[TT-10538] Service Discovery support custom method and request body

[cuongtd1301]

Is your feature request related to a problem? Please describe.

When using the service discovery with etcd, I utilize etcd v3 which only supports the POST method and requires a request body. However, Tyk only supports the GET method which is used by etcd v2.

Describe the solution you'd like

• service_discovery: add method and body field

{
    "query_endpoint": "http://127.0.0.1:4001/v3/kv/range"
    "method" : "POST",
    "body": "{\"key\":\"AA==\",\"range_end\":\"AA==\"}"
}

• ServiceDiscovery: add method and body field

type ServiceDiscovery struct {
	spec                *apidef.ServiceDiscoveryConfiguration
	isNested            bool
	isTargetList        bool
	endpointReturnsList bool
	portSeperate        bool
	dataPath            string
	parentPath          string
	portPath            string
	targetPath          string
	method              string
	body                string
}

• func getServiceData: custom method and request body

func (s *ServiceDiscovery) getServiceData(method, requestURL, body string) (string, error) {
	req, err := http.NewRequest(method, requestURL, bytes.NewBuffer([]byte(body)))
	if err != nil {
		return "", err
	}
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return "", err
	}

	defer resp.Body.Close()
	contents, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return "", err
	}

	return string(contents), nil
}

[andyo-tyk]

Hi @cuongtd1301,

Thanks for flagging this issue.

We're not actively looking at Service Discovery at the moment, but when we do then we will certainly take your idea into account.

If you want to try an implementation yourself, we welcome PRs from the Tyk community.

Thanks for supporting Tyk!