Increasing Prometheus storage retention

The default retention of Prometheus on SwarmTelemetry is 15 days, so data will be removed automatically after 15 days. Below is how to change the data retention of Prometheus.

1. Edit the prometheus.service file

   vi /usr/lib/systemd/system/prometheus.service

2. Change the value of “--storage.tsdb.retention.time=15d" below to "ExecStart=/usr/local/bin/prometheus \" line.
   The config will look like below for 45 days of data retention. (e.g. 1 year: 1y or 365d)

   # /etc/systemd/system/prometheus.service [Unit] Description=Prometheus Server Documentation=https://prometheus.io/docs/introduction/overview/ After=network-online.target [Service] User=prometheus Restart=on-failure ExecStart=/usr/local/bin/prometheus \ --config.file=/etc/prometheus/prometheus.yml \ --storage.tsdb.path=/var/lib/prometheus/data \ --storage.tsdb.retention.time=45d \ --web.console.templates=/etc/prometheus/consoles \ --web.console.libraries=/etc/prometheus/console_libraries [Install] WantedBy=multi-user.target

3. Reload systemd manager configuration

   systemctl daemon-reload

4. Restart Prometheus service

See the Prometheus documentation.