Ansible

---

• Web server with Load balancers
• Custom Inventory
  • ansible -i inventory --list-hosts all
• With ansible.cfg
  • ansible --list-hosts all
  • ansible --list-hosts webservers
  • ansible --list-hosts loadbalancers
• Ansible Tasks(run adhoc commands)
  • ansible -m ping all
  • (ansible command) (module flag) (module name) (inventory)
  • ansible --list-hosts "*"
  • ansible --list-hosts app*
  • ansible --list-hosts webservers:loadbalancers # using group functions
  • ansible --list-hosts \!control # using negate function
  • ansible --list-hosts webservers[0:10]
  • ansible -m ping all
  • With uname, RC=0,Success
  • ansible -m shell -a "uname" webservers:local
  • ansible -m shell -a "uname" app1:local
  • ansible -m shell -a "uname" local
  • Return code RC=1,Failure
  • ansible -m command -a "/bin/false" \!loadbalancers
• Playbook
  • processes & manage configuration
  • run synchronously & asynchronously
  • ability to create infrastructure as code and manage it all in source control
  • list out everything we need & want to apply to each instance
  • Group them accordingly to configuration usage
  • Ensure they are in a logically defined order
  • Run each tasks according to the order they are listed
  • Example: update, install, configure check status etc
  • Run each tasks according to the order they are listed
• Service Handlers
• Import playbook
  • import_playbook: playbook_name
• Ansible adhoc command to stop apache
  • ansible -m service -a "name=apache2 state=stopped"--become loadbalancers
• Variables
  • Gathers useful facts about host, that can be used in playbooks
  • Use status module to see all the facts gathered during the TASK[Gathering Facts]
  • Use jinja2 template and expressions
  • ansible -m setup app1
  • Variables from info returned from tasks; call the registered variables for later use
    • register: dir_contents
  • Use debug mode
• Roles
  • Ansible provides framework that makes each part of variables, tasks, templates & modules fully independent
  • Group tasks together in a way that is self containing.
  • Predefiend directory structure
  • Break configurations into files
  • Reuse code by others for similar configurations
  • Use ansible-galaxy webservers init to create predefined framework of roles
• Check Mode("Dry Run"): Reports changes that Ansible would have to make on the end hosts rather than applying the changes
  • Run Ansible without affecting the remote system
  • Reports changes back
  • Use at one node at a time basic(example: configuration management)
  • ansible-playbook settings-app.yaml --check [--check flag to check the status]
• Error Handling in Playbooks
  • changed_when: false
  • ignore_errors: yes
  • TODO

Ansible Async directive

• Async & Poll

- task:
    - command: /opt/app.py
      async: 360
      poll: 60
      register: app_result

    - name: Check status of tasks
      async_status: jid={{ app_result.ansible_job_id }}
      register: job_result
      until: job_result.finished
      retires: 30

Ansible Strategy

• Linear Strategy (Default) [Each task is finished first in each server before proceding to next task]
• Free Strategy [Independantly run task in all server]
  • strategy: free
• Batch Strategy [Based on Linear]
  • marked with serial: 3 [Ansible ll run 1st 3 server to execute task and then next]
  • serial: 30%
• Forks - Ansible uses parallel processes/forks to remote host. By default ansible can create 5 forks at a time.

Error Handling

• any_error_fatal: true
• Email after finishing deployment

- mail:
    to: devops@scp.com
    subject: Job deployed
    body: Successfull
 ignore_errors: yes

- command: cat /var/log/server.log
  register: command_output
  failed_when: "'ERROR' in command_output.stdout"

Jinja2 Templating

• String Manipulation
  • {{ os_ name }}
  • {{ os_ name | upper }}
  • {{ os_ name | lower }}
  • {{ os_ name | title }}
  • {{ os_ name | replace("Ubuntu", "CentOs") }}
  • {{ os_ name | default("Ubuntu")}} {{ "CentOs" }}
• List and Set
  • {{ [1,2,3] | min }}
  • {{ [1,2,3] | max }}
  • {{ [1,2,3,3,4] | unique }}
  • {{ [1,2,3,3,4] | union[2,3] }}
  • {{ [1,2,3,3,4] | intersect[3,5,6] }}
  • {{ 100 | random }}
  • {{ ["My", "name", "is", "Bond"] | join("") }}
• Filters in file
  • {{ "/etc/hosts" | basename }}
  • {{ "c:\windows\hosts" | win_basename }}

Lookup

• {{ lookup('csvfile', 'targer_file=file/hosts.csv delimiter=;') }}
• Lookup file - ini, dns, mongodb etc

Anisble Vault

• ansible-vault encrypt inventory
• ansible-playbook playbook.yaml -i inventory --ask-vault-pass
• Store vault password in a file
  • ansible-playbook playbook.yaml -i inventory --vault-password-file ./vault_pass.txt
  • ansible-playbook playbook.yaml -i inventory --vault-password-file ./vault_pass.py
• ansible-vault view inventory
• ansible-vault create inventory

Dynamic Inventory

• ansible-playbook playbook.yaml -i inventory.py

Ansible Inventory Command

• ansible-inventory --list -y