Ansible – Modules
Ansible[modules](https://docs.ansible.com/ansible/latest/user_guide/modules.html)are
standalone scripts that can be used inside an Ansible playbook. A playbook
consists of a play, and a play consists of tasks.
1. Package management
-
There is a module for most popular package managers, such as DNF and APT, to enable you to install any package on a system.
-
It covers YUM module (required for Python 2 compatibility) is
[yum_module](https://docs.ansible.com/ansible/latest/modules/yum_module.html), while the APT module isapt_module, the Slackpkg module is`slackpkg_module, and so on.
Example
- name: Install a list of packages
yum:
name:
- nginx
- postgresql
- postgresql-server
state: present
This installs the list of packages and helps download multiple packages
2: Service
After installing a package, you need a module to start it. The service module
enables you to start, stop, and reload installed packages; this comes in pretty
handy.
Example 1:
- name: Start service foo, based on running process /usr/bin/foo
service:
name: foo
pattern: /usr/bin/foo
state: started
This starts the service foo.
Example 2:
- name: Restart network service for interface eth0
service:
name: network
state: restarted
args: eth0
This restarts the network service of the interface eth0.
3: Copy
The[copy
module](https://docs.ansible.com/ansible/latest/modules/copy_module.html)copies
a file from the local or remote machine to a location on the remote machine.
Example 1:
- name: Copy a new "ntp.conf file into place, backing up the original if it differs from the copied version
copy:
src: /mine/ntp.conf
dest: /etc/ntp.conf
owner: root
group: root
mode: '0644'
backup: yes
Example 2:
- name: Copy file with owner and permission, using symbolic representation
copy:
src: /srv/myfiles/foo.conf
dest: /etc/foo.conf
owner: foo
group: foo
mode: u=rw,g=r,o=r
4.File
The[file
module](https://docs.ansible.com/ansible/latest/modules/file_module.html)manages
the file and its properties.
-
It sets attributes of files, symlinks, or directories.
-
It also`removes files, symlinks, or directories.
Example 1:
- name: Change file ownership, group and permissions
file:
path: /etc/foo.conf
owner: foo
group: foo
mode: '0644'
This creates a file named**foo.conf**and sets thepermission to0644.
Example 2:
- name: Create a directory if it does not exist
file:
path: /etc/some_directory
state: directory
mode: '0755'
This creates a directory named**some_directory**and sets the permission
to`0755.
5.Lineinfile
The lineinfile module manages lines in a text file.
-
It ensures a particular line is in a file or replaces an existing line using a back-referenced regular expression.
-
It’s primarily useful when you want to change just a single line in a file.
Example 1:
- name: Ensure SELinux is set to enforcing mode
lineinfile:
path: /etc/selinux/config
regexp: '^SELINUX='
line: SELINUX=enforcing
Example 2:
- name: Add a line to a file if the file does not exist, without passing regexp
lineinfile:
path: /etc/resolv.conf
line: 192.168.1.99 foo.lab.net foo
create: yes
This adds an entry for the IP and hostname in the resolv.conf file.
6.User Module
The module manages users accounts with there attributes. This is handy do to the
fact that the user properties and attributes can all be configured from this
Ansible module.
Example
# Add the user 'exampleuser' with a specific uid and a primary group of 'admin'
- user:
name: exampleuser
comment: "Example User"
uid: 1040
group: admin# Remove the user 'exampleuser'
- user:
name: exampleuser
state: absent
remove: yes
7.shell module
Ansible’s shell module executes shell commands on remote hosts.
- name: create a text file in $HOME with the /bin/sh shell
shell: echo "Hello, World!" > $HOME/test_file.txt
- name: read all text files in $HOME with the /bin/bash shell
shell: cat < $HOME/*.txt
args:
executable: /bin/bash
8.Ansible Apt
APT stands for “Advanced Packaging Tool” , It allows us to install new packages, update them, and remove the packages from Ubuntu systems. Here are 3 APT related command-line tools, such as:
-
Apt-get: All the basic package management operations can be done by using this tool. Ansible apt-get module provides this functionality.
-
Apt-add-repository: It is used for adding a new repository to the repository list. The default repository may not have the latest version of all the packages. So you need to add additional repositories for some software maintainers. Ansible apt_repository module provides the functionality for adding a new repository.
-
Apt-key: It is used to manage the list of keys for authenticating apt packages. Ansible apt_key module is used to manage the keys.
Installing new Apt Packages
-
To install the new packages, you have to give the name of the package in the name parameter and the desired state of the package.
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The default state of the package is “present”. Also, it is better to set the update_cache to true.
-
The below example will do a cache update to synchronize the index. Check if the ‘zip’ package is installed on the target server. And if it is not installed, the package will be installed. If the package is already installed, then it won’t be upgraded.
-hosts: loc tasks: -name: Ansible apt install packages apt: name: zip state: present update_cache: true
1. Installing the latest version of a package
If you set the state of the packages to “present”, then Ansible will only check
if the package is present. So if the new package is available, it will not be
able to install.
-hosts: loc
tasks:
-name: ansible apt install latest version
apt:
name: zip
state: latest
update_cache: true
2. Ansible install multiple packages
In the below example, we are going to install 3 packages: docker-ce, Nginx, and
git.
-hosts: loc
tasks:
-name: ansible apt with_items
apt:
name: ""
update_cache: true
state: present
with_items:
-'docker-ce'
-'nginx'
-'git'
3.Removing Apt Packages
You can also remove the packages using apt module by setting the state parameter
to absent.
-hosts: loc
tasks:
-name: ansible apt remove package
apt:
name: zip
state: absent