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Basic services (MySQL and RabbitMQ)

db-node

OpenStack components use an SQL database and an AMQP-compatible system to share the current status of the cloud and to communicate to each other. Multiple SQL databases are supported, although the most commonly used is MySQL. Also multiple AMQP systems are supported, but again, the most common used is RabbitMQ.

Since the architecture is higly distributed, a request done on an API service (for instance, to start a virtual instance), will trigger a series of tasks, possibly executed by different services on different machines. Usually the status of the request is saved on the database, and whenever some additional task is needed by a different service, the AMQP system is used to request it.

MySQL and RabbitMQ are therefore very important and very basic services, used by all the OpenStack components. If something is not working here, or not working properly, the whole cloud could be unresponsive or broken.

(good news is: these services are usually quite reliable, at least compared to OpenStack)

update system and install ntp package

The following steps need to be done on all the machines. We are going to execute them step by step on the db-node only, and then we will automate the process on the other nodes.

Connect to the db-node:

root@gks-NNN:[~] $ ssh root@db-node

Update the system (can take a while...):

root@db-nodes:# apt-get update -y
root@db-nodes:# aptitude upgrade -y

Install the NTP service:

root@db-nodes:# aptitude install -y ntp

On a production environment, you may want to update /etc/ntp.conf to point to a local server.

all nodes installation

Since those boring steps have to be completed on all the other nodes, we can run the following script in order to automate this process. This way the rest of the VMs will have all those steps already done by the time we are going to work on them. The following command has to run on the physical machine:

root@gks-NNN:[~] $ for host in auth-node image-node api-node \
    network-node volume-node compute-1 compute-2 neutron-node
do
ssh -n root@$host "(apt-get update -y; apt-get upgrade -y; aptitude install -y ntp) >& /dev/null &"
done

Note: Icehouse is in the main repository for Ubuntu 14.04. This means we don't need to add any additional OpenStack repositories. For info regarding OpenStack and Ubuntu Support Schedule go here.

MySQL installation

We are going to install both MySQL and RabbitMQ on the same server, but on a production environment you may want to have them installed on different servers and/or in HA. The following instructions are intended to be used for both scenarios.

Now please move on the db-node where we have to install the MySQL server. In order to do that please execute:

root@db-node # aptitude install -y mysql-server python-mysqldb

you will be prompted for a password, it is better to specify a good one, since the MySQL server will be accessible also via internet. You can use the pwgen command to generate random passwords with reasonable entropy.

For security reasons the MySQL daemon listens on localhost only, port 3306. This has to be changed in order to make the server accessible from the all the OpenStack services. Edit the /etc/mysql/my.cnf file and ensure that it contains the following line:

bind-address            = 10.0.0.3

This will make the MySQL daemon listen only on the private interface.

The OpenStack official guide states that some of the options of InnoDB storage engine must be set in the configuration file. In order to do that add the following lines in the [mysqld] section of the /etc/mysql/my.cf file:

[mysqld]
# ...
# This is already the default on MySQL 5.5
# default-storage-engine = innodb
collation-server = utf8_general_ci
init-connect = 'SET NAMES utf8'
character-set-server = utf8

After changing this line you have to restart the MySQL server:

root@db-node # service mysql restart

By default MySQL allows access also from the network. This is a security risk, so you may want to disable it.

There is a script called mysql_secure_installation that helps you modifying some of the defaults found in standard installations, we would suggest you to run it before proceeding:

root@db-node:~# mysql_secure_installation
[...]
Change the root password? [Y/n] n
[...]
Remove anonymous users? [Y/n] Y
[...]
Disallow root login remotely? [Y/n] Y
[...]
Remove test database and access to it? [Y/n] Y
[...]
Reload privilege tables now? [Y/n] Y
[...]

Check that MySQL is actually running and listening on all the interfaces using the netstat command. 3306 is the port MySQL listens to:

root@db-node:~# netstat -nlp|grep 3306
tcp        0     10 0.0.0.3:3306            0.0.0.0:*               LISTEN      21926/mysqld

RabbitMQ

RabbitMQ is an implementation of the AMQP (Advanced Message Queuing Protocol), a networking protocol that enables conforming client applications to communicate with conforming messaging middleware brokers.

Install RabbitMQ from the ubuntu repository:

root@db-node:~# aptitude install -y rabbitmq-server

RabbitMQ does not need any specific configuration. On a production environment, however, you might need to create a specific user for OpenStack services. We are not covering in this tutorial, so please refer to the official documentation.

To check if the RabbitMQ server is running use the rabbitmqctl command:

root@db-node:~# rabbitmqctl status
Status of node 'rabbit@db-node' ...
[{pid,22806},
 {running_applications,[{rabbit,"RabbitMQ","2.7.1"},
                        {mnesia,"MNESIA  CXC 138 12","4.5"},
                        {os_mon,"CPO  CXC 138 46","2.2.7"},
                        {sasl,"SASL  CXC 138 11","2.1.10"},
                        {stdlib,"ERTS  CXC 138 10","1.17.5"},
                        {kernel,"ERTS  CXC 138 10","2.14.5"}]},
 {os,{unix,linux}},
 {erlang_version,"Erlang R14B04 (erts-5.8.5) [source] [64-bit] [rq:1] [async-threads:30] [kernel-poll:true]\n"},
 {memory,[{total,24098760},
          {processes,9740136},
          {processes_used,9735768},
          {system,14358624},
          {atom,1124433},
          {atom_used,1120213},
          {binary,103368},
          {code,11134393},
          {ets,708784}]},
 {vm_memory_high_watermark,0.39999999980957235},
 {vm_memory_limit,840214118}]
...done.

Please keep the connection to the db-node open as we will need to operate on it briefly.

The message broker uses guest as default user name and password. You can change that password by simply doing:

root@db-node:~# rabbitmqctl change_password guest gridka

This will change the default password to gridka. On a production environment, please, choose a better password (again, you can use pwgen to generate one).

By default RabbitMQ listens on port 5672, on all the available interfaces:

root@db-node:~# netstat -tnlp | grep 5672
tcp6       0      0 :::5672                 :::*                    LISTEN      27903/beam

In order to prevent this, create (or modify, if it's already there) the file /etc/rabbitmq/rabbitmq-env.conf and add the following line:

RABBITMQ_NODE_IP_ADDRESS=10.0.0.3

Whenever you update this file, restart the daemon:

root@db-node:~# service rabbitmq-server restart

and check again:

root@db-node:~# netstat -tnlp | grep 5672
tcp        0      0 10.0.0.3:5672           0.0.0.0:*               LISTEN      28661/beam

Now we will proceed with the other services, but since most of the services need to create a MySQL account and database, you probably want to keep a shell opened on the db-node.

Next: Keystone - Identity service