feat(lambda-python): support poetry packaging for PythonFunction (aws…

…#11850)

This PR adds [poetry](https://python-poetry.org/) support to building Lambda dependencies for the PythonFunction.

I used the pipenv setup for inspiration. I'm not very familiar with writing integration tests, so there's a possibility that I could've missed something.

Closes aws#11753.

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

packages/@aws-cdk/aws-lambda-python/README.md

@@ -1,4 +1,5 @@
 # Amazon Lambda Python Library
+
 <!--BEGIN STABILITY BANNER-->
 
 ---
@@ -25,13 +26,13 @@ Define a `PythonFunction`:
 
 ```ts
 import * as lambda from "@aws-cdk/aws-lambda";
-import { PythonFunction } from "@aws-cdk/aws-lambda-python"
+import { PythonFunction } from "@aws-cdk/aws-lambda-python";
 
 new PythonFunction(this, 'MyFunction', {
   entry: '/path/to/my/function', // required
   index: 'my_index.py', // optional, defaults to 'index.py'
   handler: 'my_exported_func', // optional, defaults to 'handler'
-  runtime: lambda.Runtime.PYTHON_3_6 // optional, defaults to lambda.Runtime.PYTHON_3_7
+  runtime: lambda.Runtime.PYTHON_3_6, // optional, defaults to lambda.Runtime.PYTHON_3_7
 });
 ```
 
@@ -60,10 +61,19 @@ according to the `runtime`.
 ├── Pipfile.lock # your lock file
 ```
 
+**Lambda with a poetry.lock**
+
+```plaintext
+.
+├── lambda_function.py # exports a function named 'handler'
+├── pyproject.toml # has to be present at the entry path
+├── poetry.lock # your poetry lock file
+```
+
 **Lambda Layer Support**
 
 You may create a python-based lambda layer with `PythonLayerVersion`. If `PythonLayerVersion` detects a `requirements.txt`
-or `Pipfile` at the entry path, then `PythonLayerVersion` will include the dependencies inline with your code in the
+or `Pipfile` or `poetry.lock` with the associated `pyproject.toml` at the entry path, then `PythonLayerVersion` will include the dependencies inline with your code in the
 layer.
 
 ```ts

packages/@aws-cdk/aws-lambda-python/lib/Dockerfile.dependencies

@@ -6,13 +6,14 @@ FROM $IMAGE
 # Ensure rsync is installed
 RUN yum -q list installed rsync &>/dev/null || yum install -y rsync
 
-# Install pipenv so we can create a requirements.txt if we detect pipfile
-RUN pip install pipenv
+# Install pipenv and poetry so we can create a requirements.txt if we detect pipfile or poetry.lock respectively
+RUN pip install pipenv poetry
 
 # Install the dependencies in a cacheable layer
 WORKDIR /var/dependencies
-COPY Pipfile* requirements.tx[t] ./
+COPY Pipfile* pyproject* poetry* requirements.tx[t] ./
 RUN [ -f 'Pipfile' ] && pipenv lock -r >requirements.txt; \
+    [ -f 'poetry.lock' ] && poetry export --with-credentials --format requirements.txt --output requirements.txt; \
     [ -f 'requirements.txt' ] && pip install -r requirements.txt -t .;
 
 CMD [ "python" ]

packages/@aws-cdk/aws-lambda-python/lib/bundling.ts

@@ -80,6 +80,10 @@ export function hasDependencies(entry: string): boolean {
     return true;
   }
 
+  if (fs.existsSync(path.join(entry, 'poetry.lock'))) {
+    return true;
+  }
+
   if (fs.existsSync(path.join(entry, 'requirements.txt'))) {
     return true;
   }

packages/@aws-cdk/aws-lambda-python/test/bundling.test.ts

@@ -140,6 +140,17 @@ describe('Dependency detection', () => {
     expect(hasDependencies('/asset-input')).toEqual(true);
   });
 
+  test('Detects poetry', () => {
+    existsSyncMock.mockImplementation((p: fs.PathLike) => {
+      if (/poetry.lock/.test(p.toString())) {
+        return true;
+      }
+      return existsSyncOriginal(p);
+    });
+
+    expect(hasDependencies('/asset-input')).toEqual(true);
+  });
+
   test('Detects requirements.txt', () => {
     existsSyncMock.mockImplementation((p: fs.PathLike) => {
       if (/requirements.txt/.test(p.toString())) {