Ansible

Commands


ssh-keygen
ssh-copy-id cloud_user@35.173.128.238

# If the above command didn't work use the below method.

> on controlnode do: 
ssh-keygen 
cat ~/.ssh/id_rsa.pub (copy the value)

# Paste copied public key (control plane) into the authorized_keys in each managed nodes.
cd .ssh (on each workers)
nano authorized_keys 
> Paste keys from controlnode (hence managed nodes know the controlnode IP and public key)

sudo nano /etc/ansible/hosts
############################
[labclients]
10.253.1.18
10.253.1.20

# or just the ip 
10.253.1.18
#Check 
############################
ansible-inventory --list
ansible all -m ping
############################
Run an Ansible ad-hoc command to check the uptime of all remote nodes:
ansible -a "uptime" all

Ad-Hoc Commands

Ad-hoc commands run on an as-needed basis and are usually for those tasks that do not repeat.

Syntax for Ad-Hoc ansible command:


ansible [target] –m [module] –a “[module options]”

# -a "[module options]": Specifies the options or parameters to be passed to the module.

Example Ansible Ad-hoc commands:

Ping localhost


ansible localhost –m ping

Creating a file on all remote clients


ansible all –m file –a “path=/home/iafzal/adhoc1 state=touch mode=700”

Deleting a file on all remote clients


ansible all –m file –a “path=/home/iafzal/adhoc1 state=absent”

Copying a file to remote clients


ansible all –m copy –a “src=/tmp/adhoc2 dest=/home/iafzal/adhoc2”

Installing packages (telnet and httpd-manual):


ansible all -m yum -a "name=telnet state=present"
ansible all -m yum -a "name=httpd-manual state=present"

Starting httpd package service:


ansible all -m service -a "name=httpd state=started"

Start httpd and enable at boot time:


ansible all -m service -a "name=httpd state=started enabled=yes"

Checking httpd service status on remote client:


ansible all -m shell -a "systemctl status httpd"

Remove httpd package:


ansible all -m yum -a "name=httpd state=absent"
OR
ansible all -m shell -a "yum remove httpd"

Creating a user on remote clients:


ansible all -m user -a "name=jsmith home=/home/jsmith shell=/bin/bash state=present"

To add a user to a different group:


ansible all -m user -a "name=jsmith group=iafzal"

Deleting a user on remote clients:


ansible all -m user -a "name=jsmith home=/home/jsmith shell=/bin/bash state=absent"
OR
ansible all -m shell -a "userdel jsmith"

Getting system information from remote clients:


ansible all -m setup

You can run commands on the remote host without a shell module e.g. reboot client1:


ansible client1 -a "/sbin/reboot"

Ansible configuration files

/etc/ansible/ansible.cfg
/etc/ansible/hosts
/etc/ansible/roles

Terminologies

Control node or Ansible Server • Server which runs Ansible application

Modules • Module is a command meant to be executed on the client-side • Most of the IT tasks modules are already created and can be found on Ansible website • www.docs.ansible.com → search for module index • Example of modules:

Install http
Enable http service
Start http service

Task • A task is a section that consists of a single procedure to be completed. A task can have multiple modules

Playbook • Automation file with step-by-step execution of multiple tasks

YAML • A Playbook written in YAML language (Yet another markup language)

Inventory • File that has information about remote clients where tasks are executed

Tag • A reference or alias to a specific task

Variable • Variables are like containers that holds the defined value which can be used repetitively

Role • Splitting of Playbook into smaller groups. Roles let you automatically load related vars, files, tasks, handlers, and other Ansible artifacts based on a known file structure. After you group your content in roles, you can easily reuse them and share them with other users.

How Ansibel Works?

Ansible Vs Puppet and Chef

• Uses simple YAML • Agentless (Only requires SSH access) • Easy installation • Well documented product

• Uses Ruby language which is more difficult to learn, and their support is declining day by day.

• These tools require agents to be installed on clients • The installation process is very complex • Lack of documentation

Playbook

Creating First Playbook


# su - root
# mkdir /etc/ansible/playbooks
# cd /etc/ansible/playbooks
# vim first.yml
---
- name: “My first playbook”
	hosts: localhost
	tasks:
		- name: “test connectivity”
			ping:

Hosts File Syntax

State


State - What to do with the package?
- present or installed: Install
- absent or removed: Un-install
- latest: Upgrade

State - What to do with the service?
- started: Start
- stopped: Stop
- reloaded: Reload
- restarted: Restart

Task 1 - Check Remote Clients Connectivity


# su - root
# cd /etc/ansible/playbooks
# vim clientstatus.yml
---
- name: "Check remote clients connectivity status"
  hosts: all
  tasks:
    - name: Test connectivity
      ping:

# Run the playbook

anisble-playbook clientstatus.yml

Task 2 - Copy Files to Remote Clients


---
- name: Copy file from local to remote clients # Description of the playbook
  hosts: all
  tasks:
    - name: Copying file
      become: true  # Transfer as a current user.               
      copy:
        src: /home/iafzal/some.cfg
        dest: /tmp
        owner: iafzal
        group: iafzal
        mode: 0644

Task 3 - Change File Permissions


---
- name: Change file permissions
  hosts: all
  tasks:
    - name: Files Permissions
      file:
        path: /home/iafzal/linux2
        mode: a+w

Task 4 - Setup Apache and Open Firewall Port


---
- name: Setup httpd and open firewall port
  hosts: all
  tasks:
    - name: Install apache packages
      yum:
        name: httpd
        state: present

    - name: Start httpd
      service:
        name: httpd
        state: started

    - name: Open port 80 for http access
      firewalld:
        service: http
        permanent: true
        state: enabled

    - name: Restart firewalld service to load firewall changes
      service:
        name: firewalld
        state: reloaded

Task 5 - Run Shell Scripts on Remote Clients


# vim shellscript.yml
---
- name: Playbook for shell script
  hosts: all or 10.253.1.115
  tasks:
    - name: Run shell script
      shell: "/home/iafzal/cfile.sh"

#Note: Shell script /home/iafzal/cfile.sh exists on the remote client.

Task 6 - Schedule a job (crontab)


The playbook cronjob.yml will:
- Schedule a job as root.
- Run every Thursday at 10 AM.

---
- name: Create a cron job
  hosts: all
  tasks:
    - name: Schedule cron
      cron:
        name: "This job is scheduled by Ansible"
        minute: "0"
        hour: "10"
        day: "*"
        month: "*"
        weekday: "4"
        user: root
        job: "/home/iafzal/cfile.sh"

Task 7 - User Account Management


The playbook will:
- Create a user named George on remote clients.
- Set the home directory for user George to /home/George.
- Set the shell environment for user George to /bin/bash.

---
- name: Playbook for creating users
  hosts: all
  tasks:
    - name: Create users
      user:
        name: george
        home: /home/george
        shell: /bin/bash

Task 8 - Download Package from a URL


The playbook tomcat.yml will:

- Create a directory for Tomcat with required permissions.
- Download Tomcat from a URL and place it in that directory with modified permissions.

---
- name: Download Tomcat from tomcat.apache.org
  hosts: localhost
  tasks:
    - name: Create a Directory /opt/tomcat
      file:
        path: /opt/tomcat
        state: directory
        mode: 0755
        owner: root
        group: root
    - name: Download Tomcat using get_url
      get_url:
        url: https://dlcdn.apache.org/tomcat/tomcat-8/v8.5.78/bin/apache-tomcat-8.5.78.tar.gz
        dest: /opt/tomcat
        mode: 0755
        group: iafzal
        owner: iafzal

Task 9 - Kill a Running Process


The playbook killprocess.yml will:

- Find a running process by process name.
- Ignore any errors.
- Hold the result in a registry variable.
- Use the shell module to run the kill command to terminate the process identified by the registered variable.

# vim killprocess.yml
---
- name: Find a process and kill it
  hosts: 10.253.1.115
  tasks:
    - name: Get running processes from remote host
      ignore_errors: yes
      shell: "ps -few | grep top | awk '{print $2}'"
      register: running_process
    
    - name: Kill running processes
      ignore_errors: yes
      shell: "kill {{ item }}"
      with_items: "{{ running_process.stdout_lines }}"

Task 10 - Pick and Choose Steps


Start a playbook at a specific task:

- ansible-playbook yamlfile.yml --start-at-task 'Task name'
- ansible-playbook http.yml --start-at-task 'Install telnet'

---
- name: httpd and telnet
  hosts: all
  tasks:
    - name: Install httpd
      yum:
        name: httpd
        state: present

    - name: Start httpd
      service:
        name: httpd
        state: started

    - name: Install telnet
      yum:
        name: telnet
        state: present