From d1a8adcf3f8d6ebf96befed8ba1ee09654e6b222 Mon Sep 17 00:00:00 2001
From: Holger Hans Peter Freyther <holger@freyther.de>
Date: Fri, 17 May 2024 22:59:24 +0800
Subject: [PATCH] Create a formatter for config test routes (fixes #3741)

---
 cli/format/format.go          |  1 +
 cli/format/format_extended.go | 14 ++++++++++++++
 cli/format/format_json.go     |  5 +++++
 cli/format/format_simple.go   |  6 ++++++
 cli/test_routing.go           | 13 +++++++++++--
 5 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/cli/format/format.go b/cli/format/format.go
index 7bab337808..70d0c3b3cb 100644
--- a/cli/format/format.go
+++ b/cli/format/format.go
@@ -39,6 +39,7 @@ type Formatter interface {
 	FormatAlerts([]*models.GettableAlert) error
 	FormatConfig(*models.AlertmanagerStatus) error
 	FormatClusterStatus(status *models.ClusterStatus) error
+	FormatAlertReceivers([]string) error
 }
 
 // Formatters is a map of cli argument names to formatter interface object.
diff --git a/cli/format/format_extended.go b/cli/format/format_extended.go
index 3870cc7db9..1c7fb3ecc2 100644
--- a/cli/format/format_extended.go
+++ b/cli/format/format_extended.go
@@ -112,6 +112,20 @@ func (formatter *ExtendedFormatter) FormatClusterStatus(status *models.ClusterSt
 	return w.Flush()
 }
 
+func (formatter *ExtendedFormatter) FormatAlertReceivers(receivers []string) error {
+	w := tabwriter.NewWriter(formatter.writer, 0, 0, 2, ' ', 0)
+	sort.Strings(receivers)
+	fmt.Fprintln(w, "Receiver\t")
+	for _, receiver := range receivers {
+		fmt.Fprintf(
+			w,
+			"%s\t\n",
+			receiver,
+		)
+	}
+	return w.Flush()
+}
+
 func extendedFormatLabels(labels models.LabelSet) string {
 	output := []string{}
 	for name, value := range labels {
diff --git a/cli/format/format_json.go b/cli/format/format_json.go
index b6a12a60eb..b96000e4bb 100644
--- a/cli/format/format_json.go
+++ b/cli/format/format_json.go
@@ -52,3 +52,8 @@ func (formatter *JSONFormatter) FormatClusterStatus(status *models.ClusterStatus
 	enc := json.NewEncoder(formatter.writer)
 	return enc.Encode(status)
 }
+
+func (formatter *JSONFormatter) FormatAlertReceivers(receivers []string) error {
+	enc := json.NewEncoder(formatter.writer)
+	return enc.Encode(receivers)
+}
diff --git a/cli/format/format_simple.go b/cli/format/format_simple.go
index 6e7b0a1777..195b596bdc 100644
--- a/cli/format/format_simple.go
+++ b/cli/format/format_simple.go
@@ -86,6 +86,12 @@ func (formatter *SimpleFormatter) FormatClusterStatus(status *models.ClusterStat
 	return w.Flush()
 }
 
+func (formatter *SimpleFormatter) FormatAlertReceivers(receivers []string) error {
+	receiversSlug := strings.Join(receivers, ",")
+	fmt.Fprintf(formatter.writer, "%s\n", receiversSlug)
+	return nil
+}
+
 func simpleFormatMatchers(matchers models.Matchers) string {
 	output := []string{}
 	for _, matcher := range matchers {
diff --git a/cli/test_routing.go b/cli/test_routing.go
index 589a2e8cf8..2c56246292 100644
--- a/cli/test_routing.go
+++ b/cli/test_routing.go
@@ -23,6 +23,7 @@ import (
 	"github.com/xlab/treeprint"
 
 	"github.com/prometheus/alertmanager/api/v2/models"
+	"github.com/prometheus/alertmanager/cli/format"
 	"github.com/prometheus/alertmanager/dispatch"
 	"github.com/prometheus/alertmanager/matchers/compat"
 	"github.com/prometheus/alertmanager/pkg/labels"
@@ -79,6 +80,11 @@ func (c *routingShow) routingTestAction(ctx context.Context, _ *kingpin.ParseCon
 		return err
 	}
 
+	formatter, found := format.Formatters[output]
+	if !found {
+		return fmt.Errorf("unknown output formatter: %q", output)
+	}
+
 	mainRoute := dispatch.NewRoute(cfg.Route, nil)
 
 	// Parse labels to LabelSet.
@@ -99,9 +105,12 @@ func (c *routingShow) routingTestAction(ctx context.Context, _ *kingpin.ParseCon
 	}
 
 	receivers, err := resolveAlertReceivers(mainRoute, &ls)
-	receiversSlug := strings.Join(receivers, ",")
-	fmt.Printf("%s\n", receiversSlug)
+	if err := formatter.FormatAlertReceivers(receivers); err != nil {
+		kingpin.Fatalf("failed to format receivers: %v", err)
+		return err
+	}
 
+	receiversSlug := strings.Join(receivers, ",")
 	if c.expectedReceivers != "" && c.expectedReceivers != receiversSlug {
 		fmt.Printf("WARNING: Expected receivers did not match resolved receivers.\n")
 		os.Exit(1)