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tailscale/cmd/k8s-operator/sts.go

393 lines
12 KiB
Go

// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
package main
import (
"context"
_ "embed"
"fmt"
"os"
"strings"
"go.uber.org/zap"
appsv1 "k8s.io/api/apps/v1"
corev1 "k8s.io/api/core/v1"
apierrors "k8s.io/apimachinery/pkg/api/errors"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
"sigs.k8s.io/controller-runtime/pkg/client"
"sigs.k8s.io/yaml"
"tailscale.com/client/tailscale"
"tailscale.com/tailcfg"
"tailscale.com/types/opt"
"tailscale.com/util/dnsname"
)
const (
LabelManaged = "tailscale.com/managed"
LabelParentType = "tailscale.com/parent-resource-type"
LabelParentName = "tailscale.com/parent-resource"
LabelParentNamespace = "tailscale.com/parent-resource-ns"
FinalizerName = "tailscale.com/finalizer"
AnnotationExpose = "tailscale.com/expose"
AnnotationTags = "tailscale.com/tags"
AnnotationHostname = "tailscale.com/hostname"
)
type tailscaleSTSConfig struct {
ParentResourceName string
ParentResourceUID string
ChildResourceLabels map[string]string
TargetIP string
Hostname string
Tags []string // if empty, use defaultTags
}
type tailscaleSTSReconciler struct {
client.Client
tsClient tsClient
defaultTags []string
operatorNamespace string
proxyImage string
proxyPriorityClassName string
}
// Provision ensures that the StatefulSet for the given service is running and
// up to date.
func (a *tailscaleSTSReconciler) Provision(ctx context.Context, logger *zap.SugaredLogger, sts *tailscaleSTSConfig) error {
// Do full reconcile.
hsvc, err := a.reconcileHeadlessService(ctx, logger, sts)
if err != nil {
return fmt.Errorf("failed to reconcile headless service: %w", err)
}
secretName, err := a.createOrGetSecret(ctx, logger, sts, hsvc)
if err != nil {
return fmt.Errorf("failed to create or get API key secret: %w", err)
}
_, err = a.reconcileSTS(ctx, logger, sts, hsvc, secretName)
if err != nil {
return fmt.Errorf("failed to reconcile statefulset: %w", err)
}
return nil
}
// Cleanup removes all resources associated that were created by Provision with
// the given labels. It returns true when all resources have been removed,
// otherwise it returns false and the caller should retry later.
func (a *tailscaleSTSReconciler) Cleanup(ctx context.Context, logger *zap.SugaredLogger, labels map[string]string) (done bool, _ error) {
// Need to delete the StatefulSet first, and delete it with foreground
// cascading deletion. That way, the pod that's writing to the Secret will
// stop running before we start looking at the Secret's contents, and
// assuming k8s ordering semantics don't mess with us, that should avoid
// tailscale device deletion races where we fail to notice a device that
// should be removed.
sts, err := getSingleObject[appsv1.StatefulSet](ctx, a.Client, a.operatorNamespace, labels)
if err != nil {
return false, fmt.Errorf("getting statefulset: %w", err)
}
if sts != nil {
if !sts.GetDeletionTimestamp().IsZero() {
// Deletion in progress, check again later. We'll get another
// notification when the deletion is complete.
logger.Debugf("waiting for statefulset %s/%s deletion", sts.GetNamespace(), sts.GetName())
return false, nil
}
err := a.DeleteAllOf(ctx, &appsv1.StatefulSet{}, client.InNamespace(a.operatorNamespace), client.MatchingLabels(labels), client.PropagationPolicy(metav1.DeletePropagationForeground))
if err != nil {
return false, fmt.Errorf("deleting statefulset: %w", err)
}
logger.Debugf("started deletion of statefulset %s/%s", sts.GetNamespace(), sts.GetName())
return false, nil
}
id, _, err := a.DeviceInfo(ctx, labels)
if err != nil {
return false, fmt.Errorf("getting device info: %w", err)
}
if id != "" {
// TODO: handle case where the device is already deleted, but the secret
// is still around.
if err := a.tsClient.DeleteDevice(ctx, string(id)); err != nil {
return false, fmt.Errorf("deleting device: %w", err)
}
}
types := []client.Object{
&corev1.Service{},
&corev1.Secret{},
}
for _, typ := range types {
if err := a.DeleteAllOf(ctx, typ, client.InNamespace(a.operatorNamespace), client.MatchingLabels(labels)); err != nil {
return false, err
}
}
return true, nil
}
func (a *tailscaleSTSReconciler) reconcileHeadlessService(ctx context.Context, logger *zap.SugaredLogger, sts *tailscaleSTSConfig) (*corev1.Service, error) {
hsvc := &corev1.Service{
ObjectMeta: metav1.ObjectMeta{
GenerateName: "ts-" + sts.ParentResourceName + "-",
Namespace: a.operatorNamespace,
Labels: sts.ChildResourceLabels,
},
Spec: corev1.ServiceSpec{
ClusterIP: "None",
Selector: map[string]string{
"app": sts.ParentResourceUID,
},
},
}
logger.Debugf("reconciling headless service for StatefulSet")
return createOrUpdate(ctx, a.Client, a.operatorNamespace, hsvc, func(svc *corev1.Service) { svc.Spec = hsvc.Spec })
}
func (a *tailscaleSTSReconciler) createOrGetSecret(ctx context.Context, logger *zap.SugaredLogger, stsC *tailscaleSTSConfig, hsvc *corev1.Service) (string, error) {
secret := &corev1.Secret{
ObjectMeta: metav1.ObjectMeta{
// Hardcode a -0 suffix so that in future, if we support
// multiple StatefulSet replicas, we can provision -N for
// those.
Name: hsvc.Name + "-0",
Namespace: a.operatorNamespace,
Labels: stsC.ChildResourceLabels,
},
}
if err := a.Get(ctx, client.ObjectKeyFromObject(secret), secret); err == nil {
logger.Debugf("secret %s/%s already exists", secret.GetNamespace(), secret.GetName())
return secret.Name, nil
} else if !apierrors.IsNotFound(err) {
return "", err
}
// Secret doesn't exist yet, create one. Initially it contains
// only the Tailscale authkey, but once Tailscale starts it'll
// also store the daemon state.
sts, err := getSingleObject[appsv1.StatefulSet](ctx, a.Client, a.operatorNamespace, stsC.ChildResourceLabels)
if err != nil {
return "", err
}
if sts != nil {
// StatefulSet exists, so we have already created the secret.
// If the secret is missing, they should delete the StatefulSet.
logger.Errorf("Tailscale proxy secret doesn't exist, but the corresponding StatefulSet %s/%s already does. Something is wrong, please delete the StatefulSet.", sts.GetNamespace(), sts.GetName())
return "", nil
}
// Create API Key secret which is going to be used by the statefulset
// to authenticate with Tailscale.
logger.Debugf("creating authkey for new tailscale proxy")
tags := stsC.Tags
if len(tags) == 0 {
tags = a.defaultTags
}
authKey, err := a.newAuthKey(ctx, tags)
if err != nil {
return "", err
}
secret.StringData = map[string]string{
"authkey": authKey,
}
if err := a.Create(ctx, secret); err != nil {
return "", err
}
return secret.Name, nil
}
// DeviceInfo returns the device ID and hostname for the Tailscale device
// associated with the given labels.
func (a *tailscaleSTSReconciler) DeviceInfo(ctx context.Context, childLabels map[string]string) (id tailcfg.StableNodeID, hostname string, err error) {
sec, err := getSingleObject[corev1.Secret](ctx, a.Client, a.operatorNamespace, childLabels)
if err != nil {
return "", "", err
}
if sec == nil {
return "", "", nil
}
id = tailcfg.StableNodeID(sec.Data["device_id"])
if id == "" {
return "", "", nil
}
// Kubernetes chokes on well-formed FQDNs with the trailing dot, so we have
// to remove it.
hostname = strings.TrimSuffix(string(sec.Data["device_fqdn"]), ".")
if hostname == "" {
return "", "", nil
}
return id, hostname, nil
}
func (a *tailscaleSTSReconciler) newAuthKey(ctx context.Context, tags []string) (string, error) {
caps := tailscale.KeyCapabilities{
Devices: tailscale.KeyDeviceCapabilities{
Create: tailscale.KeyDeviceCreateCapabilities{
Reusable: false,
Preauthorized: true,
Tags: tags,
},
},
}
key, _, err := a.tsClient.CreateKey(ctx, caps)
if err != nil {
return "", err
}
return key, nil
}
//go:embed manifests/proxy.yaml
var proxyYaml []byte
func (a *tailscaleSTSReconciler) reconcileSTS(ctx context.Context, logger *zap.SugaredLogger, sts *tailscaleSTSConfig, headlessSvc *corev1.Service, authKeySecret string) (*appsv1.StatefulSet, error) {
var ss appsv1.StatefulSet
if err := yaml.Unmarshal(proxyYaml, &ss); err != nil {
return nil, fmt.Errorf("failed to unmarshal proxy spec: %w", err)
}
container := &ss.Spec.Template.Spec.Containers[0]
container.Image = a.proxyImage
container.Env = append(container.Env,
corev1.EnvVar{
Name: "TS_DEST_IP",
Value: sts.TargetIP,
},
corev1.EnvVar{
Name: "TS_KUBE_SECRET",
Value: authKeySecret,
},
corev1.EnvVar{
Name: "TS_HOSTNAME",
Value: sts.Hostname,
})
ss.ObjectMeta = metav1.ObjectMeta{
Name: headlessSvc.Name,
Namespace: a.operatorNamespace,
Labels: sts.ChildResourceLabels,
}
ss.Spec.ServiceName = headlessSvc.Name
ss.Spec.Selector = &metav1.LabelSelector{
MatchLabels: map[string]string{
"app": sts.ParentResourceUID,
},
}
ss.Spec.Template.ObjectMeta.Labels = map[string]string{
"app": sts.ParentResourceUID,
}
ss.Spec.Template.Spec.PriorityClassName = a.proxyPriorityClassName
logger.Debugf("reconciling statefulset %s/%s", ss.GetNamespace(), ss.GetName())
return createOrUpdate(ctx, a.Client, a.operatorNamespace, &ss, func(s *appsv1.StatefulSet) { s.Spec = ss.Spec })
}
// ptrObject is a type constraint for pointer types that implement
// client.Object.
type ptrObject[T any] interface {
client.Object
*T
}
// createOrUpdate adds obj to the k8s cluster, unless the object already exists,
// in which case update is called to make changes to it. If update is nil, the
// existing object is returned unmodified.
//
// obj is looked up by its Name and Namespace if Name is set, otherwise it's
// looked up by labels.
func createOrUpdate[T any, O ptrObject[T]](ctx context.Context, c client.Client, ns string, obj O, update func(O)) (O, error) {
var (
existing O
err error
)
if obj.GetName() != "" {
existing = new(T)
existing.SetName(obj.GetName())
existing.SetNamespace(obj.GetNamespace())
err = c.Get(ctx, client.ObjectKeyFromObject(obj), existing)
} else {
existing, err = getSingleObject[T, O](ctx, c, ns, obj.GetLabels())
}
if err == nil && existing != nil {
if update != nil {
update(existing)
if err := c.Update(ctx, existing); err != nil {
return nil, err
}
}
return existing, nil
}
if err != nil && !apierrors.IsNotFound(err) {
return nil, fmt.Errorf("failed to get object: %w", err)
}
if err := c.Create(ctx, obj); err != nil {
return nil, err
}
return obj, nil
}
// getSingleObject searches for k8s objects of type T
// (e.g. corev1.Service) with the given labels, and returns
// it. Returns nil if no objects match the labels, and an error if
// more than one object matches.
func getSingleObject[T any, O ptrObject[T]](ctx context.Context, c client.Client, ns string, labels map[string]string) (O, error) {
ret := O(new(T))
kinds, _, err := c.Scheme().ObjectKinds(ret)
if err != nil {
return nil, err
}
if len(kinds) != 1 {
// TODO: the runtime package apparently has a "pick the best
// GVK" function somewhere that might be good enough?
return nil, fmt.Errorf("more than 1 GroupVersionKind for %T", ret)
}
gvk := kinds[0]
gvk.Kind += "List"
lst := unstructured.UnstructuredList{}
lst.SetGroupVersionKind(gvk)
if err := c.List(ctx, &lst, client.InNamespace(ns), client.MatchingLabels(labels)); err != nil {
return nil, err
}
if len(lst.Items) == 0 {
return nil, nil
}
if len(lst.Items) > 1 {
return nil, fmt.Errorf("found multiple matching %T objects", ret)
}
if err := c.Scheme().Convert(&lst.Items[0], ret, nil); err != nil {
return nil, err
}
return ret, nil
}
func defaultBool(envName string, defVal bool) bool {
vs := os.Getenv(envName)
if vs == "" {
return defVal
}
v, _ := opt.Bool(vs).Get()
return v
}
func defaultEnv(envName, defVal string) string {
v := os.Getenv(envName)
if v == "" {
return defVal
}
return v
}
func nameForService(svc *corev1.Service) (string, error) {
if h, ok := svc.Annotations[AnnotationHostname]; ok {
if err := dnsname.ValidLabel(h); err != nil {
return "", fmt.Errorf("invalid Tailscale hostname %q: %w", h, err)
}
return h, nil
}
return svc.Namespace + "-" + svc.Name, nil
}