Ansible Template module Examples - Jinja2 Templates | Devops Junction

Ansible template module helps to template a file out to a remote server.

Simply put, at runtime ansible template module updates the jinja2 interpolation syntax variables with actual values and copy the template file to the remote server with the specified name.

This is most useful for configuration templating and Server provisioning. We can see more Ansible template and interpolation syntax and Ansible template can be used in detail.

What does Ansible template module do

Ansible template module does two things

1. Replace the Jinja2 interpolation syntax variables present in the template file with actual values
2. copy (scp) the file to the remote server.

Ansible template module is designed to perform only these two things and it does the same perfectly and before going to Ansible template it is necessary that we should understand  the Ansible interpolation syntax and how it works.

Ansible Interpolation Syntax and Variables

To understand the Ansible template it is necessary that you Ansible interpolation syntax and variables and how it works.

Let us consider the normal shell script where you would have to pass the value of some variable during the time of execution. For example

#!/bin/bash
# Script find and  type of files which are N days older
#

if [ $# -ne 3 ]
then
    echo Please Check and Rerun
    echo – -----------------------
    echo "$0 Directory FileExtension DaysOld"
    echo $0 /var/log/tomcat "*.log"  30
    exit
fi

DIR=$1
FILEEXT=$2
DAYSOLD=$3

find ${DIR} -type f -name ${FILEEXT} -mtime +${DAYSOLD}

the preceding script is to simply perform some find command it takes all its input from the user during the runtime, till we get the right values from the user we have variable names like DIR, FILEEXT, DAYSOLD  as a placeholder

when we start the script with the following command

./test.sh "/apps/tomcat" "*.log"  30

the variable names would be replaced by these actual values and the script would be executed as intended.

Now in the world of Ansible, let's suppose you want to perform the same task and get the inputs from the user at run time as variables.

Here is some simple playbook

While starting this playbook with ansible-playbook command you have to declare the variables just like you did with Shell script. this is what is called interpolation.

In Ansible {{ }} is the interpolation syntax whereas in shell script it is ${ }

Finally, you can start your playbook like this with the variables at runtime.

ansible-playbook findtest.yaml -e "DIR=/apps/Tomcat FILEEXT=*.log DAYSOLD=30"

Quick Example of Ansible template module

we are going to make some modifications in our previous shell script and going to the change the interpolation from Shell ${ } into Ansible Jinja 2 interpolation syntax {{ }}

Shell Script - A Source file with Jinja2 interpolation

#!/bin/bash

# Script find and type of files which are N days older

find {{DIR}} -type f -name {{FILEEXT}} -mtime +{{DAYSOLD}}

Ansible Playbook with Ansible template

---
    - name: Template Example
      hosts: hostgroup1
      tasks:
        - name: Template module to interpolate variables and copy the file
          template:
            src: test.sh
            dest: /tmp/test.sh
            owner: vagrant
            group: vagrant
            mode: 0755
        
        - name: Execute the script
          become: true
          shell:
            /tmp/test.sh
          register: scroutput
          
        - debug: var=scroutput.stdout_lines

You can notice that there two tasks in the playbook

• Ansible template module to take care of the interpolation and scp
• Ansible shell module to invoke the script once the file is placed there.

Execution output of this Playbook

Ansible Template file is used for various configuration files and to achieve configuration templating. The following example would give you a clear picture if you still have questions on the ansible template.

Configuration Templating with Ansible Template Example

Ansible templating is widely used in Ansible roles for those who are not aware of what is ansible roles, it would be little hard to grab but if you do it a couple of times you can easily understand I bet.

So I have taken the Apache httpd server setup as an example. We have created ansible role for installing and configuration apache httpd server it performs everything right from downloading the epel repo and installing apache

The setup-apache role is also designed to download the current and live copy of middlewainventory.com  and create an index.html file for the apache virtual host

  Github Repo URL : https://github.com/AKSarav/Ansible-SetupApacheRole

File and Folder structure of my local machine where am testing this role

here template-ex2.yml is our main playbook which invokes the role and here is the content of that file

- – 
    - name: Apache2 Setup
      hosts: hostgroup1
      handlers:
        - include: handlers/handlers.yaml
      roles:
        - setup-apache

Here is the content of our setup-apache/tasks/main.yml content which is heart of our role does all the job for us

---
- name: install the EPEL release rpm 
  become: yes
  become_user: root
  yum:
    name: http://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
    state: present

- name: Ensure Apache is at the Latest version
  become: yes
  become_user: root
  tags:
    - web
  yum:
    name: httpd
    state: latest

- name: "Create sites-available and sites-enabled Directories"
  become: yes
  become_user: root
  tags:
    - web
  file:
    dest: "{{ item }}"
    owner: root
    group: root
    mode: 0644
    state: directory
  with_items:
    - "/etc/httpd/sites-enabled"
    - "/etc/httpd/sites-available"

- name: Modify the Default Apache Configuration file
  become: yes
  become_user: root
  tags:
    - web
  template:
    src: "{{ item.src }}"
    dest: "{{ item.dest }}"
    owner: root
    group: root
    mode: 0644
  with_items:
    - {src: 'basic_vh.conf.j2', dest: '/etc/httpd/sites-available/{{ domain }}.conf'}
    - {src: 'httpd.conf.j2', dest: '/etc/httpd/conf/httpd.conf'}
  
- name: Create the Document Root Direcotory
  become_user: root
  become: yes
  tags:
    - web
  file:
    dest: "{{ docroot }}"
    mode: 0755
    owner: apache
    group: apache
    state: directory

- name: Symlink the sites-available VH file to sites-enabled 
  become: yes
  become_user: root
  tags:
    - web
  file:
    src: "/etc/httpd/sites-available/{{ domain }}.conf"
    dest: "/etc/httpd/sites-enabled/{{ domain }}.conf"
    state: link
  notify: restart apache

- name: Make Sure mime.types file is available
  tags:
    - web
  file:
    dest: /etc/httpd/conf/mime.types
    state: file
  register: mimeout
  ignore_errors: True

- name: Copy the /etc/mime.types file to httpd conf
  become: yes
  become_user: root
  tags:
    - web
  shell: "cp /etc/mime.types /etc/httpd/conf/mime.types"
  when: mimeout is failed

- name: Download the home page of www.middlewareinventory.com to tmp
  tags:
    - web
  become: yes
  become_user: root
  shell: 
    wget https://www.middlewareinventory.com
  args:
    chdir: "/tmp"
    creates: "index.html"

- name : Changing file permission of downloaded index.html and copy to DocRoot
  tags:
    - web
  become: yes
  become_user: root
  copy:
    remote_src: yes
    src: "/tmp/index.html"
    dest: "{{docroot}}/index.html"
    owner: apache
    group: apache
    mode: 0755

- name: Make Sure the Apache is Running
  tags:
    - web
  become: yes
  become_user: root
  service: name=httpd state=restarted enabled=yes

We have a handler which can be defined as a function in the general programming, paradigm to declare once and to use it multiple times.

Video Ansible template example

Cheers
Sarav

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