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handler_proxy.go
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handler_proxy.go
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/*
Copyright 2016 The Kubernetes Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package apiserver
import (
"context"
"net/http"
"net/url"
"strings"
"sync/atomic"
"time"
"k8s.io/apimachinery/pkg/runtime"
"k8s.io/apimachinery/pkg/util/httpstream"
"k8s.io/apimachinery/pkg/util/httpstream/spdy"
utilnet "k8s.io/apimachinery/pkg/util/net"
"k8s.io/apimachinery/pkg/util/proxy"
"k8s.io/apiserver/pkg/endpoints/handlers/responsewriters"
endpointmetrics "k8s.io/apiserver/pkg/endpoints/metrics"
genericapirequest "k8s.io/apiserver/pkg/endpoints/request"
genericfeatures "k8s.io/apiserver/pkg/features"
"k8s.io/apiserver/pkg/server/egressselector"
utilfeature "k8s.io/apiserver/pkg/util/feature"
restclient "k8s.io/client-go/rest"
"k8s.io/client-go/transport"
"k8s.io/klog"
apiregistrationv1api "k8s.io/kube-aggregator/pkg/apis/apiregistration/v1"
apiregistrationv1apihelper "k8s.io/kube-aggregator/pkg/apis/apiregistration/v1/helper"
)
const (
aggregatorComponent string = "aggregator"
aggregatedDiscoveryTimeout = 5 * time.Second
)
// proxyHandler provides a http.Handler which will proxy traffic to locations
// specified by items implementing Redirector.
type proxyHandler struct {
// localDelegate is used to satisfy local APIServices
localDelegate http.Handler
// proxyClientCert/Key are the client cert used to identify this proxy. Backing APIServices use
// this to confirm the proxy's identity
proxyClientCert []byte
proxyClientKey []byte
proxyTransport *http.Transport
// Endpoints based routing to map from cluster IP to routable IP
serviceResolver ServiceResolver
handlingInfo atomic.Value
// egressSelector selects the proper egress dialer to communicate with the custom apiserver
// overwrites proxyTransport dialer if not nil
egressSelector *egressselector.EgressSelector
}
type proxyHandlingInfo struct {
// local indicates that this APIService is locally satisfied
local bool
// name is the name of the APIService
name string
// restConfig holds the information for building a roundtripper
restConfig *restclient.Config
// transportBuildingError is an error produced while building the transport. If this
// is non-nil, it will be reported to clients.
transportBuildingError error
// proxyRoundTripper is the re-useable portion of the transport. It does not vary with any request.
proxyRoundTripper http.RoundTripper
// serviceName is the name of the service this handler proxies to
serviceName string
// namespace is the namespace the service lives in
serviceNamespace string
// serviceAvailable indicates this APIService is available or not
serviceAvailable bool
// servicePort is the port of the service this handler proxies to
servicePort int32
}
func proxyError(w http.ResponseWriter, req *http.Request, error string, code int) {
http.Error(w, error, code)
ctx := req.Context()
info, ok := genericapirequest.RequestInfoFrom(ctx)
if !ok {
klog.Warning("no RequestInfo found in the context")
return
}
// TODO: record long-running request differently? The long-running check func does not necessarily match the one of the aggregated apiserver
endpointmetrics.RecordRequestTermination(req, info, aggregatorComponent, code)
}
func (r *proxyHandler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
value := r.handlingInfo.Load()
if value == nil {
r.localDelegate.ServeHTTP(w, req)
return
}
handlingInfo := value.(proxyHandlingInfo)
if handlingInfo.local {
if r.localDelegate == nil {
http.Error(w, "", http.StatusNotFound)
return
}
r.localDelegate.ServeHTTP(w, req)
return
}
if !handlingInfo.serviceAvailable {
proxyError(w, req, "service unavailable", http.StatusServiceUnavailable)
return
}
if handlingInfo.transportBuildingError != nil {
proxyError(w, req, handlingInfo.transportBuildingError.Error(), http.StatusInternalServerError)
return
}
user, ok := genericapirequest.UserFrom(req.Context())
if !ok {
proxyError(w, req, "missing user", http.StatusInternalServerError)
return
}
// write a new location based on the existing request pointed at the target service
location := &url.URL{}
location.Scheme = "https"
rloc, err := r.serviceResolver.ResolveEndpoint(handlingInfo.serviceNamespace, handlingInfo.serviceName, handlingInfo.servicePort)
if err != nil {
klog.Errorf("error resolving %s/%s: %v", handlingInfo.serviceNamespace, handlingInfo.serviceName, err)
proxyError(w, req, "service unavailable", http.StatusServiceUnavailable)
return
}
location.Host = rloc.Host
location.Path = req.URL.Path
location.RawQuery = req.URL.Query().Encode()
newReq, cancelFn := newRequestForProxy(location, req)
defer cancelFn()
if handlingInfo.proxyRoundTripper == nil {
proxyError(w, req, "", http.StatusNotFound)
return
}
// we need to wrap the roundtripper in another roundtripper which will apply the front proxy headers
proxyRoundTripper, upgrade, err := maybeWrapForConnectionUpgrades(handlingInfo.restConfig, handlingInfo.proxyRoundTripper, req)
if err != nil {
proxyError(w, req, err.Error(), http.StatusInternalServerError)
return
}
proxyRoundTripper = transport.NewAuthProxyRoundTripper(user.GetName(), user.GetGroups(), user.GetExtra(), proxyRoundTripper)
// if we are upgrading, then the upgrade path tries to use this request with the TLS config we provide, but it does
// NOT use the roundtripper. Its a direct call that bypasses the round tripper. This means that we have to
// attach the "correct" user headers to the request ahead of time. After the initial upgrade, we'll be back
// at the roundtripper flow, so we only have to muck with this request, but we do have to do it.
if upgrade {
transport.SetAuthProxyHeaders(newReq, user.GetName(), user.GetGroups(), user.GetExtra())
}
handler := proxy.NewUpgradeAwareHandler(location, proxyRoundTripper, true, upgrade, &responder{w: w})
handler.ServeHTTP(w, newReq)
}
// newRequestForProxy returns a shallow copy of the original request with a context that may include a timeout for discovery requests
func newRequestForProxy(location *url.URL, req *http.Request) (*http.Request, context.CancelFunc) {
newCtx := req.Context()
cancelFn := func() {}
if requestInfo, ok := genericapirequest.RequestInfoFrom(req.Context()); ok {
// trim leading and trailing slashes. Then "/apis/group/version" requests are for discovery, so if we have exactly three
// segments that we are going to proxy, we have a discovery request.
if !requestInfo.IsResourceRequest && len(strings.Split(strings.Trim(requestInfo.Path, "/"), "/")) == 3 {
// discovery requests are used by kubectl and others to determine which resources a server has. This is a cheap call that
// should be fast for every aggregated apiserver. Latency for aggregation is expected to be low (as for all extensions)
// so forcing a short timeout here helps responsiveness of all clients.
newCtx, cancelFn = context.WithTimeout(newCtx, aggregatedDiscoveryTimeout)
}
}
// WithContext creates a shallow clone of the request with the same context.
newReq := req.WithContext(newCtx)
newReq.Header = utilnet.CloneHeader(req.Header)
newReq.URL = location
newReq.Host = location.Host
return newReq, cancelFn
}
// maybeWrapForConnectionUpgrades wraps the roundtripper for upgrades. The bool indicates if it was wrapped
func maybeWrapForConnectionUpgrades(restConfig *restclient.Config, rt http.RoundTripper, req *http.Request) (http.RoundTripper, bool, error) {
if !httpstream.IsUpgradeRequest(req) {
return rt, false, nil
}
tlsConfig, err := restclient.TLSConfigFor(restConfig)
if err != nil {
return nil, true, err
}
followRedirects := utilfeature.DefaultFeatureGate.Enabled(genericfeatures.StreamingProxyRedirects)
requireSameHostRedirects := utilfeature.DefaultFeatureGate.Enabled(genericfeatures.ValidateProxyRedirects)
upgradeRoundTripper := spdy.NewRoundTripper(tlsConfig, followRedirects, requireSameHostRedirects)
wrappedRT, err := restclient.HTTPWrappersForConfig(restConfig, upgradeRoundTripper)
if err != nil {
return nil, true, err
}
return wrappedRT, true, nil
}
// responder implements rest.Responder for assisting a connector in writing objects or errors.
type responder struct {
w http.ResponseWriter
}
// TODO this should properly handle content type negotiation
// if the caller asked for protobuf and you write JSON bad things happen.
func (r *responder) Object(statusCode int, obj runtime.Object) {
responsewriters.WriteRawJSON(statusCode, obj, r.w)
}
func (r *responder) Error(_ http.ResponseWriter, _ *http.Request, err error) {
http.Error(r.w, err.Error(), http.StatusInternalServerError)
}
// these methods provide locked access to fields
func (r *proxyHandler) updateAPIService(apiService *apiregistrationv1api.APIService) {
if apiService.Spec.Service == nil {
r.handlingInfo.Store(proxyHandlingInfo{local: true})
return
}
newInfo := proxyHandlingInfo{
name: apiService.Name,
restConfig: &restclient.Config{
TLSClientConfig: restclient.TLSClientConfig{
Insecure: apiService.Spec.InsecureSkipTLSVerify,
ServerName: apiService.Spec.Service.Name + "." + apiService.Spec.Service.Namespace + ".svc",
CertData: r.proxyClientCert,
KeyData: r.proxyClientKey,
CAData: apiService.Spec.CABundle,
},
},
serviceName: apiService.Spec.Service.Name,
serviceNamespace: apiService.Spec.Service.Namespace,
servicePort: *apiService.Spec.Service.Port,
serviceAvailable: apiregistrationv1apihelper.IsAPIServiceConditionTrue(apiService, apiregistrationv1api.Available),
}
if r.egressSelector != nil {
networkContext := egressselector.Cluster.AsNetworkContext()
var egressDialer utilnet.DialFunc
egressDialer, err := r.egressSelector.Lookup(networkContext)
if err != nil {
klog.Warning(err.Error())
} else {
newInfo.restConfig.Dial = egressDialer
}
} else if r.proxyTransport != nil && r.proxyTransport.DialContext != nil {
newInfo.restConfig.Dial = r.proxyTransport.DialContext
}
newInfo.proxyRoundTripper, newInfo.transportBuildingError = restclient.TransportFor(newInfo.restConfig)
if newInfo.transportBuildingError != nil {
klog.Warning(newInfo.transportBuildingError.Error())
}
r.handlingInfo.Store(newInfo)
}