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Directory environments in Puppet

Environments are individual groups of Puppet agents each environment have there own completely different manifests and module-paths. This basically is useful for testing changes to our Puppet code before implementing them on production machines. There are two types of implementation of environments structure in Puppet one if directory based and another is config file based here we will see bit of an insight about directory based. As usual for more information about this you can visit puppetlabs official website. On the master node: Append following details in puppet.conf which is placed under /etc/puppet or /etc/puppetlabs/puppet:     Under [main] section add a variable called confdir with value as /etc/puppet or /etc/puppetlabs/puppet     confdir=/etc/puppet Then add information regarding environments/manifests and modulepath in it.      #environments     environmentpath = $confdir/environments     default_manfiest = $confdir/manifests     basemodulepath =
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Manifests

Manifests Puppet programs are called “manifests,” and they use the .pp file extension. The core of the Puppet language is the resource declaration. A resource declaration describes a desired state for one resource. (Manifests can also use various kinds of logic: conditional statements, collections of resources, functions to generate text, etc. We’ll get to these later.) [root@server demo_manifests]# cat add_user.pp user { 'optimus':   ensure => 'present',   home   => '/home/optimus',   shell  => '/bin/bash', } [root@server demo_manifests]# [root@server demo_manifests]# puppet apply /root/Desktop/demo_manifests/add_user.pp notice: /Stage[main]//User[optimus]/ensure: created notice: Finished catalog run in 0.21 seconds [root@server demo_manifests]# Puppet Apply Like resource in the last chapter, apply is a Puppet subcommand. It takes the name of a manifest file as its argument, and enforces the desired state descri
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Exec in Puppet

Exec is a very useful resource type present in Puppet which is used to executes external commands. Puppet basically runs as a daemon in which it executes every 30 mins. So while writing an exec resource type make sure that the exec resource must be able to run multiple times without causing any harm to the machine i.e. it must be idempotent. Suppose you just want to run a command like reload a service for that what you can do is? exec { "reload httpd": command => "service httpd reload", path => "/usr/local/bin/:/bin/:/sbin/", } Lets break this line by line: exec { "reload httpd": This specifies that the resource type is exec type and has a human readable name as "reload httpd". command => "service httpd reload", This specified which command to execute when puppet is executed. path => "/usr/local/bin/:/bin/:/sbin/", This specifies where the binary service can be found in your mac
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Puppet agent run

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Puppet agent ==> Sends node's information and its facts to the master node and requests for Catalog [Complied manifests]. Puppet master checks who is this ? if this machine is authorized[Have a signed certificate or not?] to communicate with it and what all stuff do this machine needs. If incase this is the authorized one. Puppet master will gather all the related manifests and compile them to a catalog and then will send that catalog to the agent node. Puppet agent then will download & apply that catalog to get to the desired state and will create a [success/failure] report for the puppet master. Related docs: Puppet master   Puppet agent
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Dry run in Puppet --noop

 Dry run in puppet is a powerful feature given by puppet. This basically is used to test your Puppet manifests on any of the environment without actually making any changes to the machine. To dry-run Puppet, --noop flag needs to be used. Puppet’s ‘noop’ (no-operation) mode shows you what would happen, but actually doesn’t do anything :) This basically helps us for debugging stuff. For instance: [root@puppet manifests]# puppet apply site.pp --noop notice: /Stage[main]/Sudo/File[/etc/sudoers]/content: current_value {md5}e81452ad78198a79772447b1f2b3b614, should be {md5}e2d690ebe349d93efa84146eb854c987 (noop) notice: Class[Sudo]: Would have triggered 'refresh' from 1 events notice: /Stage[main]/Ssh::Service/Service[sshd]/ensure: current_value stopped, should be running (noop) notice: Class[Ssh::Service]: Would have triggered 'refresh' from 1 events notice: Stage[main]: Would have triggered 'refresh' from 2 events notice: Finished catalog run in 2.75 seco
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Creating a module in Puppet

Here we will try to create a module[sudo] and see how we can use it. For more information about the structure of a module you can check this link . Our mission is to add users sunny and bbee to the sudoers file. Firstly create a directory called sudo in /etc/puppet/modules/ directory. This is basically your module name. [root@puppet modules]# mkdir sudo Now create three sub-directories in it as manifests, files, templates. [root@puppet modules]# mkdir manifests files templates So your current structure is somewhat like this: sudo/ ├── files ├── manifests └── templates 3 directories, 0 files The first and foremost part is to check and install[If not installed] the necessary package. package { 'sudo':                 ensure => present,                 } The above code states that package sudo should be installed in the machine. The values applicable for ensure in case of package are absent[Un-installed] or present[Installed]. Next part is to manage the
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Puppet installation on agent/server

Puppet can be used as a standalone model or as agent/server model. There are basically 2 types of puppet version available in market. Free version of puppet. Enterprise version of puppet which is also know as puppet-enterprise. Here we will be installing the free version of puppet. 0. Enable EPEL repo, you can find the latest version of EPEL on below URL: https://fedoraproject.org/wiki/EPEL 1. Install prerequisites before installing puppet [root@rhel6 ~]# yum install ruby-shadow ruby ruby-libs 2. Resolve the dependencies like ruby(selinux). 3. Install puppetmaster and facter on the server node. [root@rhel6 ~]# yum install puppet-server facter 4. Install puppet and facter on the agent node. [root@rhel6 ~]# yum install puppet facter Once these packages are installed on both the machines. Make sure that your agent node can ping the server node with the name as puppet. [root@rhel6 ~]# ping puppet PING puppet (192.168.122.14) 56(84) bytes of data. 64 bytes fr
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