为什么Golang grpc-gateway的GET路由匹配POST请求？

Question

I found a "get" route will match both HTTP GET and HTTP POST requests. For example:

rpc aaa(User) returns (User) {
  option (google.api.http) = {
  get: "/api/v1/aaa"
};

It matches both curl -v -X GET -k https://127.0.0.1/api/v1/aaa and curl -v -X POST -k https://127.0.0.1/api/v1/aaa.

I was wondering if it's possible to strictly match all routes including methods?

Answer 1

Short answer

It is because you did not specify the content-type of the request.

Long answer

By spec, it is allowed for you to encode your GET request into a POST method with Content-Type: application/x-www-url-encoded.

So the request routing table in grpc-gateway tries to fallback from POST method to GET when the Content-Type of your request is application/x-www-url-encoded.

ref. https://groups.google.com/d/msg/grpc-io/Xqx80hG0D44/1gwmwBcnNScJ

"(Note) URL has a length limitation (go/longer-urls). It's enfoced by some browsers and proxies. If your GET request exceeds the limitation, browser may reject to send them. You may change to use a POST request with content type application/x-www-form-urlencoded instead. If the POST + URL is already been mapped to another backend function, you shall add "X-HTTP-Method-Override: GET" header to override the HTTP method and obtain the correct mapping.