Enable Shairport Sync metadata and MQTT support

config/hosts/audio/shairport-sync.conf

@@ -0,0 +1,25 @@
+// Config for MQTT and metadata.
+// For reference see:
+// https://github.com/mikebrady/shairport-sync/blob/8c607e2d61ea5fde8ed0b48b2471a543840c31e6/scripts/shairport-sync.conf
+// https://github.com/mikebrady/shairport-sync/blob/0f0f65b67649d4a25d06f13b56a6077a90b0f6cc/MQTT.md
+metadata =
+{
+	enabled = "yes"; // set this to yes to get Shairport Sync to solicit metadata from the source and to pass it on via a pipe
+	include_cover_art = "yes"; // set to "yes" to get Shairport Sync to solicit cover art from the source and pass it via the pipe. You must also set "enabled" to "yes".
+	cover_art_cache_directory = "/tmp/shairport-sync/.cache/coverart"; // artwork will be  stored in this directory if the dbus or MPRIS interfaces are enabled or if the MQTT client is in use. Set it to "" to prevent caching, which may be useful on some systems
+	pipe_name = "/tmp/shairport-sync-metadata";
+	pipe_timeout = 5000; // wait for this number of milliseconds for a blocked pipe to unblock before giving up
+};
+
+
+mqtt =
+{
+	enabled = "yes"; // set this to yes to enable the mqtt-metadata-service
+	hostname = "mqtt.ccchh.net"; // Hostname of the MQTT Broker
+	port = 1883; // Port on the MQTT Broker to connect to
+	topic = "audio"; //MQTT topic where this instance of shairport-sync should publish. If not set, the general.name value is used.
+//	publish_raw = "no"; //whether to publish all available metadata under the codes given in the 'metadata' docs.
+	publish_parsed = "yes"; //whether to publish a small (but useful) subset of metadata under human-understandable topics
+	publish_cover = "yes"; //whether to publish the cover over mqtt in binary form. This may lead to a bit of load on the broker
+//	enable_remote = "yes"; //whether to remote control via MQTT. RC is available under `topic`/remote.
+};

config/hosts/audio/shairport-sync.nix

@@ -5,4 +5,10 @@
     openFirewall = true;
     arguments = "-v -o alsa -- -d plughw:1,0 -r 48000";
   };
+
+  environment.etc.shairport-sync-config = {
+    enable = true;
+    source = ./shairport-sync.conf;
+    target = "shairport-sync.conf";
+  };
 }

flake.nix

@@ -13,12 +13,22 @@
     };
   };
 
-  outputs = { nixpkgs, nixpkgs-unstable, nixos-generators, ... }: {
+  outputs = { nixpkgs, nixpkgs-unstable, nixos-generators, ... }:
+    let
+      # Shairport Sync with metadata and MQTT support.
+      shairportSyncExtendedNixpkgsUnstableOverlay = final: prev: {
+        shairport-sync = (prev.shairport-sync.override { enableMetadata = true; }).overrideAttrs (finalAttr: previousAttr: {
+          # See: https://github.com/mikebrady/shairport-sync/blob/e78a88b64adfe7b5f88fd6faedf55c57445bb240/CONFIGURATION%20FLAGS.md
+          configureFlags = previousAttr.configureFlags ++ [ "--with-mqtt-client" ];
+          buildInputs = previousAttr.buildInputs ++ [ final.mosquitto ];
+        });
+      };
+    in {
     colmena = {
       meta = {
         nixpkgs = nixpkgs.legacyPackages."x86_64-linux";
         nodeNixpkgs = {
-          audio = nixpkgs-unstable.legacyPackages."x86_64-linux";
+          audio = nixpkgs-unstable.legacyPackages."x86_64-linux".extend shairportSyncExtendedNixpkgsUnstableOverlay;
         };
       };