DevOps Classroom Series – 18/Aug/2020

Installing Tomcat on Ubuntu

• Refer and adopt this documentation to ubuntu 18.04
• Lets look at steps

sudo apt-get update
sudo apt-get install tomcat8 -y
sudo systemctl enable tomcat8
sudo systemctl start tomcat8

• So the playbook looks as shown below

---
- hosts: appserver
  become: yes
  vars:
    tomcat_package_name: tomcat8
  pre_tasks:
    - name: update ubuntu packages
      apt:
        update_cache: yes
  tasks:
    - name: install tomcat
      package:
        name: "{{ tomcat_package_name }}"
        state: present
      notify:
        - enable and restart tomcat
  handlers:
    - name: enable and restart tomcat
      service:
        name: "{{ tomcat_package_name }}"
        enabled: yes
        state: started
      

• The hosts file is as shown below

[appserver]
172.31.3.192 ansible_python_interpreter="/usr/bin/python3"

• Lets add the tasks for centos

sudo yum install tomcat

• Now adding this to playbook

---
- hosts: appserver
  become: yes
  vars:
    tomcat_package_name: tomcat
    tomcat_additional_packages:
      - tomcat-webapps 
      - tomcat-admin-webapps 
  pre_tasks:
    - name: update ubuntu packages
      apt:
        update_cache: yes
      when: ansible_os_family == "Debian"
  tasks:
    - name: install tomcat
      package:
        name: "{{ tomcat_package_name }}"
        state: present
      notify:
        - enable and restart tomcat
    - name: install additional packages
      package:
        name: "{{ item }}"
        state: present
      loop: "{{ tomcat_additional_packages }}"
      notify:
        - enable and restart tomcat

  handlers:
    - name: enable and restart tomcat
      service:
        name: "{{ tomcat_package_name }}"
        enabled: yes
        state: started
      

• Now we have to change the existing file ‘/usr/share/tomcat/conf/tomcat.conf’

JAVA_OPTS="-Djava.security.egd=file:/dev/./urandom -Djava.awt.headless=true -Xmx512m -XX:MaxPermSize=256m -XX:+UseConcMarkSweepGC"

• Now lets go with the assumption that the values are fixed
• So lets create a file called as tomcat.conf with following

# System-wide configuration file for tomcat services
# This will be loaded by systemd as an environment file,
# so please keep the syntax. For shell expansion support
# place your custom files as /etc/tomcat/conf.d/*.conf
#
# There are 2 "classes" of startup behavior in this package.
# The old one, the default service named tomcat.service.
# The new named instances are called tomcat@instance.service.
#
# Use this file to change default values for all services.
# Change the service specific ones to affect only one service.
# For tomcat.service it's /etc/sysconfig/tomcat, for
# tomcat@instance it's /etc/sysconfig/tomcat@instance.

# This variable is used to figure out if config is loaded or not.
TOMCAT_CFG_LOADED="1"

# In new-style instances, if CATALINA_BASE isn't specified, it will
# be constructed by joining TOMCATS_BASE and NAME.
TOMCATS_BASE="/var/lib/tomcats/"

# Where your java installation lives
JAVA_HOME="/usr/lib/jvm/jre"

# Where your tomcat installation lives
CATALINA_HOME="/usr/share/tomcat"

# System-wide tmp
CATALINA_TMPDIR="/var/cache/tomcat/temp"

# You can pass some parameters to java here if you wish to
#JAVA_OPTS="-Xminf0.1 -Xmaxf0.3"
JAVA_OPTS="-Djava.security.egd=file:/dev/./urandom -Djava.awt.headless=true -Xmx512m -XX:MaxPermSize=256m -XX:+UseConcMarkSweepGC"

# Use JAVA_OPTS to set java.library.path for libtcnative.so
#JAVA_OPTS="-Djava.library.path=/usr/lib"

# You can change your tomcat locale here
#LANG="en_US"

# Run tomcat under the Java Security Manager
SECURITY_MANAGER="false"

# SHUTDOWN_WAIT has been deprecated. To change the shutdown wait time, set
# TimeoutStopSec in tomcat.service.

# If you wish to further customize your tomcat environment,
# put your own definitions here
# (i.e. LD_LIBRARY_PATH for some jdbc drivers)

• Now modify the playbook to copy the tomcat.conf

---
- hosts: appserver
  become: yes
  vars:
    tomcat_package_name: tomcat
    tomcat_additional_packages:
      - tomcat-webapps 
      - tomcat-admin-webapps
    tomcat_conf_location: "/usr/share/tomcat/conf/tomcat.conf"
  pre_tasks:
    - name: update ubuntu packages
      apt:
        update_cache: yes
      when: ansible_os_family == "Debian"
  tasks:
    - name: install tomcat
      package:
        name: "{{ tomcat_package_name }}"
        state: present
      notify:
        - enable and restart tomcat
    - name: install additional packages
      package:
        name: "{{ item }}"
        state: present
      loop: "{{ tomcat_additional_packages }}"
      notify:
        - enable and restart tomcat
    - name: copy tomcat configuration
      copy:
        src: tomcat.conf
        dest: "{{ tomcat_conf_location }}"
      notify:
        - enable and restart tomcat

  handlers:
    - name: enable and restart tomcat
      service:
        name: "{{ tomcat_package_name }}"
        enabled: yes
        state: restarted
      

• this approach is good for copying the static files, but what should be done if the values are dynamic
• In the case of ansible dynamic nature can be handled by ansible variables, but to use ansible variables in configuration files we need to learn
  • Ansible templates
  • Jinja2 (Mechanism used in ansible templates.)