Why Ansible?
If you have tens, hundreds or thousands of servers, you will need a solution like Ansible or Puppet. These products allow you to define how each server is configured in declarative languages and they can control thousands of servers.
Starting with Ansible
I provisioned an ARM64 host for Ansible yesterday. I wrote an article that explains how to install Ansible on it here. Now I want to test it.
So the Ansible host has to know about Jenkins host. I have added the following lines in /etc/ansible/hosts file.
[jenkins]
jenkins.pub.ashburn.oraclevcn.com
The hosts file can have IP address or FQDN, so I added the FQDN on OCI.
Now I should be able to ssh into the Jenkins host from Ansible host, so I added the public key of Ansible to Jenkins’ authorized_keys. Now I can ssh into the Jenkins host from the Ansible host.
On the Ansible host, test the configuration.
ansible-3 all -m ping
Output:
jenkins.pub.ashburn.oraclevcn.com | SUCCESS => {
"ansible_facts": {
"discovered_interpreter_python": "/usr/bin/python"
},
"changed": false,
"ping": "pong"
}
Test running a command on the client host.
ansible all -a "/bin/echo hello"
Output:
jenkins.pub.ashburn.oraclevcn.com | CHANGED | rc=0 >>
hello
Creating a Playbook
I am creating the following file jenkins_playbook.yaml with the content below.
- name: Jenkins Playbook
hosts: all
tasks:
- name: Create a file
shell: |
echo 'hoge hoge hoge' >> ~/test.txt
Execute the playbook.
ansible-playbook-3 jenkins_playbook.yaml
Output:
PLAY [Jenkins Playbook] **************************************************************************************************************************
TASK [Gathering Facts] ***************************************************************************************************************************
[WARNING]: Platform linux on host jenkins.pub.ashburn.oraclevcn.com is using the discovered Python interpreter at /usr/bin/python, but future
installation of another Python interpreter could change this. See
https://docs.ansible.com/ansible/2.9/reference_appendices/interpreter_discovery.html for more information.
ok: [jenkins.pub.ashburn.oraclevcn.com]
TASK [Create a file] *****************************************************************************************************************************
changed: [jenkins.pub.ashburn.oraclevcn.com]
PLAY RECAP ***************************************************************************************************************************************
jenkins.pub.ashburn.oraclevcn.com : ok=2 changed=1 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
We’ll ignore the warning for now. Now I am going to ssh into the Jenkins host and check the ~/test.txt file.
[opc@jenkins ~]$ cat test.txt
hoge hoge hoge
This concludes the very basics of how Ansible works. I am planning to dig into it more as I have time during the end of year holidays.