DevOps Classroom notes 14/Nov/2026

Ansible Jinja2 Templates

• Jinja2 is a Python-based templating engine used by Ansible.
• Templates are used to dynamically generate configuration files.

Where are templates used?

1. Playbooks: Use {{ variable }} to reference variables.
2. Template files: Use the .j2 extension to identify Jinja2 template files.

Directory Structure

├── hostname.yml
└── templates/
    └── test.j2

Note: Use the ansible.builtin.template module to generate configuration files from .j2 templates.

jinja2 template will use module ansible.builtin.template

offical docs for templating module

- name: Update sshd configuration safely, avoid locking yourself out
  ansible.builtin.template:
    src: etc/ssh/sshd_config.j2
    dest: /etc/ssh/sshd_config
    owner: root
    group: root
    mode: '0600'
    validate: /usr/sbin/sshd -t -f %s
    backup: yes

Tomact

- name: tomcat
  hosts: all
  become: true
  vars:
    tomcat_group: tomcat
    tomcat_app_version: tomcat-10
    java_package: openjdk-25-jdk
    tomcat_version: 10.1.61
    tomcat_user: tomcat
    home: /opt/tomcat
    url: "https://dlcdn.apache.org/tomcat/tomcat-10/v10.1.61/bin/apache-tomcat-10.1.61.tar.gz"
  tasks:
    - name: java installation
      ansible.builtin.apt:
        name: "{{ java_package }}"
        state: present
        update_cache: yes

    - name: create tomcat group
      ansible.builtin.group:
        name: "{{ tomcat_group }}"
        system: yes
        state: present

    - name: create tomcat user
      ansible.builtin.user:
        name: "{{ tomcat_user }}"
        group: "{{ tomcat_group }}"
        home: "{{ home }}"
        shell: /bin/false
        system: yes
        state: present

    - name: download tomcat
      ansible.builtin.get_url:
        url: "{{ url }}"
        dest: "/tmp/apache-tomcat-{{ tomcat_version }}.tar.gz"

    - name: extract tomcat
      ansible.builtin.unarchive:
        src: "/tmp/apache-tomcat-{{ tomcat_version }}.tar.gz"
        dest: /opt/tomcat
        remote_src: yes

    - name: change ownership of tomcat directory
      ansible.builtin.file:
        path: /opt/tomcat
        state: directory
        recurse: yes
        owner: "{{ tomcat_user }}"
        group: "{{ tomcat_group }}"

    - name: provide execute permission to tomcat scripts
      ansible.builtin.file:
        path: /opt/tomcat/bin
        state: directory
        recurse: yes
        mode: u+x

    - name: update java alternatives
      ansible.builtin.shell:
        cmd: update-java-alternatives -l

    - name: create tomcat service file
      ansible.builtin.copy:
        dest: /etc/systemd/system/tomcat.service
        content: |
          [Unit]
          Description=Tomcat
          After=network.target

          [Service]
          Type=forking

          User=tomcat
          Group=tomcat

          Environment="JAVA_HOME=/usr/lib/jvm/java-1.25.0-openjdk-amd64"
          Environment="JAVA_OPTS=-Djava.security.egd=file:///dev/urandom"
          Environment="CATALINA_BASE=/opt/tomcat"
          Environment="CATALINA_HOME=/opt/tomcat"
          Environment="CATALINA_PID=/opt/tomcat/temp/tomcat.pid"
          Environment="CATALINA_OPTS=-Xms512M -Xmx1024M -server -XX:+UseParallelGC"

          ExecStart=/opt/tomcat/bin/startup.sh
          ExecStop=/opt/tomcat/bin/shutdown.sh

          RestartSec=10
          Restart=always

          [Install]
          WantedBy=multi-user.target
      notify:
        - reload systemd daemon
        - start tomcat service

  handlers:
    - name: reload systemd daemon
      ansible.builtin.systemd:
        daemon_reload: yes

    - name: start tomcat service
      ansible.builtin.systemd:
        name: tomcat
        state: started
        enabled: yes

---

Tasks – Ansible Tomcat Playbook

1. Convert Tomcat Configuration Files into Templates

• Convert /opt/tomcat/conf/tomcat-users.xml into an Ansible Jinja2 template file (tomcat-users.xml.j2).
• Convert /opt/tomcat/webapps/manager/META-INF/context.xml into an Ansible Jinja2 template file (context.xml.j2).

2. Create Ansible Deployment Playbook

• Create an Ansible deployment playbook to deploy application files from the local machine to the remote Tomcat server.
• Use the copy or synchronize module to transfer application files.
• Deploy the application into the Tomcat webapps directory.
• Set the appropriate file ownership and permissions.
• Restart the Tomcat service after deployment.

3. Verify Deployment

• Verify that the Tomcat service is running.
• Check the deployed application in the Tomcat webapps directory.
• Access the application using the Tomcat server IP and port 8080.