Variables and Flow Control

Question 1

Variables to Retrieve the Results of Running Commands:

Register

Answer 1

• name: 1
  hosts: server1
  tasks:
  
  • name: create file on server1
    copy:
    dest: /tmp/hello
    content: “Hello world!”
    mode: 0644
    register: output
  • name: testing results from creation file hello
    debug:
    msg: The below results are available {{ output }}
• name: 2
  hosts: server2
  become: yes
  tasks:
  
  • name: install apache on server2
    yum:
    name: httpd
    state: latest
  • name: run and enable apache
    service:
    name: httpd
    state: started
    enabled: yes
    register: apache_state
  • name: check output of apache_state
    debug:
    msg: “{{ apache_state }}”
    …

Question 2

Handlers

Answer 2

• name: testing handlers
  hosts: server1
  become: yes
  handlers:
  
  • name: copy index.html
    copy:
    dest: /var/www/html/index.html
    content: “Hello World!!!”
    listen: “copy index”
  • name: restart apache
    service:
    name: httpd
    state: restarted
    listen: “restart apache”
    tasks:
  • name: install apache
    yum:
    name: httpd
    state: latest
  • name: enable apache
    service:
    name: httpd
    state: started
    notify:
    
    • “copy index”
    • “restart apache”
      …

Question 3

Using loops:

• with_items
• loop

Answer 3

• name: creating users with loops
  hosts: servers
  become: yes
  tasks:
  
  • name: create users
    user:
    name: “{{ item }}”
    state: present
    loop:
    
    • lisa
    • anna
    • bob
  • name: set password for new users
    shell:
    cmd: echo 123 | passwd –stdin {{ item }}
    with_items:
    
    • lisa
    • anna
    • bob
• name: creating files with loops
  hosts: localhost
  tasks:
  
  • name: create files
    copy:
    dest: /tmp/{{ item }}
    content: ‘adding data to {{ item }}’
    with_items:
    
    • file1
    • file2
    • file3
      …

Question 4

Testing when conditional and loops using dictionary key-value

Answer 4

• name: testing loops
  hosts: servers
  become: yes
  tasks:
  
  • name: create new group
    group:
    name: test
  • name: create users
    user:
    name: “{{ item.name }}”
    append: yes
    groups: “{{ item.groups }}”
    with_items:
    
    • { name: ‘lisa’, groups: ‘wheel’ }
    • { name: ‘ann’, groups: ‘test’ }
  • name: install httpd
    yum:
    name: httpd
    state: latest
    when:
    
    • ansible_host == “10.0.1.232”
      …

Question 5

Ignore errors on certain hosts:
key:
ingore_errors: yes

Answer 5

• name: ingoring errors while copying files from remote hosts
  hosts: localhost
  tasks:
  
  • name: copy content of index file to tmp dir
    get_url:
    url: http://{{ item.host }}/index.html
    dest: /tmp/{{ item.name }}
    ignore_errors: yes
    register: output
    with_items:
    
    • { host: ‘10.0.1.164’, name: ‘server1’ }
    • { host: ‘10.0.1.155’, name: ‘server2’ }
  • name: checking results
    debug:
    msg: “This is output from copying: {{ output }}”

Question 6

Block-rescue-always
Note: always is not mandatory
similar to try-except
Note: that module names after block keyword should have -, which is not common

Answer 6

–
- name: install httpd
hosts: servers
become: yes
tasks:
- name: install httpd
yum:
name: httpd
state: latest
- name: create index file
copy:
dest: /var/www/html/index.html
content: “Hello World”
- name: block-rescue-always
hosts: localhost
tasks:
- name: check if index file exists
block:
- get_url:
url: “http://{{ item.server }}/index.html”
dest: /tmp/{{ item.file }}
with_items:
- { server: “10.0.1.42”, file: ‘server1’ }
- { server: “10.0.1.176”, file: ‘server2’ }
rescue:
- debug
msg: “Service is unreacheable”
always:
- debug:
msg: “ Testing block-rescue module”
…

Question 7

tags:
should be set on the level of module
ansible-playbook -i inventory tags.yaml –skip-tags “install,start” is the same as ansible-playbook -i inventory tags.yaml –tags “users,password”

Answer 7

• name: testing creation of users
  become: yes
  hosts: servers
  tasks:
  
  • name: create users
    user:
    name: “{{ item }}”
    with_items:
    
    • lisa
    • anna
      tags:
    • users
  • name: set password
    shell:
    cmd: echo 123 | passwd –stdin {{ item }}
    with_items:
    
    • lisa
    • anna
      tags: passwords
• name: testing set up of httpd
  become: yes
  hosts: server1
  tasks:
  
  • name: install httpd
    yum:
    name: httpd
    state: latest
    tags:
    
    • install
  • name: run httpd service
    service:
    name: httpd
    state: started
    enabled: yes
    tags:
    
    • start
      …

Question 8

Force_handlers

Forces previously notifies handler to run

Answer 8

If multiple tasks are notifying the same handler and one of those tasks fail, then the handler will not run and this can leave a host in an unexpected state.
For example, a configuration file being updated, which will then notify the handler that a service needs to be restarted but then another task in the same play has a failure, which causes the handler not to run. So to force that to always run, set force handlers equal to true

Question 9

When

Answer 9

• hosts: all
  become: true
  tasks:
  
  • name: check file exists
    shell:
    cmd: “ls -la /tmp/archive1.txt “
    register: variable
    ignore_errors: true
  • name: create archive.txt
    file:
    path: /tmp/archive1.txt
    state: touch
    when: variable is failed
    …

Question 10

Failed_when

Answer 10

Defines failure conditions