infra/modules/prometheus/alert-rules.nix

{ lib }:

let
  # docker's filesystems disappear quickly, leading to false positives
  deviceFilter = ''path!~"^(/var/lib/docker|/nix/store).*"'';
in
lib.mapAttrsToList
  (name: opts: {
    alert = name;
    expr = opts.condition;
    for = opts.time or "2m";
    labels = { };
    annotations.description = opts.description;
  })
  ({

    # prometheus_too_many_restarts = {
    #   condition = ''changes(process_start_time_seconds{job=~"prometheus|alertmanager"}[15m]) > 2'';
    #   description = "Prometheus has restarted more than twice in the last 15 minutes. It might be crashlooping.";
    # };

    # alert_manager_config_not_synced = {
    #   condition = ''count(count_values("config_hash", alertmanager_config_hash)) > 1'';
    #   description = "Configurations of AlertManager cluster instances are out of sync.";
    # };

    #alert_manager_e2e_dead_man_switch = {
    #  condition = "vector(1)";
    #  description = "Prometheus DeadManSwitch is an always-firing alert. It's used as an end-to-end test of Prometheus through the Alertmanager.";
    #};

    # prometheus_not_connected_to_alertmanager = {
    #   condition = "prometheus_notifications_alertmanagers_discovered < 1";
    #   description = "Prometheus cannot connect the alertmanager\n  VALUE = {{ $value }}\n  LABELS = {{ $labels }}";
    # };

    # prometheus_rule_evaluation_failures = {
    #   condition = "increase(prometheus_rule_evaluation_failures_total[3m]) > 0";
    #   description = "Prometheus encountered {{ $value }} rule evaluation failures, leading to potentially ignored alerts.\n  VALUE = {{ $value }}\n  LABELS = {{ $labels }}";
    # };

    # prometheus_template_expansion_failures = {
    #   condition = "increase(prometheus_template_text_expansion_failures_total[3m]) > 0";
    #   time = "0m";
    #   description = "Prometheus encountered {{ $value }} template text expansion failures\n  VALUE = {{ $value }}\n  LABELS = {{ $labels }}";
    # };

    # promtail_file_lagging = {
    #   condition = ''abs(promtail_file_bytes_total - promtail_read_bytes_total) > 1e6'';
    #   time = "15m";
    #   description = ''{{ $labels.instance }} {{ $labels.job }} {{ $labels.path }} has been lagging by more than 1MB for more than 15m.'';
    # };

    filesystem_full_80percent = {
      condition = ''
        100 - ((node_filesystem_avail_bytes{fstype!="rootfs",mountpoint="/"} * 100) / node_filesystem_size_bytes{fstype!="rootfs",mountpoint="/"}) > 80'';
      time = "10m";
      description =
        "{{$labels.instance}} device {{$labels.device}} on {{$labels.mountpoint}} got less than 20% space left on its filesystem.";
    };

    # filesystem_inodes_full = {
    #   condition = ''disk_inodes_free / disk_inodes_total < 0.10'';
    #   time = "10m";
    #   description = "{{$labels.instance}} device {{$labels.device}} on {{$labels.mountpoint}} got less than 10% inodes left on its filesystem.";
    # };

    # daily_task_not_run = {
    #   # give 6 hours grace period
    #   condition = ''time() - task_last_run{state="ok",frequency="daily"} > (24 + 6) * 60 * 60'';
    #   description = "{{$labels.instance}}: {{$labels.name}} was not run in the last 24h";
    # };

    # daily_task_failed = {
    #   condition = ''task_last_run{state="fail"}'';
    #   description = "{{$labels.instance}}: {{$labels.name}} failed to run";
    # };
    # } // (lib.genAttrs [
    #   "borgbackup-turingmachine"
    #   "borgbackup-eve"
    #   "borgbackup-datastore"
    # ]
    #   (name: {
    #     condition = ''absent_over_time(task_last_run{name="${name}"}[1d])'';
    #     description = "status of ${name} is unknown: no data for a day";
    #   }))
    # // {

    # borgbackup_matchbox_not_run = {
    #   # give 6 hours grace period
    #   condition = ''time() - task_last_run{state="ok",frequency="daily",name="borgbackup-matchbox"} > 7 * 24 * 60 * 60'';
    #   description = "{{$labels.instance}}: {{$labels.name}} was not run in the last week";
    # };

    # borgbackup_matchbox = {
    #   condition = ''absent_over_time(task_last_run{name="borgbackup-matchbox"}[7d])'';
    #   description = "status of borgbackup-matchbox is unknown: no data for a week";
    # };

    # homeassistant = {
    #   condition = ''
    #     homeassistant_entity_available{domain="persistent_notification", entity!="persistent_notification.http_login"} >= 0'';
    #   description =
    #     "homeassistant notification {{$labels.entity}} ({{$labels.friendly_name}}): {{$value}}";
    # };

    swap_using_20percent = {
      condition =
        "node_memory_SwapTotal_bytes - (node_memory_SwapCached_bytes + node_memory_SwapFree_bytes) > node_memory_SwapTotal_bytes * 0.2";
      time = "30m";
      description =
        "{{$labels.instance}} is using 20% of its swap space for at least 30 minutes.";
    };

    systemd_service_failed = {
      condition = ''node_systemd_unit_state{state="failed"} == 1'';
      description =
        "{{$labels.instance}} failed to (re)start service {{$labels.name}}.";
    };

    restic_backup_too_old = {
      condition = ''(time() - restic_snapshots_latest_time)/(60*60) > 24'';
      description = "{{$labels.instance}} not backed up for more than 24 hours. ({{$value}})";
    };

    host_down = {
      condition = ''up{job="node-stats", instance!~"ahorn.wireguard:9100|kartoffel.wireguard:9100|mega.wireguard:9100"} == 0'';
      description = "{{$labels.instance}} is down!";
    };

    # service_not_running = {
    #   condition = ''systemd_units_active_code{name=~"teamspeak3-server.service|tt-rss.service", sub!="running"}'';
    #   description = "{{$labels.instance}} should have a running {{$labels.name}}.";
    # };

    ram_using_90percent = {
      condition =
        "node_memory_Buffers_bytes + node_memory_MemFree_bytes + node_memory_Cached_bytes < node_memory_MemTotal_bytes * 0.1";
      time = "1h";
      description =
        "{{$labels.instance}} is using at least 90% of its RAM for at least 1 hour.";
    };

    cpu_using_90percent = {
      condition = ''
        100 - (avg by (instance) (irate(node_cpu_seconds_total{mode="idle"}[5m])) * 100) >= 90'';
      time = "10m";
      description =
        "{{$labels.instance}} is running with cpu usage > 90% for at least 10 minutes: {{$value}}";
    };

    reboot = {
      condition = "node_boot_time_seconds < 300";
      description = "{{$labels.instance}} just rebooted.";
    };

    uptime = {
      condition = "(time() - node_boot_time_seconds ) / (60*60*24) > 30";
      description =
        "Uptime monster: {{$labels.instance}} has been up for more than 30 days.";
    };

    flake_nixpkgs_outdated = {
      condition = ''
        (time() - flake_input_last_modified{input="nixpkgs"}) / (60*60*24) > 30'';
      description =
        "Nixpkgs outdated: Nixpkgs on {{$labels.instance}} has not been updated in 30 days";
    };

    /* ping = {
      condition = "ping_result_code{type!='mobile'} != 0";
      description = "{{$labels.url}}: ping from {{$labels.instance}} has failed!";
      };

      ping_high_latency = {
      condition = "ping_average_response_ms{type!='mobile'} > 5000";
      description = "{{$labels.instance}}: ping probe from {{$labels.source}} is encountering high latency!";
      };
    */
    http_status = {
      condition = ''
        probe_http_status_code{instance!~"https://megaclan3000.de"} != 200'';
      description =
        "http request failed from {{$labels.instance}}: {{$labels.result}}!";
    };
    /* http_match_failed = {
      condition = "http_response_response_string_match == 0";
      description = "{{$labels.server}} : http body not as expected; status code: {{$labels.status_code}}!";
      };
      dns_query = {
      condition = "dns_query_result_code != 0";
      description = "{{$labels.domain}} : could retrieve A record {{$labels.instance}} from server {{$labels.server}}: {{$labels.result}}!";
      };
      secure_dns_query = {
      condition = "secure_dns_state != 0";
      description = "{{$labels.domain}} : could retrieve A record {{$labels.instance}} from server {{$labels.server}}: {{$labels.result}} for protocol {{$labels.protocol}}!";
      };
      connection_failed = {
      condition = "net_response_result_code != 0";
      description = "{{$labels.server}}: connection to {{$labels.port}}({{$labels.protocol}}) failed from {{$labels.instance}}";
      };
      healthchecks = {
      condition = "hc_check_up == 0";
      description = "{{$labels.instance}}: healtcheck {{$labels.job}} fails!";
      };
    */
    cert_expiry = {
      condition = "(probe_ssl_earliest_cert_expiry - time())/(3600*24) < 30";
      description =
        "{{$labels.instance}}: The TLS certificate will expire in less than 30 days: {{$value}}s";
    };

    # ignore devices that disabled S.M.A.R.T (example if attached via USB)

    # smart_errors = {
    #   condition = ''smart_device_health_ok{enabled!="Disabled"} != 1'';
    #   description =
    #     "{{$labels.instance}}: S.M.A.R.T reports: {{$labels.device}} ({{$labels.model}}) has errors.";
    # };

    oom_kills = {
      condition = "increase(node_vmstat_oom_kill[5m]) > 0";
      description = "{{$labels.instance}}: OOM kill detected";
    };

    /* unusual_disk_read_latency = {
      condition =
      "rate(diskio_read_time[1m]) / rate(diskio_reads[1m]) > 0.1 and rate(diskio_reads[1m]) > 0";
      description = ''
      {{$labels.instance}}: Disk latency is growing (read operations > 100ms)
      '';
      };

      unusual_disk_write_latency = {
      condition =
      "rate(diskio_write_time[1m]) / rate(diskio_write[1m]) > 0.1 and rate(diskio_write[1m]) > 0";
      description = ''
      {{$labels.instance}}: Disk latency is growing (write operations > 100ms)
      '';
      };
    */

    host_memory_under_memory_pressure = {
      condition = "rate(node_vmstat_pgmajfault[1m]) > 1000";
      description =
        "{{$labels.instance}}: The node is under heavy memory pressure. High rate of major page faults: {{$value}}";
    };

    # ext4_errors = {
    #   condition = "ext4_errors_value > 0";
    #   description =
    #     "{{$labels.instance}}: ext4 has reported {{$value}} I/O errors: check /sys/fs/ext4/*/errors_count";
    # };

    # alerts_silences_changed = {
    #   condition = ''abs(delta(alertmanager_silences{state="active"}[1h])) >= 1'';
    #   description =
    #     "alertmanager: number of active silences has changed: {{$value}}";
    # };
  })