The distributed retention modules

The high availability allow the Arbiter to send a configuration to a spare scheduler, but a spare scheduler does not have any saved states for hosts and services. It will have to recheck them all. It's better to use a distributed retention module so spares will have all the information they need to start with an accurate picture of the current states and scheduling :)

Non distributed retention modules

If you are just running tests on a single server, use the pickle or memcache retention modules You can also use MongoDB if you already have it installed for use with the WebUI.

MongoDB

MongoDB is a scalable, high-performance, open source NoSQL database written in C++.

Step 1: Install MongoDB:

We will use mongodb package from 10gen repository, so we start by adding it in apt sources list:

echo 'deb http://downloads-distro.mongodb.org/repo/debian-sysvinit dist 10gen' > /etc/apt/sources.list.d/10gen.list
apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv 7F0CEB10
apt-get update

And we install it:

apt-get install mongodb-10gen

And we install pymongo, the python interface to MongoDB, with easy_install to avoid packages versions problems (like here forums.monitoring-fr.org/index.php?topic=5205.0):

apt-get remove python-pymongo
easy_install pymongo

And finally we start MongoDB :

/etc/init.d/mongodb start

Step 2: define a mongodb_retention module in your shinken-specific.cfg file:

define module {
  module_name retention-mongodb
  module_type mongodb_retention
  uri mongodb://localhost/?safe=false
  database shinken
}

Step 3: Declare a retention module for your scheduler(s) :)

Example:

#The scheduler is a "Host manager". It get hosts and theirs
#services. It scheduler checks for them.
define scheduler{
     scheduler_name   scheduler-1   ; just the name
     address  localhost             ; ip or dns address of the daemon
     port     7768                  ; tcp port of the daemon

     #optionnal: modules for things as retention
     modules    retention-mongodb
     }

Step 4: Restart the Arbiter, and your Scheduler will now save its state between restarts. :)

Memcached

Memcached is a distributed memory resident key/value server. It's very easy to install:

sudo apt-get install memcached 
sudo /etc/init.d/memcached start

The shinken module also needs the python-memcache package to talk to this server.

sudo apt-get install python-memcache

To use it,

Step 1: define a memcache_retention module in your shinken-specific.cfg file:

define module{
     module_name      MemcacheRetention
     module_type      memcache_retention
     server           127.0.0.1
     port             11211
}

Step 2: Declare a retention module for your scheduler(s) :)

Example:

define scheduler{
     scheduler_name   scheduler-1   ; just the name
     address  localhost             ; ip or dns address of the daemon
     port     7768                  ; tcp port of the daemon

     #optional: modules for things as retention
     modules    MemcacheRetention
     }

Step 3: Restart the Arbiter, and your Scheduler will now save its state between restarts. :)

Redis

Redis is a distributed key/value server (on disk and in-memory). It's very easy to install:

sudo apt-get install redis-server
sudo /etc/init.d/redis-server start

The shinken module also need the python-redis package to talk to this server.

sudo apt-get install python-redis

Step 1: define a redis_retention module in your shinken-specific.cfg file:

define module{
     module_name      RedisRetention
     module_type      redis_retention
     server           127.0.0.1
}

Step 2: Declare a retention module for your scheduler(s) :)

Example:

#The scheduler is a "Host manager". It get hosts and theirs
#services. It scheduler checks for them.
define scheduler{
     scheduler_name   scheduler-1   ; just the name
     address  localhost             ; ip or dns address of the daemon
     port     7768                  ; tcp port of the daemon

     #optionnal: modules for things as retention
     modules    RedisRetention
     }

Step 3: Restart the Arbiter, and your Scheduler will now save its state between restarts. :)