Phone book search on AWS Lambda and S3 - python-3.x

Question

I want to make a serverless application in AWS Lambda for phone book searches.
What I've done:
Created a bucket and uploaded a CSV file to it.
Created a role with full access to the bucket.
Created a Lambda function
Created API Gateway with GET and POST methods
The Lambda function contains the following code:
import boto3
import json
s3 = boto3.client('s3')
resp = s3.select_object_content(
Bucket='namebbacket',
Key='sample_data.csv',
ExpressionType='SQL',
Expression="SELECT * FROM s3object s where s.\"Name\" = 'Jane'",
InputSerialization = {'CSV': {"FileHeaderInfo": "Use"}, 'CompressionType': 'NONE'},
OutputSerialization = {'CSV': {}},
)
for event in resp['Payload']:
if 'Records' in event:
records = event['Records']['Payload'].decode('utf-8')
print(records)
elif 'Stats' in event:
statsDetails = event['Stats']['Details']
print("Stats details bytesScanned: ")
print(statsDetails['BytesScanned'])
print("Stats details bytesProcessed: ")
print(statsDetails['BytesProcessed'])
print("Stats details bytesReturned: ")
print(statsDetails['BytesReturned'])
When I access the Invoke URL, I get the following error:
{errorMessage = Handler 'lambda_handler' missing on module 'lambda_function', errorType = Runtime.HandlerNotFound}
CSV structure: Name, PhoneNumber, City, Occupation
How to solve this problem?

Answer 1

Please refer to this documentation topic to learn how to write a Lambda function in Python. You are missing the Handler. See: AWS Lambda function handler in Python

Answer 2

Wecome to S.O. #smac2020 links you to the right place AWS Lambda function handler in Python. In short, AWS Lambda needs to know where to find your code, hence the "handler". Though a better way to think about it might be "entry-point."
Here is a close approximation of your function, refactored for use on AWS Lambda:
import json
import boto3
def function_to_be_called(event, context):
# TODO implement
s3 = boto3.client('s3')
resp = s3.select_object_content(
Bucket='stack-exchange',
Key='48836509/dogs.csv',
ExpressionType='SQL',
Expression="SELECT * FROM s3object s where s.\"breen_name\" = 'pug'",
InputSerialization = {'CSV': {"FileHeaderInfo": "Use"}, 'CompressionType': 'NONE'},
OutputSerialization = {'CSV': {}},
)
for event in resp['Payload']:
if 'Records' in event:
records = event['Records']['Payload'].decode('utf-8')
return {
'statusCode': 200,
'body': json.dumps('Hello from Lambda!'),
'pugInfo': records
}
This function produces the following result:
Response
{
"statusCode": 200,
"body": "\"Hello from Lambda!\"",
"currentWorkdingDirectory": "/var/task",
"currentdirlist": [
"lambda_function.py"
],
"pugInfo": "1,pug,toy\r\n"
}
The "entry point" for this function is in a Python file called lambda_function.py and the function function_to_be_called. Together these are the "handler." We can see this in the Console:
or using the API through Boto3
import boto3
awslambda = boto3.client('lambda')
awslambda.get_function_configuration('s3SelectFunction')
Which returns:
{'CodeSha256': 'mFVVlakisUIIsLstQsJUpeBIeww4QhJjl7wJaXqsJ+Q=',
'CodeSize': 565,
'Description': '',
'FunctionArn': 'arn:aws:lambda:us-east-1:***********:function:s3SelectFunction',
'FunctionName': 's3SelectFunction',
'Handler': 'lambda_function.function_to_be_called',
'LastModified': '2021-03-10T00:57:48.651+0000',
'MemorySize': 128,
'ResponseMetadata': ...
'Version': '$LATEST'}