robosignatory: add notes on how to drop a looping rabbitmq message from robosignatory queue

Signed-off-by: Kevin Fenzi <kevin@scrye.com>

modules/howtos/pages/fix_robosignatory.adoc

@@ -54,3 +54,38 @@ tail -f /var/log/sigul_bridge.log
 ----
 sigul_bridge -dvv
 ----
+
+.. If the service is running, but appears to be reprocessing the
+same message over and over again, you may need to drop that message
+in order to restore processing.
+
+Cases where you may need to do this:
+
+* some rpm is corrupt (you can see if this is the case in the vault logs)
+* some rpm is larger than sigul can process (you can see this in vault logs)
+
+.. First, stop robosignatory.service on autosign01. It's important that
+   nothing is processing the messages when you attempt to drop one.
+
+.. Setup a ssh tunnel to the rabbitmq web interface:
++
+----
+ssh rabbitmq01.rdu3.fedoraproject.org -L 15672:localhost:15672
+----
+
+.. Next go to localhost:15672 in your browser, there should be a rabbitmq login
+   page there.
+
+.. Login as admin. Password is in ansible-private vars
+
+.. go to 'queues'
+
+.. search for 'robosignatory'
+
+.. First get the top message on the queue and see if it's the one you want to drop.
+
+.. Then, select reject message and NAK (drop from queue)
+
+.. Select (and requeue) the next message to confirm that the one you nacked is gone.
+
+.. Restart robosignatory