Ansible Dynamic Inventory with NodeJS

Dynamic Inventory Requirements

The most famous programing language is Python used to develop a dynamic Ansible inventory.

However, I am showing here that it is possible to do that with NodeJS and any other language. The most important thing is to comply with dynamic inventory requirements:

• The file must be executable ( chmod +x inventory/myfile.py)
• The file content must start by shebang (i.e: #!/usr/bin/python)
• When it is called with “ — list” option, the stdout must be a JSON object presents all groups, and each group is an array of hosts names.
• When it is called with “ — host <myhost>”, the stdout must be JSON object presents all variables of the specific host myhost.
• The file extension is not ignored by Ansible configuration under the attribute inventory_ignore_extensions`

Requirements Compliance with NodeJs:

• The file must be executable ( chmod +x inventory/myfile.js)
• The file content must start by shebang (i.e: #!/usr/bin/node) . Check the right path by running (which node))
• “.js” must not be listed under inventory_ignore_extensions

Example

1. Download the lab environment and checkout the relevant branch:

git clone -b dynamic-inventory-nodejs https://github.com/abdennour/infra-4-ansible.git

abdennour/infra-4-ansible

2. Follow README to configure the app (generate ssh-key,….)

This is Optional as we are only playing with inventory.

3. Run the lab environment docker-compose up -d

4. Go to the control node : docker-compose exec controlnode ash

You should see the PS1 of the container /playbook # `

5. Inspect the content of inventory/dynamic_hosts.js

/playbook # cat inventory/dynamic_hosts.js

a. The first line is the shebang

b. “const option = process.argv[2];” to parse the value of the first agrument: --list or --host

c. If it is --host , “const hostName = process.argv[3];” is to parse the hostname.

d. “const printer = (data) => console.log(JSON.stringify(data))” : To print data on the STDOUT in JSON format not JS object format.

6. Play with this file:

>> --list option:

/playbook # inventory/dynamic_hosts.js --list
{"webservers":["web1","web2"],"databases":["db1","db2"]}

>> --host option:

/playbook # inventory/dynamic_hosts.js --host web1
{"webserver":"apache","welcomeMessage":"Hello Here"}

7. Validatation with ansible-inventory` command :

ansible-inventory --list

And

ansible-inventory --host web1