How does kong handle long duration requests?

Hello All,

I have a local setup of an application which has a delayed response of 60 seconds (This is my upstream on kong)

When try to access the application via curl command, I get the expected output in 60 seconds.

Whereas when I try to access the same via kong (curl -o /dev/null -s -w “%{http_code}\n” api_gateway_url/my_custom_app), my curl command doesn’t terminates. I have to explicitly cancel the request (pressing control + C)

I check the error logs and see the below error
2020/02/26 14:29:31 [error] 9352#0: *1097844 upstream timed out (110: Connection timed out) while reading response header from upstream, client: X.X.X.X

Is this an expected behavior, that if the client doesn’t set a default timeout for the connection, that kong will not return any exit code after getting a connection timeout from the upstream?

My kong/nginx keepalive_timeout is set to 60 seconds


Please increase the timeouts defined in the service object. The default timeouts are 60s for connect, read and write. You can increase them dynamically via the admin api on a per service basis.

Hello @hbagdi,
Thanks for the reply. But why I do not get any http code in the response on the client side. Is this an expected behavior ?


This happens because Kong closes the upstream closes the TCP connection.

@hbagdi : Sorry I didn’t get your sentence. Can you please re-phrase or elaborate it ?
Also, shouldn’t kong http send error code to the client?

My curl output :

date && curl -vk http://kongurl:8000/some-app
Fri Feb 28 14:30:01 CET 2020
* About to connect() to kongurl port 8000 (#0)
* Trying x.x.x.x…
* Connected to kongurl (x.x.x.x) port 8000 (#0)
> GET /some-app HTTP/1.1
> User-Agent: curl/7.29.0
> Host: kongurl:8000
> Accept: */*
< HTTP/1.1 504 Gateway Time-out
< Date: Fri, 28 Feb 2020 13:36:01 GMT
< Content-Type: text/plain; charset=UTF-8
< Transfer-Encoding: chunked
< Connection: keep-alive
< Server: kong/1.4.0
< X-Kong-Upstream-Latency: 60001
< X-Kong-Proxy-Latency: 300003
< Via: kong/1.4.0
The upstream server is timing out
* Connection #0 to host kongurl left intact

I notice that kong does sends the client a timeout but only after 6 minutes, as well as from error logs I see that kong received 6 timeouts.
Upstream application has a 60 sec delay and kong configuration for this upstream has timeout value of 60 secs (referring your previous comment)

That’s because by default the number of retries is set to 5 minutes.

Everything here is working as expected. What is your question now?

Hello @hbagdi,

This means that once the request from kong is sent to the upstream then, incase of http_500 | http_502 | http_503 | http_504 | http_403 | http_404 | http_429 or a timeout , kong will retry to send the same request 5 times right to the same upstream(as I do not have proxy_next_upstream setup)?

Service is created with defaults :
“host”: “service-xxxxxxxxxxxxxxxxxxxx”,
“created_at”: 1582898310,
“connect_timeout”: 60000,
“id”: “60d38a0e-e4df-4d46-8590-6a2e007f8b69”,
“protocol”: “http”,
“name”: “service-xxxxxxxxxxxxxxxx”,
“read_timeout”: 60000,
“port”: 80,
“path”: “/”,
“updated_at”: 1582898310,
“retries”: 5,
“write_timeout”: 60000,
“tags”: null,
“client_certificate”: null
Route is also created with defaults :
“id”: “009b9971-9f48-47a7-b072-f99fcac11108”,
“tags”: null,
“updated_at”: 1582898310,
“destinations”: null,
“headers”: null,
“protocols”: [
“created_at”: 1582898310,
“snis”: null,
“service”: {
“id”: “60d38a0e-e4df-4d46-8590-6a2e007f8b69”
“name”: “route-yyyyyyyyyyyyyyyyy”,
“preserve_host”: false,
“regex_priority”: 0,
“strip_path”: true,
“sources”: null,
“paths”: [
“https_redirect_status_code”: 426,
“hosts”: null,
“methods”: null


I’m not sure but most probably not. Kong retries based on TCP layer errors and timeouts.