Prometheus exporter for cassandra-medusa.

The metrics are collected based on result of medusa list-backups --output json command. You need to run exporter on the same host where Medusa was installed or inside Docker.

Changes from this cassandra-medusa/pull/899 PR are required for the exporter.

To get a dashboard for visualizing the collected metrics, you can use a ready-made dashboard Medusa Exporter Dashboard or make your own.

For medusa_backup_duration_seconds and medusa_node_backup_duration_seconds metrics the following logic is applied:

• if backup/node backup is complete then value calculated;
• if backup/node backup is not complete, then value is 0, labels stop_time is none;
• for missing nodes: value is 0, labels start_time and stop_time are set to none.

For missing nodes, medusa_node_backup_* metrics are set with default values:

• medusa_node_backup_info: labels release_version, server_type, and start_time are set to none;
• medusa_node_backup_status: value is 2 (missing);
• medusa_node_backup_duration_seconds, medusa_node_backup_size_bytes, medusa_node_backup_objects: value is 0.

For medusa_*_last_* metrics the following logic is applied:

• metrics are calculated only for completed backups;
• if only full completed backups exist, only backup_type="full" metrics will be set;
• if only differential backups exist, only backup_type="differential" metrics will be set;
• if both types exist, both labels will be set with their respective latest backups;
• metrics are not set if no completed backups exist at all.
• Medusa allows creating only differential backups without full backups - in this case, only backup_type="differential" metrics will be available.

git clone https://github.com/woblerr/medusa_exporter.git
cd medusa_exporter
make build
./medusa_exporter <flags>

Available configuration flags:

usage: medusa_exporter [<flags>]


Flags:
  -h, --[no-]help              Show context-sensitive help (also try --help-long and --help-man).
      --web.telemetry-path="/metrics"  
                               Path under which to expose metrics.
      --web.listen-address=:19500 ...  
                               Addresses on which to expose metrics and web interface. Repeatable for multiple
                               addresses. Examples: `:9100` or `[::1]:9100` for http, `vsock://:9100` for vsock
      --web.config.file=""     Path to configuration file that can enable TLS or authentication. See:
                               https://github.com/prometheus/exporter-toolkit/blob/master/docs/web-configuration.md
      --collect.interval=600   Collecting metrics interval in seconds.
      --medusa.config-file=""  Full path to Medusa configuration file.
      --medusa.prefix=""       Prefix for shared storage.
      --log.level=info         Only log messages with the given severity or above. One of: [debug, info, warn, error]
      --log.format=logfmt      Output format of log messages. One of: [logfmt, json]
      --[no-]version           Show application version.

Custom config for medusa command can be specified via --medusa.config flag. Full paths must be specified.
For example, --medusa.config=/tmp/medusa.conf.

When --log.level=debug is specified - information of values and labels for metrics is printing to the log.

The flag --web.config.file allows to specify the path to the configuration for TLS and/or basic authentication.
The description of TLS configuration and basic authentication can be found at exporter-toolkit/web.

• Register medusa_exporter (already builded, if not - exec make build before) as a systemd service:

make prepare-service

Validate prepared file medusa_exporter.service and run:

sudo make install-service

• View service logs:

journalctl -u medusa_exporter.service

• Delete systemd service:

sudo make remove-service

Manual register systemd service:

cp medusa_exporter.service.template medusa_exporter.service

In file medusa_exporter.service replace {PATH_TO_FILE} to full path to medusa_exporter.

sudo cp medusa_exporter.service /etc/systemd/system/medusa_exporter.service
sudo systemctl daemon-reload
sudo systemctl enable medusa_exporter.service
sudo systemctl restart medusa_exporter.service
systemctl -l status medusa_exporter.service

You can use the already prepared rpm/deb package to install the exporter. Only the medusa_exporter binary and the service file are installed by package.

For example:

rpm -ql medusa_exporter

/etc/systemd/system/medusa_exporter.service
/usr/bin/medusa_exporter

Run the unit tests:

make test

Run the end-to-end tests:

make test-e2e