Make supervisor errors parsable by Kubernetes client libs

This gives nicer errors from Kubernetes components during startup, and
reduces LOC a bit by using the upstream responsewriters module instead
of writing the headers and body by hand.

Signed-off-by: Brad Davidson <brad.davidson@rancher.com>

pkg/server/auth.go

@@ -5,7 +5,12 @@ import (
 
 	"github.com/gorilla/mux"
 	"github.com/k3s-io/k3s/pkg/daemons/config"
+	"github.com/k3s-io/k3s/pkg/generated/clientset/versioned/scheme"
 	"github.com/sirupsen/logrus"
+	apierrors "k8s.io/apimachinery/pkg/api/errors"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/apiserver/pkg/endpoints/handlers/responsewriters"
 	"k8s.io/apiserver/pkg/endpoints/request"
 )
 
@@ -24,23 +29,23 @@ func doAuth(roles []string, serverConfig *config.Control, next http.Handler, rw
 	switch {
 	case serverConfig == nil:
 		logrus.Errorf("Authenticate not initialized: serverConfig is nil")
-		rw.WriteHeader(http.StatusUnauthorized)
+		unauthorized(rw, req)
 		return
 	case serverConfig.Runtime.Authenticator == nil:
 		logrus.Errorf("Authenticate not initialized: serverConfig.Runtime.Authenticator is nil")
-		rw.WriteHeader(http.StatusUnauthorized)
+		unauthorized(rw, req)
 		return
 	}
 
 	resp, ok, err := serverConfig.Runtime.Authenticator.AuthenticateRequest(req)
 	if err != nil {
 		logrus.Errorf("Failed to authenticate request from %s: %v", req.RemoteAddr, err)
-		rw.WriteHeader(http.StatusUnauthorized)
+		unauthorized(rw, req)
 		return
 	}
 
 	if !ok || !hasRole(roles, resp.User.GetGroups()) {
-		rw.WriteHeader(http.StatusForbidden)
+		forbidden(rw, req)
 		return
 	}
 
@@ -56,3 +61,27 @@ func authMiddleware(serverConfig *config.Control, roles ...string) mux.Middlewar
 		})
 	}
 }
+
+func unauthorized(resp http.ResponseWriter, req *http.Request) {
+	responsewriters.ErrorNegotiated(
+		&apierrors.StatusError{ErrStatus: metav1.Status{
+			Status:  metav1.StatusFailure,
+			Code:    http.StatusUnauthorized,
+			Reason:  metav1.StatusReasonUnauthorized,
+			Message: "not authorized",
+		}},
+		scheme.Codecs.WithoutConversion(), schema.GroupVersion{}, resp, req,
+	)
+}
+
+func forbidden(resp http.ResponseWriter, req *http.Request) {
+	responsewriters.ErrorNegotiated(
+		&apierrors.StatusError{ErrStatus: metav1.Status{
+			Status:  metav1.StatusFailure,
+			Code:    http.StatusForbidden,
+			Reason:  metav1.StatusReasonForbidden,
+			Message: "forbidden",
+		}},
+		scheme.Codecs.WithoutConversion(), schema.GroupVersion{}, resp, req,
+	)
+}

pkg/server/router.go

@@ -19,6 +19,7 @@ import (
 	"github.com/k3s-io/k3s/pkg/bootstrap"
 	"github.com/k3s-io/k3s/pkg/cli/cmds"
 	"github.com/k3s-io/k3s/pkg/daemons/config"
+	"github.com/k3s-io/k3s/pkg/generated/clientset/versioned/scheme"
 	"github.com/k3s-io/k3s/pkg/nodepassword"
 	"github.com/k3s-io/k3s/pkg/util"
 	"github.com/k3s-io/k3s/pkg/version"
@@ -26,9 +27,12 @@ import (
 	certutil "github.com/rancher/dynamiclistener/cert"
 	coreclient "github.com/rancher/wrangler/pkg/generated/controllers/core/v1"
 	"github.com/sirupsen/logrus"
+	apierrors "k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apimachinery/pkg/util/json"
 	"k8s.io/apiserver/pkg/authentication/user"
+	"k8s.io/apiserver/pkg/endpoints/handlers/responsewriters"
 )
 
 const (
@@ -86,22 +90,20 @@ func apiserver(runtime *config.ControlRuntime) http.Handler {
 		if runtime != nil && runtime.APIServer != nil {
 			runtime.APIServer.ServeHTTP(resp, req)
 		} else {
-			data := []byte("apiserver not ready")
-			resp.WriteHeader(http.StatusInternalServerError)
-			resp.Header().Set("Content-Type", "text/plain")
-			resp.Header().Set("Content-length", strconv.Itoa(len(data)))
-			resp.Write(data)
+			responsewriters.ErrorNegotiated(
+				apierrors.NewServiceUnavailable("apiserver not ready"),
+				scheme.Codecs.WithoutConversion(), schema.GroupVersion{}, resp, req,
+			)
 		}
 	})
 }
 
 func apiserverDisabled() http.Handler {
 	return http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
-		data := []byte("apiserver disabled")
-		resp.WriteHeader(http.StatusServiceUnavailable)
-		resp.Header().Set("Content-Type", "text/plain")
-		resp.Header().Set("Content-length", strconv.Itoa(len(data)))
-		resp.Write(data)
+		responsewriters.ErrorNegotiated(
+			apierrors.NewServiceUnavailable("apiserver disabled"),
+			scheme.Codecs.WithoutConversion(), schema.GroupVersion{}, resp, req,
+		)
 	})
 }
 
@@ -111,11 +113,10 @@ func bootstrapHandler(runtime *config.ControlRuntime) http.Handler {
 	}
 	return http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
 		logrus.Warnf("Received HTTP bootstrap request from %s, but embedded etcd is not enabled.", req.RemoteAddr)
-		data := []byte("etcd disabled")
-		resp.WriteHeader(http.StatusBadRequest)
-		resp.Header().Set("Content-Type", "text/plain")
-		resp.Header().Set("Content-length", strconv.Itoa(len(data)))
-		resp.Write(data)
+		responsewriters.ErrorNegotiated(
+			apierrors.NewBadRequest("etcd disabled"),
+			scheme.Codecs.WithoutConversion(), schema.GroupVersion{}, resp, req,
+		)
 	})
 }