Fix bug which mistakes 400 error for 500

cherry-picked from upstream moby#22762

When users run/create a container without specifying a command, daemon
will return 500 error instead of 400 error.

For example:

Dockerfile:
From debian:jessie
CMD []

docker build -t test .
docker create/run test

Signed-off-by: Wang Xing hzwangxing@corp.netease.com

Signed-off-by: xiekeyang <xiekeyang@huawei.com>

api/server/httputils/errors.go

@@ -50,6 +50,7 @@ func WriteError(w http.ResponseWriter, err error) {
 			"cannot find":           http.StatusNotFound,
 			"no such":               http.StatusNotFound,
 			"bad parameter":         http.StatusBadRequest,
+			"no command":            http.StatusBadRequest,
 			"conflict":              http.StatusConflict,
 			"impossible":            http.StatusNotAcceptable,
 			"wrong login/password":  http.StatusUnauthorized,

docs/reference/api/docker_remote_api.md

@@ -133,6 +133,8 @@ This section lists each version from latest to oldest.  Each listing includes a
 * `POST /containers/create` now allows specifying `nocopy` for named volumes, which disables automatic copying from the container path to the volume.
 * `POST /auth` now returns an `IdentityToken` when supported by a registry.
 * `POST /containers/create` with both `Hostname` and `Domainname` fields specified will result in the container's hostname being set to `Hostname`, rather than `Hostname.Domainname`.
+* `POST /containers/create` now returns a HTTP 400 "bad parameter" message
+if no command is specified (instead of a HTTP 500 "server error")
 
 ### v1.22 API changes
 

docs/reference/api/docker_remote_api_v1.18.md

@@ -293,6 +293,7 @@ Query Parameters:
 Status Codes:
 
 -   **201** – no error
+-   **400** – bad parameter
 -   **404** – no such container
 -   **406** – impossible to attach (container not running)
 -   **500** – server error

docs/reference/api/docker_remote_api_v1.19.md

@@ -304,6 +304,7 @@ Query Parameters:
 Status Codes:
 
 -   **201** – no error
+-   **400** – bad parameter
 -   **404** – no such container
 -   **406** – impossible to attach (container not running)
 -   **500** – server error

docs/reference/api/docker_remote_api_v1.20.md

@@ -308,6 +308,7 @@ Query Parameters:
 Status Codes:
 
 -   **201** – no error
+-   **400** – bad parameter
 -   **404** – no such container
 -   **406** – impossible to attach (container not running)
 -   **500** – server error

docs/reference/api/docker_remote_api_v1.21.md

@@ -331,6 +331,7 @@ Query Parameters:
 Status Codes:
 
 -   **201** – no error
+-   **400** – bad parameter
 -   **404** – no such container
 -   **406** – impossible to attach (container not running)
 -   **500** – server error

docs/reference/api/docker_remote_api_v1.22.md

@@ -439,6 +439,7 @@ Query Parameters:
 Status Codes:
 
 -   **201** – no error
+-   **400** – bad parameter
 -   **404** – no such container
 -   **406** – impossible to attach (container not running)
 -   **500** – server error

docs/reference/api/docker_remote_api_v1.23.md

@@ -468,6 +468,7 @@ Query Parameters:
 Status Codes:
 
 -   **201** – no error
+-   **400** – bad parameter
 -   **404** – no such container
 -   **406** – impossible to attach (container not running)
 -   **500** – server error