Ansible Installation and Configuration on Redhat/CentOS 7
Ansible is an IT automation tool and it can configure systems, deploy software, and orchestrate more advanced IT tasks such as continuous deployments or zero downtime rolling updates.
Ansible manages machines in an agentless manner. Ansible uses OpenSSH for transport and it is decentralized, that means it relies on your existing OS credentials to control access to remote machines; if needed it can easily connect with
Kerberos, LDAP, and other centralized authentication management systems.How to Install and Configuration of Ansible IT Automation Tool on Linux.
In this step by step guide, you are going to learn how to get started with IT Automation with Ansible. This is your first step to understand the basic functionality of Ansible and how to Install/Configure Ansible IT Automation Tool on Enterprise Linux (RHEL/CentOS 7). You will also learn how to get Ansible installed with different methods and some basic concepts. you’ll learn how to execute ad-hoc commands from the master node to done some simple tasks across your nodes using Ansible command (/usr/bin/ansible). you’ll also see what sort of modules are available in Ansible’s core (though you can also write your own, which we’ll also show later). So let’s get start with your first question.
What is Ansible?
Ansible is an open-source automation engine that automates software provisioning, configuration management, and application deployment. Ansible can manage any *NIX platform through the SSH and also Ansible can manage Windows Servers and Network devices.
Ansible is the only Automation Engine that can automate the entire application lifecycle and Continues Delivery pipeline.
- Ansible is Simple to install and configure and it Can manage almost any *IX through SSH
- Ansible Requires Python 2.4 for Installation
- Windows (PowerShell, WinRM python module)
Feature and Benefits of Ansible
- Cross platform support – can support any *NIX, Windows machines, network devices etc.
- Agentless Architecture, and minimal setup on Master node. so no work for system admins to manage the agent’s on the client side
- Written in Python.
- Ansible uses OpenSSH for *NIX systems and WinRM for communication with MS Windows machines.
- Open source and activity maintained on the GitHub.
- Very easy install and configure.
- Highly scalable – Can manage Thousands of nodes
- Secure as it used SSH for the communication.
- Easy to understand and remember the command syntax. (No coding skills needed). Ansible uses simple declarative language YAML
Ansible is not just automation engine, but it is also used for:
- Configuration Management.
- Application Deployment.
- Security and Compliance
- Rolling Upgrades – Continue Deployment (CD)
- Provisioning (AWS, Virtual Platform, OpenStack etc…)
Key Components of Ansible
- Ansible Modules.
Further to the playbooks, Ansible roles can be configured for the more systematic management of the Ansible playbooks.
Step 1: Ansible Installation on Red Hat / CentOS 7: You can install Ansible control machine with many different methods. In this guide, I am going to show you Ansible installation using Python-PIP and EPEL Repository (YUM).
Ansible Master Node details:
Hostname : ansmaster
OS : CentOS 7 x86_64
IP Address : 192.168.1.80
Ansible User : ansadm
Ansible Master Node Host file: Remote host details
[ansadm@ansmaster ~]$ cat /etc/hosts
127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
::1 localhost localhost.localdomain localhost6 localhost6.localdomain6
######## Ansible Environment Setup - Master Server info #######
192.168.1.80 ansmaster.devopsmates.com ansmaster
####### Ansible Control Nodes - Remote hosts ########
192.168.1.85 awscli.devopsmates.com awscli
192.168.1.84 webapp1.devopsmates.com webapp1
192.168.1.63 testdb3.devopsmates.com testdb3
Method -1: Ansible Latest Release Installation Via Pip
Ansible can be installed via “pip”, the Python package manager. If ‘pip’ isn’t already available in your version of
Python, you can get pip install by running the below command.
[root@ansmaster ~]# easy_install pip
[root@ansmaster ~]# yum install python-pip
Ansible also uses the following Python modules that need to be installed:
[root@ansmaster ~]# pip install paramiko PyYAML jinja2 httplib2
After installation of all pre-requisites and python-pip, then install Ansible with the below command.
The below command will Ansible latest release from Python Package Manager:
[root@ansmaster ~]# pip install ansible
Method -2: Ansible Latest available Release installation Via Yum
RPMs are available from yum for EPEL 6, 7, and currently supported Fedora distributions. Ansible itself can manage earlier operating systems that contain Python 2.4 or higher. Fedora users can install Ansible directly, though if you are using RHEL or CentOS and have not already done so,
First configure EPEL Repository on Linux, because Ansible packages are available from EPEL. install the epel-release RPM if needed on CentOS, RHEL, or Scientific Linux
[root@ansmaster ~]# yum install epel-release -y
Now run the below command to install Ansible along with all dependencies.
[root@ansmaster ~]# yum install ansible -y
Step 2: Ansible Installation Verification: Just executes the ansible –version command to check Ansible available status in your Master node. Checking the Ansible Version and Config Info
[root@ansmaster ~]# ansible --version
config file = /etc/ansible/ansible.cfg
configured module search path = Default w/o overrides
python version = 2.7.5 (default, Nov 6 2016, 00:28:07) [GCC 4.8.5 20150623 (Red Hat 4.8.5-11)]
Ansible Configurations (default): check the below location for ansible defaults configuration file and inventory file
- Default Config Directory : /etc/ansible
- Default Config File : /etc/ansible/ansible.cfg
- Default Inventory File : /etc/ansible/hosts
Now that you’ve installed Ansible, it’s time to get started with some basics.
Step 3: Configuring communication between Ansible Master node and target machines
When Ansible communicates with the target machines, by default it assumes the ssh keys are exchanged and password less communication is through. If you want to use the password, can hard-code the password in the inventory file, but this is not recommended. Also, use ssh-keys for communication.
First, create one common user(ansadm) on both sides to communicate Ansible Master node with remote hosts.
[root@ansmaster ~]# useradd ansadm
[root@ansmaster ~]# passwd ansadm
Changing password for user ansadm.
BAD PASSWORD: The password is shorter than 8 characters
Retype new password:
passwd: all authentication tokens updated successfully.
Provide full sudo with no password for ansadm user
[root@ansmaster ~]# echo "ansadm ALL=(ALL) NOPASSWD:ALL" >> /etc/sudoers
Step 1. Generating the Keys on Ansible Master Server (ansmaster):
The first thing, switch from root user to ansadm user, then create ssh keys
[root@ansmaster ~]# su - ansadm
Generating ssh keys with 4096 encryption level for ansadm user
[ansadm@ansmaster ~]$ ssh-keygen -t rsa -b 4096 -C "[email protected]"
Step 2. Update Keys on Remote Host
Passing ssh keys from Ansible Master Server (ansmaster) to remote hosts, first time it will ask for the user password
Remote Host 1 ( awscli.devopmates.com = 192.168.1.85)
[ansadm@ansmaster ~]$ ssh-copy-id email@example.com
The authenticity of host 'awscli.devopsmates.com (192.168.1.85)' can't be established.
ECDSA key fingerprint is 83:12:2f:71:a7:19:15:c7:84:87:e7:0a:a9:de:0d:54.
Are you sure you want to continue connecting (yes/no)? yes
/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys
Number of key(s) added: 1
Now try logging into the machine, with: "ssh '[email protected]'"
and check to make sure that only the key(s) you wanted were added.
Remote Host 2 (testdb3.devopsmates.com = 192.168.1.63)
[ansadm@ansmaster ~]$ ssh-copy-id firstname.lastname@example.org
Remote Host 3 (webapp1.devopsmates.com = 192.168.1.84)
[ansadm@ansmaster ~]$ ssh-copy-id email@example.com
Step 3. Testing the Public Key Authentication
[ansadm@ansmaster ~]$ ssh firstname.lastname@example.org
[ansadm@ansmaster ~]$ ssh email@example.com
[ansadm@ansmaster ~]$ ssh firstname.lastname@example.org
We’ll assume you are using SSH keys for authentication. To set up SSH agent to avoid retyping passwords, you can do: after transferring the ssh keys, the next basic task is to create inventory for remote hosts. Check out next page to create an inventory file.