Using Templating Engines for Generating Ansible Playbooks

cpugovnr.tyml

- name: Enabling the {{ governor }} CPU Governor on System Boot
  hosts: server2
  remote_user: soumadeepdhar
  become: yes
  become_method: sudo
  become_user: root
  tasks:
    - name: "STEP 1 - Creating a shellscript to enable {{ governor }} governor"
      copy:
        dest: "/usr/local/bin/perf-prof.sh"
        content: |
          #!/bin/bash
          echo {{ governor }} | tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
    - name: "STEP 2 - Changing permissions for the shellscript file"
      file:
        path: "/usr/local/bin/perf-prof.sh"
        mode: 0744
    - name: "STEP 3 - Creating a systemd service to start on system boot"
      copy:
        dest: "/etc/systemd/system/perf-prof.service"
        content: |
          [Unit]
          After=network.target
          [Service]
          ExecStart=/usr/local/bin/perf-prof.sh
          [Install]
          WantedBy=default.target
    - name: "STEP 4 - Changing permissions for the systemd service"
      file:
        path: "/etc/systemd/system/perf-prof.service"
        mode: 0664
    - name: "STEP 5 - Reloading the daemon to prep new systemd services"
      ansible.builtin.systemd:
        daemon_reload: yes
    - name: "STEP 6 - Enable the created systemd service to start on system boot"
      ansible.builtin.systemd:
        name: perf-prof.service
        enabled: yes
    - name: "STEP 7 - Start the recently enabled systemd service right now"
      ansible.builtin.systemd:
        name: perf-prof.service
        state: started

main.md

Using Templating Engines for Generating Ansible Playbooks

1. Download the tempperf.py and cpugovnr.tyml to the same directory.
2. Run the following command to view the usage.

python3 tempperf.py

[ i ] CPU Governor Systemd Config
      Usage : python3 tempperf.py <tempfile> <governor> <destfile>

3. Now run the following command to swiftly create a playbook for setting powersave CPU governor on boot.

python3 tempperf.py cpugovnr.tyml powersave pwsvprof.yml

[ i ] CPU Governor Systemd Config
[ i ] Playbook written in 'pwsvprof.yml'

4. Make sure to change the attributes inside of the pwsvprof.yml file according to your liking, and then run the playbook using the following command.

ansible-playbook -i inventory.ini pwsvprof.yml

pwsvprof.yml

- name: Enabling the powersave CPU Governor on System Boot
  hosts: server2
  remote_user: soumadeepdhar
  become: yes
  become_method: sudo
  become_user: root
  tasks:
    - name: "STEP 1 - Creating a shellscript to enable performance governor"
      copy:
        dest: "/usr/local/bin/perf-prof.sh"
        content: |
          #!/bin/bash
          echo powersave | tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
    - name: "STEP 2 - Changing permissions for the shellscript file"
      file:
        path: "/usr/local/bin/perf-prof.sh"
        mode: 0744
    - name: "STEP 3 - Creating a systemd service to start on system boot"
      copy:
        dest: "/etc/systemd/system/perf-prof.service"
        content: |
          [Unit]
          After=network.target
          [Service]
          ExecStart=/usr/local/bin/perf-prof.sh
          [Install]
          WantedBy=default.target
    - name: "STEP 4 - Changing permissions for the systemd service"
      file:
        path: "/etc/systemd/system/perf-prof.service"
        mode: 0664
    - name: "STEP 5 - Reloading the daemon to prep new systemd services"
      ansible.builtin.systemd:
        daemon_reload: yes
    - name: "STEP 6 - Enable the created systemd service to start on system boot"
      ansible.builtin.systemd:
        name: perf-prof.service
        enabled: yes
    - name: "STEP 7 - Start the recently enabled systemd service right now"
      ansible.builtin.systemd:
        name: perf-prof.service
        state: started

tempperf.py

import sys

from jinja2 import Template


def read_template(tempfile:str):
	tempdata = None
	try:
		with open("cpugovnr.tyml", "r") as tempobjc:
			tempdata = tempobjc.read()
	except Exception as expt:
		print("[ ! ] File could not be read due to " + str(expt))
	return tempdata


def inherit_governor_to_template(tempdata:str, governor:str):
	appldata = None
	try:
		template = Template(tempdata)
		appldata = template.render(governor = governor)
	except Exception as expt:
		print("[ ! ] Template could not be applied due to " + str(expt))
	return appldata


def write_applied_config_to_file(appldata:str, destfile:str):
	otptrslt = -1
	try:
		with open(destfile, "w") as otptobjc:
			otptobjc.write(appldata)
		otptrslt = 0
	except Exception as expt:
		print("[ ! ] File could not be written due to " + str(expt))
	return otptrslt


def main_function(tempfile:str, governor:str, destfile:str):
	tempdata = read_template(tempfile)
	if tempdata == None:
		sys.exit(0)
	else:
		appldata = inherit_governor_to_template(tempdata, governor)
		if appldata == None:
			sys.exit(0)
		else:
			otptrslt = write_applied_config_to_file(appldata, destfile)
			if otptrslt == 0:
				print("[ i ] Playbook written in '" + destfile + "'")
			sys.exit(0)


if __name__ == "__main__":
	print("[ i ] CPU Governor Systemd Config")
	if len(sys.argv) == 4:
		main_function(sys.argv[1], sys.argv[2], sys.argv[3])
	else:
		print("      Usage : python3 tempperf.py <tempfile> <governor> <destfile>")