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cmd/k8s-operator: add APISERVER_PROXY env 

The kube-apiserver proxy in the operator would only run in
auth proxy mode but thats not always desirable. There are
situations where the proxy should just be a transparent
proxy and not inject auth headers, so do that using a new
env var APISERVER_PROXY and deprecate the AUTH_PROXY env.

THe new env var has three options `false`, `true` and `noauth`.

Updates #8317

Signed-off-by: Maisem Ali <maisem@tailscale.com>
This commit is contained in:
Maisem Ali 2023-09-14 10:53:21 -05:00 committed by Maisem Ali
parent 4c693d2ee8
commit 335a5aaf9a
2 changed files with 81 additions and 28 deletions
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23
cmd/k8s-operator/operator.go
View File

@ -47,12 +47,11 @@ func main() {
tailscale.I_Acknowledge_This_API_Is_Unstable = true
var (
tsNamespace = defaultEnv("OPERATOR_NAMESPACE", "")
tslogging = defaultEnv("OPERATOR_LOGGING", "info")
image = defaultEnv("PROXY_IMAGE", "tailscale/tailscale:latest")
priorityClassName = defaultEnv("PROXY_PRIORITY_CLASS_NAME", "")
tags = defaultEnv("PROXY_TAGS", "tag:k8s")
shouldRunAuthProxy = defaultBool("AUTH_PROXY", false)
tsNamespace = defaultEnv("OPERATOR_NAMESPACE", "")
tslogging = defaultEnv("OPERATOR_LOGGING", "info")
image = defaultEnv("PROXY_IMAGE", "tailscale/tailscale:latest")
priorityClassName = defaultEnv("PROXY_PRIORITY_CLASS_NAME", "")
tags = defaultEnv("PROXY_TAGS", "tag:k8s")
)
var opts []kzap.Opts
@ -70,10 +69,8 @@ func main() {
s, tsClient := initTSNet(zlog)
defer s.Close()
restConfig := config.GetConfigOrDie()
if shouldRunAuthProxy {
launchAuthProxy(zlog, restConfig, s)
}
startReconcilers(zlog, s, tsNamespace, restConfig, tsClient, image, priorityClassName, tags)
maybeLaunchAPIServerProxy(zlog, restConfig, s)
runReconcilers(zlog, s, tsNamespace, restConfig, tsClient, image, priorityClassName, tags)
}
// initTSNet initializes the tsnet.Server and logs in to Tailscale. It uses the
@ -180,9 +177,9 @@ waitOnline:
return s, tsClient
}
// startReconcilers starts the controller-runtime manager and registers the
// ServiceReconciler.
func startReconcilers(zlog *zap.SugaredLogger, s *tsnet.Server, tsNamespace string, restConfig *rest.Config, tsClient *tailscale.Client, image, priorityClassName, tags string) {
// runReconcilers starts the controller-runtime manager and registers the
// ServiceReconciler. It blocks forever.
func runReconcilers(zlog *zap.SugaredLogger, s *tsnet.Server, tsNamespace string, restConfig *rest.Config, tsClient *tailscale.Client, image, priorityClassName, tags string) {
var (
isDefaultLoadBalancer = defaultBool("OPERATOR_DEFAULT_LOAD_BALANCER", false)
)

86
cmd/k8s-operator/proxy.go
View File

@ -45,12 +45,52 @@ func addWhoIsToRequest(r *http.Request, who *apitype.WhoIsResponse) *http.Reques
var counterNumRequestsProxied = clientmetric.NewCounter("k8s_auth_proxy_requests_proxied")
// launchAuthProxy launches the auth proxy, which is a small HTTP server that
// authenticates requests using the Tailscale LocalAPI and then proxies them to
// the kube-apiserver.
func launchAuthProxy(zlog *zap.SugaredLogger, restConfig *rest.Config, s *tsnet.Server) {
type apiServerProxyMode int
const (
apiserverProxyModeDisabled apiServerProxyMode = iota
apiserverProxyModeEnabled
apiserverProxyModeNoAuth
)
func parseAPIProxyMode() apiServerProxyMode {
haveAuthProxyEnv := os.Getenv("AUTH_PROXY") != ""
haveAPIProxyEnv := os.Getenv("APISERVER_PROXY") != ""
switch {
case haveAPIProxyEnv && haveAuthProxyEnv:
log.Fatal("AUTH_PROXY and APISERVER_PROXY are mutually exclusive")
case haveAuthProxyEnv:
var authProxyEnv = defaultBool("AUTH_PROXY", false) // deprecated
if authProxyEnv {
return apiserverProxyModeEnabled
}
return apiserverProxyModeDisabled
case haveAPIProxyEnv:
var apiProxyEnv = defaultEnv("APISERVER_PROXY", "") // true, false or "noauth"
switch apiProxyEnv {
case "true":
return apiserverProxyModeEnabled
case "false", "":
return apiserverProxyModeDisabled
case "noauth":
return apiserverProxyModeNoAuth
default:
panic(fmt.Sprintf("unknown APISERVER_PROXY value %q", apiProxyEnv))
}
}
return apiserverProxyModeDisabled
}
// maybeLaunchAPIServerProxy launches the auth proxy, which is a small HTTP server
// that authenticates requests using the Tailscale LocalAPI and then proxies
// them to the kube-apiserver.
func maybeLaunchAPIServerProxy(zlog *zap.SugaredLogger, restConfig *rest.Config, s *tsnet.Server) {
mode := parseAPIProxyMode()
if mode == apiserverProxyModeDisabled {
return
}
hostinfo.SetApp("k8s-operator-proxy")
startlog := zlog.Named("launchAuthProxy")
startlog := zlog.Named("launchAPIProxy")
cfg, err := restConfig.TransportConfig()
if err != nil {
startlog.Fatalf("could not get rest.TransportConfig(): %v", err)
@ -69,18 +109,18 @@ func launchAuthProxy(zlog *zap.SugaredLogger, restConfig *rest.Config, s *tsnet.
if err != nil {
startlog.Fatalf("could not get rest.TransportConfig(): %v", err)
}
go runAuthProxy(s, rt, zlog.Named("auth-proxy").Infof)
go runAPIServerProxy(s, rt, zlog.Named("apiserver-proxy").Infof, mode)
}
// authProxy is an http.Handler that authenticates requests using the Tailscale
// apiserverProxy is an http.Handler that authenticates requests using the Tailscale
// LocalAPI and then proxies them to the Kubernetes API.
type authProxy struct {
type apiserverProxy struct {
logf logger.Logf
lc *tailscale.LocalClient
rp *httputil.ReverseProxy
}
func (h *authProxy) ServeHTTP(w http.ResponseWriter, r *http.Request) {
func (h *apiserverProxy) ServeHTTP(w http.ResponseWriter, r *http.Request) {
who, err := h.lc.WhoIs(r.Context(), r.RemoteAddr)
if err != nil {
h.logf("failed to authenticate caller: %v", err)
@ -91,28 +131,38 @@ func (h *authProxy) ServeHTTP(w http.ResponseWriter, r *http.Request) {
h.rp.ServeHTTP(w, addWhoIsToRequest(r, who))
}
// runAuthProxy runs an HTTP server that authenticates requests using the
// runAPIServerProxy runs an HTTP server that authenticates requests using the
// Tailscale LocalAPI and then proxies them to the Kubernetes API.
// It listens on :443 and uses the Tailscale HTTPS certificate.
// s will be started if it is not already running.
// rt is used to proxy requests to the Kubernetes API.
//
// mode controls how the proxy behaves:
// - apiserverProxyModeDisabled: the proxy is not started.
// - apiserverProxyModeEnabled: the proxy is started and requests are impersonated using the
// caller's identity from the Tailscale LocalAPI.
// - apiserverProxyModeNoAuth: the proxy is started and requests are not impersonated and
// are passed through to the Kubernetes API.
//
// It never returns.
func runAuthProxy(s *tsnet.Server, rt http.RoundTripper, logf logger.Logf) {
func runAPIServerProxy(s *tsnet.Server, rt http.RoundTripper, logf logger.Logf, mode apiServerProxyMode) {
if mode == apiserverProxyModeDisabled {
return
}
ln, err := s.Listen("tcp", ":443")
if err != nil {
log.Fatalf("could not listen on :443: %v", err)
}
u, err := url.Parse(fmt.Sprintf("https://%s:%s", os.Getenv("KUBERNETES_SERVICE_HOST"), os.Getenv("KUBERNETES_SERVICE_PORT_HTTPS")))
if err != nil {
log.Fatalf("runAuthProxy: failed to parse URL %v", err)
log.Fatalf("runAPIServerProxy: failed to parse URL %v", err)
}
lc, err := s.LocalClient()
if err != nil {
log.Fatalf("could not get local client: %v", err)
}
ap := &authProxy{
ap := &apiserverProxy{
logf: logf,
lc: lc,
rp: &httputil.ReverseProxy{
@ -120,6 +170,12 @@ func runAuthProxy(s *tsnet.Server, rt http.RoundTripper, logf logger.Logf) {
// Replace the URL with the Kubernetes APIServer.
r.URL.Scheme = u.Scheme
r.URL.Host = u.Host
if mode == apiserverProxyModeNoAuth {
// If we are not providing authentication, then we are just
// proxying to the Kubernetes API, so we don't need to do
// anything else.
return
}
// We want to proxy to the Kubernetes API, but we want to use
// the caller's identity to do so. We do this by impersonating
@ -157,7 +213,7 @@ func runAuthProxy(s *tsnet.Server, rt http.RoundTripper, logf logger.Logf) {
Handler: ap,
}
if err := hs.ServeTLS(ln, "", ""); err != nil {
log.Fatalf("runAuthProxy: failed to serve %v", err)
log.Fatalf("runAPIServerProxy: failed to serve %v", err)
}
}
@ -177,7 +233,7 @@ type impersonateRule struct {
// addImpersonationHeaders adds the appropriate headers to r to impersonate the
// caller when proxying to the Kubernetes API. It uses the WhoIsResponse stashed
// in the context by the authProxy.
// in the context by the apiserverProxy.
func addImpersonationHeaders(r *http.Request) error {
who := whoIsFromRequest(r)
rules, err := tailcfg.UnmarshalCapJSON[capRule](who.CapMap, capabilityName)