python.md

Getting Started with Python

Prerequisites

• Terraform >= v0.12
• Node.js >= v12.16
• Python >= v3.7

Install CDK for Terraform CLI

Install with Homebrew:

$ brew install cdktf

Or install with npm (requires Node.js):

npm install -g cdktf-cli

Learn more how to use the cdktf command-line interface here.

Initialize a new CDK for Terraform project

mkdir hello-terraform
cd hello-terraform

There are two Python templates available that you can choose from. The python template uses Pipenv for package management wheras the python-pip template just uses pip with a simple requirements.txt file.

Here's how to choose between the two

pipenv

Note: Make sure Pipenv is installed.

cdktf init --template="python" --local

pip

cdktf init --template="python-pip" --local

This will initialize a brand new CDK for Terraform project in Python using an interactive command.

Note: By supplying '--local' option you have chosen local storage mode for storing the state of your stack.
This means that your Terraform state file will be stored locally on disk in a file 'terraform.tfstate' in the root of your project.

We will now set up the project. Please enter the details for your project.
If you want to exit, press ^C.

Project Name: (default: 'hello-terraform')
Project Description: (default: 'A simple getting started project for cdktf.')

Also, this command installs the cdktf library so that it can be used in the project.

CDK for Terraform Application

You can now open up the main.py file to view your application code.

vim main.py

#!/usr/bin/env python
from constructs import Construct
from cdktf import App, TerraformStack


class MyStack(TerraformStack):
    def __init__(self, scope: Construct, ns: str):
        super().__init__(scope, ns)

        # define resources here


app = App()
MyStack(app, "hello-terraform")

app.synth()

Refer to the examples directory for additional examples.

Let's take a simple Python application that uses the CDK for Terraform package.

#!/usr/bin/env python
from constructs import Construct
from cdktf import App, TerraformStack
from imports.aws import Instance, AwsProvider


class MyStack(TerraformStack):
  def __init__(self, scope: Construct, ns: str):
    super().__init__(scope, ns)

    AwsProvider(self, 'Aws', region='us-east-1')
    Instance(self, "hello", ami="ami-2757f631", instance_type="t2.micro")

app = App()
MyStack(app, "hello-terraform")

app.synth()

Synthesize Application

When you are ready you can run the synthesize command to generate Terraform JSON configuration for the application.

cdktf synth

Generated Terraform code in the output directory: cdktf.out

This command will generate a directory called cdktf.out. This directory contains the Terraform JSON configuration for the application.

cd cdktf.out

Terraform AWS provider and instance expressed as Terraform JSON configuration.

cat cdk.json
{
  "terraform": {
    "required_providers": {
      "aws": "~> 2.0"
    }
  },
  "provider": {
    "aws": [
      {
        "region": "us-east-1"
      }
    ]
  },
  "resource": {
    "aws_instance": {
      "examplepythonhello3532B955": {
        "ami": "ami-2757f631",
        "instance_type": "t2.micro"
      }
    }
  }
}

Note: You can generate the Terraform JSON configuration while synthesizing the code by running cdktf synth --json.

Deploy Application

Note: You can use Terraform commands like terraform init, terraform plan, and terraform apply with the generated Terraform JSON configuration (learn more here) or optionally continue to use the CDK for Terraform CLI for a first-class experience.

You can now deploy your CDK for Terraform application using the cdktf deploy command.

cdktf deploy

This command will ask for confirmation on a generated diff and then deploy the application.

Stack: helloterraform
Resources
 + AWS_INSTANCE         hello aws_instance.helloterraform_hello_A790281A

Diff: 1 to create, 0 to update, 0 to delete.
Do you want to continue (Y/n)? y

Deployed application

Deploying Stack: helloterraform
Resources
 ✔ AWS_INSTANCE         hello aws_instance.helloterraform_hello_A790281A

Summary: 1 created, 0 updated, 0 destroyed.

The cdktf deploy command runs a terraform apply in the background. If you are using local storage mode then it creates a terraform.tfstate file in the root of the project.

Destroy Application

You can destroy the application by running cdktf destroy.

cdktf destroy

This command will ask for confirmation on a generated diff and then destroy the application if the user confirms that they want to continue with the destroy operation.

Stack: helloterraform
Resources
 - AWS_INSTANCE         hello aws_instance.helloterraform_hello_A790281A

Diff: 0 to create, 0 to update, 1 to delete.
Do you want to continue (Y/n)?

Destroyed application

Destroying Stack: helloterraform
Resources
 ✔ AWS_INSTANCE         hello aws_instance.helloterraform_hello_A790281A

Summary: 1 destroyed.