Description of the problem
I have created a Lambda function with API Gateway in SAM, then deployed it and it was working as expected. In API Gateway I used HttpApi not REST API.
Then, I wanted to add a Lambda authorizer with Simple Response. So, I followed the SAM and API Gateway docs and I came up with the code below.
When I call the route items-list it now returns 401 Unauthorized, which is expected.
However, when I add the header myappauth with the value "test-token-abc", I get a 500 Internal Server Error.
I checked this page but it seems all of the steps listed there are OK https://aws.amazon.com/premiumsupport/knowledge-center/api-gateway-http-lambda-integrations/
I enabled logging for the API Gateway, following these instructions: https://docs.aws.amazon.com/apigateway/latest/developerguide/http-api-logging.html
But all I get is something like this (redacted my IP and request ID):
[MY-IP] - - [07/Jul/2021:08:24:06 +0000] "GET GET /items-list/{userNumber} HTTP/1.1" 500 35 [REQUEST-ID]
(Perhaps I can configure the logger in such a way that it prints a more meaningful error message? EDIT: I've tried adding $context.authorizer.error to the logs, but it doesn't print any specific error message, just prints a dash: -)
I also checked the logs for the Lambda functions, there is nothing there (all logs where from the time before I added the authorizer). So, what am I doing wrong?
What I tried:
This is my Lambda Authorizer function which I have deployed using sam deploy, when I test it in isolation using an event with the myappauth header, it works:
exports.authorizer = async (event) => {
let response = {
"isAuthorized": false,
};
if (event.headers.myappauth === "test-token-abc") {
response = {
"isAuthorized": true,
};
}
return response;
};
and this is the SAM template.yml which I deployed using sam deploy:
AWSTemplateFormatVersion: 2010-09-09
Description: >-
myapp-v1
Transform:
- AWS::Serverless-2016-10-31
Globals:
Function:
Runtime: nodejs14.x
MemorySize: 128
Timeout: 100
Environment:
Variables:
MYAPP_TOKEN: "test-token-abc"
Resources:
MyAppAPi:
Type: AWS::Serverless::HttpApi
Properties:
FailOnWarnings: true
Auth:
Authorizers:
MyAppLambdaAuthorizer:
AuthorizerPayloadFormatVersion: "2.0"
EnableSimpleResponses: true
FunctionArn: !GetAtt authorizerFunction.Arn
FunctionInvokeRole: !GetAtt authorizerFunctionRole.Arn
Identity:
Headers:
- myappauth
DefaultAuthorizer: MyAppLambdaAuthorizer
itemsListFunction:
Type: AWS::Serverless::Function
Properties:
Handler: src/handlers/v1-handlers.itemsList
Description: A Lambda function that returns a list of items.
Policies:
- AWSLambdaBasicExecutionRole
Events:
Api:
Type: HttpApi
Properties:
Path: /items-list/{userNumber}
Method: get
ApiId: MyAppAPi
authorizerFunction:
Type: AWS::Serverless::Function
Properties:
Handler: src/handlers/v1-handlers.authorizer
Description: A Lambda function that authorizes requests.
Policies:
- AWSLambdaBasicExecutionRole
Edit:
User @petey suggested that I tried returning an IAM policy in my authorizer function, so I changed EnableSimpleResponses to false in the template.yml, then I changed my function as below, but got the same result:
exports.authorizer = async (event) => {
let response = {
"principalId": "my-user",
"policyDocument": {
"Version": "2012-10-17",
"Statement": [{
"Action": "execute-api:Invoke",
"Effect": "Deny",
"Resource": event.routeArn
}]
}
};
if (event.headers.myappauth == "test-token-abc") {
response = {
"principalId": "my-user",
"policyDocument": {
"Version": "2012-10-17",
"Statement": [{
"Action": "execute-api:Invoke",
"Effect": "Allow",
"Resource": event.routeArn
}]
}
};
}
return response;
};