Alerting: Use default page size of 5000 when querying Loki for state history (#66315)

Always specify limit of 5000

pkg/services/ngalert/state/historian/loki_http.go

@@ -17,6 +17,8 @@ import (
 	"github.com/weaveworks/common/http/client"
 )
 
+const defaultPageSize = 5000
+
 func NewRequester() client.Requester {
 	return &http.Client{}
 }
@@ -222,6 +224,7 @@ func (c *httpLokiClient) setAuthAndTenantHeaders(req *http.Request) {
 		req.Header.Add("X-Scope-OrgID", c.cfg.TenantID)
 	}
 }
+
 func (c *httpLokiClient) rangeQuery(ctx context.Context, logQL string, start, end int64) (queryRes, error) {
 	// Run the pre-flight checks for the query.
 	if start > end {
@@ -234,6 +237,7 @@ func (c *httpLokiClient) rangeQuery(ctx context.Context, logQL string, start, en
 	values.Set("query", logQL)
 	values.Set("start", fmt.Sprintf("%d", start))
 	values.Set("end", fmt.Sprintf("%d", end))
+	values.Set("limit", fmt.Sprintf("%d", defaultPageSize))
 
 	queryURL.RawQuery = values.Encode()
 

pkg/services/ngalert/state/historian/loki_http_test.go

@@ -1,6 +1,7 @@
 package historian
 
 import (
+	"bytes"
 	"context"
 	"encoding/json"
 	"fmt"
@@ -116,6 +117,28 @@ func TestLokiHTTPClient(t *testing.T) {
 		exp := fmt.Sprintf(`{"streams": [{"stream": {}, "values": [["%d", "some line"]]}]}`, now.UnixNano())
 		require.JSONEq(t, exp, sent)
 	})
+
+	t.Run("range query", func(t *testing.T) {
+		t.Run("passes along page size", func(t *testing.T) {
+			req := NewFakeRequester().WithResponse(&http.Response{
+				Status:        "200 OK",
+				StatusCode:    200,
+				Body:          io.NopCloser(bytes.NewBufferString(`{}`)),
+				ContentLength: int64(0),
+				Header:        make(http.Header, 0),
+			})
+			client := createTestLokiClient(req)
+			now := time.Now().UTC().UnixNano()
+			q := `{from="state-history"}`
+
+			_, err := client.rangeQuery(context.Background(), q, now-100, now)
+
+			require.NoError(t, err)
+			params := req.lastRequest.URL.Query()
+			require.True(t, params.Has("limit"), "query params did not contain 'limit': %#v", params)
+			require.Equal(t, fmt.Sprint(defaultPageSize), params.Get("limit"))
+		})
+	})
 }
 
 // This function can be used for local testing, just remove the skip call.