Useful Ansible commands

Help: [#> ansible --help]

Version: [#> ansible --version]

#> ansible --version
ansible 2.0.0.2
config file = /etc/ansible/ansble.cfg
configured module search path = Default w/o overrides

Check: [#> ansible foo.yml --check]

Inventory: [#> ansible -i 192.x.x.x, x.x.x.x]

ListHosts: [#> ansible -list-hosts]

OneLine: [#> ansible –-one-line]

SyntaxCheck: [#> ansible –-syntax-check]

TimeOut: [#> ansible –timeout=X]

Verbose: [#> ansible –verbose]

Example: Run an ad hoc command against an Ansible inventory group and limit the execution of a playbook to a max of 5 simultaneous servers:
$ ansible europe -a "whoami" -f 5

Example: Execute a playbook against the Europe group as a privileged account (different from the SSH account
$ ansible europe -a "/usr/bin/foo" -u username --become [--ask-become-pass]

Example: Transfer a local (on the ansible control server) file to a set of remote hosts simultaneously 
$ ansible europe -m copy -a "src=/opt/myfile dest=/opt/myfile"

Example: Running an ansible playbook against a single hostname or IP address
#> ansible-playbook -i "192.168.10.10," -c local hellodevopsworld.yml

Example: Running an ansible playbook against an inventory group
#> ansible-playbook myplaybook.yml

1. Configuring Ansible

 /etc/ansible/ansible.cfg 

# some basic default values...

#inventory = /etc/ansible/hosts
#library = /usr/share/my_modules/
#module_utils = /usr/share/my_module_utils/
#remote_tmp = ~/.ansible/tmp
#local_tmp = ~/.ansible/tmp
#forks = 5
#poll_interval = 15
#sudo_user = root
#ask_sudo_pass = True
#ask_pass = True
#transport = smart
#remote_port = 22
#module_lang = C
#module_set_locale = False

2. Defined inventory groups

/etc/ansible/hosts

[databaseservers]
mydbserver105.example.org
mydbserver205.example.org

[webservers]
mywbserver105.example.org
mywbserver205.example.org

3. Executing playbook's and targeting specific inventory files and groups

#> ansible playbookfoo.yml -l 'groupname'

Let's take a peek at how Jinja fits in with YAML:

# Example Jinja Playbook
- hosts: all
  vars:
    foo: "{{ lookup('env', 'FOO' }}"
  tasks:
    - name: Copy file
      copy: src="{{ foo }}" dest=/some/path mode=0775 owner=user group=user

---
- hosts: all
  vars :
    http_port : 80
    tasks:
    - name: Install nginx web server
      apt: pkg=nginx state=installed update_cache=true
      notify:
        - start nginx

tasks:
    - name: Can we use Ansible to Install Apache2 web server
      apt: pkg=apache2 state=installed update_cache=true

tasks:
    - name: Use Ansible to Install nginx web server
      apt: pkg=nginx state=installed update_cache=true

tasks:
    - name: Use Ansible to Install MySQL web server
      apt: pkg=mysql-server state=installed update_cache=true

 

4. Variables and Variable Files

---
- hosts: all
  vars:
    myvar: helloworld
  vars_files:
    - /vars/my_vars.yml

Example: Simple Key/Value Variables in Ansible. 
---
- hosts: all
  vars:
    # Single Variable(s) Example
    myvar: helloworld

  tasks:
    - name: $myvar
      ping:

# Task specific variables
tasks:
  - name: copy files
    copy: src={{ item }} dest=/opt/{{ item }}
    with_items:
      - foo
      - bar

# my_vars_file.yml
---
east_coast_host_local: virginia
west_coast_host_local: oregon
definitions:
- servers: web
   instance: apache
- servers: db
   instance: cassandra
ping_server: 192.168.10.10

# Example: Simple Variables File in Ansible. 
---
- hosts: all
  vars_files:
    - my_vars_file.yml

  tasks:
    - name: ping target server
      ping: $ping_server

# Example: Simple Variables File in Ansible. 
---
- hosts: all
  tasks:
    - name: include default step variables
      include_vars: my_vars_file.yml
      ping: $ping_server

a. 

# Example: Simple Variables File in Ansible. 
---
- hosts: all
  vars_files:
    - my_vars_file.yml
    - "/opt/varsfiles/{{ env_vars }}.yml"
  
  tasks:
    - name: ping target server
      ping: $ping_server

$> ansible-playbook site.yml -e "env_vars=dev" -c local

Hosts and Inventory

Ansible offers a default inventory file, which is typically located in the /etc/ansible/hosts file location.

# This example uses the default hosts file provided by Ansible
# and executes playbook.yml
$> ansible-playbook -i hosts playbook.yml

# This example specifies an alternative hosts file
# and executes playbook.yml
$> ansible-playbook -i /opt/mynewinventoryfile playbook.yml

# This example specifies a set of hosts directly on the
# command line and executes playbook.yml
$> ansible-playbook -i fqdn.example.com,playbook.yml

Ansible hosts file example (/etc/ansible/hosts):

# Example Ansible hosts file with two defined groups

[WEB]
192.168.10.10
[DATABASE]
192.168.10.11

Targeting the WEB hosts group via an Ansible playbook (playbook.yml):

# Example Ansible Playbook, which targets the 'WEB' group
---
- hosts: WEB
  vars :
    http_port : 80
  tasks:
    - name: Install nginx web server
      apt: pkg=nginx state=installed update_cache=true
      notify:
        - start nginx

# Run Ansible and instruct it to execute the contents of
# playbook.yml against the inventory file of hosts
# (the default Ansible inventory)
$> ansible-playbook playbook.yml -i hosts

# Example hosts line values:

hosts: all -- Applies the current playbook to all hosts in the specified inventory file
  hosts: hostname -- Applies the playbook ONLY to the specified host 'hostname'
  hosts: groupname -- Applies the playbook to all hosts in specified groupname
  hosts: groupA,groupB -- Applies the playbook to hosts in groupB and groupB
  hosts: group1,host1 -- A combination of single hosts and groups
  hosts: *.google.com -- Applies the playbook to wildcard matches

https://docs.ansible.com/ansible/latest/collections/index_module.html