Many companies like mine use AWS infrastructure as a service (IaaS) heavily. Sometimes we want to perform a potentially risky operation on an EC2 instance. As long as we do not work with immutable infrastructure it is imperative to be prepared for instant revert.
One of the solutions is to use a script that will perform instance duplication, but in modern environments, where unification is an essence it would be wiser to use more common known software instead of making up a custom script.
Here comes the Ansible!
Ansible is a simple automation software. It handles configuration management, application deployment, cloud provisioning, ad-hoc task execution, network automation, and multi-node orchestration. It is marketed as a tool for making complex changes like zero-downtime rolling patching, therefore we have used it for this straightforward snapshotting task.
For this example we will only need an Ansible, in my case it was version 2.9 - in subsequent releases there is a major change with introducing collections so let's stick with this one for simplicity.
Due to working with AWS we require a minimal set of permissions, which include permissions to create:
- AWS snapshots
- Register images (AMI)
- Start and stop EC2
Since I am forced to work on Windows I have utilized Vagrant instances. Please find below a Vagrantfile content.
We are launching a virtual machine, with Centos 7 and Ansible installed.
For security reasons Ansible, by default, has disabled reading configuration from mounted location, therefore we have to implcity indicate path /vagrant/ansible.cfg.
Listing 1. Vagrantfile for our research
Vagrant.configure("2") do |config| config.vm.box = "geerlingguy/centos7" config.vm.hostname = "awx" config.vm.provider "virtualbox" do |vb| vb.name = "AWX" vb.memory = "2048" vb.cpus = 3 end config.vm.provision "shell", inline: "yum install -y git python3-pip" config.vm.provision "shell", inline: "pip3 install ansible==2.9.10" config.vm.provision "shell", inline: "echo 'export ANSIBLE_CONFIG=/vagrant/ansible.cfg' >> /home/vagrant/.bashrc" end
In the first lines of the Ansible we specify few meta values. Most of them, like name, hosts and tasks are mandatory. Others provide auxiliary functions.
Listing 2. duplicate_ec2.yml playbook first lines ---