Introduction
At 1Strategy, we are big fans of AWS CloudFormation to manage AWS resources as code. With CloudFormation, you can define all the AWS resources required for your application and create and manage them together as a Stack. Unfortunately, coding and testing a complex CloudFormation template requires many iterations to get it just right. Each of those iterations can take two to five minutes if you do it via the AWS GUI Console, plus you have to context-switch between your text editor and your web browser.
There is a better way. You can validate, deploy, and delete stacks all within your text editor, avoiding context-switching away from your editor to the AWS Console. By doing this, you will shorten your CloudFormation dev cycle from minutes to seconds, and complete your CloudFormation template that much faster.
In this post, I’ll show you how to configure Microsoft’s VSCode text editor to validate, deploy, and delete CloudFormation templates via VSCode built-in Tasks
If you want to follow along, clone the sample git repo and open it in VSCode.
Step One: AWS Command Line
The first step is to run the CloudFormation commands from the command-line. After we have the correct AWS CLI commands, we can configure VSCode to run the commands as Tasks.
We’ll cover commands to validate a CloudFormation template, deploy a template, show stack outputs, and finally, delete a deployed stack. These cover the basic commands you’ll need during the development lifecycle.
Validate Template
The first command is validate-template. It returns an error if your template isn’t valid. Here’s an example:
aws cloudformation validate-template --template-body file://ec2-instance.yaml
Deploy Template
The next command is deploy. It “deploys the specified AWS CloudFormation template by creating and then executing a change set.”
aws cloudformation deploy --template-file ec2-instance.yaml --stack-name ec2-instance --parameter-overrides VPCParameter=vpc-abcd1234
View Stack Outputs
Once you have deployed a CloudFormation stack, you may want to view the Stack Outputs, e.g. Load Balancer DNS name, RDS endpoint, EC2 instance public IP, etc. You do this by viewing the Outputs section of the describe-stacks command.
aws cloudformation describe-stacks --stack-name ec2-instance --query 'Stacks[0].Outputs[0]'
Delete Stack
Finally, during development you may want to delete the running stack and start over. You accomplish this with the delete-stack command.
aws cloudformation delete-stack --stack-name ec2-instance
Tasks in VSCode
Since VSCode doesn’t have built-in Tasks support for AWS CloudFormation, we’ll have to configure our own custom Tasks. VSCode allows you to create and run Custom Tasks. You can even configure a task to be the default build task, which is executed with Cmd + Shift + B on a Mac, or Ctrl + Shift + B on Windows/Linux.
Create a tasks.json file
If you did clone the sample git repo, you’ll already have a tasks.json with the four CloudFormation-related tasks already defined. You will still need to open .vscode/tasks.json file and set the --parameter-overrides for the correct VPC, Subnet, and SSHKey parameters for your AWS account.
If you didn’t clone the sample git repo above, you won’t have a tasks.json file, so you’ll need to create it. In VSCode, open the Command Palette, and run Tasks: Configure Default Build Task, then select Create tasks.json file from template. Select “Others” as the task template. You can look at the tasks.json file in the sample git repo for how you might create these tasks.
One thing to note is how I used VSCode’s Task Variable Substitution for the template file and stack name variables. This is a nice way to make the tasks.json somewhat generic.
Run the Tasks
One of the things I love about VSCode is that Test and Build are first-class concepts. In CloudFormation, validate-template maps to the Test task, and deploy maps to the Build task.
Validate Template
Let’s run the validate-template task. Assuming you’ve cloned the sample git repo, and are in the “ec2-instance.yaml” template, open the Command Palette and run Tasks: Run Task and select validate-template. This will open the VSCode terminal and execute the Validate Template task.
Deploying
Although normally used for things like compiling Go code, or transpiling TypeScript into JavaScript, you can also define any custom task as a “build” task. I’ve defined the AWS CloudFormation deploy task as the default Build task. Hitting Cmd + Shift + B on a Mac, or Ctrl + Shift + B on Windows/Linux runs the default Build task. This gives you a simple key combination to deploy your CloudFormation template right from your editor. It opens a new VSCode terminal panel to display the results of deploying your stack.
Showing the Stack Outputs
Besides the Test and Build tasks, I’ve also defined a task to show the Stack Outputs. Open the Command Palette and run Tasks: Run Task and select outputs. This will open a new VSCode terminal and show you the CloudFormation outputs from the deployed stack.
Deleting the Stack
Finally, I’ve defined a command to delete the stack. Open the Command Palette and run Tasks: Run Task and select delete-stack. This will not open a new VSCode terminal, but it will delete the running stack. VSCode will display a wrench & screwdriver icon in the status bar to indicate the task is running.
Summary
CloudFormation is a great way to define and deploy your infrastructure as code. But, it can take many cycles to get a complex CloudFormation template perfected. Using VSCode Tasks keeps you in your editor and dramatically shortens your dev cycle. Tasks allow you to validate, deploy, and delete stacks all within your text editor, so you don’t have to spend time context-switching away from your editor to the AWS Console. I hope you try it the next complex CloudFormation template you have to develop.
As usual, if you have questions or your company needs help with anything AWS-related, let me know – Doug@1Strategy.com.
Check out other articles on Cloudformation:
CloudFormation: Automating new LVM volumes for EC2 instances
Using CloudFormation Cross-Stack References
