Ansible Modules From The Command Line
To get you ready for bigger things.
Ansible comes with over 1,300 modules as part of the installation and you’re most likely wanting to get these modules running with playbooks. But before you get started with playbooks, it could be good to get used to the syntax and arguments used for a lot of the more popular modules you might be using.
Ansible provides a handy index to all their modules. Due to the large number provided, the documentation has separated them into specific categories to help you search through for the specific ones you need. The full index of modules can be located at the following location:
http://docs.ansible.com/ansible/latest/modules_by_category.html
In our earlier post we got through the basics of installing and configuring Ansible. So now let’s have a look at some more modules and run them from the command line.
Ping
One of the first modules a lot of people will learn is the ping module. As it suggests, the module performs a ping test on the specified host requesting a reply if the host is accessible and powered on:
ansible mylaptop -i hosts -m ping
localhost | SUCCESS => {
“changed”: false,
“ping”: “pong”
}Setup
The setup module provides us with over six hundred lines of information out our system. All of which presented in a friendly to view JSON format, with all values being preceded with “ansible_” as you can see from the cut down output provided below.
ansible mylaptop -i hosts -m setup
localhost | SUCCESS => {
“ansible_facts”: {
“ansible_all_ipv4_addresses”: [
“10.0.2.15”,
“172.18.0.1”,
“192.168.56.101”,
“172.17.0.1”
],
…
“ansible_virtualization_role”: “guest”,
“ansible_virtualization_type”: “virtualbox”,
“gather_subset”: [
“All”
],
“module_setup”: true
},
“changed”: false
}Git
The git module allows you to perform git commands via Ansible. If you need to deploy software directly from a git repository, this would be the perfect reason to use this module:
ansible mylaptop -i hosts -m git -a “repo=’https://github.com/vincesesto/markdown-cheatsheet.git' dest=~/test/”
localhost | SUCCESS => {
“after”: “ecfb900a44a84dcd0d798ad3b0c98ea838ea5668”,
“before”: “ecfb900a44a84dcd0d798ad3b0c98ea838ea5668”,
“changed”: false,
“remote_url_changed”: false
}In the above example, we have called the git module with the -m option and used the -a option to provide all the relevant arguments for it to successfully complete. In this case, we have specified the repository with repo and then provided a destination folder. If the folder is not present, Ansible will create it, so we should see the file downloaded and available in our destination folder.
Shell
We have used the shell module previously, but we can now use it to verify our previous command worked by performing a listing of the files in the ~/test/ directory
ansible mylaptop -i hosts -m shell -a “ls -l ~/test/”
localhost | SUCCESS | rc=0 >>
total 4
-rw-rw-r — 1 vince vince 3453 Jan 23 15:13 README.mdAll of this should be looking very familiar by now as we are simply specifying the arguments of a directory listing with the -a option.
Apt(or Yum)
A majority of modules will be able to be run across different versions of Linux, but one which may differ is the package manager which is being used on the system. The command below uses apt as the module, but of course for Red Hat or Centos, you would use the yum module with the name being equal to httpd.
ansible — become -K mylaptop -i hosts -m apt -a “name=apache2 state=present”
SUDO password:
localhost | SUCCESS => {
“cache_update_time”: 1516762375,
“cache_updated”: false,
“changed”: true,
“stderr”: “”,
“stderr_lines”: [],
…
“Processing triggers for ufw (0.35–5) …”
]
}We have removed quite a few lines of output above to help with our explanation. The new options you will notice is the — become -K options, which ensures Ansible becomes a user which can install programs on this system, such as the root user, and it then requests a password for allow the install to continue. You will then see the arguments then provided as name of the application we want to install and the state, which in this case is present. If we wanted to remove the application, we would use the same command but change the state to absent.
Get_url
We can now test the above command with the get_url module which grabs content from HTTP, HTTPS or other internet protocols. As we should have a working Apache server running, we can now download the default page running at localhost.
ansible mylaptop -i hosts -m get_url -a “url=http://localhost dest=~/test/”
localhost | SUCCESS => {
“changed”: true,
“checksum_dest”: null,
“checksum_src”: “07993837ce7f0273…823da7e1e”,
“dest”: “/home/vince/test/index.html”,
“gid”: 1000,
“group”: “vince”,
“md5sum”: “3526531ccd6c6a1d2340574a305a18f8”,
“mode”: “0664”,
“msg”: “OK (10918 bytes)”,
“owner”: “vince”,
“size”: 10918,
“src”: “/tmp/tmprthNJQ”,
“state”: “file”,
“status_code”: 200,
“uid”: 1000,
“url”: “http://localhost”
}Once again, we need to specify the destination as part of the arguments, as the module needs somewhere to place the content it downloads.
User
Setting up users is a snap with this module. We can control the state of the account on the system as being absent or present to determine if they are created or removed.
ansible mylaptop — become -K -i hosts -m user -a “name=jsmith comment=’Jane Smith’ state=present”
SUDO password:
localhost | SUCCESS => {
“changed”: true,
“comment”: “Jane Smith”,
“createhome”: true,
“group”: 1002,
“home”: “/home/jsmith”,
“name”: “jsmith”,
“shell”: “”,
“state”: “present”,
“system”: false,
“uid”: 1002
}Our output from the Ansible command give us clear details of the account created. Even though the user would not be accessible as it does not have a password set. We could also add the password as an argument to set this upon creation.
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