3.16. plg

This role installs a Prometheus-Loki-Grafana stack as monitoring server.

On the one hand those services are a common combination and on the other hand Incus which is often used for virtualization in this project provides easy integration with those.

The components roughly have the following objectives:

• Prometheus: Aggregate metrics (pull)

• Loki: Aggregate logs (push)

• Grafana: Visualize collected metrics & logs

The counterpart is Grafana Alloy as agent on the instances to monitor (see alloy role).

Check Examples -> Production -> Extended as an example usage.

It can be configured by the following options (p, l or g after plg_ state if they are needed for Prometheus, Loki or Grafana):

• Parameters:

  • plg_p_incus_connection: URL for Incus connection, default works for Incus host containing this server as instance

  • plg_p_incus_servername: Hostname of Incus, has to match the real hostname (at the time of Incus installation when a certificate was created with the name)

  • plg_p_certs: Dictionary containing paths for certificates needed for the Incus connection, a path where to find them and a directory where to put them (see Examples -> Production -> Extended)

  • plg_p_alloy_targets: List of dictionaries with an URL and a label for agents to pull metrics from

  • plg_g_smtp: Use SMTP if true (for email alerts)

  • plg_g_smtp_host: Connection information of SMTP host

  • plg_g_smtp_user: Email address used for sending

  • plg_g_stmp_pw: Email password, usually overtaken from vault_plg_g_stmp_pw to be encrypted

• Variables:

  • plg_p_user: OS user for Prometheus

  • plg_p_url: URL for downloading an archive

  • plg_p_checksum: Checksum of the archive

  • plg_p_parent_dir: Directory to put Prometheus inside

  • plg_p_base_dir: Prometheus base directory (by default inside parent directory)

  • plg_p_config_path: Path of main config file

  • plg_p_service_path: Path where to put the systemd service file

  • plg_l_apt: Dictionary for APT installation of Loki containing key_url for downloading a GPG key to key_dest and repo as APT repository sources entry.

  • plg_l_config_path: Main config path for Loki

  • plg_g_apt: Dictionary for APT installation of Grafana containing key_url for downloading a GPG key to key_dest and repo as APT repository sources entry (same as Loki currently).

  • plg_g_config_path: Main config path for Grafana

  • plg_file_mode: Default file mode.

  • plg_dir_mode: Default directory mode.

  • plg_ansible_comment: Put plg_template_comment on top of templates if true

  • plg_template_comment: Comment put on top of every template delivered by Ansible