Iain Sproat
f2872d6dea
* Update screenshot to match current output * Log level is configurable * Alert name is provided in log line, where available. * Capitalise Discord, check err in integration test, and other syntax issues * Go formatting syntax fixes * Log the common alert name or group alert name, in that precedence
120 lines
3.3 KiB
Go
120 lines
3.3 KiB
Go
package server
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import (
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"context"
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"fmt"
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"net/http"
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"os"
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"os/signal"
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"time"
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"github.com/specklesystems/alertmanager-discord/pkg/alertforwarder"
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"github.com/specklesystems/alertmanager-discord/pkg/metrics"
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"github.com/prometheus/client_golang/prometheus/promhttp"
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"github.com/rs/zerolog/log"
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)
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const (
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DefaultListenAddress = "0.0.0.0:9094"
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)
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const (
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FaviconPath = "/favicon.ico"
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LivenessPath = "/liveness"
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ReadinessPath = "/readiness"
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)
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type AlertManagerDiscordServer struct {
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httpServer *http.Server
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MaximumBackoffTimeSeconds time.Duration
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}
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func (amds *AlertManagerDiscordServer) ListenAndServe(webhookUrl, listenAddress string) (chan os.Signal, error) {
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stop := make(chan os.Signal, 1)
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mux := http.NewServeMux()
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ok, _, err := alertforwarder.CheckWebhookURL(webhookUrl)
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if !ok {
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return stop, fmt.Errorf("url is invalid: %w", err)
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}
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if listenAddress == "" {
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log.Info().Msgf("Listen address not provided. Using default: '%s'", DefaultListenAddress)
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listenAddress = DefaultListenAddress
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}
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log.Info().Msgf("Listening on: %s", listenAddress)
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discordClient := &http.Client{
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Timeout: 5 * time.Second,
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}
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transformAndForwardWithInstrumentation := promhttp.InstrumentHandlerDuration(metrics.RequestsToAlertForwarderDuration,
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promhttp.InstrumentHandlerCounter(metrics.RequestsToAlertForwarderTotal,
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promhttp.InstrumentHandlerInFlight(metrics.RequestsToAlertForwarderInFlight,
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alertforwarder.NewAlertForwarderHandler(discordClient,
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webhookUrl,
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amds.MaximumBackoffTimeSeconds,
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),
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),
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),
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)
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mux.HandleFunc("/", transformAndForwardWithInstrumentation)
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mux.HandleFunc("/readiness", func(w http.ResponseWriter, r *http.Request) {
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log.Debug().Msg("Readiness probe encountered.")
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})
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mux.HandleFunc("/liveness", func(w http.ResponseWriter, r *http.Request) {
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log.Debug().Msg("Liveness probe encountered.")
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})
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mux.HandleFunc("/favicon.ico", func(w http.ResponseWriter, r *http.Request) {
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// purposefully empty
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})
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mux.Handle("/metrics", promhttp.Handler())
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amds.httpServer = &http.Server{
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Addr: listenAddress,
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Handler: mux,
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ReadTimeout: 10 * time.Second,
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WriteTimeout: 10 * time.Second,
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MaxHeaderBytes: 1 << 20,
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}
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// Setting up signal capturing
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signal.Notify(stop, os.Interrupt)
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go func() {
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// check for nil prevents race condition if we have already shutdown the server before this goroutine attempts to start
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if amds.httpServer != nil {
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if err := amds.httpServer.ListenAndServe(); err != nil {
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close(stop)
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}
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}
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}()
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return stop, nil
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}
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func (amds *AlertManagerDiscordServer) Shutdown() error {
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log.Info().Msg("Received signal to shut down server. Shutting down server...")
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ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
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defer cancel()
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if amds.httpServer == nil {
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// http server is not referenced, or was never created, so we're unable to shut it down
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return nil
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}
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if err := amds.httpServer.Shutdown(ctx); err != nil {
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// prevent race condition if shutdown signal was sent prior to server starting, we remove server reference to prevent it starting
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amds.httpServer = nil
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return err
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}
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// prevent race condition if shutdown signal was sent prior to server starting, we remove server remove to prevent it starting
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amds.httpServer = nil
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return nil
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}
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