add notification apis (#2066)

add alerting apis

add generic proxy

pkg/kapis/generic/generic.go

@@ -0,0 +1,96 @@
+package generic
+
+import (
+	"fmt"
+	"github.com/emicklei/go-restful"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/apimachinery/pkg/util/proxy"
+	"k8s.io/klog"
+	"kubesphere.io/kubesphere/pkg/api"
+	"kubesphere.io/kubesphere/pkg/apiserver/runtime"
+	"net/http"
+	"net/url"
+	"strings"
+)
+
+// genericProxy is a simple proxy for external service.
+type genericProxy struct {
+	// proxy service endpoint
+	Endpoint *url.URL
+
+	// api group name exposed to clients
+	GroupName string
+
+	// api version
+	Version string
+}
+
+func NewGenericProxy(endpoint string, groupName string, version string) (*genericProxy, error) {
+	parse, err := url.Parse(endpoint)
+	if err != nil {
+		return nil, err
+	}
+
+	// trim path suffix slash
+	parse.Path = strings.Trim(parse.Path, "/")
+
+	return &genericProxy{
+		Endpoint:  parse,
+		GroupName: groupName,
+		Version:   version,
+	}, nil
+}
+
+func (g *genericProxy) AddToContainer(container *restful.Container) error {
+	webservice := runtime.NewWebService(schema.GroupVersion{
+		Group:   g.GroupName,
+		Version: g.Version,
+	})
+
+	webservice.Route(webservice.GET("/{path:*}").
+		To(g.handler).
+		Returns(http.StatusOK, api.StatusOK, nil))
+
+	webservice.Route(webservice.PUT("/{path:*}").
+		To(g.handler).
+		Returns(http.StatusOK, api.StatusOK, nil))
+
+	webservice.Route(webservice.POST("/{path:*}").
+		To(g.handler).
+		Returns(http.StatusOK, api.StatusOK, nil))
+
+	webservice.Route(webservice.DELETE("/{path:*}").
+		To(g.handler).
+		Returns(http.StatusOK, api.StatusOK, nil))
+
+	container.Add(webservice)
+	return nil
+
+}
+
+func (g *genericProxy) handler(request *restful.Request, response *restful.Response) {
+	u := g.makeURL(request)
+
+	httpProxy := proxy.NewUpgradeAwareHandler(u, http.DefaultTransport, false, false, &errorResponder{})
+	httpProxy.ServeHTTP(response, request.Request)
+}
+
+func (g *genericProxy) makeURL(request *restful.Request) *url.URL {
+	u := *(request.Request.URL)
+	u.Host = g.Endpoint.Host
+	u.Scheme = g.Endpoint.Scheme
+	u.Path = strings.Replace(request.Request.URL.Path, fmt.Sprintf("/kapis/%s", g.GroupName), "", 1)
+
+	// prepend path from endpoint
+	if len(g.Endpoint.Path) != 0 {
+		u.Path = fmt.Sprintf("/%s%s", g.Endpoint.Path, u.Path)
+	}
+
+	return &u
+}
+
+type errorResponder struct{}
+
+func (e *errorResponder) Error(w http.ResponseWriter, req *http.Request, err error) {
+	klog.Error(err)
+}