The advanced exercise, 14-3, is a relatively easy task this time. You are guided through the procedure of creating a playbook that runs a command before the reboot, schedules a cron job at the next reboot, and, using that cron job, ensures that after rebooting a specific command is used as well. To make sure you see what happens when, you work with a temporary file to which lines are added.
::: box Exercise 14-3 Managing the Boot Process and Services
1. Use your editor to create the file exercise143.yaml and write the playbook header as follows:
---
- name: exercise143
hosts: ansible2
tasks:
2. Write the first task. This task is not really functional but enables you to check what is happening in the remaining tasks in the playbook. In this task, you use the lineinfile module to add a line to the end of the check file /tmp/rebooted. Notice how the time, including a second indicator, is written using two Ansible facts. It’s required to operate this way because not one single fact has the time in an hh:mm:ss format. Write this task code as follows:
- name: add a line to file before rebooting
lineinfile:
create: true
state: present
path: /tmp/rebooted
insertafter: EOF
line: rebooted at {{ ansible_facts[’date_time’][’time’] }}:{{ ansible_facts[’date_time’][’second’] }}
3. At this point, you can add a cron job that runs at reboot. The job that runs will add a message to the /tmp/rebooted file, and to make sure that it is working correctly, you use bash shell command substitution to print the results of the Linux date command. Notice that this is possible in the cron module because commands are executed by a bash shell, but it’s not possible in the previous task that uses the lineinfile module because in that task the commands are not processed by a shell. Now add the task as follows:
- name: run a cron job on reboot
cron:
name: "run on reboot"
state: present
special_time: reboot
job: "echo rebooted at $(date) >> /tmp/rebooted"
4. Add another task that uses the reboot module to reboot the managed host:
- name: reboot managed host
reboot:
msg: reboot initiated by Ansible
test_command: whoami
- name: show reboot success
debug:
msg: just rebooted successfully
5. Now that the playbook is complete, you can run it by using ansible-playbook exercise143.yaml. Notice that it needs a minute because it has to wait until the target host is back. When it is back, use ansible ansible2 -a “cat /tmp/rebooted”. You then see that both reboot messages are written, and there is about 30 seconds between the pre-reboot and the post-reboot commands. :::
Lab 14-1 #
Write a playbook according to the following specifications:
• The cron module must be used to restart your managed servers at 2 a.m. each weekday.
• After rebooting, a message must be written to syslog, with the text “CRON initiated reboot just completed.”
• The default systemd target must be set to multi-user.target.
• The last task should use service facts to show the current version of the cron process.