/
health_check.go
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/
health_check.go
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// Copyright (c) 2019 Baidu, Inc.
//
// 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.
// health check for backend
package backend
import (
"fmt"
"net"
"net/http"
"strings"
"time"
)
import (
"github.com/baidu/go-lib/log"
)
import (
"github.com/baidu/bfe/bfe_config/bfe_cluster_conf/cluster_conf"
"github.com/baidu/bfe/bfe_debug"
)
func UpdateStatus(backend *BfeBackend, cluster string) bool {
// get conf of health check, which is separately stored for each cluster
checkConf := getCheckConf(cluster)
if checkConf == nil {
// just ingore if not found health check conf
return false
}
// UpdateStatus update backend status.
// if backend's status become fail, start healthcheck.
// at most start 1 check goroutine for each backend.
if backend.UpdateStatus(*checkConf.FailNum) {
go check(backend, cluster)
return true
}
return false
}
func check(backend *BfeBackend, cluster string) {
log.Logger.Info("start healthcheck for %s", backend.Name)
// backend close chan
c := backend.CloseChan()
loop:
for {
select {
case <-c: // backend deleted
break loop
default:
}
// get lastest conf for health check
checkConf := getCheckConf(cluster)
if checkConf == nil {
// never come here
time.Sleep(time.Second)
continue
}
checkInterval := time.Duration(*checkConf.CheckInterval) * time.Millisecond
// health check
if ok, err := CheckConnect(backend, checkConf); !ok {
backend.ResetSuccNum()
if bfe_debug.DebugHealthCheck {
log.Logger.Debug("backend %s still not avail (check failure: %s)", backend.Name, err)
}
time.Sleep(checkInterval)
continue
}
// check whether backend becomes available
backend.AddSuccNum()
if !backend.CheckAvail(*checkConf.SuccNum) {
if bfe_debug.DebugHealthCheck {
log.Logger.Debug("backend %s still not avail (check success, waiting for more checks)", backend.Name)
}
time.Sleep(checkInterval)
continue
}
log.Logger.Info("backend %s back to Normal", backend.Name)
backend.SetAvail(true)
break loop
}
}
func getHealthCheckAddrInfo(backend *BfeBackend, checkConf *cluster_conf.BackendCheck) string {
if checkConf.Host != nil {
// if port for health check is configured, use it instead of backend port
hostInfo := strings.Split(*checkConf.Host, ":")
if len(hostInfo) == 2 {
port := hostInfo[1]
return fmt.Sprintf("%s:%s", backend.GetAddr(), port)
}
}
return backend.GetAddrInfo()
}
func checkTCPConnect(backend *BfeBackend, checkConf *cluster_conf.BackendCheck) (bool, error) {
addrInfo := getHealthCheckAddrInfo(backend, checkConf)
var conn net.Conn
var err error
if checkConf.CheckTimeout != nil {
conn, err = net.DialTimeout("tcp", addrInfo,
time.Duration(*checkConf.CheckTimeout)*time.Millisecond)
} else {
conn, err = net.Dial("tcp", addrInfo)
}
if err != nil {
return false, err
}
conn.Close()
return true, nil
}
func doHTTPHealthCheck(request *http.Request, timeout time.Duration) (int, error) {
client := &http.Client{
// Note: disable following an HTTP redirect
CheckRedirect: func(*http.Request, []*http.Request) error { return http.ErrUseLastResponse },
// Note: timeout of zero means no timeout
Timeout: timeout,
}
response, err := client.Do(request)
if err != nil {
return -1, err
}
defer response.Body.Close()
return response.StatusCode, nil
}
func checkHTTPConnect(backend *BfeBackend, checkConf *cluster_conf.BackendCheck) (bool, error) {
// prepare health check request
addrInfo := getHealthCheckAddrInfo(backend, checkConf)
urlStr := fmt.Sprintf("%s://%s%s", "http", addrInfo, *checkConf.Uri)
request, err := http.NewRequest("GET", urlStr, nil)
if err != nil {
return false, err
}
// modify http host header if needed
if checkConf.Host != nil {
request.Host = *checkConf.Host
}
// add headers required by downstream servers
request.Header.Set("Accept", "*/*")
// do http health check
checkTimeout := time.Duration(0)
if checkConf.CheckTimeout != nil {
checkTimeout = time.Duration(*checkConf.CheckTimeout) * time.Millisecond
}
statusCode, err := doHTTPHealthCheck(request, checkTimeout)
if err != nil {
return false, err
}
return cluster_conf.MatchStatusCode(statusCode, *checkConf.StatusCode)
}
// CheckConnect checks whether backend server become available.
func CheckConnect(backend *BfeBackend, checkConf *cluster_conf.BackendCheck) (bool, error) {
switch *checkConf.Schem {
case "http":
return checkHTTPConnect(backend, checkConf)
case "tcp":
return checkTCPConnect(backend, checkConf)
default:
// never come here
return checkHTTPConnect(backend, checkConf)
}
}
// CheckConfFetcher returns current health check conf for cluster.
type CheckConfFetcher func(cluster string) *cluster_conf.BackendCheck
var checkConfFetcher CheckConfFetcher
func getCheckConf(cluster string) *cluster_conf.BackendCheck {
if checkConfFetcher == nil {
return nil
}
return checkConfFetcher(cluster)
}
// SetCheckConfFetcher initializes CheckConfFetcher handler.
func SetCheckConfFetcher(confFetcher CheckConfFetcher) {
checkConfFetcher = confFetcher
}