Terraform Support

When you run chalice deploy, chalice will deploy your application using the AWS SDK for Python). Chalice also provides functionality that allows you to manage deployments yourself using terraform. This is provided via the chalice package --pkg-format terraform command.

When you run this command, chalice will generate the AWS Lambda deployment package that contains your application and a Terraform configuration file. You can then use the terraform cli to deploy your chalice application.

Considerations

Using the chalice package command is useful when you don’t want to use chalice deploy to manage your deployments. There’s several reasons why you might want to do this:

• You have pre-existing infrastructure and tooling set up to manage Terraform deployments.
• You want to integrate with other Terraform resources to manage all your application resources, including resources outside of your chalice app.
• You’d like to integrate with AWS CodePipeline to automatically deploy changes when you push to a git repo.

Keep in mind that you can’t switch between chalice deploy and chalice package + Terraform for deploying your app.

If you choose to use chalice package and Terraform to deploy your app, you won’t be able to switch back to chalice deploy. Running chalice deploy would create an entirely new set of AWS resources (API Gateway Rest API, AWS Lambda function, etc).

Example

In this example, we’ll create a chalice app and deploy it using the AWS CLI.

First install the necessary packages:

$ virtualenv /tmp/venv
$ . /tmp/venv/bin/activate
$ pip install chalice awscli
$ chalice new-project test-tf-deploy
$ cd test-tf-deploy

At this point we’ve installed chalice and the AWS CLI and we have a basic app created locally. Next we’ll run the package command:

$ chalice package --pkg-format terraform /tmp/packaged-app/
Creating deployment package.
$ ls -la /tmp/packaged-app/
-rw-r--r--   1 j         wheel  3355270 May 25 14:20 deployment.zip
-rw-r--r--   1 j         wheel     3068 May 25 14:20 chalice.tf.json

$ unzip -l /tmp/packaged-app/deployment.zip  | tail -n 5
    17292  05-25-17 14:19   chalice/app.py
      283  05-25-17 14:19   chalice/__init__.py
      796  05-25-17 14:20   app.py
 --------                   -------
  9826899                   723 files

As you can see in the above example, the package --pkg-format command created a directory that contained two files, a deployment.zip file, which is the Lambda deployment package, and a chalice.tf.json file, which is the Terraform template that can be deployed using Terraform. Next we’re going to use the Terraform CLI to deploy our app.

Note terraform will deploy run against all terraform files in this directory, so we can add additional resources for our application by adding terraform additional files here. The Chalice terraform template includes two static data values (app and stage names) that we can optionally use when constructing these additional resources, ie. ${data.null_data_source.chalice.outputs.app}

First let’s run Terraform init to install the AWS Terraform Provider:

$ cd /tmp/packaged-app
$ terraform init

Now we can deploy our app using the terraform apply command:

$ terraform apply
data.aws_region.chalice: Refreshing state...
data.aws_caller_identity.chalice: Refreshing state...

An execution plan has been generated and is shown below.
Resource actions are indicated with the following symbols:
+ create

... (omit plan output)

Plan: 14 to add, 0 to change, 0 to destroy.

Do you want to perform these actions?
  Terraform will perform the actions described above.
  Only 'yes' will be accepted to approve.
Enter a value: yes

... (omit apply output)

Apply complete! Resources: 14 added, 0 changed, 0 destroyed.

Outputs:

EndpointURL = https://7bnxriulj5.execute-api.us-east-1.amazonaws.com/dev

This will take a minute to complete, but once it’s done, the endpoint url will be available as an output which we can then curl:

$ http "$(terraform output EndpointURL)"
HTTP/1.1 200 OK
Connection: keep-alive
Content-Length: 18
Content-Type: application/json
...

{
    "hello": "world"
}