From f80bf11782382685d82d33b07e014eadb005bbe8 Mon Sep 17 00:00:00 2001
From: Alexander Weaver <weaver.alex.d@gmail.com>
Date: Tue, 7 Feb 2023 14:26:43 -0600
Subject: [PATCH] Alerting: Make time range query parameters not required when
 querying Loki (#62985)

* Make from and to not required

* Move default range calculation up to loki.go
---
 pkg/services/ngalert/state/historian/loki.go      | 15 +++++++++++++--
 pkg/services/ngalert/state/historian/loki_http.go |  2 +-
 .../ngalert/state/historian/loki_http_test.go     |  4 ++--
 3 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/pkg/services/ngalert/state/historian/loki.go b/pkg/services/ngalert/state/historian/loki.go
index 4158887aa1d..a4a63d063a9 100644
--- a/pkg/services/ngalert/state/historian/loki.go
+++ b/pkg/services/ngalert/state/historian/loki.go
@@ -34,10 +34,12 @@ const (
 	StateHistoryLabelValue = "state-history"
 )
 
+const defaultQueryRange = 6 * time.Hour
+
 type remoteLokiClient interface {
 	ping(context.Context) error
 	push(context.Context, []stream) error
-	query(ctx context.Context, selectors []Selector, start, end int64) (QueryRes, error)
+	rangeQuery(ctx context.Context, selectors []Selector, start, end int64) (QueryRes, error)
 }
 
 type RemoteLokiBackend struct {
@@ -78,8 +80,17 @@ func (h *RemoteLokiBackend) QueryStates(ctx context.Context, query models.Histor
 	if err != nil {
 		return nil, fmt.Errorf("failed to build the provided selectors: %w", err)
 	}
+
+	now := time.Now().UTC()
+	if query.To.IsZero() {
+		query.To = now
+	}
+	if query.From.IsZero() {
+		query.From = now.Add(-defaultQueryRange)
+	}
+
 	// Timestamps are expected in RFC3339Nano.
-	res, err := h.client.query(ctx, selectors, query.From.UnixNano(), query.To.UnixNano())
+	res, err := h.client.rangeQuery(ctx, selectors, query.From.UnixNano(), query.To.UnixNano())
 	if err != nil {
 		return nil, err
 	}
diff --git a/pkg/services/ngalert/state/historian/loki_http.go b/pkg/services/ngalert/state/historian/loki_http.go
index 37a87e73add..459a08d64c1 100644
--- a/pkg/services/ngalert/state/historian/loki_http.go
+++ b/pkg/services/ngalert/state/historian/loki_http.go
@@ -186,7 +186,7 @@ func (c *httpLokiClient) setAuthAndTenantHeaders(req *http.Request) {
 		req.Header.Add("X-Scope-OrgID", c.cfg.TenantID)
 	}
 }
-func (c *httpLokiClient) query(ctx context.Context, selectors []Selector, start, end int64) (QueryRes, error) {
+func (c *httpLokiClient) rangeQuery(ctx context.Context, selectors []Selector, start, end int64) (QueryRes, error) {
 	// Run the pre-flight checks for the query.
 	if len(selectors) == 0 {
 		return QueryRes{}, fmt.Errorf("at least one selector required to query")
diff --git a/pkg/services/ngalert/state/historian/loki_http_test.go b/pkg/services/ngalert/state/historian/loki_http_test.go
index 86b856f3a4e..1c862abc633 100644
--- a/pkg/services/ngalert/state/historian/loki_http_test.go
+++ b/pkg/services/ngalert/state/historian/loki_http_test.go
@@ -101,7 +101,7 @@ func TestLokiHTTPClient(t *testing.T) {
 		require.NoError(t, err)
 	})
 
-	t.Run("smoke test querying Loki", func(t *testing.T) {
+	t.Run("smoke test range querying Loki", func(t *testing.T) {
 		url, err := url.Parse("https://logs-prod-eu-west-0.grafana.net")
 		require.NoError(t, err)
 
@@ -127,7 +127,7 @@ func TestLokiHTTPClient(t *testing.T) {
 		end := time.Now().UnixNano()
 
 		// Authorized request should not fail against Grafana Cloud.
-		res, err := client.query(context.Background(), selectors, start, end)
+		res, err := client.rangeQuery(context.Background(), selectors, start, end)
 		require.NoError(t, err)
 		require.NotNil(t, res)
 	})