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- Execute ad-hoc commands against servers using Ansible
- Write Ansible configuration playbooks to deploy a 3-tier web application
- Configure Ansible roles with tasks, handlers, files, templates, and default variables
- Write operational playbooks to check cluster status and perform a cluster restart.
- Optimize Ansible playbooks to reduce playbook execution time.
- Test and troubleshoot Ansible playbook execution.
- You should have a Linux or Mac OS X computer, or access to at lease one Linux virtual machine for installing Ansible.
- You'll need a code editor or IDE of your choice.
- You'll need a terminal and ssh client for running Ansible against target hosts.
- You should have access to 5 Linux servers (bare-metal or virtual machine) if you want to setup the course environment and follow along step-by-step.
Mastering Ansible is a step-by-step journey of learning Ansible for configuration management and orchestration.
The course is designed as a journey through configuring a realistic application stack from the ground up. Instead of going page-by-page through the Ansible documentation, topics are ordered to align with the growing complexity of our application as we build it up and refactor it.
In addition to the core concepts of configuration with Ansible, we spend time on building tools to help us maintain and troubleshoot our application. The goal is to have a workflow where all of the configuration and troubleshooting is done through ansible playbooks that can be committed to a repository and improved over time.
The course is divided into 6 sections, starting with initial installation and foundational concepts. Starting in section 3, we build up a sample application environment layer-by-layer, learning a new concept in each lecture. After the application is up and running, we refactor our setup in section 4 with an emphasis on modularity and encapsulation. In section 5, we optimize our code and learn about techniques to reduce the playbook execution time. The course finishes with a final section on troubleshooting and testing.
For each lecture, we introduce a new Ansible concept and apply it to our playbooks. For most lectures, we execute the new concept in the demo environment so you can see what the output should look like. In the notes of each lecture, you'll find a link to the relevant documentation pages, along with a snapshot of the codebase at the end of that lecture.
This course was built with Ansible version 1.9.3, applied to a 3-tiered web application environment leveraging NGINX, Apache2, Python, and MySQL on Ubuntu Linux servers. We do not cover administering Windows servers in this course.
This course is designed as an introduction to Ansible, but also as a guide for engineers interested in configuration management, orchestration, infrastructure-as-code, and devops principles.
- The course is designed for students who have little or no experience with Ansible, but are familiar with Linux systems administration concepts.
- No programming or previous automation experience is required.
- If you've never logged into a Linux shell and run commands before, you will learn the Ansible syntax but you may not understand the 'why' behind the tasks that we configure. We try to explain all systems concept that we cover, but we aren't starting from the beginning with Linux in this course.
Welcome to Mastering Ansible! This lecture covers the course goals and format. The course is divided into 6 sections, starting with Environment Setup and Foundational Concepts. For the bulk of the course, we configure a realistic 3-tier web application, refactor it, and then optimize it. We finish the course with a section on testing and troubleshooting. Prior linux systems administration experience is expected.
Understand broad automation concepts: configuration management and orchestration. Configuration management is concerned with getting a single server into a desired state. Orchestration is focused on executing tasks in a specific order across one or many hosts. Throughout this course, we'll use Ansible to do both.
In this course, we will implement a 3-tier web application topology using one (1) NGINX load-balancer, two (2) application nodes running Apache2 and Python, one (1) MySQL database server, and one (1) control machine for running Ansible. If you want to follow along, you can setup an environment that fits these requirements:
- Access to a control machine that can run Ansible
- Servers running Ubuntu Trusty (14.04) - 5 in total
- SSH keypair trusts from the control machine to all other nodes (so no password is required to login via ssh)
- Access via a user that has superuser (sudo) privileges on the end hosts
In the Appendix (Lecture 55), I provide details on the docker setup that I use throughout the course.
In the materials below, is a Vagrantfile that can be used to create a similar vagrant setup. Rename "Vagrantfile.txt" to "Vagrantfile" and read the "README" comments inside of the file to get started.
We need to populate an inventory file so that Ansible can reach our environment hosts. Rather than populate the default location on the control machine, we can create a simple file in our local repository and tell Ansible to use it, by default. In this lecture, we will:
- Configure a local inventory file with hostnames and groups (dev)
- Configure a local config file to use the new inventory file by default (ansible.cfg)
Running ad-hoc Ansible commands are great for troubleshooting and discovery, but the real power of Ansible is in coding those tasks into playbooks that you can save and run, as needed. In this lecture, we will:
- Group tasks for a common set of hosts together into plays.
- Create our first playbook (hostname.yml) to encode the command task into an Ansible YAML file.
With our playbook written, it's time to execute it and review the output. In this lecture, we will:
- Execute the hostname.yml playbook against hosts using the ansible-playbook command.
- Review the output of the ansible-playbook command.
Now that you understand the framework for encoding tasks and executing playbooks, we will start building up our application environment. For every task, we'll find a relevant module and add the necessary parameters to our playbooks. You can browse the module documentation if you're looking for the right module or parameters to fit your needs.
We start our configuration with installing the necessary packages for each tier. In this lecture, we will:
- Install packages with the apt module
- Set package installed state using one of: present, latest, absent.
- Ensure the apt cache is updated before package installation with update_cache=yes
While executing Ansible tasks, you may run into "permission denied" errors. This generally means the task you're executing requires some sort of superuser or sudo privilege. In this lecture, we will:
- Enable privilege escalation in Ansible with become/sudo at the play level. This will resolve "permission denied" errors on the end hosts where superuser privileges are required.
- Execute the configuration playbooks to apply the package installation changes on the load-balancer and database hosts.
For the webserver hosts, we need to install multiple packages via apt. Rather than create four individual apt tasks, we'll learn about a new Ansible feature: loops using with_items. In this lecture, we will:
- Loop through a task multiple times by providing a list of inputs using with_items
- Install multiple packages with a single task on the webserver hosts using with_items
- Extend the stack status playbook to perform http requests against the application using the uri module.
- Save the contents of the HTTP request using the register module
- Check the contents of a variable and conditionally cause a failure using the when and fail modules.
- Execute a shell command on a target host with the shell module.
- Capture the output of a shell command with the register module.
- Loop through the items in a registered array variable using with_items.
- Conditionally perform an action on the target host using when.