Return 503 on connection errors

Signed-off-by: rustyclock <rustyclock@protonmail.com>

cmd/main.go

@@ -89,27 +89,17 @@ func probeHandler(w http.ResponseWriter, r *http.Request, logger log.Logger, con
 		level.Error(logger).Log("msg", "Failed to create metrics list from config", "err", err) //nolint:errcheck
 	}
 
-	probeSuccessGauge := prometheus.NewGauge(prometheus.GaugeOpts{
-		Name: "probe_success",
-		Help: "Displays whether or not the probe was a success",
-	})
-
 	target := r.URL.Query().Get("target")
 	if target == "" {
 		http.Error(w, "Target parameter is missing", http.StatusBadRequest)
 		return
 	}
 
-	registry.MustRegister(probeSuccessGauge)
-
 	data, err := internal.FetchJson(ctx, logger, target, config)
 	if err != nil {
-		level.Error(logger).Log("msg", "Failed to fetch JSON response", "err", err) //nolint:errcheck
+		http.Error(w, "Failed to fetch JSON response. TARGET: "+target+", ERROR: "+err.Error(), http.StatusServiceUnavailable)
 	} else {
 		internal.Scrape(logger, metrics, data)
-
-		probeSuccessGauge.Set(1)
-		//level.Info(logger).Log("msg", "Probe succeeded", "duration_seconds", duration) // Too noisy
 	}
 
 	h := promhttp.HandlerFor(registry, promhttp.HandlerOpts{})

internal/util.go

@@ -15,6 +15,7 @@ package internal
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"io/ioutil"
 	"math"
@@ -129,13 +130,17 @@ func FetchJson(ctx context.Context, logger log.Logger, endpoint string, config c
 	}
 	resp, err := client.Do(req)
 	if err != nil {
-		return nil, fmt.Errorf("failed to fetch json from endpoint;endpoint:<%s>,err:<%s>", endpoint, err)
+		return nil, err
 	}
 	defer resp.Body.Close()
 
+	if resp.StatusCode != 200 {
+		return nil, errors.New(resp.Status)
+	}
+
 	data, err := ioutil.ReadAll(resp.Body)
 	if err != nil {
-		return nil, fmt.Errorf("failed to read response body;err:<%s>", err)
+		return nil, err
 	}
 
 	return data, nil