infra/modules/loki/default.nix

{ config
, lib
, pkgs
, flake
, ...
}: {
  # source: https://gist.github.com/rickhull/895b0cb38fdd537c1078a858cf15d63e
  # https://grafana.com/docs/loki/latest/configure/examples/#1-local-configuration-exampleyaml
  services.loki = {
    enable = true;
    configuration = {
      server.http_listen_port = 3100;
      auth_enabled = false;
      common = {
        ring = {
          instance_addr = "127.0.0.1";
          kvstore = {
            store = "inmemory";
          };
        };
        replication_factor = 1;
        path_prefix = "/var/lib/loki";
        storage = {
          filesystem = {
            chunks_directory = "chunks/";
            rules_directory = "rules/";
          };
        };
      };
      # Keep logs for 4 weeks
      # https://grafana.com/docs/loki/latest/operations/storage/retention/
      limits_config.retention_period = "4w";
      compactor = {
        shared_store = "filesystem";
        compaction_interval = "10m";
        retention_enabled = true;
        retention_delete_delay = "2h";
        retention_delete_worker_count = 150;
      };
      schema_config = {
        configs = [{
          from = "2020-05-15";
          store = "boltdb-shipper";
          object_store = "filesystem";
          schema = "v11";
          index = {
            prefix = "index_";
            period = "24h";
          };
        }];
      };
    };
  };

  services.promtail = {
    enable = true;
    configuration = {
      server = {
        http_listen_port = 9080;
        grpc_listen_port = 0;
      };
      positions = {
        filename = "/tmp/positions.yaml";
      };
      clients = [{
        url = "http://127.0.0.1:${toString config.services.loki.configuration.server.http_listen_port}/loki/api/v1/push";
      }];
      scrape_configs = [{
        job_name = "journal";
        journal = {
          max_age = "24h";
          labels = {
            job = "systemd-journal";
            host = "flora-6";
          };
        };
        relabel_configs = [{
          source_labels = [ "__journal__systemd_unit" ];
          target_label = "unit";
        }];
      }];
    };
  };
}