FIX: Redis hostname may resolve to nothing.

lib/discourse_redis.rb

@@ -81,7 +81,10 @@ class DiscourseRedis
         client = ::Redis::Client.new(options)
         client.call([:role])[0]
         @options
-      rescue Redis::ConnectionError, Redis::CannotConnectError => ex
+      rescue Redis::ConnectionError, Redis::CannotConnectError, RuntimeError => ex
+        # A consul service name may be deregistered for a redis container setup
+        raise ex if ex.class == RuntimeError && ex.message != "Name or service not known"
+
         return @slave_options if !@fallback_handler.master
         @fallback_handler.master = false
         raise ex

spec/components/discourse_redis_spec.rb

@@ -53,6 +53,28 @@ describe DiscourseRedis do
         fallback_handler.master = true
       end
     end
+
+    it "should return the slave config when master's hostname cannot be resolved" do
+      begin
+        error = RuntimeError.new('Name or service not known')
+
+        Redis::Client.any_instance.expects(:call).raises(error).twice
+        expect { connector.resolve }.to raise_error(error)
+
+        config = connector.resolve
+
+        expect(config[:host]).to eq(slave_host)
+        expect(config[:port]).to eq(slave_port)
+      ensure
+        fallback_handler.master = true
+      end
+    end
+
+    it "should raise the right error" do
+      error = RuntimeError.new('test error')
+      Redis::Client.any_instance.expects(:call).raises(error).twice
+      2.times { expect { connector.resolve }.to raise_error(error) }
+    end
   end
 
   describe DiscourseRedis::FallbackHandler do