Response body breaks with cors middlewares usage.

[niteshgrg]

Response body which is a valid json becomes something of sort. WHile using with serverless cors:true and cors middleware.

"HTTP/1.1 201 OK X-Powered-By: Express Access-Control-Allow-Origin: * Content-Type: application/json; charset=utf-8 Content-Length: 979 ETag: W/"3d3-lsMbiatDuk11/kGt2lF+ji87gW8" Date: Sun, 19 Apr 2020 06:07:04 GMT Connection: keep-alive

{..json }"

[sometimescool22]

Getting this even without CORS. Copied from https://serverless.com/blog/serverless-express-rest-api/

const serverless = require('serverless-http');
const express = require('express')

const app = express()

app.get('/', function (req, res) {
  res.send('Hello World!')
})

module.exports.handler = serverless(app);

functions:
  server:
    handler: src/server.handler
    # timeout: 30
    events:
      - http: ANY /
      - http: 'ANY {proxy+}'

First request is normal, then it returns the headers like above.

[dougmoscrop]

What versions of everything?

On Mon., Apr. 20, 2020, 7:13 p.m. Harry, notifications@github.com wrote:

Getting this even without CORS. Server:

import serverless from 'serverless-http'import express from 'express' const app = express();

app.get('/', async (req, res) => { res.send("hello world") }) export const main = serverless(app);

functions: server: handler: dist/server.main events:

• http: ANY /
• http: 'ANY {proxy+}'

First request is normal, then it returns the headers like above.

— You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub https://github.com/dougmoscrop/serverless-http/issues/151#issuecomment-616858598, or unsubscribe https://github.com/notifications/unsubscribe-auth/AAEPGFFL76YZO72L543KCSDRNTJIZANCNFSM4MLVBG3Q .

[Fatxx]

I'm facing a similar issue, in development and at the first request the body is a well-formatted json after that it seems to add the headers into the response body.

As you can see the headers seem to be added to the response body somehow which invalidates the JSON body:

I'm using just a simple expressjs endpoint which returns an object:

const app = express();
app.use(express.json({ limit: '10mb' }));
app.post('/validate-license', async (req, res) => {
 return res.send({id: "", key: "", ...})
})

Also with the following serverless.yml:

provider:
  name: aws
  runtime: nodejs12.x

functions:
  licenseServer:
    handler: index.handler
    events:
      - http:
          path: /
          method: ANY
          cors: true
      - http:
          path: /{any+}
          method: ANY
          cors: true

[Fatxx]

I tried this with versions 2.3.2 and 2.0.0

[mark-carrington]

Is there any update on this issue? I'm seeing this with the following versions: serverless: 1.67.3 serverless-http: 2.3.2

I also noticed this occurring without CORS. I tried stripping the code right back to the following (and still saw the issue):

import serverless from 'serverless-http'
import express from 'express'

const app = express()
app.get('/news', (req, res) => res.status(200).json({“message”: “hello world"})

const handler = serverless(app)
module.exports.handler = async (event, context) => {
  const result = await handler(event, context)
  return result
}

With the following serverless.yml:

provider:
  name: aws
  runtime: nodejs12.x

functions:
    app:
        handler: src/app.handler
        events:
            - http:
                  path: /
                  method: get
                  private: true
            - http:
                  path: /{proxy+}
                  method: get
                  private: true
    getNews:
        handler: src/app.handler
        events:
            - http:
                  path: /news/{proxy+}
                  method: get
                  private: true

[csuermann]

I'm experiencing the same issue with these versions:

serverless: 1.67.3 serverless-http: 2.5.0 express: 4.17.1

Cold-starts behave like expected but subsequent requests include header duplications as part of the body.

1st request (cold-start)

curl --location -i --request POST 'https://xxxxx.execute-api.eu-central-1.amazonaws.com/dev/foo'

HTTP/2 200 
content-type: text/xml; charset=utf-8
content-length: 479
date: Fri, 05 Jun 2020 11:58:34 GMT
x-amzn-requestid: 8ce24e23-3dda-4f0a-b2c0-c529f5da26f5
x-amzn-remapped-content-length: 479
x-amz-apigw-id: Npi4TG-AliAGs5g=
etag: W/"1df-8OH65yBjlV5aKoyDEt4SeA+4A0I"
x-powered-by: Express
x-amzn-trace-id: Root=1-6eda3368-1817e362a9b35e9ae15c8c74;Sampled=0
x-cache: Miss from cloudfront
via: 1.1 117c54f007fbf41fc2a4bbbd8e88fc31.cloudfront.net (CloudFront)
x-amz-cf-pop: TXL52-C1
x-amz-cf-id: tpQHTYt_bmUkCa_4BxosgZbjzSc5NaF3cHUgUYJIm8-1Yk3uoFgiew==

<?xml version="1.0" encoding="UTF-8"?><foo><bar></bar</foo>%

subsequent requests

curl --location -i --request POST 'https://xxxxx.execute-api.eu-central-1.amazonaws.com/dev/foo'

HTTP/2 200 
content-type: text/xml; charset=utf-8
content-length: 685
date: Fri, 05 Jun 2020 11:36:01 GMT
x-amzn-requestid: 5d71548d-9a61-4fd1-b346-a2c735faa063
x-amzn-remapped-content-length: 479
x-amz-apigw-id: NpwlKMNGFiAEoHg=
etag: W/"1df-5JxnLUWg3mxL4XsqY+aTm9fLyps"
x-powered-by: Express
x-amzn-trace-id: Root=1-5fda2e20-6611d65472a90ccc2b8d31d8;Sampled=0
x-cache: Miss from cloudfront
via: 1.1 e64eb476d8f76d461d21278e018e195f.cloudfront.net (CloudFront)
x-amz-cf-pop: FRA50-C1
x-amz-cf-id: DtoP4_Iiaux2ecnWyvKR5uoD5YjI3boqw62XNQpzf-kxBeGfLW6f0A==

HTTP/1.1 200 OK
X-Powered-By: Express
Content-Type: text/xml; charset=utf-8
Content-Length: 479
ETag: W/"1df-5JxnLUWg1mxL4XsqY+aTl9fLyps"
Date: Fri, 05 Jun 2020 11:36:01 GMT
Connection: keep-alive

<?xml version="1.0" encoding="UTF-8"?><foo><bar></bar</foo>%

[dougmoscrop]

Is it reproducible every time or at least often? Can you push a repo or gist?

[csuermann]

The observed behavior was totally reproducible. But when I set up a new repo to share here, it suddenly worked. My guess is that something with the dependencies was wrong (perhaps unmet peer dependencies?) and got fixed by npm install. I apologize for any inconvenience.

[dougmoscrop]

No need to apologize, I would prefer to know/fix if possible, is there any chance you could try to take your package.json, strip any ~ and ^ and do another npm install? It won't help with transitive dependencies, but that might be a clue.