In this blog, we will explore some more common usecases which will help you in the automation.

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Checkout my article on some more Ansible usecases

Agenda:

1. How to check the connectivity of nodes from the master node ?
2. How to create a system group and user in linux ?
3. How to create a single directory?
4. How to create a multiple directory in linux using loop?
5. How to remove a file ?
6. How to check if files exist and then used when and block to execute the tasks
7. How to assign permissions to all folders and sub-folders recursively ?
8. How to copy from templates folder ?
9. How to call roles from the main.yml file ?
10. How to change the directory for a specific task ?
11. How to import Java certs ?

Lets explore all the scenarios one by one

1. How to check the connectivity of nodes from the master node ?

• gather_facts: This will check whether the ssh connection is setup between master and other nodes.
• By default this command is already set to true
• You should set this to no for the subsequent tasks to improve the performance

- hosts: all
  gather_facts: True
- hosts: children
gather_facts: no

2. How to create a system group and user in linux ?

• We are creating a test_group group and test_user user on the linux machine
• Setting not to create a home directory of this user
• Setting nologin to this user

- name: "Create system group"
  group:
    name: "test_group"
    state: present

- name: "Create system user"
  user:
    name: "test_user"
    group: "test_group"
    createhome: no
    shell: "/sbin/nologin"
    comment: "Test user"
    state: present

3. How to create a single directory?

- name: Create directory
  file: 
    path: "/opt"
    state: directory
    mode: 0777
  become: true

4. How to create a multiple directory in linux using loop?

• Creating a directory by setting its owner, group and mode
• Using with_items to iterate over multiple folders

- name: "Creating directories"
  file:
    path: "{{ item }}"
    state: directory
    owner: "test_user"
    group: "test_group"
    mode: "u=rwx,g=rx,o="
  with_items:
    - "{{ directory_1}}"
    - "{{ directory_2}}"
    - "{{ directory_3}}"
    - "{{ directory_4}}"

• Create a variable FOLDER_CREATE in your variable file as shown below

FOLDER_CREATE:
   - /opt
   - /temp
   - /test

• Now in your playbook use this as shown below:

- name: "Creating directories"
  file:
    path: "{{ item }}"
    state: directory
    owner: "test_user"
    group: "test_group"
    mode: "u=rwx,g=rx,o="
  with_items:
    - "{{ FOLDER_CREATE}}"

5. How to remove a file ?

- name: "Remove file"
    file:
      path: "/tmp/test.sh"
      state: absent

6. How to check if files exist and then used when and block to execute the tasks

• Store the result in variable binary_stat if file exist
• Use block to execute multiple tasks based on the when condition

- name: "Ensure file exists"
  stat:
    path: "/opt/test.sh"
  register: binary_stat


- block:
   - name: "Remove file"
     file:
       path: "/opt/test.sh"
       state: absent
when: not binary_stat.stat.exists

7. How to assign permissions to all folders and sub-folders recursively ?

- name: "Set File permission"
  file:
    path: "/tmp/test"
    state: directory
    recurse: yes
    owner: "test_user"
    group: "test_group"
    mode: "go-w"

8. How to copy from templates folder ?

• Create a file under /templates/test.properties.j2
• Copy it to the destination test/test.properties

- name: "copy test.properties using template
  template:
    src: "test.properties.j2"
    dest: "test/test.properties"
    owner: "test_user"
    group: "test_group"
    mode: "u=rw,g=r,o="

9 . How to call roles from the main.yml file ?

• Below command will run the main.yml file which is present in the roles/install_java folder

- hosts: host
  gather_facts: no
  become: true
  tasks:
    - include_role:
        name: install_java
  

• If you want to run the specific yaml file then do as shown below:

- hosts: host
  gather_facts: no
  become: true
  tasks:
    - include_role:
        name: installl_java
        tasks_from: test.yml

10. How to change the directory for a specific task ?

• Find the specific file and provide the path from where playbook should run using args

- name: "Ensure file exists"
  stat:
    path: "test.sh"
  register: binary_stat
  args:
     chdir: "/opt"

11. How to import java certs ?

- name: Import certs using keytool
  java_cert:
   cert_path: "test.jks"
   keystore_path: "cacerts"
   keystore_pass: "test"
   cert_alias: "test"
   executable: "keytool"
   state: present
  become: yes
  become_user: root

Congratulations, you have successfully learnt some common usecases which will help you in the automation.