diff --git a/modules/prometheus/alert-rules.nix b/modules/prometheus/alert-rules.nix
new file mode 100644
index 0000000..4561388
--- /dev/null
+++ b/modules/prometheus/alert-rules.nix
@@ -0,0 +1,260 @@
+{ 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}}";
+    # };
+  })
diff --git a/modules/prometheus/default.nix b/modules/prometheus/default.nix
index de5d88b..1cad3a3 100644
--- a/modules/prometheus/default.nix
+++ b/modules/prometheus/default.nix
@@ -73,5 +73,50 @@
         ];
       }
     ];
+
+    ruleFiles = [
+      (pkgs.writeText "prometheus-rules.yml" (builtins.toJSON {
+        groups = [{
+          name = "alerting-rules";
+          rules = import ./alert-rules.nix { inherit lib; };
+        }];
+      }))
+    ];
+
+    alertmanagers = [{ static_configs = [{ targets = [ "localhost:9093" ]; }]; }];
+
+    alertmanager = {
+      enable = true;
+      # port = 9093; # Default
+      webExternalUrl = "https://alerts.pub.solar"; # TODO use a proper url?
+      # environmentFile = "${config.age.secrets.nachtigall-alertmanager-envfile.path}";
+      configuration = {
+
+        route = {
+          receiver = "all";
+          group_by = [ "instance" ];
+          group_wait = "30s";
+          group_interval = "2m";
+          repeat_interval = "24h";
+        };
+
+        receivers = [{
+          name = "all";
+          # Email config documentation: https://prometheus.io/docs/alerting/latest/configuration/#email_config
+          email_configs = [{
+            send_resolved = true;
+            to = "TODO";
+            from = "alerts@pub.solar";
+            smarthost = "TODO";
+            auth_username = "TODO";
+            auth_password_file = "${config.age.secrets.nachtigall-alertmanager-smtp-password.path}";
+            require_tls = true;
+          }];
+          # TODO:
+          # For matrix notifications, look into: https://github.com/pinpox/matrix-hook and add a webhook
+          #   webhook_configs = [ { url = "http://127.0.0.1:11000/alert"; } ];
+        }];
+      };
+    };
   };
 }