Push Based Vs Pull Based CM

• In PUll Based CM, on the nodes we need to install software agents of CM Server who will be responsible for communication
• In Push based CM, no agents are required on the nodes.
• In Push based CM, CM Server needs to have
  • a list of nodes to communicate
  • credentials to login
  • Communication Protocol (SSH/Winrm) enabled on nodes
• In both pull based and push based CM, we would have the following properties
  • Idempotance: Result of execution of the script should be same (desired state) irrespective of execution count.
• Advantages of Push based CM
  • Simpler to use
  • Control over the entire system
  • No agents are required to be installed on nodes
• Advantages of Pull Based CM
  • Easier to Scale
  • No need of credentials of nodes

Installing Ansible:

• Ansible is written in Python, To run ansible we need python to be installed on Ansible Control Server (CM Server) and also nodes

• Ansible Control Server can be installed on

  • Linux
  • FreeBSD
  • macOS

• Nodes can be

  • Linux
  • Free BSD
  • MacOS
  • Windows
  • Network Switches
  • Routers

• Lets install ansible based on the below architecture

• Configure Windows Terminal Refer Here

• Installing ansible on

  • Ubuntu Refer Here
  • Redhat, Centos , Fedora Refer Here
  • Refer Here for all the possibilities

• Lets create a ubuntu vm

  • AWS Refer Here
  • Azure Refer Here

• Login in to the ubuntu instance and execute the following commands

sudo apt update
sudo apt install software-properties-common
sudo apt-add-repository --yes --update ppa:ansible/ansible
sudo apt install ansible -y
python --version
ansible --version

• Create an ubuntu 18 node in aws/azure as mentioned above
• The only requirement for any machine to be ansible node is python should be installed.
• For today lets try to install the same version of python as in ansible control server.

sudo apt update
sudo apt install software-properties-common
sudo apt-add-repository --yes --update ppa:ansible/ansible
sudo apt install python -y

• Now we have node and ansible control server ready, so lets try to understand what ansible does to connect to a node
  • Ansible needs to have ipaddress/dns name of the node in a file which is referred as inventory
  • Ansible needs the credentials of the node (username & password) or (username and key)
• So lets create a inventory is

172.31.45.255

• Now create a file called as inventory in /home/ubuntu/inventory with the following content

172.31.45.255

• At this moment lets run the test command to verify if ansible can communicate with the node

ansible -i inventory -m ping all

• Lets understand how ansible works and resolve the error in the next class