Add until option

README.md

@@ -30,8 +30,8 @@ set the query parameters as appropriate:
 - **query**: required. Prometheus query to execute.
 - **title**: chart title
 - **stacked**: set to create an area chart instead of a line chart
-- **since**: [time.ParseDuration][1] to set distance in the past to start
-  charting from
+- **since**, **until**: [time.ParseDuration][1] to set distance in the past to
+  start charting from or until
 - **width**, **height**: adjust chart dimensions in inches
 - **step**: number of seconds between data points
 - **min**, **max**: Y axis limits

go.mod

@@ -3,6 +3,7 @@ module git.sr.ht/~sircmpwn/chartsrv
 go 1.15
 
 require (
+	github.com/dustin/go-humanize v1.0.0 // indirect
 	github.com/go-chi/chi v4.1.2+incompatible
 	gonum.org/v1/plot v0.8.0
 )

go.sum

@@ -5,6 +5,8 @@ github.com/ajstarks/svgo v0.0.0-20180226025133-644b8db467af h1:wVe6/Ea46ZMeNkQjj
 github.com/ajstarks/svgo v0.0.0-20180226025133-644b8db467af/go.mod h1:K08gAheRH3/J6wwsYMMT4xOr94bZjxIelGM0+d/wbFw=
 github.com/boombuler/barcode v1.0.0/go.mod h1:paBWMcWSl3LHKBqUq+rly7CNSldXjb2rDl3JlRe0mD8=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/dustin/go-humanize v1.0.0 h1:VSnTsYCnlFHaM2/igO1h6X3HA71jcobQuxemgkq4zYo=
+github.com/dustin/go-humanize v1.0.0/go.mod h1:HtrtbFcZ19U5GC7JDqmcUSB87Iq5E25KnS6fMYU6eOk=
 github.com/fogleman/gg v1.2.1-0.20190220221249-0403632d5b90/go.mod h1:R/bRT+9gY/C5z7JzPU0zXsXHKM4/ayA+zqcVNZzPa1k=
 github.com/fogleman/gg v1.3.0 h1:/7zJX8F6AaYQc57WQCyN9cAIz+4bCJGO9B+dyW29am8=
 github.com/fogleman/gg v1.3.0/go.mod h1:R/bRT+9gY/C5z7JzPU0zXsXHKM4/ayA+zqcVNZzPa1k=

main.go

@@ -13,6 +13,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/dustin/go-humanize"
 	"github.com/go-chi/chi"
 	"github.com/go-chi/chi/middleware"
 	"gonum.org/v1/plot"
@@ -154,6 +155,10 @@ func main() {
 			d, _ := time.ParseDuration(s[0])
 			start = time.Now().Add(-d)
 		}
+		if u, ok := args["until"]; ok {
+			d, _ := time.ParseDuration(u[0])
+			end = time.Now().Add(-d)
+		}
 
 		width := 12*vg.Inch
 		height := 6*vg.Inch
@@ -166,6 +171,12 @@ func main() {
 			height = vg.Length(h)*vg.Inch
 		}
 
+		// Undocumented option
+		var legend string
+		if l, ok := args["legend"]; ok {
+			legend = l[0]
+		}
+
 		// Set step so that there's approximately 25 data points per inch
 		step := int(end.Sub(start).Seconds() / (25 * float64(width / vg.Inch)))
 		if s, ok := args["step"]; ok {
@@ -194,6 +205,8 @@ func main() {
 			m, _ := strconv.ParseFloat(ms[0], 64)
 			p.Y.Max = m
 		}
+
+		p.Y.Tick.Marker = humanTicks{}
 		if ms, ok := args["min"]; ok {
 			m, _ := strconv.ParseFloat(ms[0], 64)
 			p.Y.Min = m
@@ -238,7 +251,11 @@ func main() {
 				nextColor = 0
 			}
 			plotters[i] = l
-			p.Legend.Add(res.Metric, l)
+			if legend != "" {
+				p.Legend.Add(legend, l)
+			} else {
+				p.Legend.Add(res.Metric, l)
+			}
 		}
 		for i := len(plotters) - 1; i >= 0; i-- {
 			p.Add(plotters[i])
@@ -287,3 +304,17 @@ func (dt dateTicks) Ticks(min, max float64) []plot.Tick {
 	}
 	return tks
 }
+
+type humanTicks struct{}
+
+func (ht humanTicks) Ticks(min, max float64) []plot.Tick {
+	tks := plot.DefaultTicks{}.Ticks(min, max)
+	for i, t := range tks {
+		if t.Label == "" { // Skip minor ticks, they are fine.
+			continue
+		}
+		d, _ := strconv.ParseFloat(t.Label, 64)
+		tks[i].Label = humanize.SI(d, "")
+	}
+	return tks
+}