How to send parameters through AWS HTTP API to Lambda - amazon-web-services

Question

I have switched from the REST API to HTTP API for it's cost efficiency. I am a noob to AWS so please be patient with me.
LAMBDA
I have a simple Lambda function that returns the same value it's given. It works fine when tested from the actual Lambda console.
exports.handler = async (event) => {
// TODO implement
const response = {
statusCode: 200,
body: "hello" + event["key1"]
};
return response;
};
When the function is tested from the Lambda console with JSON input:
{ "key1":"value1" }, it returns "hellovalue1".
This is what I want my GET/POST request to return.
API GATEWAY (HTTP API)
I created a simple HTTP API which leads to the lambda function above.
https://39lzilxqm2.execute-api.eu-central-1.amazonaws.com/MS_APITest
When the link above is called from the browser, it returns helloundefined.
I would assume the way of passing an argument would be [THE LINK ABOVE]?key1=value1, but that also returns helloundefined
When using other online tools to send JSON data to the link above through GET/POST requests, the result is, again, helloundefined
Honorable mention: When sending a request through postman, it displays an error:
CORS Error: The request has been blocked because of the CORS policy
How do I pass an argument to AWS Lambda using HTTP API?
Thank you in advance.

Answer 1

I tried to replicate the issue using HTTP API. I noticed that the event has the following form.
{
version: '2.0',
routeKey: 'ANY /MS_APITest',
rawPath: '/MS_APITest',
rawQueryString: 'key1=value1',
headers: {
accept: '*/*',
'content-length': '0',
host: 'xxxxx.execute-api.us-east-1.amazonaws.com',
'user-agent': 'curl/7.72.0',
'x-amzn-trace-id': 'Root=1-5f5afd55-332693f425fbcc7a032809da',
'x-forwarded-for': 'xxxxxxxxx',
'x-forwarded-port': '443',
'x-forwarded-proto': 'https'
},
queryStringParameters: { key1: 'value1' },
requestContext: {
accountId: '820872329501',
apiId: 'sg5mhha5ic',
domainName: 'xxxx.execute-api.us-east-1.amazonaws.com',
domainPrefix: 'sg5mhha5ic',
http: {
method: 'GET',
path: '/MS_APITest',
protocol: 'HTTP/1.1',
sourceIp: 'xxxxxx',
userAgent: 'curl/7.72.0'
},
requestId: 'SryFYjtUIAMEV5w=',
routeKey: 'ANY /MS_APITest',
stage: '$default',
time: '11/Sep/2020:04:30:13 +0000',
timeEpoch: 1599798613551
},
isBase64Encoded: false
}
As can be seen the ?key1=value1 is passed as
queryStringParameters: { key1: 'value1' },
Therefore, the lambda function should be:
exports.handler = async (event) => {
// TODO implement
console.log(event)
const response = {
statusCode: 200,
body: "hello" + event['queryStringParameters']["key1"]
};
return response;
};
I verified that it works using:
curl https://xxxx.execute-api.us-east-1.amazonaws.com/MS_APITest?key1=value1
which resulted in:
hellovalue1

Answer 2

it would be up to your api gateway configuration to properly map something - query parameters, POST or PUT body (note GET request bodies are disregarded), form data - to Json input for your lambda. Look closely at https://docs.aws.amazon.com/apigateway/latest/developerguide/api-gateway-create-api-as-simple-proxy-for-lambda.html - note how
the entire request is sent to the backend Lambda function as-is, via a catch-all ANY method that represents any HTTP method. The actual HTTP method is specified by the client at run time. The ANY method allows you to use a single API method setup for all of the supported HTTP methods: DELETE, GET, HEAD, OPTIONS, PATCH, POST, and PUT.
Later they show how
curl -v -X POST "https://r275xc9bmd.execute-api.us-east-1.amazonaws.com/test/helloworld?name=John&city=Seattle" -H "content-type: application/json" -H "day: Thursday" -d "{ \"time\": \"evening\" }"
or, for a GET request,
curl -X GET \
'https://r275xc9bmd.execute-api.us-east-1.amazonaws.com/test/helloworld?name=John&city=Seattle' \
-H 'content-type: application/json' \
-H 'day: Thursday'
all are captured in the catch-all configuration provided there.
However, if that integration isn't quite right, the data won't be passed properly, so look closely.