Skip to main content

Lab 001: Ansible Facts Gathering

Requirements​

The Nautilus DevOps team is trying to setup a simple Apache web server on all app servers in Stratos DC using Ansible. They also want to create a sample html page for now with some app specific data on it. Below you can find more details about the task.

  • You will find a valid inventory file /home/thor/playbooks/inventory on jump host (which we are using as an Ansible controller).

  • Create a playbook index.yml under /home/thor/playbooks directory on jump host. Using blockinfile Ansible module create a file facts.txt under /root directory on all app servers and add the following given block in it.

  • You will need to enable facts gathering for this task.

    Ansible managed node IP is <default ipv4 address>

  • You can obtain default ipv4 address from Ansible's gathered facts by using the correct Ansible variable while taking into account Jinja2 syntax

  • Install httpd server on all apps. After that make a copy of facts.txt file as index.html under /var/www/html directory.

  • Make sure to start httpd service after that.

Note: Do not create a separate role for this task, just add all of the changes in index.yml playbook.

Steps​

Proceed to the specified directory.

cd /home/thor/playbooks/

Check the inventory file and verify if the defined parameters are correct. For the server credentials, check out the Project Nautilus documentation.

$ cat inventory;echo

stapp01 ansible_host=172.16.238.10 ansible_ssh_pass=********** ansible_user=tony
stapp02 ansible_host=172.16.238.11 ansible_ssh_pass=********** ansible_user=steve
stapp03 ansible_host=172.16.238.12 ansible_ssh_pass=********** ansible_user=banner

To verify if the inventory is correct, let's run a simple ping test. It should return the "ping:pong" response.

$ ansible -m ping -i inventory all

stapp03 | SUCCESS => {
    "ansible_facts": {
        "discovered_interpreter_python": "/usr/bin/python"
    }, 
    "changed": false, 
    "ping": "pong"
}
stapp02 | SUCCESS => {
    "ansible_facts": {
        "discovered_interpreter_python": "/usr/bin/python"
    }, 
    "changed": false, 
    "ping": "pong"
}
stapp01 | SUCCESS => {
    "ansible_facts": {
        "discovered_interpreter_python": "/usr/bin/python"
    }, 
    "changed": false, 
    "ping": "pong"
}

Create the playbook index.yml based on the requirements.

---
- name: Create the sample html page and install Apache
  hosts: all
  gather_facts: true
  become: yes
  become_method: sudo
  tasks:
    - name: Use blockinfile to create facts.txt
      blockinfile:
        create: yes
        path: /root/facts.txt
        block: |
          Ansible managed node IP is {{ ansible_default_ipv4.address }}

    - name: Install Apache
      package:
        name: httpd

    - name: Copy facts.txt to index.html
      shell: |
        cp /root/facts.txt /var/www/html/index.html

    - name: Ensure httpd is running
      systemd:
        name: httpd
        state: restarted

Run the playbook.

ansible-playbook -i inventory index.yml

If successful, it should return the following PLAY RECAP.

PLAY RECAP *******************************************************************************************************************
stapp01                    : ok=5    changed=4    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0   
stapp02                    : ok=5    changed=4    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0   
stapp03                    : ok=5    changed=4    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

If in case you get the following errors:

TASK [Use blockinfile to create facts.txt] ***************************************************************
fatal: [stapp01]: FAILED! => {"msg": "The task includes an option with an undefined variable. The error was: 'ansible_default_ipv4' is undefined. 'ansible_default_ipv4' is undefined

The error appears to be in '/home/thor/playbooks/index.yml': line 8, column 7, but may
be elsewhere in the file depending on the exact syntax problem.

The offending line appears to be:

  tasks:
    - name: Use blockinfile to create facts.txt
      ^ here
"}
fatal: [stapp02]: FAILED! => {"msg": "The task includes an option with an undefined variable. The error was: 'ansible_default_ipv4' is undefined. 'ansible_default_ipv4' is undefined

The error appears to be in '/home/thor/playbooks/index.yml': line 8, column 7, but may
be elsewhere in the file depending on the exact syntax problem.

The offending line appears to be:

  tasks:
    - name: Use blockinfile to create facts.txt
      ^ here
"}
fatal: [stapp03]: FAILED! => {"msg": "The task includes an option with an undefined variable. The error was: 'ansible_default_ipv4' is undefined. 'ansible_default_ipv4' is undefined

The error appears to be in '/home/thor/playbooks/index.yml': line 8, column 7, but may
be elsewhere in the file depending on the exact syntax problem.

The offending line appears to be:

  tasks:
    - name: Use blockinfile to create facts.txt
      ^ here
"}

You can try to use the playbook below instead:

---
- name: Create the sample html page and install Apache
  hosts: all
  gather_facts: true
  become: yes
  become_method: sudo
  tasks:
    - name: Use blockinfile to create facts.txt
      blockinfile:
        create: yes
        path: /root/facts.txt
        block: |
          Ansible managed node IP is {{ ansible_host | default('IP not available') }}


    - name: Install Apache
      package:
        name: httpd
    - name: Copy facts.txt to index.html
      shell: |
        cp /root/facts.txt /var/www/html/index.html
    - name: Ensure httpd is running
      systemd:
        name: httpd
        state: restarted

To confirm if the web server is running and the newly created index.html is being served, we can do a curl request from the jumphost to all the three App servers.

$ curl http://stapp01
# BEGIN ANSIBLE MANAGED BLOCK
Ansible managed node IP is 172.16.238.10
# END ANSIBLE MANAGED BLOCK

$ curl http://stapp02
# BEGIN ANSIBLE MANAGED BLOCK
Ansible managed node IP is 172.16.238.11
# END ANSIBLE MANAGED BLOCK

$ curl http://stapp03
# BEGIN ANSIBLE MANAGED BLOCK
Ansible managed node IP is 172.16.238.12
# END ANSIBLE MANAGED BLOCK

Another way to verify that the HTTP is running is by running a systemctl command from the jump host.

thor@jump_host ~/playbooks$ ansible all -i inventory -a "sudo systemctl status httpd"

stapp01 | CHANGED | rc=0 >>
● httpd.service - The Apache HTTP Server
   Loaded: loaded (/usr/lib/systemd/system/httpd.service; disabled; vendor preset: disabled)
   Active: active (running) since Sat 2023-08-19 04:07:21 UTC; 50s ago
     Docs: man:httpd.service(8)  

stapp03 | CHANGED | rc=0 >>
● httpd.service - The Apache HTTP Server
   Loaded: loaded (/usr/lib/systemd/system/httpd.service; disabled; vendor preset: disabled)
   Active: active (running) since Sat 2023-08-19 04:07:22 UTC; 50s ago
     Docs: man:httpd.service(8)    

stapp02 | CHANGED | rc=0 >>
● httpd.service - The Apache HTTP Server
   Loaded: loaded (/usr/lib/systemd/system/httpd.service; disabled; vendor preset: disabled)
   Active: active (running) since Sat 2023-08-19 04:07:21 UTC; 50s ago
     Docs: man:httpd.service(8)

Resources​