refactor: make Prometheus & Loki config reusable

1 files changed, 55 insertions, 0 deletions

diff --git a/nixos/hosts/tente/exporters.nix b/nixos/hosts/tente/exporters.nix
new file mode 100644
index 0000000..1ed53e5
--- /dev/null
+++ b/nixos/hosts/tente/exporters.nix
@@ -0,0 +1,55 @@
+{ config, lib, pkgs, ... }:
+
+let
+  cfg = config.exporters;
+in
+{
+  options.exporters = {
+    sqlExporterPort = lib.mkOption {
+      type = lib.types.int;
+    };
+  };
+
+  imports = [
+    <top/shared/prometheus-sql-exporter/service.nix>
+  ];
+
+  config = {
+    services.prometheus-sql-exporter = {
+      enable = true;
+      port = cfg.sqlExporterPort;
+      config = {
+        target = {
+          # This URL should be postgresql:///postgres?host=/run/postgresql
+          # but sql_exporter uses xo/dburl which isn't spec-compliant: https://github.com/xo/dburl/issues/46
+          data_source_name = "postgresql:/run/postgresql:/postgres";
+          collectors = ["db-sizes"];
+        };
+        collectors = [
+          {
+            collector_name = "db-sizes";
+            metrics = [
+              {
+                metric_name = "pg_db_size_bytes";
+                help = "disk space used by the database";
+                type = "gauge";
+                key_labels = ["database_name"];
+                values = ["size"];
+                query = "SELECT datname AS database_name, pg_database_size(datname) as size from pg_database";
+              }
+            ];
+          }
+        ];
+      };
+    };
+
+    monitoring.prometheusScrapeConfigs = [
+      {
+        job_name = "sql";
+        static_configs = [{
+          targets = [ "localhost:${toString cfg.sqlExporterPort}" ];
+        }];
+      }
+    ];
+  };
+}