Let’s try to automate something and write our Ansible playbook. For our first example playbook, we’ll configure a server to run a web server using Nginx.
Table of Contents
Inventory
To begin with, we would like to create an inventory and specify the hosts that we want to configure as web servers. Inventory files are in the .ini file format. Next, edit your playbooks/hosts file. And then put a [webservers] line above the dev-server and prod-server. This change indicates that dev-server and prod-server are in the webservers group.
~/playbooks/hosts
[webservers]
dev-server:
ansible_host=192.168.1.1 ansible_port=2222
prod-server
ansible_host=192.168.1.2 ansible_port=2222The group webservers here define the scope. We are using IP addresses here. But you can use hostnames too. You can also change the standard port for SSH to 2222.
Ansible playbook
Let’s create our playbook using a collection of tasks:
Start a playbook
Our next stop is the main YAML file which is a playbook. We will start with — sign at the top of the book followed by the play’s name. Next, we will use reference to the webservers group from our inventory file. Finally, our automation flow will need root privileges (aka sudo). Thus, we are going to use the statement “become: True”. So, our file is going to look like this:
---
- name: Configure NGINX on the webserver
hosts: webservers
become: TruePlaybook task to install Nginx
We will write several tasks in the correct order. Please note that Ansible executes the tasks sequentially.
Let’s declare the tasks section and start with installing the Nginx. If you were to do it manually, you would execute the following command on a Linux shell:
sudo apt update
sudo apt install nginxIn the Ansible world, it will look like this:
tasks:
- name: install nginx
apt: name=nginx update_cache=yesPlaybook task to configure Nginx
As a next step, we need to configure basic Nginx settings. The settings include the server port, HTML/CSS content location, index, and so on (nginx.conf). If you were to do it manually, you would probably use a text editor (vim or nano) and change the config in place. But, the easiest way to do it is by copying the config file to the respective folder.
- name: copy nginx config file
copy: src=files/nginx.conf dest=/etc/nginx/sites-available/defaultPlaybook task to create a Symlink
Next, let’s enable the file by creating a link from it to the sites-enabled directory. Nginx reads from the site-enabled directory during startup. In Linux shell the command would look like this:
sudo ln -s /etc/nginx/sites-available/default /etc/nginx/sites-enabled/The command mentioned above will look like the YAML below:
- name: enable configuration
file: >
dest=/etc/nginx/sites-enabled/default
src=/etc/nginx/sites-available/default state=linkPlaybook task to add a webpage
The most miniature version of a website is a single HTML page. Let’s copy our primitive index.html to the Nginx destination path. Take note that the mode here is used to set the correct permissions using octal notation. It is equivalent to the Linux chmod command.
- name: copy index.html
template:src=your_templates/index.html.j2 >
dest=/usr/share/nginx/html/index.html mode=0644
Playbook task to restart Nginx
Finally, you must restart the webserver once you have configured all the settings. Again, the Ansible module service is meant to solve it for us, and it is just as easy as if you were to execute service restart from the Linux shell.
- name: restart nginx
service: name=nginx state=restartedThe final Anible playbook
Let’s compile all the bits and pieces into a single Ansible playbook called websrv-provisoning.yml:
---
- name: Configure NGINX on the webserver
hosts: webservers
become: True
tasks:
- name: install nginx
apt: name=nginx update_cache=yes
- name: copy nginx config file
copy: src=files/nginx.conf dest=/etc/nginx/sites-available/default
- name: enable configuration
file: >
dest=/etc/nginx/sites-enabled/default
src=/etc/nginx/sites-available/default state=link
- name: copy index.html
template:src=your_templates/index.html.j2 >
dest=/usr/share/nginx/html/index.html mode=0644
- name: restart nginx
service: name=nginx state=restartedRunning your Ansible playbook
All we need to do now is to run the playbook and set up our web server:
ansible-playbook websrv-provisoning.ymlThe output is going to look like this everything is configured correctly:
PLAY [Configure webservers with nginx] *******************************
GATHERING FACTS ******************************************************
ok: [dev-server]
ok: [prod-server]
TASK: [install nginx] ************************************************
changed: [dev-server]
changed: [prod-server]
TASK: [copy nginx config file] ***************************************
changed: [dev-server]
changed: [prod-server]
TASK: [enable configuration] *****************************************
ok: [dev-server]
ok: [prod-server]
TASK: [copy index.html] ********************************************* changed: [dev-server]
changed: [prod-server]
TASK: [restart nginx] ************************************************
changed: [dev-server]
changed: [prod-server]
PLAY RECAP *************************8*********************************
dev-server : ok=6 changed=4 unreachable=0 failed=0
prod-server : ok=6 changed=4 unreachable=0 failed=Wrapping up
We have written a highly scalable yet simple playbook that installs NGINX on a Linux server and performs basic configuration. As a result, we can add our entire fleet to the inventory and watch automation at scale.
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