What is the best way to setup and test Lambda API? - amazon-web-services

Question

Wanting to build a microservice within Lambda.
I want it to be accessible via an HTTP request so I believe I need to configure it with API gateway. I am unsure if I should use API Gateway Proxy Request Event or API Gateway Proxy Response Event.
Also in terms of authenticating the user, what is the best way?
I am thinking using Auth0 so a user will essentially just send a JWT with the HTTP request.
Thanks

Answer 1

I use API Gateway Proxy Request. I configure the Integration Request to use Use Lambda Proxy integration which will result in Integration Response updating to Proxy integrations cannot be configured to transform responses.
I then handle responses within the lambda function itself. For example, I will have the following for a successful response:
context.succeed({
statusCode: 200,
headers: { 'Content-Type': 'Application/json'},
body
});
And for an example of an expected fail, I have:
context.succeed({
statusCode: 404,
headers: { 'Content-Type': 'Application/json'},
body: JSON.stringify({'Error': error})
});
NOTE: It is important to note I use context.succeed on error handling and not context.fail.
I developed my lambda locally in Node and used a combination of lambda-local and lambda-tester for debugging/testing functionality. For example, I would run the following command to pass in the lambda and the event:
lambda-local -f ~/Desktop/lambdaNode/myNewAPI.js -e ~/Desktop/lambdaEvents/testEvent.json
An example event will look like this:
{
"queryStringParameters":
{
"param1": "1234567890",
"param2": "0987654321",
}
}
For my unit tests, I used lambda-tester along with mocha as follows:
const LambdaTester = require( 'lambda-tester' );
describe('handle my new lambda: ', () => {
it('should do exactly what I expect', () => {
return LambdaTester( myNewAPI.handler )
.event( testEvents.newLambdaEvent )
.expectSucceed( ( result ) => {
expect( result.statusCode ).to.equal(200);
});
});
});
Test the above with npm test if you're setup for that, otherwise just mocha testFile
For my use case, authentication is handled differently as it is an internal API. For your case, I think JWT is the best way forward there, although I am sorry I cannot provide more info in that regard.