How can I response exact error status code and message by Serverless framework?

Question

I created Serverless framework's function by command below:

sls function create some/api

Then schelton code was created:

'use strict';

module.exports.handler = function(event, context, cb) {
  return cb({
    message: 'Go Serverless! Your Lambda function executed successfully!'
  });
};

and, response template is like below:

s-function.json

  "responses": {
    "400": {
      "statusCode": "400"
    },
    "default": {
      "statusCode": "200",
      "responseParameters": {},
      "responseModels": {
        "application/json;charset=UTF-8": "Empty"
      },
      "responseTemplates": {
        "application/json;charset=UTF-8": ""
      }
    }
  }

But, when I returned error object to callback function like cb(err, null), then error message was properly shown, but statusCode is 200.

If I changed to call callback function like cb("400", err), then statusCode properly returns 400, but response body is not good: {"errorMessage":"400"}.

Are there any good settings to show bot statusCode(Not only 400, but also 401,403,404,500...and so on) and error messages?

Assuming you are using API gateway to expose the Lambda functions, there is a good discussion here: stackoverflow.com/questions/31329495/… — Rodrigo M
Thank you! It's not I'm imagined, but with it, I can solve my problem by another way. I'll summarize the result later. — kochizufan

Rumesh Eranga Hapuarachchi Rumesh Eranga Hapuarachchi · Accepted Answer · 2016-06-29T06:15:45

I use following response template. If the message returned from the lambda function matches the selectionPattern specified in the response template, it will return the correct status code.

"responseTemplate": {
    "400": {
        "selectionPattern": "^\\[BadRequest\\].*",
        "statusCode": "400"
    },
    "401": {
        "selectionPattern": "^\\[Unauthorized\\].*",
        "statusCode": "401"
    },
    "403": {
        "selectionPattern": "^\\[Forbidden\\].*",
        "statusCode": "403"
    },
    "404": {
        "selectionPattern": "^\\[NotFound\\].*",
        "statusCode": "404"
    },
    "409": {
        "selectionPattern": "^\\[Conflict\\].*",
        "statusCode": "409"
    },
    "500": {
        "selectionPattern": "^\\[Process exited|ServerError\\].*",
        "statusCode": "500"
    },
    "504": {
        "selectionPattern": "^\\[Task timed out\\].*",
        "statusCode": "504"
    },
    "default": {
        "statusCode": "200",
        "responseParameters": {},
        "responseModels": {},
        "responseTemplates": {
            "application/json": ""
        }
    }
}

How can I response exact error status code and message by Serverless framework?

1 Answers