AWS Classroomnotes 05/Mar/2022

Exposing Lambda function over http

• Lets create a simple lambda function with python runtime
  
• Now lets integrate this Lambda function with API Gateway
  
  
  
  
  
  
  
  
  
  
  
  
• Now as discussed in the class we have exposed lambda function using API Gateway

import json
import boto3

def stop_instances_by_tag(region, tag_name, tag_value):
    """
    This method will find the instances in a region
    """
    ec2 = boto3.client('ec2', region_name=region)
    response = ec2.describe_instances(Filters=[
        {
            'Name': f'tag:{tag_name}',
            'Values': [tag_value]
        }
    ])
    instances_found = response['Reservations'][0]['Instances']
    print(f"found {len(instances_found)} instances")
    #for instance in response['Reservations'][0]['Instances']:
    #    ec2.start_instances(InstanceIds=[instance['InstanceId']])
    instance_ids = [ instance['InstanceId'] for instance in response['Reservations'][0]['Instances']]
    response = ec2.stop_instances(InstanceIds=instance_ids)
    print(response)

def lambda_handler(event, context):
    tag_value = event['queryStringParameters']['tagvalue']
    tag_name  = event['queryStringParameters']['tagname']
    region = event['queryStringParameters']['region']
    stop_instances_by_tag(region, tag_name, tag_value)
    return {
        'statusCode': 200,
        'body': json.dumps('Hello from Lambda!')
    }

• Next Steps:
  • Message Queues using AWS Managed Services.
  • Event-based architecture using AWS Managed Services.