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api.go
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api.go
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// Copyright 2019 Authors of Cilium
//
// 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 main
import (
"context"
"fmt"
"net"
"net/http"
"syscall"
"github.com/cilium/cilium/pkg/k8s"
"github.com/cilium/cilium/pkg/kvstore"
"golang.org/x/sys/unix"
)
// startServer starts an api server listening on the given address.
func startServer(shutdownSignal <-chan struct{}, allSystemsGo <-chan struct{}, addrs ...string) {
http.HandleFunc("/healthz", func(w http.ResponseWriter, r *http.Request) {
select {
// only start serving the real health check once all systems all up and running
case <-allSystemsGo:
healthHandler(w, r)
default:
healthHandlerOK(w, r)
}
})
errs := make(chan error, 1)
nServers := 0
// Since we are opening this on localhost only, we need to make sure
// we can open for both v4 and v6 localhost. In case the user is running
// v4-only or v6-only.
for _, addr := range addrs {
if addr == "" {
continue
}
nServers++
srv := &http.Server{Addr: addr}
errCh := make(chan error, 1)
lc := net.ListenConfig{Control: setsockoptReuseAddrAndPort}
ln, err := lc.Listen(context.Background(), "tcp", addr)
if err != nil {
log.WithError(err).Fatalf("Unable to listen on %s for healthz apiserver", addr)
}
go func() {
err := srv.Serve(ln)
if err != nil {
errCh <- err
errs <- err
}
}()
go func() {
select {
case <-shutdownSignal:
if err := srv.Shutdown(context.Background()); err != nil {
log.WithError(err).Error("apiserver shutdown")
}
case err := <-errCh:
log.Warnf("Unable to start status api: %s", err)
}
}()
log.Infof("Starting apiserver on address %s", addr)
}
for err := range errs {
nServers--
if nServers == 0 {
log.Fatalf("Unable to start status api: %s", err)
}
}
}
func healthHandlerOK(w http.ResponseWriter, r *http.Request) {
w.WriteHeader(http.StatusOK)
if _, err := w.Write([]byte("ok")); err != nil {
log.WithError(err).Error("Failed to write liveness-probe response")
}
}
func healthHandler(w http.ResponseWriter, r *http.Request) {
statusCode := http.StatusOK
reply := "ok"
if err := checkStatus(); err != nil {
statusCode = http.StatusInternalServerError
reply = err.Error()
log.WithError(err).Warn("Health check status")
}
w.WriteHeader(statusCode)
if _, err := w.Write([]byte(reply)); err != nil {
log.WithError(err).Error("Failed to write liveness-probe response")
}
}
// checkStatus checks the connection status to the kvstore and
// k8s apiserver and returns an error if any of them is unhealthy
func checkStatus() error {
if kvstoreEnabled() {
// We check if we are the leader here because only the leader has
// access to the kvstore client. Otherwise, the kvstore client check
// will block. It is safe for a non-leader to skip this check, as the
// it is the leader's responsibility to report the status of the
// kvstore client.
if leader, ok := isLeader.Load().(bool); ok && leader {
if client := kvstore.Client(); client == nil {
return fmt.Errorf("kvstore client not configured")
} else if _, err := client.Status(); err != nil {
return err
}
}
}
if _, err := k8s.Client().Discovery().ServerVersion(); err != nil {
return err
}
return nil
}
// setsockoptReuseAddrAndPort sets SO_REUSEADDR and SO_REUSEPORT
func setsockoptReuseAddrAndPort(network, address string, c syscall.RawConn) error {
var soerr error
if err := c.Control(func(su uintptr) {
s := int(su)
// Allow reuse of recently-used addresses. This socket option is
// set by default on listeners in Go's net package, see
// net setDefaultListenerSockopts
soerr = unix.SetsockoptInt(s, unix.SOL_SOCKET, unix.SO_REUSEADDR, 1)
if soerr != nil {
return
}
// Allow reuse of recently-used ports. This gives the agent a
// better change to re-bind upon restarts.
soerr = unix.SetsockoptInt(s, unix.SOL_SOCKET, unix.SO_REUSEPORT, 1)
}); err != nil {
return err
}
return soerr
}