better processing crash errors

lib/karafka/web/errors.rb

@@ -17,9 +17,18 @@ module Processing
         # If you see this error, it probably means, that you did not bootstrap Web-UI correctly
         MissingConsumersStateError = Class.new(BaseError)
 
-        # Similar to the above. It should be created during install
+        # Raised when we try to materialize the state but the consumers states topic does not
+        # exist and we do not have a way to get the initial state.
+        # It differs from the above because above indicates that the topic exists but that there
+        # is no initial state, while this indicates, that there is no consumers states topic.
+        MissingConsumersStatesTopicError = Class.new(BaseError)
+
+        # Similar to the above. It should be created during install / migration
         MissingConsumersMetricsError = Class.new(BaseError)
 
+        # Similar to the one related to consumers states
+        MissingConsumersMetricsTopicError = Class.new(BaseError)
+
         # This error occurs when consumer running older version of the web-ui tries to materialize
         # states from newer versions. Karafka Web-UI provides only backwards compatibility, so
         # you need to have an up-to-date consumer materializing reported states.

lib/karafka/web/installer.rb

@@ -18,7 +18,7 @@ def install(replication_factor: 1)
         puts 'Creating necessary topics and populating state data...'
         puts
         Management::CreateTopics.new.call(replication_factor)
-        puts
+        wait_for_topics
         Management::CreateInitialStates.new.call
         puts
         Management::ExtendBootFile.new.call
@@ -36,6 +36,7 @@ def migrate(replication_factor: 1)
         puts 'Creating necessary topics and populating state data...'
         puts
         Management::CreateTopics.new.call(replication_factor)
+        wait_for_topics
         Management::CreateInitialStates.new.call
         puts
         puts("Migration #{green('completed')}. Have fun!")
@@ -51,7 +52,7 @@ def reset(replication_factor: 1)
         Management::DeleteTopics.new.call
         puts
         Management::CreateTopics.new.call(replication_factor)
-        puts
+        wait_for_topics
         Management::CreateInitialStates.new.call
         puts
         puts("Resetting #{green('completed')}. Have fun!")
@@ -74,6 +75,30 @@ def uninstall
       def enable!
         Management::Enable.new.call
       end
+
+      private
+
+      # Waits with a message, that we are waiting on topics
+      # This is not doing much, just waiting as there are some cases that it takes a bit of time
+      # for Kafka to actually propagate new topics knowledge across the cluster. We give it that
+      # bit of time just in case.
+      def wait_for_topics
+        puts
+        print 'Waiting for the topics to synchronize in the cluster'
+        wait(5)
+        puts
+      end
+
+      # Waits for given number of seconds and prints `.` every second.
+      # @param time_in_seconds [Integer] time of wait
+      def wait(time_in_seconds)
+        time_in_seconds.times do
+          sleep(1)
+          print '.'
+        end
+
+        print "\n"
+      end
     end
   end
 end

lib/karafka/web/processing/consumers/metrics.rb

@@ -20,6 +20,10 @@ def current!
               return metrics_message.payload if metrics_message
 
               raise(::Karafka::Web::Errors::Processing::MissingConsumersMetricsError)
+            rescue Rdkafka::RdkafkaError => e
+              raise(e) unless e.code == :unknown_partition
+
+              raise(::Karafka::Web::Errors::Processing::MissingConsumersMetricsTopicError)
             end
           end
         end

lib/karafka/web/processing/consumers/state.rb

@@ -20,6 +20,10 @@ def current!
               return state_message.payload if state_message
 
               raise(::Karafka::Web::Errors::Processing::MissingConsumersStateError)
+            rescue Rdkafka::RdkafkaError => e
+              raise(e) unless e.code == :unknown_partition
+
+              raise(::Karafka::Web::Errors::Processing::MissingConsumersStatesTopicError)
             end
           end
         end

spec/lib/karafka/web/processing/consumers/metrics_spec.rb

@@ -15,6 +15,16 @@
       it { expect { metrics }.to raise_error(expected_error) }
     end
 
+    context 'when metrics topic does not exist' do
+      let(:expected_error) do
+        ::Karafka::Web::Errors::Processing::MissingConsumersMetricsTopicError
+      end
+
+      before { Karafka::Web.config.topics.consumers.metrics = SecureRandom.uuid }
+
+      it { expect { metrics }.to raise_error(expected_error) }
+    end
+
     context 'when current state exists' do
       before { produce(metrics_topic, fixture) }
 

spec/lib/karafka/web/processing/consumers/state_spec.rb

@@ -15,6 +15,16 @@
       it { expect { state }.to raise_error(expected_error) }
     end
 
+    context 'when states topic does not exist' do
+      let(:expected_error) do
+        ::Karafka::Web::Errors::Processing::MissingConsumersStatesTopicError
+      end
+
+      before { Karafka::Web.config.topics.consumers.states = SecureRandom.uuid }
+
+      it { expect { state }.to raise_error(expected_error) }
+    end
+
     context 'when current state exists' do
       before { produce(states_topic, fixture) }