RabbitMQ broker setup

As we have seen, it is very easy start working with RabbitMQ. If we are happy with the default setting we can be up and running in a matter of minutes. It is still easy, but requires a bit of work to change the rabbit broker setup to use a different port and restrict the access to authorized users.

From the point of view of a broker client, there are a few things that could go wrong when trying to connect. As usual, these problems are converted in exceptions, that your client should make available to the user is some form. Here is the three of them I bumped in while doing some testing.

The broker is down:

java.net.ConnectException: Connection refused: connect
    at java.net.TwoStacksPlainSocketImpl.socketConnect(Native Method)
    at java.net.AbstractPlainSocketImpl.doConnect(Unknown Source)
    at java.net.AbstractPlainSocketImpl.connectToAddress(Unknown Source)
    at java.net.AbstractPlainSocketImpl.connect(Unknown Source)
    at java.net.PlainSocketImpl.connect(Unknown Source)
    at java.net.SocksSocketImpl.connect(Unknown Source)
    at java.net.Socket.connect(Unknown Source)
...

The user password is wrong:

com.rabbitmq.client.PossibleAuthenticationFailureException: Possibly caused by authentication failure
    at com.rabbitmq.client.impl.AMQConnection.start(AMQConnection.java:342)
    at com.rabbitmq.client.ConnectionFactory.newConnection(ConnectionFactory.java:516)
    at com.rabbitmq.client.ConnectionFactory.newConnection(ConnectionFactory.java:533)
...

The user is unknown:

java.io.IOException
    at com.rabbitmq.client.impl.AMQChannel.wrap(AMQChannel.java:106)
    at com.rabbitmq.client.impl.AMQChannel.wrap(AMQChannel.java:102)
    at com.rabbitmq.client.impl.AMQChannel.exnWrappingRpc(AMQChannel.java:124)
    at com.rabbitmq.client.impl.AMQConnection.start(AMQConnection.java:375)
...
Caused by: com.rabbitmq.client.ShutdownSignalException: connection error;
reason: java.io.EOFException
    at com.rabbitmq.utility.ValueOrException.getValue(ValueOrException.java:67)
...

There is a rabbit plugin designed to provide administrator capabilities, but before using it, we have to enable it through this command:

rabbitmq-plugins enable rabbitmq_management

On Windows you should get this feedback:

The following plugins have been enabled:
  mochiweb
  webmachine
  rabbitmq_mochiweb
  amqp_client
  rabbitmq_management_agent
  rabbitmq_management

Plugin configuration has changed. Restart RabbitMQ for changes to take effect.
If you have RabbitMQ running as a service then you must reinstall by running
  rabbitmq-service.bat stop
  rabbitmq-service.bat install
  rabbitmq-service.bat start

As you could expect, if you don't need it anymore, you can get rid of it:

rabbitmq-plugins disable rabbitmq_management

Once you have installed the plugin, and restarted the broker, you can access the rabbit administrator via your preferred browser, by an user with administration rights, by default guest with password guest:

http://localhost:15672/

[edit]
When I wrote the post, the default port was 55672, with version 3.0 it has be changed to 15672
[/edit]

We can create a virtual host, so to keep insulated all the message streams relative to a specific environment. Just go to the "Virtual Hosts" tab, click on "Add a new virtual host", specify a meaningful name (shame on me, I called it "test") and click on the "Add virtual host" button. So easy just that, and we have a new virtual host.

Still a virtual host with no user associated is not very useful and, as we see in the "All virtual hosts" section, a newly created virtual host has "No users" associated.

So we access the "Add / update a user" section in the "Users" tab, and create a new user. Insert a reasonable user-password couple (again, I didn't pay attention to my good suggestion, and I entered a lousy "user"-"password") and choose the priviledge for the new user among Management, Monitoring, and Administrator. You can also not enter any tag, meaning it is just a simple user with no access to the management plugin. This make perfectly sense in my case, and so I went for it.

We still have to associate the new user to the new virtual host, so we get back to the "Virtual Hosts" tab, select your v-host from the "All virtual hosts" table, click on the "Set permission" section, select the newly created user from the drop-down list and then click on "Set permession".

That's it. Now we have a brand new v-host that works only for the newly specified user.

But before using them in a client, let's mess it up a little bit more. Say that we don't want to use the standard rabbit port but a custom 6391. We can tell to rabbit which port to use setting the environment variable RABBITMQ_NODE_PORT to the required value. So, in Windows we could write a tiny command shell like this one:

@echo off
setlocal
set RABBITMQ_NODE_PORT=6391
rabbitmq-server.bat
endlocal

Running the standard rabbitmq-server.bat the rabbit broker would run on its standard port 15672 (or 55672 for versions before 3.0), running our script it would refer to our 6391 port.

Having changed the configuration as described, now we want to write a very simple direct exchange rabbit application that uses it. It is quite easy, but I went out of time, and I am forced to show you that in the next post.