add icecast metrics exporter

packages/icecast-exporter/default.nix

@@ -0,0 +1,27 @@
+{ pkgs ? import <nixpkgs> {} }:
+
+with pkgs;
+
+let
+  metadata = import ./metadata.nix;
+in buildGoModule rec {
+  pname = "icecast_exporter";
+  version = metadata.rev;
+
+  src = fetchFromGitHub {
+    owner = "markuslindenberg";
+    repo = pname;
+    rev = metadata.rev;
+    sha256 = metadata.sha256;
+  };
+
+  vendorSha256 = metadata.vendorSha256;
+
+  meta = with stdenv.lib; {
+    homepage    = "https://github.com/markuslindenberg/icecast_exporter";
+    description = "Icecast exporter for Prometheus";
+    platforms   = platforms.unix;
+    maintainers = with maintainers; [ markuslindenberg ];
+    license     = licenses.apache2;
+  };
+}

packages/icecast-exporter/metadata.nix

@@ -0,0 +1,5 @@
+{
+  vendorSha256 = "0000000000000000000000000000000000000000000000000000";
+  rev = "ce5cb4055d987ab0f8b95061ef7bf75dc547c787";
+  sha256 = "0000000000000000000000000000000000000000000000000000";
+}

services/icecast.nix

@@ -1,6 +1,8 @@
 { config, lib, pkgs, ... }:
 with lib;
 let
+  metrics-pkg = import ../../../packages/icecast-exporter { inherit pkgs; };
+  port = 8002;
   tld = config.redbrick.tld;
   admin-secret = "/var/secrets/icecast-admin.secret";
   source-secret = "/var/secrets/icecast-source.secret";
@@ -29,7 +31,7 @@ in {
       password = "${lib.fileContents admin-secret}";
     };
     listen = {
-      port = 8002;
+      inherit port;
       address = listenAddress;
     };
     logDir = "/var/log/icecast/";
@@ -64,5 +66,18 @@ in {
     <fileserve>1</fileserve>
     '';
   };
-  networking.firewall.allowedTCPPorts = [ 8002 ];
+
+  systemd.services.icecast-exporter = {
+    description = "Icecast Metrics exporter";
+    after = [ "network.target" ];
+    wantedBy = [ "multi-user.target" ];
+    serviceConfig = {
+      ExecStart = "${metrics-pkg}/bin/icecast_exporter -log.format='logger:stdout?json=true' -icecast.scrape-uri='http://${listenAddress}:${port}/status-json.xsl'";
+      User = "icecast";
+      Restart = "always";
+      RestartSec = "10s";
+    };
+  };
+
+  networking.firewall.allowedTCPPorts = [ 8002 9146 ];
 }

services/prometheus.nix

@@ -54,6 +54,10 @@ in {
         job_name = "bind";
         static_configs = [{ targets = ["m1cr0man.internal:9119"]; }];
       }
+      {
+        job_name = "icecast";
+        static_configs = [{ targets = ["localhost:9146"]; }];
+      }
       {
         job_name = "collectd";
         static_configs = [{ targets = ["zeus.internal:9103"]; }];