Lambda invoke Lambda via API Gateway - amazon-web-services

Question

I can't seem to get this to work. I create 2 lambdas via C9. I'm using boto3 to invoke one lambda from another. Everything seems to work just fine via C9 but when I publish and try to access via API Gateway I keep getting "Endpoint request timed out" errors.
I know it can't be a timeout issue because I've set up my yaml files to have enough time to execute and the lambda right now are really simple (only returning a string)
here are my current yaml file. I'm wondering if maybe there are some sort of permissions I need to include for API Gateway in the second yaml
Lambda1
AWSTemplateFormatVersion: '2010-09-09'
Transform: 'AWS::Serverless-2016-10-31'
Description: An AWS Serverless Specification template describing your function.
Resources:
api:
Type: 'AWS::Serverless::Function'
Properties:
Description: ''
Handler: api/lambda_function.lambda_handler
MemorySize: 256
Role: 'arn:aws:iam::820788395625:role/service-role/api_int-role'
Runtime: python3.6
Timeout: 30
VpcConfig:
SecurityGroupIds:
- ...
SubnetIds:
- ...
Policies: AWSLambdaFullAccess
Lambda2
AWSTemplateFormatVersion: '2010-09-09'
Transform: 'AWS::Serverless-2016-10-31'
Description: An AWS Serverless Specification template describing your function.
Resources:
api:
Type: 'AWS::Serverless::Function'
Properties:
Description: ''
Handler: api/lambda_function.lambda_handler
MemorySize: 512
Role: 'arn:aws:iam::820788395625:role/service-role/api_int-role'
Runtime: python3.6
Timeout: 15
VpcConfig:
SecurityGroupIds:
- ...
SubnetIds:
- ...
I just set up an API Gateway endpoint directly to Lambda2 and it returned no problem. So...
API Gateway -> Lambda 2 (works)
API Gateway -> Lambda 1 -> Lambda 2 (does not work)
So for some reason when I want to call Lambda 2 via Lambda 1 over API Gateway it doesn't work.
Here is the code that is calling the 2nd Lambda
import json
import boto3
def lambda_handler(event, context):
print('call boto3 client')
lambda_client = boto3.client('lambda', region_name='us-east-1')
print('boto3 client called')
print('invoke lambda')
env_response = lambda_client.invoke(
FunctionName='cloud9-apiAlpha-api-TBSOYXLVBCLX',
InvocationType='RequestResponse',
Payload=json.dumps(event)
)
print('lambda invoked')
print('env_response')
print(env_response)
print(env_response['Payload'])
print(env_response['Payload'].read())
return {
'statusCode': 200,
'headers': {
'Content-Type': 'application/json',
'Access-Control-Allow-Methods': 'POST,GET,OPTIONS,PUT,DELETE',
'Access-Control-Allow-Origin': '*'
},
'body': 'HELLO WORLD!',
'isBase64Encoded': False
}
Now when I look at the logs it gets to print('invoke lambda') but then stops and timesout

Answer 1

1.Invoking a Lambda from another Lambda can't be done without some configuration. In your .yml file, permission must be specified in order to invoke another Lambda. This can be accomplished by adding an iamRoleStatements section under the provider property
or
by add the simple policy AWSLambdaRole to the existing role attached to the lambda function_1.
provider:
name: aws
runtime: <runtime goes here> # e.g. python3.6 or nodejs6.10
iamRoleStatements:
- Effect: Allow
Action:
- lambda:InvokeFunction
Resource: "*"
or do this add/attach this policy to your existing role attached to your lambda function_1
2.Invoking lambda function_1 code attached.
global LAMBDA_CLIENT
if not LAMBDA_CLIENT:
LAMBDA_CLIENT = boto3.client('lambda')
try:
encoded_payload = json.dumps({'message': 'this is an invokcation call form lambda_1'}).encode(UTF_8)
invoke_resp = lambda_client.invoke(
FunctionName='function_2',
InvocationType='RequestResponse',
Payload=encoded_payload)
status_code = invoke_resp['StatusCode']
if status_code != 200:
LOGGER.error('error ')
paylaod = invoke_resp['Payload'].read()
resp = json.loads(payload)
print(resp)
except Exception:
IF you are using InvocationType=RequestResponse then you can return some response form function_2.

Answer 2

Finally found the solution. The answer to my particular problem was Lambda 1 & Lambda 2 were operating over VPC thus no internet connection. Once I removed VPC from Lambda 1 the invocation of Lambda 2 worked without any problems.
Just wanted to share in case I can save anyone else a weeks worth of debugging LOL