HTTP API: Support duration and float formats for step parameter

docs/api.md

@@ -204,7 +204,7 @@ accepts the following query parameters in the URL:
 - `limit`: The max number of entries to return
 - `start`: The start time for the query as a nanosecond Unix epoch. Defaults to one hour ago.
 - `end`: The start time for the query as a nanosecond Unix epoch. Defaults to now.
-- `step`: Query resolution step width in seconds. Defaults to a dynamic value based on `start` and `end`.
+- `step`: Query resolution step width in `duration` format or float number of seconds. `duration` refers to Prometheus duration strings of the form `[0-9]+[smhdwy]`. For example, 5m refers to a duration of 5 minutes. Defaults to a dynamic value based on `start` and `end`.
 - `direction`: Determines the sort order of logs. Supported values are `forward` or `backward`. Defaults to `backward.`
 
 Requests against this endpoint require Loki to query the index store in order to

pkg/loghttp/params.go

@@ -8,6 +8,9 @@ import (
 	"strings"
 	"time"
 
+	"github.com/pkg/errors"
+	"github.com/prometheus/common/model"
+
 	"github.com/grafana/loki/pkg/logproto"
 )
 
@@ -50,11 +53,22 @@ func bounds(r *http.Request) (time.Time, time.Time, error) {
 }
 
 func step(r *http.Request, start, end time.Time) (time.Duration, error) {
-	s, err := parseInt(r.URL.Query().Get("step"), defaultQueryRangeStep(start, end))
-	if err != nil {
-		return 0, err
+	value := r.URL.Query().Get("step")
+	if value == "" {
+		return time.Duration(defaultQueryRangeStep(start, end)) * time.Second, nil
+	}
+
+	if d, err := strconv.ParseFloat(value, 64); err == nil {
+		ts := d * float64(time.Second)
+		if ts > float64(math.MaxInt64) || ts < float64(math.MinInt64) {
+			return 0, errors.Errorf("cannot parse %q to a valid duration. It overflows int64", value)
+		}
+		return time.Duration(ts), nil
+	}
+	if d, err := model.ParseDuration(value); err == nil {
+		return time.Duration(d), nil
 	}
-	return time.Duration(s) * time.Second, nil
+	return 0, errors.Errorf("cannot parse %q to a valid duration", value)
 }
 
 // defaultQueryRangeStep returns the default step used in the query range API,

pkg/loghttp/params_test.go

@@ -63,7 +63,7 @@ func TestHttp_ParseRangeQuery_Step(t *testing.T) {
 				Direction: logproto.BACKWARD,
 			},
 		},
-		"should use the input step parameter if provided": {
+		"should use the input step parameter if provided as an integer": {
 			reqPath: "/loki/api/v1/query_range?query={}&start=0&end=3600000000000&step=5",
 			expected: &RangeQuery{
 				Query:     "{}",
@@ -74,6 +74,50 @@ func TestHttp_ParseRangeQuery_Step(t *testing.T) {
 				Direction: logproto.BACKWARD,
 			},
 		},
+		"should use the input step parameter if provided as a float without decimals": {
+			reqPath: "/loki/api/v1/query_range?query={}&start=0&end=3600000000000&step=5.000",
+			expected: &RangeQuery{
+				Query:     "{}",
+				Start:     time.Unix(0, 0),
+				End:       time.Unix(3600, 0),
+				Step:      5 * time.Second,
+				Limit:     100,
+				Direction: logproto.BACKWARD,
+			},
+		},
+		"should use the input step parameter if provided as a float with decimals": {
+			reqPath: "/loki/api/v1/query_range?query={}&start=0&end=3600000000000&step=5.500",
+			expected: &RangeQuery{
+				Query:     "{}",
+				Start:     time.Unix(0, 0),
+				End:       time.Unix(3600, 0),
+				Step:      5.5 * 1e9,
+				Limit:     100,
+				Direction: logproto.BACKWARD,
+			},
+		},
+		"should use the input step parameter if provided as a duration in seconds": {
+			reqPath: "/loki/api/v1/query_range?query={}&start=0&end=3600000000000&step=5s",
+			expected: &RangeQuery{
+				Query:     "{}",
+				Start:     time.Unix(0, 0),
+				End:       time.Unix(3600, 0),
+				Step:      5 * time.Second,
+				Limit:     100,
+				Direction: logproto.BACKWARD,
+			},
+		},
+		"should use the input step parameter if provided as a duration in days": {
+			reqPath: "/loki/api/v1/query_range?query={}&start=0&end=3600000000000&step=5d",
+			expected: &RangeQuery{
+				Query:     "{}",
+				Start:     time.Unix(0, 0),
+				End:       time.Unix(3600, 0),
+				Step:      5 * 24 * 3600 * time.Second,
+				Limit:     100,
+				Direction: logproto.BACKWARD,
+			},
+		},
 	}
 
 	for testName, testData := range tests {