monitoring: set retention time to 90d

hosts/monitoring/configuration.nix

@@ -21,13 +21,27 @@ with lib;
   networking.defaultGateway = { address = "10.42.10.1"; interface = "ens18"; };
   networking.defaultGateway6 = { address = "2a01:4f8:1c0c:8221::1"; interface = "ens18"; };
 
+  environment = {
+    etc = {
+      "snmp-exporter/snmp.yml".source = ./snmp.yml;
+    };
+  };
+
   services.influxdb2.enable = true;
 
-  services.prometheus.exporters.blackbox = {
-    enable = true;
-    listenAddress = "[::1]";
-    port = 9115;
-    configFile = ./blackbox.yml;
+  services.prometheus.exporters = {
+    blackbox = {
+      enable = true;
+      listenAddress = "[::1]";
+      port = 9115;
+      configFile = ./blackbox.yml;
+    };
+    snmp = {
+      enable = true;
+      port= 9116;
+      listenAddress = "[::1]";
+      configurationPath = "/etc/snmp-exporter/snmp.yml";
+    };
   };
   services.prometheus.exporters.node.enable = true;
 
@@ -60,6 +74,7 @@ with lib;
   };
   services.prometheus = {
     enable = true;
+    retentionTime = "90d";
     listenAddress = "[::1]";
     scrapeConfigs = [
       {
@@ -253,6 +268,17 @@ with lib;
           }
         ];
       }
+      {
+        job_name = "snmp";
+        scrape_interval = "5m";
+        static_configs = [
+          {
+            targets = [
+              "[::1]:9116"
+            ];
+          }
+        ];
+      }
     ];
     alertmanagers = [
       {