feat: Add python support to cdk init (#2130)

* First take on an init template for a Python CDK project.

* The cdk.context.json should not be ignored.

* Fixing some review issues

* Restructured to move app into a separate file outside of package directory.  Also some formatting changes.

* Slight change to code formatting.

* Remove reference to app.sh

* Moving this over to sample-app since it actually creates a sample app, not an empty project.  Will need to create a separate issue to move the others over and create templates for empty projects.

* Adding an app template for Python.

* Keep all dependencies in setup.py and use -e . in requirements.txt to use those and automatically run the python setup.py develop step.  Also use templating feature for blank app.

* Templatize the class name.

packages/aws-cdk/lib/init-templates/app/python/%name%/%name%_stack.template.py

@@ -0,0 +1,9 @@
+from aws_cdk import cdk
+
+
+class %name.PascalCased%Stack(cdk.Stack):
+
+    def __init__(self, app: cdk.App, id: str, **kwargs) -> None:
+        super().__init__(app, id)
+
+        # The code that defines your stack goes here

packages/aws-cdk/lib/init-templates/app/python/.gitignore

@@ -0,0 +1,6 @@
+*.swp
+package-lock.json
+__pycache__
+.pytest_cache
+.env
+*.egg-info

packages/aws-cdk/lib/init-templates/app/python/README.md

@@ -0,0 +1,37 @@
+
+# Welcome to your CDK Python project!
+
+This is a blank project for Python development with CDK.
+
+The `cdk.json` file tells the CDK Toolkit how to execute your app.
+
+This project is set up like a standard Python project.  The initialization process also creates
+a virtualenv within this project, stored under the .env directory.
+
+After the init process completes, you can use the following steps to get your project set up.
+
+```
+$ source .env/bin/activate
+$ pip install -r requirements.txt
+$ python setup.py develop
+```
+
+At this point you can now synthesize the CloudFormation template for this code.
+
+```
+$ cdk synth
+```
+
+To add additional dependencies, for example other CDK libraries, just add to
+your requirements.txt file and rerun the `pip install -r requirements.txt`
+command.
+
+# Useful commands
+
+ * `cdk ls`          list all stacks in the app
+ * `cdk synth`       emits the synthesized CloudFormation template
+ * `cdk deploy`      deploy this stack to your default AWS account/region
+ * `cdk diff`        compare deployed stack with current state
+ * `cdk docs`        open CDK documentation
+
+Enjoy!

packages/aws-cdk/lib/init-templates/app/python/app.template.py

@@ -0,0 +1,11 @@
+#!/usr/bin/env python3
+
+from aws_cdk import cdk
+
+from %name%.%name%_stack import PyStack
+
+
+app = cdk.App()
+PyStack(app, "%name%-cdk-1")
+
+app.run()

packages/aws-cdk/lib/init-templates/app/python/cdk.json

@@ -0,0 +1,3 @@
+{
+    "app": "python3 app.py"
+}

packages/aws-cdk/lib/init-templates/app/python/requirements.txt

@@ -0,0 +1 @@
+-e .

packages/aws-cdk/lib/init-templates/app/python/setup.template.py

@@ -0,0 +1,45 @@
+import setuptools
+
+
+with open("README.md") as fp:
+    long_description = fp.read()
+
+
+setuptools.setup(
+    name="%name%",
+    version="0.0.1",
+
+    description="An empty CDK Python app",
+    long_description=long_description,
+    long_description_content_type="text/markdown",
+
+    author="author",
+
+    package_dir={"": "%name%"},
+    packages=setuptools.find_packages(where="%name%"),
+
+    install_requires=[
+        "aws-cdk.cdk",
+    ],
+
+    python_requires=">=3.6",
+
+    classifiers=[
+        "Development Status :: 4 - Beta",
+
+        "Intended Audience :: Developers",
+
+        "License :: OSI Approved :: Apache Software License",
+
+        "Programming Language :: JavaScript",
+        "Programming Language :: Python :: 3 :: Only",
+        "Programming Language :: Python :: 3.6",
+        "Programming Language :: Python :: 3.7",
+        "Programming Language :: Python :: 3.8",
+
+        "Topic :: Software Development :: Code Generators",
+        "Topic :: Utilities",
+
+        "Typing :: Typed",
+    ],
+)

packages/aws-cdk/lib/init-templates/sample-app/python/.gitignore

@@ -0,0 +1,6 @@
+*.swp
+package-lock.json
+__pycache__
+.pytest_cache
+.env
+*.egg-info

packages/aws-cdk/lib/init-templates/sample-app/python/README.md

@@ -0,0 +1,44 @@
+
+# Welcome to your CDK Python project!
+
+You should explore the contents of this template. It demonstrates a CDK app with two instances of
+a stack (`HelloStack`) which also uses a user-defined construct (`HelloConstruct`).
+
+The `cdk.json` file tells the CDK Toolkit how to execute your app.
+
+This project is set up like a standard Python project.  The initialization process also creates
+a virtualenv within this project, stored under the .env directory.
+
+After the init process completes, you can use the following steps to get your project set up.
+
+```
+$ source .env/bin/activate
+$ pip install -r requirements.txt
+```
+
+At this point you can now synthesize the CloudFormation template for this code.
+
+```
+$ cdk synth
+```
+
+You can now begin exploring the source code, contained in the hello directory.
+There is also a very trivial test included that can be run like this:
+
+```
+$ pytest
+```
+
+To add additional dependencies, for example other CDK libraries, just add to
+your requirements.txt file and rerun the `pip install -r requirements.txt`
+command.
+
+# Useful commands
+
+ * `cdk ls`          list all stacks in the app
+ * `cdk synth`       emits the synthesized CloudFormation template
+ * `cdk deploy`      deploy this stack to your default AWS account/region
+ * `cdk diff`        compare deployed stack with current state
+ * `cdk docs`        open CDK documentation
+
+Enjoy!

packages/aws-cdk/lib/init-templates/sample-app/python/app.py

@@ -0,0 +1,12 @@
+#!/usr/bin/env python3
+
+from aws_cdk import cdk
+
+from hello.hello_stack import MyStack
+
+
+app = cdk.App()
+MyStack(app, "hello-cdk-1", env={'region': 'us-east-2'})
+MyStack(app, "hello-cdk-2", env={'region': 'us-west-2'})
+
+app.run()

packages/aws-cdk/lib/init-templates/sample-app/python/cdk.json

@@ -0,0 +1,3 @@
+{
+    "app": "python3 app.py"
+}

packages/aws-cdk/lib/init-templates/sample-app/python/hello/hello_construct.py

@@ -0,0 +1,22 @@
+from aws_cdk import (
+    aws_iam as iam,
+    aws_s3 as s3,
+    cdk,
+)
+
+
+class HelloConstruct(cdk.Construct):
+
+    @property
+    def buckets(self):
+        return tuple(self._buckets)
+
+    def __init__(self, scope: cdk.Construct, id: str, num_buckets: int) -> None:
+        super().__init__(scope, id)
+        self._buckets = []
+        for i in range(0, num_buckets):
+            self._buckets.append(s3.Bucket(self, f"Bucket-{i}"))
+
+    def grant_read(self, principal: iam.IPrincipal):
+        for b in self.buckets:
+            b.grant_read(principal, "*")

packages/aws-cdk/lib/init-templates/sample-app/python/hello/hello_stack.py

@@ -0,0 +1,30 @@
+from aws_cdk import (
+    aws_iam as iam,
+    aws_sqs as sqs,
+    aws_sns as sns,
+    cdk
+)
+
+from hello_construct import HelloConstruct
+
+
+class MyStack(cdk.Stack):
+
+    def __init__(self, app: cdk.App, id: str, **kwargs) -> None:
+        super().__init__(app, id, **kwargs)
+
+        queue = sqs.Queue(
+            self, "MyFirstQueue",
+            visibility_timeout_sec=300,
+        )
+
+        topic = sns.Topic(
+            self, "MyFirstTopic",
+            display_name="My First Topic"
+        )
+
+        topic.subscribe_queue(queue)
+
+        hello = HelloConstruct(self, "MyHelloConstruct", num_buckets=4)
+        user = iam.User(self, "MyUser")
+        hello.grant_read(user)

packages/aws-cdk/lib/init-templates/sample-app/python/requirements.txt

@@ -0,0 +1,2 @@
+-e .
+pytest

packages/aws-cdk/lib/init-templates/sample-app/python/setup.py

@@ -0,0 +1,49 @@
+import setuptools
+
+
+with open("README.md") as fp:
+    long_description = fp.read()
+
+
+setuptools.setup(
+    name="hello",
+    version="0.0.1",
+
+    description="A sample CDK Python app",
+    long_description=long_description,
+    long_description_content_type="text/markdown",
+
+    author="author",
+
+    package_dir={"": "hello"},
+    packages=setuptools.find_packages(where="hello"),
+
+    install_requires=[
+        "aws-cdk.cdk",
+        "aws-cdk.aws_iam",
+        "aws-cdk.aws_sqs",
+        "aws-cdk.aws_sns",
+        "aws-cdk.aws_s3",
+    ],
+
+    python_requires=">=3.6",
+
+    classifiers=[
+        "Development Status :: 4 - Beta",
+
+        "Intended Audience :: Developers",
+
+        "License :: OSI Approved :: Apache Software License",
+
+        "Programming Language :: JavaScript",
+        "Programming Language :: Python :: 3 :: Only",
+        "Programming Language :: Python :: 3.6",
+        "Programming Language :: Python :: 3.7",
+        "Programming Language :: Python :: 3.8",
+
+        "Topic :: Software Development :: Code Generators",
+        "Topic :: Utilities",
+
+        "Typing :: Typed",
+    ],
+)

packages/aws-cdk/lib/init-templates/sample-app/python/tests/unit/test_hello_construct.py

@@ -0,0 +1,16 @@
+import unittest
+
+from aws_cdk import cdk
+
+from hello.hello_construct import HelloConstruct
+
+class TestHelloConstruct(unittest.TestCase):
+
+    def setUp(self):
+        self.app = cdk.App()
+        self.stack = cdk.Stack(self.app, "TestStack")
+
+    def test_num_buckets(self):
+        num_buckets = 10
+        hello = HelloConstruct(self.stack, "Test1", num_buckets)
+        assert len(hello.buckets) == num_buckets

packages/aws-cdk/lib/init.ts

@@ -231,6 +231,8 @@ async function postInstall(language: string, canUseNetwork: boolean) {
     return await postInstallTypescript(canUseNetwork);
   case 'java':
     return await postInstallJava(canUseNetwork);
+  case 'python':
+    return await postInstallPython(canUseNetwork);
   }
 }
 
@@ -260,6 +262,20 @@ async function postInstallJava(canUseNetwork: boolean) {
   await execute('mvn', 'package');
 }
 
+async function postInstallPython(canUseNetwork: boolean) {
+  if (!canUseNetwork) {
+    print(`Please run ${colors.green('python -m venv .env')}!`);
+    return;
+  }
+
+  print(`Executing ${colors.green('python -m venv .env')}`);
+  try {
+    await execute('python3', '-m venv', '.env');
+  } catch (e) {
+    throw new Error(`${colors.green('python3 -m venv .env')} failed: ` + e.message);
+  }
+}
+
 /**
  * @param dir a directory to be checked
  * @returns true if ``dir`` is within a git repository.