Ansible Reference Card

1 Overview

1.1 Inventory

1.1.1 Documentation

• show all inventory plugins

ansible-doc -t inventory -l

• show ini style inventory (default)

ansible-doc -t inventory ini

1.1.2 Examples

/etc/ansible/hosts

[apache]
web[01:05] ansible_user=devops

[nginx]
web[10:12]
web13 ansible_port=222 has_java = False
10.0.1.[250:253]

[nginx:vars]
http_port=8080

[webservers:children]
nginx
apache

1.1.3 Dynamic Inventory Example

cat inventory/dynamic-inventory.sh
#!/bin/bash
echo '{
   "web": ["www1", "www2", "www3"],
   "db": ["db1", "db2", "oracle1"]
}'

cat inventory/hosts [sudo] vm20 ansible_user=ansible

chmod 700 inventory/dynamic-inventory.sh ls -l inventory/

  -rwxr-xr-x. 1 root root 94 Dec 14 15:01 dynamic-inventory.sh
  -rw-r--r--. 1 root root 34 Dec 14 15:03 hosts

</source>

<source lang="bash"> [root@ansible lab]# ansible -i inventory/ --list-hosts web

 hosts (3):
   www1
   www2
   www3

[root@ansible lab]# ansible -i inventory/ --list-hosts sudo

 hosts (1):
   vm20

</source>

1.1.4 Commands

• query inventory for specific hosts

ansible web01 --list-hosts
ansible 'all:!kvm' -i /etc/ansible/hosts --list-hosts

• show host involved by playbook

ansible-playbook --list-hosts tests/qa.yml

• run module on specific host

ansible vm06 -m setup

2 Setup Ansible

yum list installed python
yum -y install ansible
 
#install public key on destination
ssh-copy-id root@web1 

2.1 Configure Ansible

• Order of config file sources

ANSIBLE_CONFIG=/opt/ansible.cfg -> ./ansible.cfg -> $HOME/.ansible.cfg -> /etc/ansible/ansible.cfg

• Config Sections

egrep '^\['  /etc/ansible/ansible.cfg
  [defaults]
  [privilege_escalation]
  [ssh_connection]
  [accelerate]
  [selinux]
  [colors]

2.1.1 defaults

forks          = 5    # specify number of parallel processes to use
host_key_checking = True
vault_password_file = /path/to/vault_password_file
ansible_managed = Ansible managed: {file} on {host}
display_skipped_hosts = True
display_args_to_stdout = True

2.1.2 privilege_escalation

become=True # to enable privilege escalation

2.1.2.1 Example

<source lang="bash">

1. define user in inventory on ansible host

vm20 ansible_user=ansible

1. create and configure user on destination host

useradd ansible

su - ansible mkdir .ssh chmod 700 .ssh vi .ssh/authorized_keys # add ansible host pub key chmod 600 .ssh/authorized_keys

echo 'ansible ALL=(ALL)NOPASSWD: ALL' > /etc/sudoers.d/ansible visudo -cf /etc/sudoers.d/ansible

1. verify configuration

[root@ansible lab]# ansible vm20 -m command -a w vm20 | SUCCESS | rc=0 >>

14:24:49 up 48 min,  2 users,  load average: 0.00, 0.01, 0.05

USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT root pts/0 192.168.223.59 13:43 5:05 0.05s 0.00s tail -f /var/log/secure ansible pts/1 192.168.223.43 14:24 0.00s 0.10s 0.00s /bin/bash -c sudo -H -S -n -u root /bin/bash -c 'echo BECOME-SUCCESS-fwkpkpwhbtkkrxdktmuwvgjmi... </source>

2.2 vim settings

• $HOME/.vimrc

autocmd Filetype yml setlocal ai sw=2 et

3 Working with Playbooks

3.1 Loop examples

---
- hosts: localhost
  vars:
    var1: this is one var
    array1: [aaa, bbb]
    array2:
      - ccc
      - ddd
    dictionary1: { key1: value1, key2: value2 }
    dictionary2:
      key3: value3
      key4: value4
    multi_array1:
      user1:
        name: bob
        nr: 123
      user2:
        name: mike
        nr: 456
  tasks:
  - name: show var1
    debug:
      msg: "{{ var1 }}"

  - name: loop array1
    debug:
      msg: "{{ item }}"
    with_items: "{{ array1 }}"

  - name: loop array2
    debug:
      msg: "{{ item }}"
    with_items: "{{ array2 }}"

  - name: loop dictionary1
    debug:
      msg: "{{ item.key }}: {{ item.value }}"
    with_dict: "{{ dictionary1 }}"

  - name: loop dictionary2
    debug:
      msg: "{{ item.key }}: {{ item.value }}"
    with_dict: "{{ dictionary2 }}"

  - name: "multi_array1['user1']['name']" 
    debug:
      msg: "multi_array1['user1']['name']: {{ multi_array1['user1']['name'] }}"
  - name: "multi_array1.user2'.name"
    debug:
      msg: "multi_array1.user2'.name: {{ multi_array1.user2.name }}"

  - name: multi_array1 loop with_dict
    debug: 
      msg: "User {{ item.key }} is {{ item.value.name }} with nr {{ item.value.nr }}"
    with_dict: '{{ multi_array1 }}'

  - name: loop with with_fileglob
    debug:
      msg: "/etc/ansible/{{item}}"
    with_fileglob: "/etc/ansible/*"
...

3.1.1 Example Output

PLAY [localhost] ******************************************************************************************************

TASK [Gathering Facts] ************************************************************************************************
ok: [localhost]

TASK [show var1] ******************************************************************************************************
ok: [localhost] => {
    "msg": "this is one var"
}

TASK [loop array1] ****************************************************************************************************
ok: [localhost] => (item=aaa) => {
    "item": "aaa", 
    "msg": "aaa"
}
ok: [localhost] => (item=bbb) => {
    "item": "bbb", 
    "msg": "bbb"
}

TASK [loop array2] ****************************************************************************************************
ok: [localhost] => (item=ccc) => {
    "item": "ccc", 
    "msg": "ccc"
}
ok: [localhost] => (item=ddd) => {
    "item": "ddd", 
    "msg": "ddd"
}

TASK [loop dictionary1] ***********************************************************************************************
ok: [localhost] => (item={'key': u'key2', 'value': u'value2'}) => {
    "item": {
        "key": "key2", 
        "value": "value2"
    }, 
    "msg": "key2: value2"
}
ok: [localhost] => (item={'key': u'key1', 'value': u'value1'}) => {
    "item": {
        "key": "key1", 
        "value": "value1"
    }, 
    "msg": "key1: value1"
}

TASK [loop dictionary2] ***********************************************************************************************
ok: [localhost] => (item={'key': u'key3', 'value': u'value3'}) => {
    "item": {
        "key": "key3", 
        "value": "value3"
    }, 
    "msg": "key3: value3"
}
ok: [localhost] => (item={'key': u'key4', 'value': u'value4'}) => {
    "item": {
        "key": "key4", 
        "value": "value4"
    }, 
    "msg": "key4: value4"
}

TASK [multi_array1['user1']['name']] **********************************************************************************
ok: [localhost] => {
    "msg": "multi_array1['user1']['name']: bob"
}

TASK [multi_array1.user2'.name] ***************************************************************************************
ok: [localhost] => {
    "msg": "multi_array1.user2'.name: mike"
}

TASK [multi_array1 loop with_dict] ************************************************************************************
ok: [localhost] => (item={'key': u'user2', 'value': {u'nr': 456, u'name': u'mike'}}) => {
    "item": {
        "key": "user2", 
        "value": {
            "name": "mike", 
            "nr": 456
        }
    }, 
    "msg": "User user2 is mike with nr 456"
}
ok: [localhost] => (item={'key': u'user1', 'value': {u'nr': 123, u'name': u'bob'}}) => {
    "item": {
        "key": "user1", 
        "value": {
            "name": "bob", 
            "nr": 123
        }
    }, 
    "msg": "User user1 is bob with nr 123"
}

TASK [loop with with_fileglob] ****************************************************************************************
ok: [localhost] => (item=/etc/ansible/hosts) => {
    "item": "/etc/ansible/hosts", 
    "msg": "/etc/ansible//etc/ansible/hosts"
}
ok: [localhost] => (item=/etc/ansible/ansible.cfg) => {
    "item": "/etc/ansible/ansible.cfg", 
    "msg": "/etc/ansible//etc/ansible/ansible.cfg"
}
ok: [localhost] => (item=/etc/ansible/ansible.cfg.rpmnew) => {
    "item": "/etc/ansible/ansible.cfg.rpmnew", 
    "msg": "/etc/ansible//etc/ansible/ansible.cfg.rpmnew"
}

PLAY RECAP ************************************************************************************************************
localhost                  : ok=10   changed=0    unreachable=0    failed=0   

3.2 condition examples

<source lang="yaml">

</source>

4 Variables and Inclusions

4.1 Ansible variable precedence

Ansible variable overriding documentation

In 2.x, we have made the order of precedence more specific (with the last listed variables winning prioritization):

• role defaults [1]
• inventory file or script group vars [2]
• inventory group_vars/all
• playbook group_vars/all
• inventory group_vars/*
• playbook group_vars/*
• inventory file or script host vars [2]
• inventory host_vars/*
• playbook host_vars/*
• host facts
• play vars
• play vars_prompt
• play vars_files
• role vars (defined in role/vars/main.yml)
• block vars (only for tasks in block)
• task vars (only for the task)
• role (and include_role) params
• include params
• include_vars
• set_facts / registered vars
• extra vars (always win precedence)

Basically, anything that goes into “role defaults” (the defaults folder inside the role) is the most malleable and easily overridden. Anything in the vars directory of the role overrides previous versions of that variable in namespace. The idea here to follow is that the more explicit you get in scope, the more precedence it takes with command line -e extra vars always winning. Host and/or inventory variables can win over role defaults, but not explicit includes like the vars directory or an include_vars task.

5 Task Control

5.1 shell

- name: get list of services without Ansible warning
  shell: "service --status-all 2>&1 | awk {'print $4'}"
  args:
    warn: false # set warn=false to prevent warning
  register: services_list

5.2 error handling

- name: this will not be counted as a failure
  command: /bin/false
  ignore_errors: yes

- name: Fail task when the command error output prints FAILED
  command: /usr/bin/example-command -x -y -z
  register: command_result
  failed_when: "'FAILED' in command_result.stderr"

- name: Fail task when both files are identical
  raw: diff foo/file1 bar/file2
  register: diff_cmd
  failed_when: diff_cmd.rc == 0 or diff_cmd.rc >= 2

- name: Check if a file exists in temp and fail task if it does
  command: ls /tmp/this_should_not_be_here
  register: result
  failed_when:
    - result.rc == 0
    - '"No such" not in result.stdout'

- name: example of many failed_when conditions with OR
  shell: "./myBinary"
  register: ret
  failed_when: >
    ("No such file or directory" in ret.stdout) or
    (ret.stderr != '') or
    (ret.rc == 10)

- command: /bin/fake_command
  register: result
  ignore_errors: True
  changed_when:
    - '"ERROR" in result.stderr'
    - result.rc == 2