Cheatsheet collection

[/tʃiːt/] To act dishonestly or unfairly in order to gain an advantage.

Cheatsheet collection

ANSIBLE

  • Agentless (uses as transport layer Open SSH)
  • Configuration (/etc/ansible/ansible.cfg) check: $ansible-config list
  • Ansible inventory commands: $ansible-inventory --list or $ansible-inventory --graph

Ansible configuration

  • Is defined in anisble.cfg in the current directory or ~/.ansible.cfg or /etc/ansible/ansible.cfg:
[defaults]
# define default inventory to bypass -i usage
inventory = hosts.yml

# gives freedom of not specifying the encryption password or the password file every time
vault_password_file = ~/.vault_pass

retry_files_enabled = false
hash_behaviour=merge
forks = 10
## OpenSSH needed to use jumphost. See hosts.yml
transport = ssh
merge_multiple_cli_tags=True
# Use the YAML callback plugin.
stdout_callback = yaml

#interpreter discovery
interpreter_python = /usr/bin/python3
  • Use ansible_python_interpreter inventory variable in hosts.yml or the interpreter_python key in the [defaults] section of ansible.cfg to set the desired python interpreter.

AD-HOC

  • Can be used to reboot servers, copy files, manage packages and users etc: ansible <HOST_GROUP> -m <MODULE> -a "ARGUMENTS"

# ping 
ansible <GROUP> -v -m ping -i <HOSTS_INVENTORY>
ansbile <GROUP> -m shell -a "uptime" -i <HOSTS_INVENTORY>

# transfer file  (sudo yum install -y libselinux-python )
ansible <GROUP> -m copy -a "src=/path/to/file dest=/path/on/target/" -i <HOSTS_INVENTORY>

Inventory

# ansible view inventory
ansible-inventory -i <HOSTS_INVENTORY> --graph

# run playbook just on one machine from inventory limit
ansible-playbook -i <HOSTS_INVENTORY> -l machine.fqdn
  • Run playbook on local host: ansible-playbook --connection=local <PLAYBOOK>.yml:
# ansible-playbook run play on localhost
-

  name: playbook for localhost

  hosts: localhost

  connection: local

Tags

# ansible-playbook list tags
ansible-playbook -i <HOSTS_INVENTORY> <PLAYBOOK.yml> --list-tags
ansible-playbook -i <HOSTS_INVENTORY> <PLAYBOOK.yml> -t <TAG_NAME>

# ansible playbook run with tags
# also we can use `--skip-tags` flag 
ansible-playbook -l <HOSTNAME/GROUP> -i <HOSTS_INVENTORY> <PLAYBOOK.yml> -t "<TAG_NAME>"
ansible-playbook -l <HOSTNAME/GROUP> -i <HOSTS_INVENTORY> --tags "selected-tag" -u root <PLAYBOOK>.yml`

Extra Vars

# ansible playbook with --extra-vars
ansible-playbook -i <HOSTS_INVENTORY> <PLAYBOOK.yml> -e "instance_name=search_term"

# playbook with vars

- name: "Play with var as cmd argument"

      shell: grep -l 


# use env variables

- name: "Debug"

    debug:

      msg: " value for HOME var"

 

  - name: "Get api key from file"

    shell: "cat /home//name "

    register: api_key

    args:

      executable: /bin/sh

Test/verify/lint playbooks

1) Dry Run using check module: ansible-playbook <PLAYBOOK>.yml --check or just syntax check it ansible-module <PLAYBOOK>.yml --syntax-check

2) Linter: ansible molecule to test your ansible roles: pip install molecule

3) List playbook tags: ansible-playbook --list-tags <PLAYBOOK>.yml

Ansible Vault

  • Ansible Vault encrypts variables and files:
  • Ansible vault file: variables_encrypted.yml:
#environment variable to specify that file
echo $ANSIBLE_VAULT_PASSWORD_FILE

# vault file for sensitive data
variables_encrypted.yml

# encrypt/devrypt vault file
ansible-vault encrypt variables_encrypted.yml --encrypt-vault-id default
ansible-vault decrypt variables_encrypted.yml --encrypt-vault-id default
ansible-vault view variables_encrypted.yml

Variables

  • Inventory variables
# Ansible <2.0:
[all:vars]
ansible_connection=ssh
ansible_ssh_user=vagrant 
ansible_ssh_pass=vagrant

# Ansible >=2.0:
[all:vars]
ansible_connection=ssh # actually default mode smart is OK
ansible_user=vagrant
ansible_pass=vagrant # or ansible_ssh_pass=vagrant
  • Print/register var/output
- name: Test connection
  #hosts: "prometheus_host"
  hosts: "grafana_host"
  gather_facts: no
  tasks:
    - name: Check user
      shell: id
      register: shellcmd
        
    - debug: msg=""

    # - debug:
    #     var: shellcmd

                    ___ _____
                   /\ (_)    \
                  /  \      (_,
                 _)  _\   _    \
                /   (_)\_( )____\
                \_     /    _  _/
                  ) /\/  _ (o)(
                  \ \_) (o)   /
                   \/________/         @dejanualex