Alerting: Support Unified Alerting with Grafana HA (#37920)

* Alerting: Support Unified Alerting in Grafana's HA mode.

pkg/setting/setting_unified_alerting_test.go

@@ -0,0 +1,39 @@
+package setting
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestCfg_ReadUnifiedAlertingSettings(t *testing.T) {
+	cfg := NewCfg()
+	err := cfg.Load(CommandLineArgs{HomePath: "../../", Config: "../../conf/defaults.ini"})
+	require.NoError(t, err)
+
+	// It sets the correct defaults.
+	{
+		require.Equal(t, 60*time.Second, cfg.AdminConfigPollInterval)
+		require.Equal(t, 60*time.Second, cfg.AlertmanagerConfigPollInterval)
+		require.Equal(t, 15*time.Second, cfg.HAPeerTimeout)
+		require.Equal(t, "0.0.0.0:9094", cfg.HAListenAddr)
+		require.Equal(t, "", cfg.HAAdvertiseAddr)
+		require.Len(t, cfg.HAPeers, 0)
+		require.Equal(t, 200*time.Millisecond, cfg.HAGossipInterval)
+		require.Equal(t, 60*time.Second, cfg.HAPushPullInterval)
+	}
+
+	// With peers set, it correctly parses them.
+	{
+		require.Len(t, cfg.HAPeers, 0)
+		s, err := cfg.Raw.NewSection("unified_alerting")
+		require.NoError(t, err)
+		_, err = s.NewKey("ha_peers", "hostname1:9090,hostname2:9090,hostname3:9090")
+		require.NoError(t, err)
+
+		require.NoError(t, cfg.ReadUnifiedAlertingSettings(cfg.Raw))
+		require.Len(t, cfg.HAPeers, 3)
+		require.ElementsMatch(t, []string{"hostname1:9090", "hostname2:9090", "hostname3:9090"}, cfg.HAPeers)
+	}
+}