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main.go
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main.go
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package main
import (
"bytes"
"crypto/tls"
"encoding/base64"
"encoding/json"
"errors"
"flag"
"fmt"
"io/ioutil"
"log"
"net/http"
"os"
"runtime"
"strings"
"time"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
)
const supportedWebhookVersion = "4"
var (
addr = "localhost:9097"
application = "alertmanager2es"
// See AlertManager docs for info on alert groupings:
// https://prometheus.io/docs/alerting/configuration/#route-<route>
esType = "alert_group"
// Index by month as we don't produce enough data to warrant a daily index
esIndexDateFormat = "2006.01"
esIndexName = "alertmanager"
esURL string
esUser string
esPass string
disableCertCheck = false
revision = "unknown"
versionString = fmt.Sprintf("%s %s (%s)", application, revision, runtime.Version())
notificationsErrored = prometheus.NewCounter(prometheus.CounterOpts{
Namespace: application,
Name: "notifications_errored_total",
Help: "Total number of alert notifications that errored during processing and should be retried",
})
notificationsInvalid = prometheus.NewCounter(prometheus.CounterOpts{
Namespace: application,
Name: "notifications_invalid_total",
Help: "Total number of invalid alert notifications received",
})
notificationsReceived = prometheus.NewCounter(prometheus.CounterOpts{
Namespace: application,
Name: "notifications_received_total",
Help: "Total number of alert notifications received",
})
)
func empty(s string) bool {
return len(strings.TrimSpace(s)) == 0
}
func basicAuth(username, password string) string {
auth := username + ":" + password
return base64.StdEncoding.EncodeToString([]byte(auth))
}
func init() {
prometheus.MustRegister(notificationsErrored)
prometheus.MustRegister(notificationsInvalid)
prometheus.MustRegister(notificationsReceived)
}
func main() {
var showVersion bool
flag.StringVar(&addr, "addr", addr, "host:port to listen to")
flag.StringVar(&esIndexDateFormat, "esIndexDateFormat", esIndexDateFormat, "Elasticsearch index date format")
flag.StringVar(&esIndexName, "esIndexName", esIndexName, "Elasticsearch index name")
flag.StringVar(&esType, "esType", esType, "Elasticsearch document type ('_type')")
flag.StringVar(&esURL, "esURL", esURL, "Elasticsearch HTTP URL")
flag.StringVar(&esUser, "esUser", os.Getenv("ES_USER"), "Elasticsearch user (default value is taken from $ES_USER environment variable)")
flag.StringVar(&esPass, "esPass", os.Getenv("ES_PASS"), "Elasticsearch password (default value is taken from $ES_PASS environment variable)")
flag.BoolVar(&disableCertCheck, "disableCertCheck", false, "Disable SSL certificate check")
flag.BoolVar(&showVersion, "version", false, "Print version number and exit")
flag.Parse()
if showVersion {
fmt.Println(versionString)
os.Exit(0)
}
if esURL == "" {
fmt.Fprintln(os.Stderr, "Must specify HTTP URL for Elasticsearch")
flag.Usage()
os.Exit(2)
}
http.DefaultClient.Timeout = 10 * time.Second
s := &http.Server{
Addr: addr,
ReadTimeout: 10 * time.Second,
WriteTimeout: 10 * time.Second,
}
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
fmt.Fprint(w, versionString)
})
http.Handle("/metrics", promhttp.Handler())
http.HandleFunc("/webhook", prometheus.InstrumentHandlerFunc("webhook", http.HandlerFunc(handler)))
log.Print(versionString)
log.Printf("Listening on %s", addr)
log.Fatal(s.ListenAndServe())
}
func handler(w http.ResponseWriter, r *http.Request) {
notificationsReceived.Inc()
if r.Body == nil {
notificationsInvalid.Inc()
err := errors.New("got empty request body")
http.Error(w, err.Error(), http.StatusBadRequest)
log.Print(err)
return
}
b, err := ioutil.ReadAll(r.Body)
if err != nil {
notificationsErrored.Inc()
http.Error(w, err.Error(), http.StatusInternalServerError)
log.Print(err)
return
}
defer r.Body.Close()
var msg notification
err = json.Unmarshal(b, &msg)
if err != nil {
notificationsInvalid.Inc()
http.Error(w, err.Error(), http.StatusBadRequest)
log.Print(err)
return
}
if msg.Version != supportedWebhookVersion {
notificationsInvalid.Inc()
err := fmt.Errorf("do not understand webhook version %q, only version %q is supported", msg.Version, supportedWebhookVersion)
http.Error(w, err.Error(), http.StatusBadRequest)
log.Print(err)
return
}
now := time.Now()
// ISO8601: https://github.com/golang/go/issues/2141#issuecomment-66058048
msg.Timestamp = now.Format(time.RFC3339)
index := fmt.Sprintf("%s-%s/%s", esIndexName, now.Format(esIndexDateFormat), esType)
url := fmt.Sprintf("%s/%s", esURL, index)
b, err = json.Marshal(&msg)
if err != nil {
notificationsErrored.Inc()
http.Error(w, err.Error(), http.StatusInternalServerError)
log.Print(err)
return
}
if disableCertCheck {
http.DefaultTransport.(*http.Transport).TLSClientConfig = &tls.Config{InsecureSkipVerify: true}
}
req, err := http.NewRequest("POST", url, bytes.NewBuffer(b))
if err != nil {
notificationsErrored.Inc()
http.Error(w, err.Error(), http.StatusInternalServerError)
log.Print(err)
return
}
req.Header.Set("User-Agent", versionString)
req.Header.Set("Content-Type", "application/json")
client := new(http.Client)
if !empty(esUser) && !empty(esPass) {
req.Header.Add("Authorization", "Basic "+basicAuth(esUser, esPass))
client.CheckRedirect = func(req *http.Request, via []*http.Request) error {
req.Header.Add("Authorization", "Basic "+basicAuth(esUser, esPass))
return nil
}
}
resp, err := client.Do(req)
if err != nil {
notificationsErrored.Inc()
http.Error(w, err.Error(), http.StatusInternalServerError)
log.Print(err)
return
}
body, err := ioutil.ReadAll(resp.Body)
defer resp.Body.Close()
if err != nil {
notificationsErrored.Inc()
http.Error(w, err.Error(), http.StatusInternalServerError)
log.Print(err)
return
}
if resp.StatusCode/100 != 2 {
notificationsErrored.Inc()
err := fmt.Errorf("POST to Elasticsearch on %q returned HTTP %d: %s", url, resp.StatusCode, body)
http.Error(w, err.Error(), http.StatusInternalServerError)
log.Print(err)
return
}
}
type notification struct {
Alerts []struct {
Annotations map[string]string `json:"annotations"`
EndsAt time.Time `json:"endsAt"`
GeneratorURL string `json:"generatorURL"`
Labels map[string]string `json:"labels"`
StartsAt time.Time `json:"startsAt"`
Status string `json:"status"`
} `json:"alerts"`
CommonAnnotations map[string]string `json:"commonAnnotations"`
CommonLabels map[string]string `json:"commonLabels"`
ExternalURL string `json:"externalURL"`
GroupLabels map[string]string `json:"groupLabels"`
Receiver string `json:"receiver"`
Status string `json:"status"`
Version string `json:"version"`
GroupKey string `json:"groupKey"`
// Timestamp records when the alert notification was received
Timestamp string `json:"@timestamp"`
}