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injector.go
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injector.go
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// ------------------------------------------------------------
// Copyright (c) Microsoft Corporation and Dapr Contributors.
// Licensed under the MIT License.
// ------------------------------------------------------------
package injector
import (
"context"
"encoding/json"
"fmt"
"io"
"net/http"
"time"
v1 "k8s.io/api/admission/v1"
corev1 "k8s.io/api/core/v1"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/runtime"
"k8s.io/apimachinery/pkg/runtime/serializer"
"k8s.io/client-go/kubernetes"
"github.com/dapr/kit/logger"
scheme "github.com/dapr/dapr/pkg/client/clientset/versioned"
"github.com/dapr/dapr/pkg/injector/monitoring"
"github.com/dapr/dapr/utils"
)
const (
port = 4000
getKubernetesServiceAccountTimeoutSeconds = 10
systemGroup = "system:masters"
)
var log = logger.NewLogger("dapr.injector")
var allowedControllersServiceAccounts = []string{
"replicaset-controller",
"deployment-controller",
"cronjob-controller",
"job-controller",
"statefulset-controller",
"daemon-set-controller",
}
// Injector is the interface for the Dapr runtime sidecar injection component.
type Injector interface {
Run(ctx context.Context)
}
type injector struct {
config Config
deserializer runtime.Decoder
server *http.Server
kubeClient kubernetes.Interface
daprClient scheme.Interface
authUIDs []string
}
// toAdmissionResponse is a helper function to create an AdmissionResponse
// with an embedded error.
func toAdmissionResponse(err error) *v1.AdmissionResponse {
return &v1.AdmissionResponse{
Result: &metav1.Status{
Message: err.Error(),
},
}
}
func getAppIDFromRequest(req *v1.AdmissionRequest) string {
// default App ID
appID := ""
// if req is not given
if req == nil {
return appID
}
var pod corev1.Pod
if err := json.Unmarshal(req.Object.Raw, &pod); err != nil {
log.Warnf("could not unmarshal raw object: %v", err)
} else {
appID = getAppID(pod)
}
return appID
}
// NewInjector returns a new Injector instance with the given config.
func NewInjector(authUIDs []string, config Config, daprClient scheme.Interface, kubeClient kubernetes.Interface) Injector {
mux := http.NewServeMux()
i := &injector{
config: config,
deserializer: serializer.NewCodecFactory(
runtime.NewScheme(),
).UniversalDeserializer(),
server: &http.Server{
Addr: fmt.Sprintf(":%d", port),
Handler: mux,
},
kubeClient: kubeClient,
daprClient: daprClient,
authUIDs: authUIDs,
}
mux.HandleFunc("/mutate", i.handleRequest)
return i
}
// AllowedControllersServiceAccountUID returns an array of UID, list of allowed service account on the webhook handler.
func AllowedControllersServiceAccountUID(ctx context.Context, kubeClient kubernetes.Interface) ([]string, error) {
allowedUids := []string{}
for i, allowedControllersServiceAccount := range allowedControllersServiceAccounts {
saUUID, err := getServiceAccount(ctx, kubeClient, allowedControllersServiceAccount)
// i == 0 => "replicaset-controller" is the only one mandatory
if err != nil {
if i == 0 {
return nil, err
}
log.Warnf("Unable to get SA %s UID (%s)", allowedControllersServiceAccount, err)
continue
}
allowedUids = append(allowedUids, saUUID)
}
return allowedUids, nil
}
func getServiceAccount(ctx context.Context, kubeClient kubernetes.Interface, allowedControllersServiceAccount string) (string, error) {
ctxWithTimeout, cancel := context.WithTimeout(ctx, getKubernetesServiceAccountTimeoutSeconds*time.Second)
defer cancel()
sa, err := kubeClient.CoreV1().ServiceAccounts(metav1.NamespaceSystem).Get(ctxWithTimeout, allowedControllersServiceAccount, metav1.GetOptions{})
if err != nil {
return "", err
}
return string(sa.ObjectMeta.UID), nil
}
func (i *injector) Run(ctx context.Context) {
doneCh := make(chan struct{})
go func() {
select {
case <-ctx.Done():
log.Info("Sidecar injector is shutting down")
shutdownCtx, cancel := context.WithTimeout(
context.Background(),
time.Second*5,
)
defer cancel()
i.server.Shutdown(shutdownCtx) // nolint: errcheck
case <-doneCh:
}
}()
log.Infof("Sidecar injector is listening on %s, patching Dapr-enabled pods", i.server.Addr)
err := i.server.ListenAndServeTLS(i.config.TLSCertFile, i.config.TLSKeyFile)
if err != http.ErrServerClosed {
log.Errorf("Sidecar injector error: %s", err)
}
close(doneCh)
}
func (i *injector) handleRequest(w http.ResponseWriter, r *http.Request) {
defer r.Body.Close()
monitoring.RecordSidecarInjectionRequestsCount()
var body []byte
if r.Body != nil {
if data, err := io.ReadAll(r.Body); err == nil {
body = data
}
}
if len(body) == 0 {
log.Error("empty body")
http.Error(w, "empty body", http.StatusBadRequest)
return
}
contentType := r.Header.Get("Content-Type")
if contentType != runtime.ContentTypeJSON {
log.Errorf("Content-Type=%s, expect %s", contentType, runtime.ContentTypeJSON)
http.Error(
w,
fmt.Sprintf("invalid Content-Type, expect `%s`", runtime.ContentTypeJSON),
http.StatusUnsupportedMediaType,
)
return
}
var admissionResponse *v1.AdmissionResponse
var patchOps []PatchOperation
var err error
patchedSuccessfully := false
ar := v1.AdmissionReview{}
_, gvk, err := i.deserializer.Decode(body, nil, &ar)
if err != nil {
log.Errorf("Can't decode body: %v", err)
} else {
if !(utils.StringSliceContains(ar.Request.UserInfo.UID, i.authUIDs) || utils.StringSliceContains(systemGroup, ar.Request.UserInfo.Groups)) {
log.Errorf("service account '%s' not on the list of allowed controller accounts", ar.Request.UserInfo.Username)
} else if ar.Request.Kind.Kind != "Pod" {
log.Errorf("invalid kind for review: %s", ar.Kind)
} else {
patchOps, err = i.getPodPatchOperations(&ar, i.config.Namespace, i.config.SidecarImage, i.config.SidecarImagePullPolicy, i.kubeClient, i.daprClient)
if err == nil {
patchedSuccessfully = true
}
}
}
diagAppID := getAppIDFromRequest(ar.Request)
if err != nil {
admissionResponse = toAdmissionResponse(err)
log.Errorf("Sidecar injector failed to inject for app '%s'. Error: %s", diagAppID, err)
monitoring.RecordFailedSidecarInjectionCount(diagAppID, "patch")
} else if len(patchOps) == 0 {
admissionResponse = &v1.AdmissionResponse{
Allowed: true,
}
} else {
var patchBytes []byte
patchBytes, err = json.Marshal(patchOps)
if err != nil {
admissionResponse = toAdmissionResponse(err)
} else {
admissionResponse = &v1.AdmissionResponse{
Allowed: true,
Patch: patchBytes,
PatchType: func() *v1.PatchType {
pt := v1.PatchTypeJSONPatch
return &pt
}(),
}
}
}
admissionReview := v1.AdmissionReview{}
if admissionResponse != nil {
admissionReview.Response = admissionResponse
if ar.Request != nil {
admissionReview.Response.UID = ar.Request.UID
admissionReview.SetGroupVersionKind(*gvk)
}
}
log.Infof("ready to write response ...")
respBytes, err := json.Marshal(admissionReview)
if err != nil {
http.Error(
w,
err.Error(),
http.StatusInternalServerError,
)
log.Errorf("Sidecar injector failed to inject for app '%s'. Can't deserialize response: %s", diagAppID, err)
monitoring.RecordFailedSidecarInjectionCount(diagAppID, "response")
}
w.Header().Set("Content-Type", runtime.ContentTypeJSON)
if _, err := w.Write(respBytes); err != nil {
log.Error(err)
} else {
if patchedSuccessfully {
log.Infof("Sidecar injector succeeded injection for app '%s'", diagAppID)
monitoring.RecordSuccessfulSidecarInjectionCount(diagAppID)
} else {
log.Errorf("Admission succeeded, but pod was not patched. No sidecar injected for '%s'", diagAppID)
monitoring.RecordFailedSidecarInjectionCount(diagAppID, "pod_patch")
}
}
}