stack.py

from typing_extensions import runtime
import os
from aws_cdk import (
    core,
    aws_lambda as _lambda,
    aws_iam as iam
)


class MediumLambdaStack(core.Stack):
    '''
    DOCSTRING: Create a Cloudformation stack
    '''

    def __init__(self, scope: core.Construct, construct_id: str, **kwargs) -> None:
        super().__init__(scope, construct_id, **kwargs)
        '''
        DOCSTRING: Main program on which the objects are declared
        '''

        # Get all the variables from the cdk.json file
        myenv = os.environ['MYENV']
        environments = self.node.try_get_context("ENVIRONMENTS")
        environment = environments.get(myenv)

        # We will use the iam role for all the func
        lambda_iam_role = iam.Role.from_role_arn(self, 'Role', f'arn:aws:iam::{environment["context"].get("account")}:role/{environment["context"].get("lambda_iam_role")}', mutable=False)

        # Define the lambdas functions and the parameters
        # Structure
        # Lambda_name
        #  asset: folder on which the lambda is located
        #  handler: python file + handler
        my_lambdas = {
            "medium_lambda": {
                "asset": "lambda",
                "handler": "hello.handler"
            },
            "medium_lambda2": {
                "asset": "lambda",
                "handler": "hello2.handler"
            },
        }

        # Loop to dynamically create the lambdas
        for my_lambda in my_lambdas:
            my_lambdas[my_lambda]['func'] = create_lambda(self, my_lambda, my_lambdas[my_lambda].get('asset'), my_lambdas[my_lambda].get('handler'), environment.get('variables'), lambda_iam_role)
            if "cfn_output" not in my_lambdas[my_lambda].keys():
                my_lambdas[my_lambda]["cfn_output"] = []
            my_lambdas[my_lambda]["cfn_output"].append(create_cfn_output(self, f"{my_lambda}Name", my_lambdas[my_lambda]['func'].function_name))

def create_lambda(self, name:str, asset:str, handler:str, env_var:dict, role:iam.Role.from_role_arn) -> _lambda.Function:
    '''
    DOCSTRING: Create a Lambda function
    INPUTS: 
        - name -> Function id + function name
        - asset -> Folder where we can find the code
        - handler -> File + handler
        - variable -> dict which contains all the variables
        - role -> iam role to map to the function
    '''
    return _lambda.Function(
            self, name,
            function_name=name,
            runtime=_lambda.Runtime.PYTHON_3_9,
            code=_lambda.Code.from_asset(asset),
            handler=handler,
            environment=env_var,
            role=role
        )

def create_cfn_output(self, output_name:str, value) -> core.CfnOutput:
    '''
    DOCSTRING: Add a cloudformation output based on an item
    INPUT: 
        - ouput_name -> The name of the output you want to use
        - value -> output value
    '''
    return core.CfnOutput(self, output_name, value=value)