API Gateway call results in [ERROR] KeyError: 'path'

[Laz80UK]

Python Version

3.8

Package Version

2.12.1

Description

I'm trying to call this really simple app with API Gateway (REST) Lambda integration:

#!/usr/bin/python3
import urllib3
from flask import Flask
from apig_wsgi import make_lambda_handler

app = Flask(__name__)
lambda_handler = make_lambda_handler(app)

@app.route('/eventprint', methods=['GET'])
def print_event():
    return {"status": 200, "message": "OK"}

if __name__ == "__main__":
    app.run(debug=True)

but I got the following error:

[ERROR] KeyError: 'path'
Traceback (most recent call last):
  File "/var/lang/lib/python3.8/site-packages/apig_wsgi.py", line 45, in handler
    environ = get_environ_v1(
  File "/var/lang/lib/python3.8/site-packages/apig_wsgi.py", line 73, in get_environ_v1
    "PATH_INFO": urllib.parse.unquote(event["path"], encoding="iso-8859-1"),

The application works with ALB.
Has anybody run into this issue before? What am I doing wrong?

[adamchainz]

Can you compare your deployment setup with the example app?

apig-wsgi/example/deployment/files/cloudformation_site.yml

Lines 135 to 180 in 8ce41e4

	# ALB
	LoadBalancer:
	Type: AWS::ElasticLoadBalancingV2::LoadBalancer
	Condition: ShouldDeployAlb
	Properties:
	Scheme: internet-facing
	Subnets:
	- !Ref SubnetId1
	- !Ref SubnetId2
	SecurityGroups: [!Ref SecurityGroup]
	TargetGroup:
	Type: AWS::ElasticLoadBalancingV2::TargetGroup
	Condition: ShouldDeployAlb
	DependsOn: LambdaPermissionALB
	Properties:
	TargetType: lambda
	Targets:
	- Id: !GetAtt LambdaFunction.Arn
	TargetGroupAttributes:
	- Key: lambda.multi_value_headers.enabled
	Value: True
	HttpListener:
	Type: AWS::ElasticLoadBalancingV2::Listener
	Condition: ShouldDeployAlb
	Properties:
	LoadBalancerArn: !Ref LoadBalancer
	Port: 80
	Protocol: HTTP
	DefaultActions:
	- TargetGroupArn: !Ref TargetGroup
	Type: forward
	SecurityGroup:
	Type: AWS::EC2::SecurityGroup
	Condition: ShouldDeployAlb
	Properties:
	GroupDescription: Allow http on port 80
	VpcId: !Ref VpcId
	SecurityGroupIngress:
	- IpProtocol: tcp
	FromPort: 80
	ToPort: 80
	CidrIp: 0.0.0.0/0

For whatever reason your ALB seems not to be sending path. Perhaps there's a change in config that causes that.

[Laz80UK]

Hi Adam,

Thank you for the quick response. The app works with ALB.
The problem happens when I call it from API Gateway.

[Laz80UK]

OK, I looked into the API Gateway integration example.
I made it work with +proxy resource. Thanks again!