Add instance id support (#2828)

* Add instance id support

* actually use env variable for instance ID

* Default to ersatztv.org for instance id

* simplify

* fix ordering

* update changelog

---------

Co-authored-by: Jason Dove <1695733+jasongdove@users.noreply.github.com>

CHANGELOG.md

@@ -18,6 +18,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
   - This controls how many (optional) seconds of black video and silent audio to insert between *every* playout item
   - This will drift playback from the wall clock as slugs are not scheduled in the playout, but are inserted dynamically during playback
   - If this feature turns out to be popular, methods to correct the drift may be investigated
+- Add `ETV_INSTANCE_ID` environment variable to disambiguate EPG data from multiple ErsatzTV instances
+  - When set, the value will be used in channel identifiers before the final `.ersatztv.org`
 
 ### Changed
 - Move dark/light mode toggle to **Settings** > **UI**

ErsatzTV.Core/Iptv/ChannelIdentifier.cs

@@ -17,6 +17,9 @@ public static class ChannelIdentifier
             number /= 10;
         }
 
-        return $"C{channelNumber}.{id}.ersatztv.org";
+        string instanceId = SystemEnvironment.InstanceId;
+        return !string.IsNullOrWhiteSpace(instanceId)
+            ? $"C{channelNumber}.{id}.{instanceId}.ersatztv.org"
+            : $"C{channelNumber}.{id}.ersatztv.org";
     }
 }

ErsatzTV.Core/SystemEnvironment.cs

@@ -10,6 +10,8 @@ public class SystemEnvironment
 
         TranscodeFolder = Environment.GetEnvironmentVariable("ETV_TRANSCODE_FOLDER");
 
+        InstanceId = Environment.GetEnvironmentVariable("ETV_INSTANCE_ID");
+
         string uiPortVariable = Environment.GetEnvironmentVariable("ETV_UI_PORT");
         if (!int.TryParse(uiPortVariable, out int uiPort))
         {
@@ -63,6 +65,7 @@ public class SystemEnvironment
     public static string BaseUrl { get; }
     public static string ConfigFolder { get; }
     public static string TranscodeFolder { get; }
+    public static string InstanceId { get; }
     public static int UiPort { get; }
     public static int StreamingPort { get; }
     public static bool AllowSharedPlexServers { get; }