Service create API returns 5xx status instead of 4xx #38140
Description
(as reported by @waseemshahwan in #31909 (comment))
Looks like a regression was introduced somewhere between Docker 17.07 and 17.09.1, causing the status code for a "conflict" to change from a 409 to a 500;
To reproduce; run a "service create" request twice (second time should return a "conflict";
curl -v \
--unix-socket /var/run/docker.sock \
-X POST \
"http://localhost/v1.30/services/create" \
-H "Content-Type: application/json" \
-d '{"EndpointSpec":{"Mode":"vip"},"Labels":{},"Mode":{"Replicated":{}},"Name":"testing","TaskTemplate":{"ContainerSpec":{"DNSConfig":{},"Image":"nginx:alpine@sha256:ae5da813f8ad7fa785d7668f0b018ecc8c3a87331527a61d83b3b5e816a0f03c","Init":false},"ForceUpdate":0,"Placement":{"Platforms":[{"Architecture":"amd64","OS":"linux"},{"OS":"linux"},{"Architecture":"arm64","OS":"linux"},{"Architecture":"386","OS":"linux"},{"Architecture":"ppc64le","OS":"linux"},{"Architecture":"s390x","OS":"linux"}]},"Resources":{"Limits":{},"Reservations":{}}}}'On Docker 17.07.0-ce
> POST /v1.30/services/create HTTP/1.1
> Host: localhost
> User-Agent: curl/7.61.1
> Accept: */*
> Content-Type: application/json
> Content-Length: 536
>
* upload completely sent off: 536 out of 536 bytes
< HTTP/1.1 409 Conflict
< Api-Version: 1.31
< Content-Type: application/json
< Docker-Experimental: false
< Ostype: linux
< Server: Docker/17.07.0-ce (linux)
< Date: Mon, 05 Nov 2018 16:10:58 GMT
< Content-Length: 86
<
{"message":"rpc error: code = Unknown desc = name conflicts with an existing object"}
On Docker 17.09.1-ce
> POST /v1.30/services/create HTTP/1.1
> Host: localhost
> User-Agent: curl/7.61.1
> Accept: */*
> Content-Type: application/json
> Content-Length: 536
>
* upload completely sent off: 536 out of 536 bytes
< HTTP/1.1 500 Internal Server Error
< Api-Version: 1.32
< Content-Type: application/json
< Docker-Experimental: false
< Ostype: linux
< Server: Docker/17.09.1-ce (linux)
< Date: Mon, 05 Nov 2018 16:11:59 GMT
< Content-Length: 86
<
{"message":"rpc error: code = Unknown desc = name conflicts with an existing object"}
On 18.06.1-ce (still reproduces)
* Trying /var/run/docker.sock...
* Connected to localhost (/var/run/docker.sock) port 80 (#0)
> POST /v1.30/services/create HTTP/1.1
> Host: localhost
> User-Agent: curl/7.61.1
> Accept: */*
> Content-Type: application/json
> Content-Length: 536
>
* upload completely sent off: 536 out of 536 bytes
< HTTP/1.1 500 Internal Server Error
< Api-Version: 1.38
< Content-Type: application/json
< Docker-Experimental: false
< Ostype: linux
< Server: Docker/18.06.1-ce (linux)
< Date: Mon, 05 Nov 2018 10:31:29 GMT
< Content-Length: 86
<
{"message":"rpc error: code = Unknown desc = name conflicts with an existing object"}
* Connection #0 to host localhost left intact