journald-exporter

This is all written in Rust for simplicity and performance.

• Installation and updating
• Contributing
• Metrics emitted
• License

Installation and updating

See the installation guide. Be sure to also save a link to this README in your runbook, in the rare event things go wrong. While this is extensively tested and tries its best to handle all reasonable error modes, no software is perfect, and this is no exception.

Contributing

See the contributing guide. It also documents the internals at a high level. Consider checking it out if you want to contribute!

Metrics emitted

• Counter journald_entries_ingested: The total number of entries ingested.
• Counter journald_fields_ingested: The total number of data fields read. Normally it's 5 fields (_SYSTEMD_UNIT, PRIORITY, _UID, _GID, and MESSAGE) for message entries, but may be fewer in the case of incomplete fields and such.
• Counter journald_data_ingested_bytes: The total number of data field bytes ingested across all fields, including both keys and their values.
• Counter journald_faults: The total number of faults encountered while reading the journal.
• Counter journald_cursor_double_retries: Total number of faults encountered while recovering after a previous fault. Also increments if it fails on first read. Note: too many of these in a short period of time will cause entire program to crash.
• Counter journald_unreadable_fields: The total number of fields unreadable for reasons other than being corrupted (usually, too large to be read).
• Counter journald_corrupted_fields: The total number of corrupted entries detected while reading the journal that could still be read.
• Counter journald_metrics_requests: The total number of requests received, including requests to paths other than the standard GET /metrics route.
  • This can also be used to ensure the server's live and receiving requests.
  • This can also be used to ensure that anything like Grafana Agent is in fact scraping metrics at the desired frequency, and if done locally, it can isolate that very easily from network malfunctions.
• Counter journald_messages_ingested: Number of message entries successfully processed.
• Counter journald_messages_ingested_bytes: Total number of MESSAGE field bytes ingested.

The journald_messages_ingested and journald_messages_ingested_bytes metrics include a few extra dimensions to allow more in-depth inspection:

• Key service: A systemd service name, usually ending in .service, or ? if no service is present.
• Key priority: A syslog priority keyword in uppercase. If none can be discerned, ERR is used.
  • priority="EMERG"
  • priority="ALERT"
  • priority="CRIT"
  • priority="ERR" (also used in case of missing priority)
  • priority="WARNING"
  • priority="NOTICE"
  • priority="INFO"
  • priority="DEBUG"
• Key severity: A syslog severity number, an integer from 0 to 7 inclusive. Corresponds with priority.
• Key user: The name of the active user as per the data point given, the UID if it could not be discerned, or ? if no UID is present.
• Key group: The name of the active group as per the data point given, the GID if it could not be discerned, or ? if no GID is present.

To ensure global sum works, the above two metrics return a simple unlabeled 0 if no entries have been added yet.

License

Copyright 2023 Claudia Meadows

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 or in the LICENSE.txt file of this directory.

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.