[LINUX] A miscellaneous summary of what I researched about Ansible

variable

Official documentation --Using Variables

It seems that it can be described in either ini file format or YAML format. Is this an inventory file ...?

#ini format
[atlanta]
host1
host2

[atlanta:vars]
ntp_server=ntp.atlanta.example.com
proxy=proxy.atlanta.example.com

#YAML format
atlanta:
  hosts:
    host1:
    host2:
  vars:
    ntp_server: ntp.atlanta.example.com
    proxy: proxy.atlanta.example.com

Host variables and group variables

In addition to defining variables in the inventory, you can also define host variables and group variables. In that case, it seems necessary to use YAML format. Create a group name / host name file in the group_vars and host_vars directories under the / etc / ansible / directory and the current directory, and describe the settings.

/etc/ansible/group_vars/raleigh #The file extension is'.yml'、 '.yaml', Or'.json'
/etc/ansible/group_vars/webservers
/etc/ansible/host_vars/foosball

The definition file of variables associated with role may be a little different. Or main.yml. I also want to read the following. Official Documents --Best Practices

Iterative processing

You can use loop orwith_ *to perform iterative processing. loop seems to be a function added in version 2.5 of Ansible. Some modules allow you to pass a list directly to a parameter, which can be more efficient than looping tasks. Read the module manual.

Official documentation --Loops

Iterating over a simple list

- name: add several users
  user:
    name: "{{ item }}"
    state: present
    groups: "wheel"
  loop: # with_items:
     - testuser1
     - testuser2

Iterative processing of hash list

- name: add several users
  user:
    name: "{{ item.name }}"
    state: present
    groups: "{{ item.groups }}"
  loop: # with_items:
    - { name: 'testuser1', groups: 'wheel' }
    - { name: 'testuser2', groups: 'root' }

When referencing a variable

When iterating using a predefined variable, specify the variable in loop. Variables cannot be referenced unless they are enclosed in " {{}} ". What you should pay attention to is the variable name, and there are variables that are implicitly declared, so if you are in conflict with it, it will not work well and you will be addicted to it. .. .. Like groups. Check Special Variables in Official Documents. .. ..

vars:
  users:
    - { name: 'testuser1', groups: 'wheel' }
    - { name: 'testuser2', groups: 'root' }

- name: add several users
  user:
    name: "{{ item.name }}"
    state: present
    groups: "{{ item.groups }}"
  loop: "{{ users }}"

Run the task as an admin user

If you cannot ssh as root, use become to run the task with administrator privileges.

Official Document --Understanding privilege escalation: become

When describing in the playbook, describe in the following form.

---
- hosts: all
  become: yes
  become_user: root
  become_method: su
  become_flags: '-s /bin/sh'

Or set a variable. I think that variables should be specified in an appropriate file according to the scope of application.

---
# group_vars/all.yml
ansible_become: yes
ansible_become_method: su
ansible_become_password: somepassword

It seems that become_password cannot specify a password hash. If you want to protect sensitive data, use Ansible Vault.

Run

DRY-RUN Execute with the --check option. There is also a --diff option, but what's the difference ...

Syntax check

Execute with the --syntax-check option.

Check the task list

Execute with the --list-tasks option.

Run from a specific task

ʻRun the ansible-playbookcommand with the--start-at-taskoption. To step, add the--step` option.

ansible-playbook -i hosts -l hostname site.yml --start-at-task="some task name" --step