nixos/grafana-agent: remove (#395514)

- [testers.shellcheck](https://nixos.org/manual/nixpkgs/unstable/#tester-shellcheck) now warns when `name` is not provided.

  The `name` argument will become mandatory in a future release.

- `grafana-agent` and `services.grafana-agent` have been removed in favor of

  Grafana Alloy (`grafana-alloy` and `services.alloy`), as they depend on an EOL compiler version

  and will become EOL during the 25.05 lifecycle.

  Grafana recommends migrating to `grafana-alloy` (`services.alloy`).

  See https://grafana.com/docs/alloy/latest/set-up/migrate/ for details.

- `xdragon` package has been renamed to `dragon-drop`.

  `xdragon` is an alias to `dragon-drop` and the package still provides `bin/xdragon`.

  `bin/dragon` is no longer supplied.

  ./services/monitoring/glances.nix

  ./services/monitoring/glpi-agent.nix

  ./services/monitoring/goss.nix

  ./services/monitoring/grafana-agent.nix

  ./services/monitoring/grafana-image-renderer.nix

  ./services/monitoring/grafana-reporter.nix

  ./services/monitoring/grafana-to-ntfy.nix

    ] "The fourStoreEndpoint module has been removed")

    (mkRemovedOptionModule [ "services" "fprot" ] "The corresponding package was removed from nixpkgs.")

    (mkRemovedOptionModule [ "services" "frab" ] "The frab module has been removed")

    (mkRemovedOptionModule

      [

        "services"

        "grafana-agent"

      ]

      "The grafana-agent module has been removed. Consider migrating to `grafana-alloy` (`services.alloy.enable`). See <https://grafana.com/docs/alloy/latest/set-up/migrate/>"

    )

    (mkRemovedOptionModule [ "services" "homeassistant-satellite" ]

      "The `services.homeassistant-satellite` module has been replaced by `services.wyoming-satellite`."

    )

{

  lib,

  pkgs,

  config,

  generators,

  ...

}:

let

  cfg = config.services.grafana-agent;

  settingsFormat = pkgs.formats.yaml { };

  configFile = settingsFormat.generate "grafana-agent.yaml" cfg.settings;

in

{

  meta = {

    maintainers = with lib.maintainers; [

      flokli

      zimbatm

    ];

  };

  options.services.grafana-agent = {

    enable = lib.mkEnableOption "grafana-agent";

    package = lib.mkPackageOption pkgs "grafana-agent" { };

    credentials = lib.mkOption {

      description = ''

        Credentials to load at service startup. Keys that are UPPER_SNAKE will be loaded as env vars. Values are absolute paths to the credentials.

      '';

      type = lib.types.attrsOf lib.types.str;

      default = { };

      example = {

        logs_remote_write_password = "/run/keys/grafana_agent_logs_remote_write_password";

        LOGS_REMOTE_WRITE_URL = "/run/keys/grafana_agent_logs_remote_write_url";

        LOGS_REMOTE_WRITE_USERNAME = "/run/keys/grafana_agent_logs_remote_write_username";

        metrics_remote_write_password = "/run/keys/grafana_agent_metrics_remote_write_password";

        METRICS_REMOTE_WRITE_URL = "/run/keys/grafana_agent_metrics_remote_write_url";

        METRICS_REMOTE_WRITE_USERNAME = "/run/keys/grafana_agent_metrics_remote_write_username";

      };

    };

    extraFlags = lib.mkOption {

      type = with lib.types; listOf str;

      default = [ ];

      example = [

        "-enable-features=integrations-next"

        "-disable-reporting"

      ];

      description = ''

        Extra command-line flags passed to {command}`grafana-agent`.

        See <https://grafana.com/docs/agent/latest/static/configuration/flags/>

      '';

    };

    settings = lib.mkOption {

      description = ''

        Configuration for {command}`grafana-agent`.

        See <https://grafana.com/docs/agent/latest/configuration/>

      '';

      type = lib.types.submodule {

        freeformType = settingsFormat.type;

      };

      default = { };

      defaultText = lib.literalExpression ''

        {

          metrics = {

            wal_directory = "\''${STATE_DIRECTORY}";

            global.scrape_interval = "5s";

          };

          integrations = {

            agent.enabled = true;

            agent.scrape_integration = true;

            node_exporter.enabled = true;

          };

        }

      '';

      example = {

        metrics.global.remote_write = [

          {

            url = "\${METRICS_REMOTE_WRITE_URL}";

            basic_auth.username = "\${METRICS_REMOTE_WRITE_USERNAME}";

            basic_auth.password_file = "\${CREDENTIALS_DIRECTORY}/metrics_remote_write_password";

          }

        ];

        logs.configs = [

          {

            name = "default";

            scrape_configs = [

              {

                job_name = "journal";

                journal = {

                  max_age = "12h";

                  labels.job = "systemd-journal";

                };

                relabel_configs = [

                  {

                    source_labels = [ "__journal__systemd_unit" ];

                    target_label = "systemd_unit";

                  }

                  {

                    source_labels = [ "__journal__hostname" ];

                    target_label = "nodename";

                  }

                  {

                    source_labels = [ "__journal_syslog_identifier" ];

                    target_label = "syslog_identifier";

                  }

                ];

              }

            ];

            positions.filename = "\${STATE_DIRECTORY}/loki_positions.yaml";

            clients = [

              {

                url = "\${LOGS_REMOTE_WRITE_URL}";

                basic_auth.username = "\${LOGS_REMOTE_WRITE_USERNAME}";

                basic_auth.password_file = "\${CREDENTIALS_DIRECTORY}/logs_remote_write_password";

              }

            ];

          }

        ];

      };

    };

  };

  config = lib.mkIf cfg.enable {

    services.grafana-agent.settings = {

      # keep this in sync with config.services.grafana-agent.settings.defaultText.

      metrics = {

        wal_directory = lib.mkDefault "\${STATE_DIRECTORY}";

        global.scrape_interval = lib.mkDefault "5s";

      };

      integrations = {

        agent.enabled = lib.mkDefault true;

        agent.scrape_integration = lib.mkDefault true;

        node_exporter.enabled = lib.mkDefault true;

      };

    };

    systemd.services.grafana-agent = {

      wantedBy = [ "multi-user.target" ];

      script = ''

        set -euo pipefail

        shopt -u nullglob

        # Load all credentials into env if they are in UPPER_SNAKE form.

        if [[ -n "''${CREDENTIALS_DIRECTORY:-}" ]]; then

          for file in "$CREDENTIALS_DIRECTORY"/*; do

            key=$(basename "$file")

            if [[ $key =~ ^[A-Z0-9_]+$ ]]; then

              echo "Environ $key"

              export "$key=$(< "$file")"

            fi

          done

        fi

        # We can't use Environment=HOSTNAME=%H, as it doesn't include the domain part.

        export HOSTNAME=$(< /proc/sys/kernel/hostname)

        exec ${lib.getExe cfg.package} -config.expand-env -config.file ${configFile} ${lib.escapeShellArgs cfg.extraFlags}

      '';

      serviceConfig = {

        Restart = "always";

        DynamicUser = true;

        RestartSec = 2;

        SupplementaryGroups = [

          # allow to read the systemd journal for loki log forwarding

          "systemd-journal"

        ];

        StateDirectory = "grafana-agent";

        LoadCredential = lib.mapAttrsToList (key: value: "${key}:${value}") cfg.credentials;

        Type = "simple";

      };

    };

  };

}

  gotify-server = handleTest ./gotify-server.nix { };

  gotosocial = runTest ./web-apps/gotosocial.nix;

  grafana = handleTest ./grafana { };

  grafana-agent = handleTest ./grafana-agent.nix { };

  graphite = handleTest ./graphite.nix { };

  grav = runTest ./web-apps/grav.nix;

  graylog = handleTest ./graylog.nix { };