add pve exporter

hosts/monitoring/prometheus.nix

@@ -47,6 +47,36 @@
           }
         ];
       }
+      {
+        # https://github.com/prometheus-pve/prometheus-pve-exporter
+        job_name = "pve";
+        scrape_interval = "15s";
+        static_configs = [
+          {
+            targets = ["ellsberg.berlin.ccc.de"];
+          }
+        ];
+        metrics_path = "/pve";
+        params = {
+          module = [ "default" ];
+          cluster = [ "1" ];
+          node = [ "1" ];
+        };
+        relabel_configs = {
+          {
+            source_labels = [ "__address__" ];
+            target_label = "__param_target";
+          }
+          {
+            source_labels = [ "__param_target" ];
+            target_label = "instance";
+          }
+          {
+            target_label = "__address__";
+            replacement = "[::1]:${toString config.services.prometheus.exporters.pve.port}";
+          }
+        };
+      }
     ];
     ruleFiles = [
       # https://github.com/element-hq/synapse/tree/master/contrib/prometheus
@@ -88,5 +118,11 @@
             expr: 'synapse_federation_transaction_queue_pending_pdus + 0'
       '')
     ];
+    exporters.pve = {
+      enable = true;
+      listenAddress = "::1";
+      environmentFile = config.age.secrets.pve-exporter.path;
+      #configFile = "";
+    };
   };
 }