The OnApp vCD integration requires the usage of RabbitMQ to keep vCD and OnApp synchronized. At times we may get this error while trying to start the Rabbitmq-server.

Here at Ibmi Media, as part of our Server Management Services, we regularly help our Customers to perform related OnApp queries.

What triggers OnApp "Error unable to connect to node rabbit" ?

Following are the reason which may cause this error:

• This issue can happen during power outages.
• The error can also be seen when we restart the Control Panel server by using the Reset button.

How to fix OnApp "Error unable to connect to node rabbit" ?

The root cause can be checked in the default rabbitmq logging directory (/var/log/rabbitmq). Moreover, it can be found specifically in the "rabbit@cp.log" file.

Following are two examples of the most widespread root causes, which can be easily checked and fixed:

1. After checking the logs, from the following output we can understand that the rabbitmq queues have been corrupted:

# tail -n 25 /var/log/rabbitmq/rabbit\@cp.log

=INFO REPORT==== 4-Jan-2017::22:57:24 ===
Error description:
   {could_not_start,rabbit,
       {{badmatch,
            {error,
                {{{{case_clause,undefined},
                   [{rabbit_queue_index,add_segment_relseq_entry,3,
                        [{file,"src/rabbit_queue_index.erl"},{line,1091}]},
                    {rabbit_queue_index,parse_segment_entries,3,
                        [{file,"src/rabbit_queue_index.erl"},{line,1075}]},
                    {rabbit_queue_index,'-recover_journal/1-fun-0-',1,
                        [{file,"src/rabbit_queue_index.erl"},{line,863}]},
                    {lists,map,2,[{file,"lists.erl"},{line,1239}]},
                    {rabbit_queue_index,segment_map,2,
                        [{file,"src/rabbit_queue_index.erl"},{line,989}]},
                    {rabbit_queue_index,recover_journal,1,
                        [{file,"src/rabbit_queue_index.erl"},{line,856}]},
                    {rabbit_queue_index,scan_segments,3,
                        [{file,"src/rabbit_queue_index.erl"},{line,676}]},
                    {rabbit_queue_index,queue_index_walker_reader,2,
                        [{file,"src/rabbit_queue_index.erl"},{line,664}]}]},
                  {gen_server2,call,[<0.288.0>,out,infinity]}},

We can fix this issue by moving all the available queues off from the working rabbitmq directory.

This can be done using the following command:

# ls /var/lib/rabbitmq/mnesia/rabbit@cp/queues

17BD92SOBZHLASJ4UE5VT5EHQ 3UM4MIP6TJ0PEAHMBSCNUX731 621MT7APTTVO66OSRLB1R7FY5 9R728VE21EGPVSMK9AJ7YH67E A4SL081HP0B21UALPRHLK069R ACJVPWBZHI24WLV6QHBPNT5JE ETHYXYWKQVKD3Q2EYD84UWIS2

# mkdir -p /tmp/badrabbit/; mv /var/lib/rabbitmq/mnesia/rabbit@cp/queues/* /tmp/badrabbit/;

2. If we see the following output from the logs, we can assume that the dets table file has been corrupted:

# tail -n 15 /var/log/rabbitmq/rabbit\@cp.log

=INFO REPORT==== 16-Jan-2017::09:11:03 ===
Error description:
   {could_not_start,rabbit,
       {{badmatch,
            {error,
                {{{badmatch,
                      {error,
                          {not_a_dets_file,
                              "/var/lib/rabbitmq/mnesia/rabbit@cp/recovery.dets"}}},
                  [{rabbit_recovery_terms,open_table,0,
                       [{file,"src/rabbit_recovery_terms.erl"},{line,126}]},
                   {rabbit_recovery_terms,init,1,
                       [{file,"src/rabbit_recovery_terms.erl"},{line,107}]},
                   {gen_server,init_it,6,[{file,"gen_server.erl"},{line,328}]},

We can fix these corrupt table files by moving dets file off from the working rabbitmq directory. For this we can use the following command:

# mkdir -p /tmp/badrabbit/; mv /var/lib/rabbitmq/mnesia/rabbit@cp/recovery.dets /tmp/badrabbit/;

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