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Ansible

Ansible is a configuration/devOps tool that can be used to manage a range of servers and deployments

  • Ansible only needs to be installed on the machines that you use to manage your infrastructure. It does not need a client.

Installation

Ansible is based on python and can be installed using the python2 package manager pip (pip2). Ansible is python compiled and needs python2-devel installed

 sudo pip2 install ansible

it can also be installed from source from github.

Configuration

Ansible uses server configuration files in /etc/ansible

Getting Started

  • ping
  • setup - get server configuration
  • file - get or modify a file
  • copy - copy a file to the sever
  • command - execute a remote command on the server
  • shell - execute command as a shell

Ping

The servers can be ping'd

$  ansible  localhost  -u root -k -m ping

You will be prompted to the SSH password: and if the the message succeeds one should see

localhost | success >> {
    "changed": false,
    "ping": "pong"
}
  • if you have SSH key set up for the remote system then then leave off the -k
  • To use a specific username it can be configuring
  • per host basis
  • global Ansible configuration in /etc/ansible/ansible.cfg and change [defaults] section.

An example to configure and configured username, password and ssh port

[webservers]     
site01 ansible_ssh_user=root    
site02 ansible_ssh_user=daniel      
site01-dr ansible_ssh_host=site01.dr ansible_ssh_port=65422

An example user and private key location

[production]     
site01      
site02      
db01 ansible_ssh_user=fred ansible_ssh_private_key_file=/home/fred/.ssh.id_rsa bastion

Get Server configuration

This setup module connects to the configured node, gathers data about the system, and then returns those values.

ansible machinename -u root -k -m setup

This will return a long list of information

localhost | success >> {
    "ansible_facts": {
        "ansible_all_ipv4_addresses": [
            "172.17.42.1",
            "192.168.0.5"
        ],
        "ansible_all_ipv6_addresses": [
            "fe80::2677:3ff:fe52:b67c"                                                                           
        ],                                                                                                       
        "ansible_architecture": "x86_64",                                                                        
        "ansible_bios_date": "11/29/2011",                                                                       
        "ansible_bios_version": "8CET51WW (1.31 )",                                                              
        "ansible_cmdline": {                                                                                     
            "BOOT_IMAGE": "/boot/vmlinuz-3.16.7-7-desktop",                                                      
            "quiet": true,                                                                                       
            "resume": "/dev/disk/by-uuid/b513c1dc-927d-409d-9249-a81571b55dfd",                                  
            "root": "UUID=30a1f145-c23c-419a-a92c-aec2d718e250",                                                 
            "showopts": true,                                                                                    
            "splash": "silent"                                                                                   
        },                                         
etc. etc

File command/module

  • file without arguments returns he file contents
$ ansible machinename -u root -k -m file -a 'path=/etc/fstab'

returns

localhost | success >> {
    "changed": false,
    "gid": 0,
    "group": "root",
    "mode": "0644",
    "owner": "root",
    "path": "/etc/fstab",
    "size": 1418,
    "state": "file",
    "uid": 0
}

Copy

The copy module takes a file on the controller machine, copies it to the managed machine, and sets the attributes

For example, to copy the /etc/fstab file to /tmp on the managed machine, you will use the following command:

$ ansible machinename -m copy -a 'path=/tmp/fstab mode=0700 owner=root'

Command

Command that will run any arbitrary command on the managed machine.

 ansible localhost -m command -a 'rm -rf /tmp/testing removes=/tmp/testing'

If there is no file or directory named /tmp/testing, the command output will indicate that it was skipped, as follows:

localhost | skipped

Otherwise, if the file did exist, it will look as follows:

ansibletest | success | rc=0 >>

Shell

shell module allow you to execute a command as well as redirection, pipes, or job backgrounding.

$ ansible machinename -m shell -a '/opt/fancyapp/bin/installer.sh > 
/var/log/fancyappinstall.log creates=/var/log/fancyappinstall.log'

Using Ansible Playbooks

Yaml defined files are used to manage more complex and repetitive commands. The Yaml file can have the following sections

hosts:
users:
vars:
tasks:
handlers:

Ansible repository - Galaxy

The ansible-galaxy can be used to retrive playbooks from the Galaxy repository The ansible command options include

ansible-galaxy [init|info|install|list|remove]

For example to install a playbook

ansible-galaxy install alexanderjardim.tomcat

Links and References