Add the ability to listen on UNIX sockets (#5112)

src/invidious/config.cr

@@ -8,6 +8,13 @@ struct DBConfig
   property dbname : String
 end
 
+struct SocketBindingConfig
+  include YAML::Serializable
+
+  property path : String
+  property permissions : String
+end
+
 struct ConfigPreferences
   include YAML::Serializable
 
@@ -138,6 +145,8 @@ class Config
   property port : Int32 = 3000
   # Host to bind (overridden by command line argument)
   property host_binding : String = "0.0.0.0"
+  # Path and permissions to make Invidious listen on a UNIX socket instead of a TCP port
+  property socket_binding : SocketBindingConfig? = nil
   # Pool size for HTTP requests to youtube.com and ytimg.com (each domain has a separate pool of `pool_size`)
   property pool_size : Int32 = 100
   # HTTP Proxy configuration
@@ -255,6 +264,24 @@ class Config
       end
     end
 
+    # Check if the socket configuration is valid
+    if sb = config.socket_binding
+      if sb.path.ends_with?("/") || File.directory?(sb.path)
+        puts "Config: The socket path " + sb.path + " must not be a directory!"
+        exit(1)
+      end
+      d = File.dirname(sb.path)
+      if !File.directory?(d)
+        puts "Config: Socket directory " + sb.path + " does not exist or is not a directory!"
+        exit(1)
+      end
+      p = sb.permissions.to_i?(base: 8)
+      if !p || p < 0 || p > 0o777
+        puts "Config: Socket permissions must be an octal between 0 and 777!"
+        exit(1)
+      end
+    end
+
     return config
   end
 end