Puppet module for setting up Multiple mongo’s with replication

In this blog I’ll be talking about a puppet module, that can be used to installing multiple mongo’s with replication on a single machine. Since I’m very new to puppet so you may find this module very crude, but it works :). Their were couple of puppet module already available but most of them are only for installing a single instance of mongo at a machine & I’ve a specific requirement of installing multiple instances of mongo having master slave replication between them. As I already said that this module may be quiet crude or basic so please bear with that & my approach may also seem a bit unconventional so please let me know what all can be improved in this module or how things could have been done in a better way.

So let’s start with the actual details first of this module is hosted on github(https://github.com/sandy724/Mongo), if you want to look at the source code you can clone it from github. For installing mongo you would be executing the command
puppet apply -e “class {mongo:port => , replSet => ,master => ,master_port => ,}”

Command for installing master
puppet apply -e “class {mongo:port => 27017, replSet => sdrepsetcommon,master => master, master_port => 27017,}”

Command for installing slave
puppet apply -e “class {mongo:port => 27018, replSet => sdrepsetcommon,master => slave,master_port => 27017,}”

Before going into the details what all this module is doing I will share some details of mongo

• You can start mongo by executing mongod command
• You can provide a configration file which contains details such as
• log directory where mongo would be generating the logs
• port at which mongo would be listening for requests
• dbpath where mongo would be storing all the data
• pidfilepath containg process id of mongo instance, that would be used to check whether mongo is running or not
• replSet name of the replicaset
• You need to have a mongo as a service installed in you system to start an instance of mongo
• For replication you need to execute rs.initiate command on the master mongo
• For adding another instance into replication you need to execute rs.add(“:”)  command on the master mongo

• As you can figure out this module is expecting few parameters :
• port : port at which mongo would be listening,
• replSet : name of replicaset which would be used for managing replication
• master : A string parameter which would signify whether the mongo setup is for master or slave
• master_port : Port at which master instance of mongo would be listening
• First of all we create a mongo user
• Parent Log directory for the mongo instance is created if it doesn’t exists with mongo user as owner.
• Mongo db directory is created under /data/mongo with a naming convention replSet_port, i.e if replSet parameter is sdrepsetcommon & port is 27017 then the data directory for this mongo instance would be  /data/mongo/sdrepsetcommon_27017. This directory would be owned by mongo user.
• A mongo service would be installed if not already their.
• A mongo restart shell script is also placed at the mongo db directory
• A file is also placed under the mongo db directory that have a mongo command to setup replication, this file is created conditionally depending on whether we are setting up a master or slave instance.
• Finally the replication command is executed on mongo server & restart script is also executed