matrix-alertmanager-receiver/main.go

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package main
import (
"os"
"flag"
"fmt"
"log"
"net/http"
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"encoding/json"
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"github.com/prometheus/alertmanager/template"
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"github.com/matrix-org/gomatrix"
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)
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func generateMatrixMessageBody(alert template.Alert) string {
return alert.Status + " // " + alert.Annotations["summary"]
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}
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func main() {
// Initialize logger.
var logger *log.Logger = log.New(os.Stdout, "", log.Flags())
// Handle command-line arguments.
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var homeserver = flag.String("homeserver", "https://matrix.org", "Address of Matrix homeserver")
var user = flag.String("user", "", "Full MXID (e.g. @example.domain.tld) of Matrix user")
var token = flag.String("token", "", "Access Token of Matrix user")
var target = flag.String("target-room", "", "Matrix room to be notified of alerts.")
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var port = flag.Int("port", 9088, "HTTP port to listen on (incoming alertmanager webhooks)")
flag.Parse()
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if *user == "" {
logger.Fatal("Matrix user is required. See --help for usage.")
}
if *token == "" {
logger.Fatal("Matrix access token is required. See --help for usage.")
}
if *target== "" {
logger.Fatal("Matrix target room is required. See --help for usage.")
}
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// Initialize Matrix client.
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matrixClient, err := gomatrix.NewClient(*homeserver, *user, *token)
if err != nil {
logger.Fatalf("Could not log in to Matrix (%v): %v", *homeserver, err)
}
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joinedRooms, err := matrixClient.JoinedRooms()
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if err != nil {
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logger.Fatalf("Could not fetch joined rooms: %v", err)
}
alreadyJoinedTarget := false
for _, roomID := range joinedRooms.JoinedRooms {
// FIXME: will only work if target is a roomID, not an alias.
if *target == roomID {
alreadyJoinedTarget = true
}
}
if !alreadyJoinedTarget {
logger.Printf("Trying to join %v...", *target)
_, err := matrixClient.JoinRoom(*target, "", nil)
if err != nil {
logger.Fatalf("Failed to join %v: %v", *target, err)
}
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}
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// Initialize HTTP serve (= listen for incoming requests).
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
fmt.Fprintf(w, `Hi! I receive prometheus-alertmanager webhooks on /alert and forward them to Matrix.
You will find more details on: http://git.sr.ht/~fnux/matrix-prometheus-alertmanager`)
})
http.HandleFunc("/alert", func(w http.ResponseWriter, r *http.Request) {
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if r.Method != http.MethodPost {
w.WriteHeader(http.StatusMethodNotAllowed)
return
}
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payload := template.Data{}
if err := json.NewDecoder(r.Body).Decode(&payload); err != nil {
w.WriteHeader(http.StatusBadRequest)
}
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logger.Printf("Received valid hook from %v", r.RemoteAddr)
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for _, alert := range payload.Alerts {
body := generateMatrixMessageBody(alert)
logger.Printf("> %v", body)
_, err := matrixClient.SendText(*target, body)
if err != nil {
logger.Fatalf("Could not forward to Matrix: %v", err)
}
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}
w.WriteHeader(http.StatusOK)
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})
var listenAddr = fmt.Sprintf(":%v", *port)
logger.Printf("Listening for HTTP requests (webhooks) on %v", listenAddr)
log.Fatal(http.ListenAndServe(listenAddr, nil))
}