Documentation Grafana Loki documentation Send data Promtail Pipeline stages eventlogmessage

eventlogmessage

The eventlogmessage stage is a parsing stage that extracts data from the Message string that appears in the Windows Event Log.

Schema

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eventlogmessage:
  # Name from extracted data to parse, defaulting to the name
  # used by the windows_events scraper
  [source: <string> | default = message]

  # If previously extracted data exists for a key that occurs
  # in the Message, when true, the previous value will be
  # overwriten by the value in the Message. Otherwise,
  # '_extracted' will be appended to the key that is used for
  # the value in the Message.
  [overwrite_existing: <bool> | default = false]

  # When true, keys extracted from the Message that are not
  # valid labels will be dropped, otherwise they will be
  # automatically converted into valid labels replacing invalid
  # characters with underscores
  [drop_invalid_labels: <bool> | default = false]

The extracted data can hold non-string values and this stage does not do any type conversions; downstream stages will need to perform correct type conversion of these values as necessary. Please refer to the the template stage for how to do this.

Example combined with json

For the given pipeline:

yaml Copy

- json:
    expressions:
      message:
      Overwritten:
- eventlogmessage:
    source: message
    overwrite_existing: true

Given the following log line:

Copy

{"event_id": 1, "Overwritten": "old", "message": "Message type:\r\nOverwritten: new\r\nImage: C:\\Users\\User\\promtail.exe"}

The first stage would create the following key-value pairs in the set of extracted data:

• message: Message type:\r\nOverwritten: new\r\nImage: C:\Users\User\promtail.exe
• Overwritten: old

The second stage will parse the value of message from the extracted data and append/overwrite the following key-value pairs to the set of extracted data:

• Image: C:\\Users\\User\\promtail.exe
• Message_type: (empty string)
• Overwritten: new