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Documentation Grafana Loki Clients Promtail Stages output

output stage

The output stage is an action stage that takes data from the extracted map and changes the log line that will be sent to Loki.

Schema

yaml Copy

output:
  # Name from extracted data to use for the log entry.
  source: <string>

Example

For the given pipeline:

yaml Copy

- json:
    expressions:
      user: user
      message: message
- labels:
    user:
- output:
    source: message

And the given log line:

Copy

{"user": "alexis", "message": "hello, world!"}

Then the first stage will extract the following key-value pairs into the extracted map:

• user: alexis
• message: hello, world!

The second stage will then add user=alexis to the label set for the outgoing log line, and the final output stage will change the log line from the original JSON to hello, world!