support apiserver url rewrite

Signed-off-by: huiwq1990 <[email protected]>

pkg/apiserver/apiserver.go

@@ -17,15 +17,18 @@ import (
 	"k8s.io/client-go/discovery"
 	clientrest "k8s.io/client-go/rest"
 	"k8s.io/client-go/restmapper"
+	"k8s.io/klog/v2"
 
 	internal "github.com/clusterpedia-io/api/clusterpedia"
 	"github.com/clusterpedia-io/api/clusterpedia/install"
+	"github.com/clusterpedia-io/clusterpedia/pkg/apiserver/features"
 	"github.com/clusterpedia-io/clusterpedia/pkg/apiserver/registry/clusterpedia/collectionresources"
 	"github.com/clusterpedia-io/clusterpedia/pkg/apiserver/registry/clusterpedia/resources"
 	"github.com/clusterpedia-io/clusterpedia/pkg/generated/clientset/versioned"
 	informers "github.com/clusterpedia-io/clusterpedia/pkg/generated/informers/externalversions"
 	"github.com/clusterpedia-io/clusterpedia/pkg/kubeapiserver"
 	"github.com/clusterpedia-io/clusterpedia/pkg/storage"
+	clusterpediafeature "github.com/clusterpedia-io/clusterpedia/pkg/utils/feature"
 	"github.com/clusterpedia-io/clusterpedia/pkg/utils/filters"
 )
 
@@ -139,6 +142,10 @@ func (config completedConfig) New() (*ClusterPediaServer, error) {
 		handler := handlerChainFunc(apiHandler, c)
 		handler = filters.WithRequestQuery(handler)
 		handler = filters.WithAcceptHeader(handler)
+		if clusterpediafeature.FeatureGate.Enabled(features.ApiServerURLRewrite) {
+			klog.InfoS("Enable rewrite apiserver url")
+			handler = filters.WithRewriteFilter(handler)
+		}
 		return handler
 	}
 

pkg/apiserver/features/features.go

@@ -0,0 +1,26 @@
+package features
+
+import (
+	"k8s.io/apimachinery/pkg/util/runtime"
+	"k8s.io/component-base/featuregate"
+
+	clusterpediafeature "github.com/clusterpedia-io/clusterpedia/pkg/utils/feature"
+)
+
+const (
+
+	// ApiServerURLRewrite is a feature gate for rewrite apiserver request's URL
+	// owner: @huiwq1990
+	// alpha: v0.7.0
+	ApiServerURLRewrite featuregate.Feature = "ApiServerURLRewrite"
+)
+
+func init() {
+	runtime.Must(clusterpediafeature.MutableFeatureGate.Add(defaultApiServerFeatureGates))
+}
+
+// defaultApiServerFeatureGates consists of all known apiserver feature keys.
+// To add a new feature, define a key for it above and add it here.
+var defaultApiServerFeatureGates = map[featuregate.Feature]featuregate.FeatureSpec{
+	ApiServerURLRewrite: {Default: false, PreRelease: featuregate.Alpha},
+}

pkg/utils/filters/rewrite.go

@@ -0,0 +1,157 @@
+package filters
+
+import (
+	"fmt"
+	"net/http"
+	"net/url"
+	"path"
+	"regexp"
+	"strings"
+
+	"k8s.io/klog/v2"
+)
+
+const OriginURIHeaderKey = "X-Rewrite-Original-URI"
+
+type Rule struct {
+	Pattern string
+	To      string
+	*regexp.Regexp
+}
+
+var regfmt = regexp.MustCompile(`:[^/#?()\.\\]+`)
+
+func NewRule(pattern, to string) (*Rule, error) {
+	pattern = regfmt.ReplaceAllStringFunc(pattern, func(m string) string {
+		return fmt.Sprintf(`(?P<%s>[^/#?]+)`, m[1:])
+	})
+
+	reg, err := regexp.Compile(pattern)
+	if err != nil {
+		return nil, err
+	}
+
+	return &Rule{
+		pattern,
+		to,
+		reg,
+	}, nil
+}
+
+func (r *Rule) Rewrite(req *http.Request) bool {
+	oriPath := req.URL.Path
+
+	if strings.HasPrefix(oriPath, OldResourceApiServerPrefix) {
+		return false
+	}
+
+	if !r.MatchString(oriPath) {
+		return false
+	}
+
+	klog.V(4).InfoS("Rewrite url from", "URL", req.URL.EscapedPath())
+
+	to := path.Clean(r.Replace(req.URL))
+
+	u, e := url.Parse(to)
+	if e != nil {
+		return false
+	}
+
+	req.Header.Set(OriginURIHeaderKey, req.URL.RequestURI())
+
+	req.URL.Path = u.Path
+	req.URL.RawPath = u.RawPath
+	if u.RawQuery != "" {
+		req.URL.RawQuery = u.RawQuery
+	}
+
+	klog.V(4).InfoS("Rewrite url to", "URL", req.URL.EscapedPath())
+
+	return true
+}
+
+func (r *Rule) Replace(u *url.URL) string {
+	if !hit("\\$|\\:", r.To) {
+		return r.To
+	}
+
+	uri := u.RequestURI()
+
+	regFrom := regexp.MustCompile(r.Pattern)
+	match := regFrom.FindStringSubmatchIndex(uri)
+
+	result := regFrom.ExpandString([]byte(""), r.To, uri, match)
+
+	str := string(result[:])
+
+	if hit("\\:", str) {
+		return r.replaceNamedParams(uri, str)
+	}
+
+	return str
+}
+
+func (r *Rule) replaceNamedParams(from, to string) string {
+	fromMatches := r.FindStringSubmatch(from)
+
+	if len(fromMatches) > 0 {
+		for i, name := range r.SubexpNames() {
+			if len(name) > 0 {
+				to = strings.Replace(to, ":"+name, fromMatches[i], -1)
+			}
+		}
+	}
+
+	return to
+}
+
+func NewHandler(rules map[string]string) RewriteHandler {
+	var h RewriteHandler
+
+	for key, val := range rules {
+		r, e := NewRule(key, val)
+		if e != nil {
+			panic(e)
+		}
+
+		h.rules = append(h.rules, r)
+	}
+
+	return h
+}
+
+const OldResourceApiServerPrefix = "/apis/clusterpedia.io/v1beta1/resources"
+
+func WithRewriteFilter(handler http.Handler) http.Handler {
+	rh := NewHandler(map[string]string{
+		"/(.*)": fmt.Sprintf("%s/$1", OldResourceApiServerPrefix),
+	})
+
+	return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
+		rh.ServeHTTP(w, req)
+		handler.ServeHTTP(w, req)
+	})
+}
+
+type RewriteHandler struct {
+	rules []*Rule
+}
+
+func (h *RewriteHandler) ServeHTTP(res http.ResponseWriter, req *http.Request) {
+	for _, r := range h.rules {
+		ok := r.Rewrite(req)
+		if ok {
+			break
+		}
+	}
+}
+
+func hit(pattern, str string) bool {
+	r, e := regexp.MatchString(pattern, str)
+	if e != nil {
+		return false
+	}
+
+	return r
+}

pkg/utils/filters/rewrite_test.go

@@ -0,0 +1,69 @@
+package filters
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+type testFixture struct {
+	from string
+	to   string
+}
+
+type testCase struct {
+	pattern  string
+	to       string
+	fixtures []testFixture
+}
+
+func TestRewrite(t *testing.T) {
+	tests := []testCase{
+		{
+			pattern: "/(.*)",
+			to:      "/apis/clusterpedia.io/v1beta1/resources/$1",
+			fixtures: []testFixture{
+				{from: "/api/v1/namespaces/default/pods", to: "/apis/clusterpedia.io/v1beta1/resources/api/v1/namespaces/default/pods"},
+				{from: "/apis/clusterpedia.io/v1beta1/clusters", to: "/apis/clusterpedia.io/v1beta1/resources/apis/clusterpedia.io/v1beta1/clusters"},
+				{from: "/apis/clusterpedia.io/v1beta1/resources/api/v1/namespaces/default/pods", to: "/apis/clusterpedia.io/v1beta1/resources/api/v1/namespaces/default/pods"},
+				{from: "/apis/clusterpedia.io/v1beta1/resources/apis/clusterpedia.io/v1beta1/clusters", to: "/apis/clusterpedia.io/v1beta1/resources/apis/clusterpedia.io/v1beta1/clusters"},
+			},
+		},
+	}
+
+	for _, test := range tests {
+		t.Logf("Test - pattern: %s, to: %s", test.pattern, test.to)
+
+		for _, fixture := range test.fixtures {
+			req, err := http.NewRequest("GET", fixture.from, nil)
+			if err != nil {
+				t.Fatalf("Fixture %v - create HTTP request error: %v", fixture, err)
+			}
+
+			h := NewHandler(map[string]string{
+				test.pattern: test.to,
+			})
+
+			t.Logf("From: %s", req.URL.EscapedPath())
+			if req.URL.EscapedPath() != fixture.from {
+				t.Errorf("Invalid test fixture: %s", fixture.from)
+			}
+
+			res := httptest.NewRecorder()
+			h.ServeHTTP(res, req)
+
+			t.Logf("Rewrited: %s", req.URL.EscapedPath())
+			if req.URL.EscapedPath() != fixture.to {
+				t.Errorf("Test failed \n pattern: %s, to: %s, \n fixture: %s to %s, \n result: %s",
+					test.pattern, test.to, fixture.from, fixture.to, req.URL.EscapedPath())
+			}
+
+			if req.Header.Get(OriginURIHeaderKey) != "" {
+				// matched
+				if req.Header.Get(OriginURIHeaderKey) != fixture.from {
+					t.Error("incorrect flag")
+				}
+			}
+		}
+	}
+}