DevOps Series: Extending vagrant with Puppet for configuration management
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The document discusses the use of Vagrant as a wrapper for virtual machine providers and its integration with Puppet for configuration management. Puppet is described as a declarative language that defines system state without dictating execution order, utilizing resources like exec, package, and file to manage system configurations. It highlights the importance of idempotency in Puppet resources and provides examples of manifest files and resource definitions for effective system provisioning.
![Manifest files - II
Example manifest file - Clone project rails/rails from github:
Exec {
path => [ "/bin/", "/sbin/" , "/usr/bin/", "/usr/sbin/","/usr/local/bin" ]
}
exec { 'sys_update':
command => 'apt-get update --fix-missing',
}
package { 'git-core':
require => Exec['sys_update'],
ensure => 'installed',
}
exec{ 'clone rails project':
command => 'git clone https://github.com/rails/rails.git',
cwd => '/home/foo/',
require => Package['git-core'],
}
define a command
install a package but only after system
update (this is the command you’ve
define above)
set defaults for a
resource (in this case,
default path for Execs)
clone a project using git
but first make sure the
git package is installed](https://image.slidesharecdn.com/extendingvagrantwithpuppetforconfigurationmanagement-140703123241-phpapp02/85/DevOps-Series-Extending-vagrant-with-Puppet-for-configuration-management-5-320.jpg)
![Classes
● Just a simple way to group resources together, introducing modularization
and reuse:
class python {
package{'python-dev':
ensure => 'installed',
}
package{'python-pip':
ensure =>'installed',
require => Package['python-dev'],
}
}
include python
enforce ordering
between resources
don’t forget to
include what you
have defined](https://image.slidesharecdn.com/extendingvagrantwithpuppetforconfigurationmanagement-140703123241-phpapp02/85/DevOps-Series-Extending-vagrant-with-Puppet-for-configuration-management-12-320.jpg)
DevOps Series: Extending vagrant with Puppet for configuration management
- 1. Extending Vagrant with Puppet for Configuration Management 30-40 minutes Updated in July 2014 [email protected]
- 2. What Vagrant is and what it isn’t ● Vagrant is a wrapper for Virtual Machine providers (VirtualBox, VMWare, etc) . ● Vagrant can use provisioners, including shell scripts, puppet, chef and others. ● Puppet (which we’ll cover here) is but one option of provisioners supported by Vagrant; there are others like Chef, Ansible, Salt, etc. ● Vagrant is no configuration management tool.
- 3. What is Puppet and where does it fit in? ● Puppet can be seen series of system-level asserts. Puppet resources are meant to be idempotent, i.e. stateless (just like HTTP). ● Puppet is a declarative language. In other words, it does not specify steps, but states your system must be in. ● Couldn’t I just do everything Puppet does using shell provisioners? ○ Well, yeah but: You would have to write distribution-specific code for each box (think apt-get vs yum, deb vs rpm, etc). ○ Things will quickly get messy if you need complex provisioning steps that depend on each other, files to include, third-party modules, etc. ○ Your code would be order-dependent (stateful).
- 4. Manifest files - I ● These are the config files for Puppet: This is where you define resources for your system. ● The main manifest file (entry script) must be pointed to in your Vagrantfile ● Puppet is a Ruby-inspired DSL. ● Resources are not necessarily applied to the target system in the order they are written in the manifests. If a resource must be applied before or after some other resource, you must explicitly say so.
- 5. Manifest files - II Example manifest file - Clone project rails/rails from github: Exec { path => [ "/bin/", "/sbin/" , "/usr/bin/", "/usr/sbin/","/usr/local/bin" ] } exec { 'sys_update': command => 'apt-get update --fix-missing', } package { 'git-core': require => Exec['sys_update'], ensure => 'installed', } exec{ 'clone rails project': command => 'git clone https://github.com/rails/rails.git', cwd => '/home/foo/', require => Package['git-core'], } define a command install a package but only after system update (this is the command you’ve define above) set defaults for a resource (in this case, default path for Execs) clone a project using git but first make sure the git package is installed
- 6. Resources ● Resources are the basic building blocks in Puppet. ● Resources are state definitions. They are not commands that get run, but assertions that get verified. They should not have side-effects. ● A resource looks like this: type {'title': attribute => 'value', } ● Common resource types are Exec, Package, File and Service. ● Official docs entry for resources.
- 7. Resource types: Package I ● This resource type is used to assert that a package is in a given state. ● Attribute provider is used to define what kind of package will be used (it defaults to your system’s default package manager but others can be used, including things like pip, gem and npm. ● install a package using default provider (depending on your OS): package {'apache2': ensure => 'installed', }
- 8. Resource types: Package II ● Making sure a pip package is updated: package {'Django': ensure => 'latest', provider => 'pip', } More info: Puppet Docs for Package Resource
- 9. Resource types: Exec ● This resource type defines a shell command to be run in your virtual machine. ● The command must be idempotent or stateless: it should be able to run multiple times with no errors. Use attributes like onlyif, unless and creates to control when they run. ● example: exec {'install chrome browser': command => 'dpkg -i google-chrome-stable_current_i386.deb', cwd => "/home/username/Downloads", creates => "/usr/bin/google-chrome", } this command creates a file, so Puppet knows it shouldn’t be run if the file already exists
- 10. Resource types: File ● It merely asserts that a file exists. So if it doesn’t exist, it is created; if it already exists, nothing is done. ● Assert that a file exists and is owned by a given user: file {'make sure my-file exists': path => '/path/to/my-file', ensure => 'present', owner => 'johndoe', }
- 11. Resource types: File II ● Make sure a directory exists and has given mode file {'settings-directory', ensure => 'directory', path => '/path/to/settings-directory', mode => 755, recurse => true, } all child files will have given mode as well
- 12. Classes ● Just a simple way to group resources together, introducing modularization and reuse: class python { package{'python-dev': ensure => 'installed', } package{'python-pip': ensure =>'installed', require => Package['python-dev'], } } include python enforce ordering between resources don’t forget to include what you have defined
- 13. Heads-up ● In order to be able to launch 64-bit boxes, make sure you have ‘Virtualization Support’ enabled in your computer BIOS. ● You need to include all classes you want to be able to use, even though they are not your ‘entry point’.
- 14. Links and References ● Latest Docs (version 3.6) ● Visual Index for all Syntax Elements in the Puppet DSL ● Resource types full reference. ● Wikipedia Article comparing Configuration Management engines