Is here assuming all responses are using "Content-Type: application/json"?

https://github.com/awslabs/aws-sam-local/blob/629e6277c88b6a41edcc38f5f7227ad29888b78d/runtime.go#L544

I am hitting an issue that sam-local response contains multiple contradicted “Content-Type” header. Please see the following curl command debugging output. In my API, the only Content-Type defined is text/plain format, but using the sam-local test, its response message contains an extra “Content-Type” header application/json. Could you please confirm is this line injecting the header, if so, can this assumption be removed and honor the response header returned by Lambda functions?

Please see the following out console output.

$> curl -v -H "Accept: text/plain" http://127.0.0.1:3000/resources/greeting
* Trying 127.0.0.1...
* TCP_NODELAY set
* Connected to 127.0.0.1 (127.0.0.1) port 3000 (#0)
> GET /resources/greeting HTTP/1.1
> Host: 127.0.0.1:3000
> User-Agent: curl/7.54.0
> Accept: text/plain
>
< HTTP/1.1 200 OK
< Content-Type: application/json
< Content-Type: text/plain
< Date: Mon, 19 Mar 2018 07:21:00 GMT
< Content-Length: 5
<
* Connection #0 to host 127.0.0.1 left intact
Hello

[ronaldwidha]

confirmed.

$ curl -v --header 'Accept:text/html' 'http://localhost:8080/'

yields

...
< HTTP/1.1 200 OK
< Content-Type: application/json
< Content-Type: text/html
< Date: Thu, 12 Apr 2018 13:40:56 GMT
...

[jfuss]

This should be fixed in our newest release: https://github.com/awslabs/aws-sam-cli/releases/tag/v0.3.0

Please feel free to reopen if the issue persists.