Create CloudFormation stack from AWS Lambda function, passing API Gateway parameters

Question

I am unable to get parameters in Lambda function. If I mention parameters value in lambda it works fine. when I remove parameters values from Lambda function and try from API gateway or test lambda it process default parameters values. please help My Lambda function is :

import boto3
import time
import json

datetime = time.strftime("%Y%m%d%H%M%S")
stackname = 'myec2'
client = boto3.client('cloudformation')
response = client.create_stack(
  StackName= (stackname+ '-' + datetime),
  TemplateURL='https://testnaeem.s3.amazonaws.com/ec2tags.yaml',
  Parameters=[
  {
    "ParameterKey": "MyInstanceName",
    "ParameterValue": " "
  },
  {
    "ParameterKey": "MyInstanceType",
    "ParameterValue": " "
  }
]
)


def lambda_handler(event, context):
            return(response)

My CloudFormation template is:

---
Parameters:
  MyInstanceType:
    Description: Instance type description
    Type: String
  MyInstanceName:
    Description: Instance type description
    Type: String  

Resources:
  MyInstance:
    Type: AWS::EC2::Instance
    Properties:
      AvailabilityZone: us-east-1a
      ImageId:  ami-047a51fa27710816e
      InstanceType: !Ref MyInstanceType
      KeyName: miankeyp
      Tags:
        - Key : Name
          Value : !Ref MyInstanceName
        - Key : app 
          Value : demo

Please help what changes required in the Lambda function.

My test Values are:

{
  "MyInstanceName": "demott",
  "MyInstanceType": "t2.micro"
}

Answer 1

I modified the code of your lambda function. Please check comments in the code for clarification:

import boto3
import time
import json

datetime = time.strftime("%Y%m%d%H%M%S")
stackname = 'myec2'
client = boto3.client('cloudformation')

def lambda_handler(event, context):

    print(event) # to check what your even actually is
    # it will be printed out in CloudWatch Logs for your
    # function

    # you have to check what the event actually looks like
    # and adjust event['MyInstanceName'] and event['MyInstanceType']
    # in the following code

    response = client.create_stack(
      StackName= (stackname+ '-' + datetime),
      TemplateURL='https://testnaeem.s3.amazonaws.com/ec2tags.yaml',
      Parameters=[
      {
        "ParameterKey": "MyInstanceName",
        "ParameterValue": event['MyInstanceName']
      },
      {
        "ParameterKey": "MyInstanceType",
        "ParameterValue": event['MyInstanceType']
      }
    ]
    )

    return(response)

By the way, such function and API gateway can spin up a lot of ec2 instances very quickly. So that you are aware of this.