lavinmqctl on follower nodes

src/lavinmq/clustering/client.cr

@@ -33,6 +33,8 @@ module LavinMQ
           @unix_amqp_proxy = Proxy.new(@config.unix_path) unless @config.unix_path.empty?
           @unix_http_proxy = Proxy.new(@config.http_unix_path) unless @config.http_unix_path.empty?
         end
+        HTTP::Server.follower_internal_socket_http_server
+
         Signal::INT.trap { close_and_exit }
         Signal::TERM.trap { close_and_exit }
       end

src/lavinmq/http/http_server.cr

@@ -14,6 +14,8 @@ module LavinMQ
     Log = ::Log.for "http"
 
     class Server
+      getter http
+
       def initialize(@amqp_server : LavinMQ::Server)
         handlers = [
           StrictTransportSecurity.new,
@@ -64,9 +66,9 @@ module LavinMQ
         addr
       end
 
-      def bind_internal_unix
+      def self.bind_internal_unix(http)
         File.delete?(INTERNAL_UNIX_SOCKET)
-        addr = @http.bind_unix(INTERNAL_UNIX_SOCKET)
+        addr = http.bind_unix(INTERNAL_UNIX_SOCKET)
         File.chmod(INTERNAL_UNIX_SOCKET, 0o660)
         Log.info { "Bound to #{addr}" }
         addr
@@ -80,6 +82,20 @@ module LavinMQ
         @http.try &.close
         File.delete?(INTERNAL_UNIX_SOCKET)
       end
+
+      # Starts a HTTP server that binds to the internal UNIX socket used by lavinmqctl.
+      # The server returns 503 to signal that the node is a follower and can not handle the request.
+      def self.follower_internal_socket_http_server
+        http_server = ::HTTP::Server.new do |context|
+          context.response.status_code = 503
+          context.response.status_message = "This node is a follower and does not handle HTTP requests."
+        end
+        self.bind_internal_unix(http_server)
+
+        spawn(name: "HTTP listener") do
+          http_server.listen
+        end
+      end
     end
   end
 end

src/lavinmq/launcher.cr

@@ -146,7 +146,7 @@ module LavinMQ
         @http_server.bind_unix(@config.http_unix_path)
       end
 
-      @http_server.bind_internal_unix
+      HTTP::Server.bind_internal_unix(@http_server.http)
       spawn(name: "HTTP listener") do
         @http_server.not_nil!.listen
       end

src/lavinmqctl.cr

@@ -250,6 +250,11 @@ class LavinMQCtl
 
   private def handle_response(resp, *ok)
     return if ok.includes? resp.status_code
+    if resp.status_code == 503
+      puts "[ERROR] This node is a follower and does not handle lavinmqctl commands."
+      puts "Please connect to the leader node by using the --host option."
+      exit 2
+    end
     puts "#{resp.status_code} - #{resp.status}"
     puts resp.body if resp.body? && !resp.headers["Content-Type"]?.try(&.starts_with?("text/html"))
     exit 1