Setting up Tomcat : Ansible Playbook

Use the below playbook for reference for installing tomcat.

Create mentioned handlers separately.

---
	- name: Install Java 1.7
	yum: name=java-1.7.0-openjdk state=present
	- name: add group "tomcat"
	group: name=tomcat

Difference between Shell & Command module : Ansible

• The command module takes the command name followed by a list of space-delimited arguments.
• The given command will be executed on all selected nodes. It will not be processed through the shell, so variables like $HOME and operations like “<”, “>”, “|”, ”;” and “&” will not work (use the shell module if you need these features).

Command args (common for shell & command)

chdir - Change into this directory before running the command.

creates - A filename or (since 2.0) glob pattern, when it already exists, this step will not be run.

removes - A filename or (since 2.0) glob pattern, when it does not exist, this step will not be run.

args: only for shell module

executable - change the shell used to execute the command. Should be an absolute path to the executable.

Adding pre-tasks and post-tasks to playbooks

---
- hosts: www
  remote_user: vagrant
  sudo: yes
  pre_tasks:
     - shell: echo 'I":" Beginning to configure web server..'
  roles:
     - nginx
  post_tasks:
     - shell: echo 'I":" Done configuring nginx web server...'

System information: Adding colors to Shell script

#!/bin/bash
# Sample script written for Part 4 of the RHCE series
# This script will return the following set of system information:
# -Hostname information:
echo -e "\e[31;43m***** HOSTNAME INFORMATION *****\e[0m"
hostnamectl
echo ""
# -File system disk space usage:
echo -e "\e[31;43m***** FILE SYSTEM DISK SPACE USAGE *****\e[0m"
df -h
echo ""
# -Free and used memory in the system:
echo -e "\e[31;43m ***** FREE AND USED MEMORY *****\e[0m"
free
echo ""
# -System uptime and load:
echo -e "\e[31;43m***** SYSTEM UPTIME AND LOAD *****\e[0m"
uptime
echo ""
# -Logged-in users:
echo -e "\e[31;43m***** CURRENTLY LOGGED-IN USERS *****\e[0m"
who
echo ""
# -Top 5 processes as far as memory usage is concerned
echo -e "\e[31;43m***** TOP 5 MEMORY-CONSUMING PROCESSES *****\e[0m"
ps -eo %mem,%cpu,comm --sort=-%mem | head -n 6
echo ""
echo -e "\e[1;32mDone.\e[0m"

Run this script in bash shell and you will get an output similar below.

Note that the headers of each section are shown in color for better visualization:

That functionality is provided by this command:

echo -e "\e[COLOR1;COLOR2m<YOUR TEXT HERE>\e[0m"

Where COLOR1 and COLOR2 are the foreground and background colors, respectively (more info and options are explained in this entry from the Arch Linux Wiki) and <YOUR TEXT HERE> is the string that you want to show in color.

Enable direct ssh access to EC2 instance without .pem key

Enable password authentication by editing /etc/ssh/sshd_config: change PasswordAuthentication no to PasswordAuthentication yes

Restart ssh:

sudo /etc/init.d/ssh restart

systemctl  restart sshd (for RHEL7)

Ansible : Privilege escalation (become)

Ansible uses the become, become_user, and become_method directives to achieve privilege escalation. You can apply them to an entire play or playbook, set them in an included playbook, or set them for a particular task.

- name: checkout repo
  git: repo=https://github.com/some/repo.git version=master dest={{ dst }}
  become: yes
  become_user: some_user

You can use become_with to specify how the privilege escalation is achieved, the default being sudo.

More Examples:

- name: Ensure the httpd service is running
  service:
    name: httpd
    state: started
  become: yes

To run a command as the apache user:

- name: Run a command as the apache user
  command: somecommand
  become: yes
  become_user: apache

To do something as the nobody user when the shell is nologin:

- name: Run a command as nobody
  command: somecommand
  become: yes
  become_method: su
  become_user: nobody
  become_flags: '-s /bin/sh'

Setting up Ansible in AWS Linux RHEL

Enable PING
Edit Security Groups>Add Rule>>ICMP

Connect to AWS using putty
Follow the steps mentioned here/
https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/putty.html

To convert the .pem to .ppk file use the latest PuttyGen otherwise you will encounter the issues like 'Cant load the private key'

Modify the shell prompt

vi /etc/bashrc
Edit the below line as you like
[ "$PS1" = "\\s-\\v\\\$ " ] && PS1="[\u@MyServer>\w]\\$ "

Enable Root Login in AWS Linux machine

Uncomment PermitRootLogin in /etc/ssh/sshd_config

Setup SSH Passwordless authentication

copy the generated .pem file to he server using winscp (if you are using windows)
1. As root run ssh-keygen (generate the key to id_rsa.pub)
2. As ec2-user copy this file to Target server:/home/ec2-user
scp -i "/home/ec2-user/clients.pem" /root/.ssh/id_rsa.pub ec2-user@x.x.x.x:/home/ec2-user/
2. Login to target Server
    cat /home/ec2-user/id_rsa.pub >> /root/.ssh/authorized_keys

Now you have setup the SSH passwordless login for Ansible.