support match[] encoding (#1875)

pkg/loghttp/series.go

@@ -2,6 +2,7 @@ package loghttp
 
 import (
 	"net/http"
+	"sort"
 
 	"github.com/grafana/loki/pkg/logproto"
 )
@@ -18,18 +19,40 @@ func ParseSeriesQuery(r *http.Request) (*logproto.SeriesRequest, error) {
 	}
 
 	xs := r.Form["match"]
+	// Prometheus encodes with `match[]`; we use both for compatibility.
+	ys := r.Form["match[]"]
+
+	deduped := union(xs, ys)
+	sort.Strings(deduped)
 
 	// ensure matchers are valid before fanning out to ingesters/store as well as returning valuable parsing errors
 	// instead of 500s
-	_, err = Match(xs)
+	_, err = Match(deduped)
 	if err != nil {
 		return nil, err
 	}
 
 	return &logproto.SeriesRequest{
 		Start:  start,
 		End:    end,
-		Groups: xs,
+		Groups: deduped,
 	}, nil
 
 }
+
+func union(cols ...[]string) []string {
+	m := map[string]struct{}{}
+
+	for _, col := range cols {
+		for _, s := range col {
+			m[s] = struct{}{}
+		}
+	}
+
+	res := make([]string, 0, len(m))
+	for k := range m {
+		res = append(res, k)
+	}
+
+	return res
+}

pkg/loghttp/series_test.go

@@ -41,6 +41,28 @@ func TestParseSeriesQuery(t *testing.T) {
 			false,
 			mkSeriesRequest(t, "1000", "2000", []string{`{a="1"}`, `{b="2", c=~"3", d!="4"}`}),
 		},
+		{
+			"mixes match encodings",
+			withForm(url.Values{
+				"start":   []string{"1000"},
+				"end":     []string{"2000"},
+				"match":   []string{`{a="1"}`},
+				"match[]": []string{`{b="2"}`},
+			}),
+			false,
+			mkSeriesRequest(t, "1000", "2000", []string{`{a="1"}`, `{b="2"}`}),
+		},
+		{
+			"dedupes match encodings",
+			withForm(url.Values{
+				"start":   []string{"1000"},
+				"end":     []string{"2000"},
+				"match":   []string{`{a="1"}`, `{b="2"}`},
+				"match[]": []string{`{b="2"}`, `{c="3"}`},
+			}),
+			false,
+			mkSeriesRequest(t, "1000", "2000", []string{`{a="1"}`, `{b="2"}`, `{c="3"}`}),
+		},
 	} {
 		t.Run(tc.desc, func(t *testing.T) {
 			out, err := ParseSeriesQuery(tc.input)