Setup ssh/promtail/loki for grafana ssh dashboard

nixos/viridian/services/promtail.nix

@@ -0,0 +1,31 @@
+{ config, ... }:
+
+{
+  services.promtail = {
+    enable = true;
+    configuration = {
+      server = {
+        http_listen_port = 9080;
+        grpc_listen_port = 0;
+      };
+      positions = {
+        filename = "/tmp/positions.yaml";
+      };
+      clients = [{
+        url = "http://127.0.0.1:${toString config.services.loki.configuration.server.http_listen_port}/loki/api/v1/push";
+      }];
+      scrape_configs = [{
+        job_name = "system";
+        static_configs = [{
+          targets = [ "localhost" ]; # Promtail target is localhost
+          labels = {
+            instance = "viridian.kanto.dev"; # Label identifier for instance
+            env = "kanto"; # Environment label
+            job = "secure"; # Job label
+            __path__ = "/var/log/sshd.log";
+          };
+        }];
+      }];
+    };
+  };
+}