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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: [email protected]
    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