One advantage Docker gives is the ability to install the production environment on our laptop. In Chapter 12, Deploying Docker Swarm to AWS EC2 Using Terraform, we converted a Docker setup that ran on our laptop so that it could be deployed on real cloud hosting infrastructure. That relied on converting a Docker Compose file into a Docker Stack file, along with customization for the environment we built on AWS EC2 instances.
In this section, we’ll repurpose the Stack file as test infrastructure deployed to a Docker Swarm. One approach is to simply run the same deployment, to AWS EC2, and substitute new values for the var.project_name and var.vpc_name variables. In other words, the EC2 infrastructure could be deployed this way:
$ terraform apply –var project_name=notes-test –var vpc_name=notes- test-vpc
This would deploy a second VPC with a different name that’s explicitly for test execution and that would not disturb the production deployment. It’s quite common in Terraform to customize the deployment this way for different targets.
In this section, we’ll try something different. We can use Docker Swarm in other contexts, not just the AWS EC2 infrastructure we set up. Specifically, it is easy to use Docker Swarm with the Docker for Windows or Docker for macOS that’s running on our laptop.
What we’ll do is configure Docker on our laptop so that it supports swarm mode and create a slightly modified version of the Stack file in order to run the tests on our laptop. This will solve the issue of running tests against a MySQL database server, and also lets us test the long-neglected MongoDB module. This will demonstrate how to use Docker Swarm for test infrastructure and how to perform semi-automated test execution inside the containers using a shell script.
Let’s get started.
Source: Herron David (2020), Node.js Web Development: Server-side web development made easy with Node 14 using practical examples, Packt Publishing.