-interval: # STAN ping interval
      ping-retry: # STAN ping retry

Using subject config value a user can specify the STAN subject to which to send all subscriptions updates for all targets

If a user wants to separate updates by targets and by subscriptions, subject-prefix can be used. if subject-prefix is specified subject is ignored.