/
server.go
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/
server.go
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// Copyright 2018 Istio Authors
//
// 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 status
import (
"context"
"encoding/json"
"fmt"
"net"
"net/http"
"os"
"regexp"
"strconv"
"strings"
"sync"
"syscall"
"time"
"istio.io/istio/pilot/pkg/model"
"istio.io/istio/pilot/cmd/pilot-agent/status/ready"
"istio.io/istio/pkg/log"
corev1 "k8s.io/api/core/v1"
"k8s.io/apimachinery/pkg/util/intstr"
)
const (
// readyPath is for the pilot agent readiness itself.
readyPath = "/healthz/ready"
// KubeAppProberEnvName is the name of the command line flag for pilot agent to pass app prober config.
// The json encoded string to pass app HTTP probe information from injector(istioctl or webhook).
// For example, --ISTIO_KUBE_APP_PROBERS='{"/app-health/httpbin/livez":{"path": "/hello", "port": 8080}.
// indicates that httpbin container liveness prober port is 8080 and probing path is /hello.
// This environment variable should never be set manually.
KubeAppProberEnvName = "ISTIO_KUBE_APP_PROBERS"
)
var (
appProberPattern = regexp.MustCompile(`^/app-health/[^\/]+/(livez|readyz)$`)
)
// KubeAppProbers holds the information about a Kubernetes pod prober.
// It's a map from the prober URL path to the Kubernetes Prober config.
// For example, "/app-health/hello-world/livez" entry contains livenss prober config for
// container "hello-world".
type KubeAppProbers map[string]*corev1.HTTPGetAction
// Config for the status server.
type Config struct {
StatusPort uint16
AdminPort uint16
ApplicationPorts []uint16
// KubeAppHTTPProbers is a json with Kubernetes application HTTP prober config encoded.
KubeAppHTTPProbers string
NodeType model.NodeType
}
// Server provides an endpoint for handling status probes.
type Server struct {
statusPort uint16
ready *ready.Probe
mutex sync.RWMutex
lastProbeSuccessful bool
appKubeProbers KubeAppProbers
}
// NewServer creates a new status server.
func NewServer(config Config) (*Server, error) {
s := &Server{
statusPort: config.StatusPort,
ready: &ready.Probe{
AdminPort: config.AdminPort,
ApplicationPorts: config.ApplicationPorts,
NodeType: config.NodeType,
},
}
if config.KubeAppHTTPProbers == "" {
return s, nil
}
if err := json.Unmarshal([]byte(config.KubeAppHTTPProbers), &s.appKubeProbers); err != nil {
return nil, fmt.Errorf("failed to decode app http prober err = %v, json string = %v", err, config.KubeAppHTTPProbers)
}
// Validate the map key matching the regex pattern.
for path, prober := range s.appKubeProbers {
if !appProberPattern.Match([]byte(path)) {
return nil, fmt.Errorf(`invalid key, must be in form of regex pattern ^/app-health/[^\/]+/(livez|readyz)$`)
}
if prober.Port.Type != intstr.Int {
return nil, fmt.Errorf("invalid prober config for %v, the port must be int type", path)
}
}
return s, nil
}
// FormatProberURL returns a pair of HTTP URLs that pilot agent will serve to take over Kubernetes
// app probers.
func FormatProberURL(container string) (string, string) {
return fmt.Sprintf("/app-health/%v/readyz", container),
fmt.Sprintf("/app-health/%v/livez", container)
}
// Run opens a the status port and begins accepting probes.
func (s *Server) Run(ctx context.Context) {
log.Infof("Opening status port %d\n", s.statusPort)
// Add the handler for ready probes.
http.HandleFunc(readyPath, s.handleReadyProbe)
http.HandleFunc("/", s.handleAppProbe)
http.HandleFunc("/app-health", s.handleAppProbe)
l, err := net.Listen("tcp", fmt.Sprintf(":%d", s.statusPort))
if err != nil {
log.Errorf("Error listening on status port: %v", err.Error())
return
}
// for testing.
if s.statusPort == 0 {
addrs := strings.Split(l.Addr().String(), ":")
allocatedPort, _ := strconv.Atoi(addrs[len(addrs)-1])
s.mutex.Lock()
s.statusPort = uint16(allocatedPort)
s.mutex.Unlock()
}
defer l.Close()
go func() {
if err := http.Serve(l, nil); err != nil {
log.Errora(err)
// If the server errors then pilot-agent can never pass readiness or liveness probes
// Therefore, trigger graceful termination by sending SIGTERM to the binary pid
p, err := os.FindProcess(os.Getpid())
if err != nil {
log.Errora(err)
}
log.Errora(p.Signal(syscall.SIGTERM))
}
}()
// Wait for the agent to be shut down.
<-ctx.Done()
log.Info("Status server has successfully terminated")
}
func (s *Server) handleReadyProbe(w http.ResponseWriter, _ *http.Request) {
err := s.ready.Check()
s.mutex.Lock()
if err != nil {
w.WriteHeader(http.StatusServiceUnavailable)
log.Infof("Envoy proxy is NOT ready: %s", err.Error())
s.lastProbeSuccessful = false
} else {
w.WriteHeader(http.StatusOK)
if !s.lastProbeSuccessful {
log.Info("Envoy proxy is ready")
}
s.lastProbeSuccessful = true
}
s.mutex.Unlock()
}
func (s *Server) handleAppProbe(w http.ResponseWriter, req *http.Request) {
// Validate the request first.
path := req.URL.Path
if !strings.HasPrefix(path, "/") {
path = "/" + req.URL.Path
}
prober, exists := s.appKubeProbers[path]
if !exists {
log.Errorf("Prober does not exists url %v", path)
w.WriteHeader(http.StatusBadRequest)
w.Write([]byte(fmt.Sprintf("app prober config does not exists for %v", path)))
return
}
// Construct a request sent to the application.
httpClient := &http.Client{
// TODO: figure out the appropriate timeout?
Timeout: 10 * time.Second,
}
url := fmt.Sprintf("http://127.0.0.1:%v%s", prober.Port.IntValue(), prober.Path)
appReq, err := http.NewRequest("GET", url, nil)
if err != nil {
log.Errorf("Failed to create request to probe app %v, original url %v", err, path)
w.WriteHeader(http.StatusInternalServerError)
return
}
for _, header := range prober.HTTPHeaders {
appReq.Header[header.Name] = []string{header.Value}
}
// Send the request.
response, err := httpClient.Do(appReq)
if err != nil {
log.Errorf("Request to probe app failed: %v, original URL path = %v\napp URL path = %v", err, path, prober.Path)
w.WriteHeader(http.StatusInternalServerError)
return
}
defer response.Body.Close()
// We only write the status code to the response.
w.WriteHeader(response.StatusCode)
}