~sircmpwn/chartsrv: Initial commit

5 files changed, 395 insertions(+), 0 deletions(-)

A LICENSE
A README.md
A go.mod
A go.sum
A main.go

A  => LICENSE +19 -0

@@ 1,19 @@
+Copyright (c) 2020 Drew DeVault
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+of the Software, and to permit persons to whom the Software is furnished to do
+so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

A  => README.md +33 -0

@@ 1,33 @@
+# chartsrv
+
+chartsrv is a dead-simple web application which runs [Prometheus][0] queries and
+charts the result as an SVG.
+
+[0]: https://prometheus.io/
+
+## Running the daemon
+
+```
+$ go build -o chartsrv main.go
+$ ./chartsrv https://prometheus.example.org
+Listening on :8142
+```
+
+Forward `/chart.svg` to this address with your favorite reverse proxy.
+
+## Usage
+
+Create a URL like `https://chartsrv.example.org/chart.svg?query=...&args...` and
+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
+- **width**: chart width in inches
+- **height**: chart height in inches
+- **step**: number of seconds between data points
+- **max**: maximum Y value
+
+[1]: https://golang.org/pkg/time/#ParseDuration

A  => go.mod +8 -0

@@ 1,8 @@
+module git.sr.ht/~sircmpwn/promsvg
+
+go 1.15
+
+require (
+	github.com/go-chi/chi v4.1.2+incompatible // indirect
+	gonum.org/v1/plot v0.8.0 // indirect
+)

A  => go.sum +63 -0

@@ 1,63 @@
+dmitri.shuralyov.com/gpu/mtl v0.0.0-20190408044501-666a987793e9/go.mod h1:H6x//7gZCb22OMCxBHrMx7a5I7Hp++hsVxbQ4BYO7hU=
+gioui.org v0.0.0-20200628203458-851255f7a67b/go.mod h1:jiUwifN9cRl/zmco43aAqh0aV+s9GbhG13KcD+gEpkU=
+github.com/BurntSushi/xgb v0.0.0-20160522181843-27f122750802/go.mod h1:IVnqGOEym/WlBOVXweHU+Q+/VP0lqqI8lqeDx9IjBqo=
+github.com/ajstarks/svgo v0.0.0-20180226025133-644b8db467af h1:wVe6/Ea46ZMeNkQjjBW6xcqyQA/j5e0D6GytH95g0gQ=
+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/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=
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+github.com/go-chi/chi v1.0.0 h1:s/kv1cTXfivYjdKJdyUzNGyAWZ/2t7duW1gKn5ivu+c=
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+github.com/go-fonts/dejavu v0.1.0/go.mod h1:4Wt4I4OU2Nq9asgDCteaAaWZOV24E+0/Pwo0gppep4g=
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A  => main.go +272 -0

@@ 1,272 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"image/color"
+	"log"
+	"net/http"
+	"net/url"
+	"os"
+	"sort"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/go-chi/chi"
+	"github.com/go-chi/chi/middleware"
+	"gonum.org/v1/plot"
+	"gonum.org/v1/plot/plotter"
+	"gonum.org/v1/plot/plotutil"
+	"gonum.org/v1/plot/vg"
+)
+
+var (
+	upstream string
+)
+
+type PromResponse struct {
+	Status string `json:"status"`
+	Data   struct {
+		ResultType string `json:"resultType"`
+		Result     []struct {
+			Metric map[string]string `json:"metric"`
+			Values [][]interface{}   `json:"values"`
+		} `json:"result"`
+	} `json:"data"`
+}
+
+type Datapoint struct {
+	Time  time.Time
+	Value float64
+}
+
+type PromResult struct {
+	Metric string
+	Values []Datapoint
+}
+
+func Query(q string, start time.Time, end time.Time, step int) ([]PromResult, error) {
+	body := url.Values{}
+	body.Set("query", q)
+	body.Set("start", fmt.Sprintf("%d", start.Unix()))
+	body.Set("end", fmt.Sprintf("%d", end.Unix()))
+	body.Set("step", fmt.Sprintf("%d", step))
+	resp, err := http.Post(fmt.Sprintf("%s/api/v1/query_range", upstream),
+		"application/x-www-form-urlencoded", strings.NewReader(body.Encode()))
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != 200 {
+		return nil, fmt.Errorf("Received %d response from upstream", resp.StatusCode)
+	}
+
+	var data PromResponse
+	if err := json.NewDecoder(resp.Body).Decode(&data); err != nil {
+		return nil, err
+	}
+
+	if data.Data.ResultType != "matrix" {
+		return nil, fmt.Errorf("result type isn't of type matrix: %s",
+			data.Data.ResultType)
+	}
+
+	if len(data.Data.Result) == 0 {
+		return nil, fmt.Errorf("No data")
+	}
+
+	var results []PromResult
+	for _, res := range data.Data.Result {
+		r := PromResult{}
+		r.Metric = metricName(res.Metric)
+
+		var values []Datapoint
+		for _, vals := range res.Values {
+			timestamp := vals[0].(float64)
+			value := vals[1].(string)
+			fv, _ := strconv.ParseFloat(value, 64)
+			values = append(values, Datapoint{
+				time.Unix(int64(timestamp), 0),
+				fv,
+			})
+		}
+		r.Values = values
+
+		results = append(results, r)
+	}
+	return results, nil
+}
+
+func metricName(metric map[string]string) string {
+	if len(metric) == 0 {
+		return "{}"
+	}
+
+	out := ""
+	var inner []string
+	for key, value := range metric {
+		if key == "__name__" {
+			out = value
+			continue
+		}
+		inner = append(inner, fmt.Sprintf(`%s="%s"`, key, value))
+	}
+
+	if len(inner) == 0 {
+		return out
+	}
+
+	sort.Slice(inner, func(i, j int) bool {
+		return inner[i] < inner[j]
+	})
+
+	return out + "{" + strings.Join(inner, ",") + "}"
+}
+
+func main() {
+	plotutil.DefaultDashes = [][]vg.Length{{}}
+
+	upstream = os.Args[1]
+	router := chi.NewRouter()
+	router.Use(middleware.RealIP)
+	router.Use(middleware.Logger)
+
+	router.Get("/chart.svg", func(w http.ResponseWriter, r *http.Request) {
+		args := r.URL.Query()
+		var query string
+		if q, ok := args["query"]; !ok {
+			w.WriteHeader(400)
+			w.Write([]byte("Expected ?query=... parameter"))
+			return
+		} else {
+			query = q[0]
+		}
+
+		start := time.Now().Add(-24 * 60 * time.Minute)
+		end := time.Now()
+		if s, ok := args["since"]; ok {
+			d, _ := time.ParseDuration(s[0])
+			start = time.Now().Add(-d)
+		}
+
+		width := 12*vg.Inch
+		height := 6*vg.Inch
+		if ws, ok := args["width"]; ok {
+			w, _ := strconv.ParseFloat(ws[0], 32)
+			width = vg.Length(w)*vg.Inch
+		}
+		if hs, ok := args["height"]; ok {
+			h, _ := strconv.ParseFloat(hs[0], 32)
+			height = vg.Length(h)*vg.Inch
+		}
+
+		// 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 {
+			d, _ := strconv.ParseInt(s[0], 10, 32)
+			step = int(d)
+		}
+		_, stacked := args["stacked"]
+
+		data, err := Query(query, start, end, step)
+		if err != nil {
+			w.WriteHeader(400)
+			w.Write([]byte(fmt.Sprintf("%v", err)))
+			return
+		}
+
+		p, err := plot.New()
+		if err != nil {
+			panic(err)
+		}
+		if t, ok := args["title"]; ok {
+			p.Title.Text = t[0]
+		}
+		p.X.Label.Text = "Time"
+		p.X.Tick.Marker = dateTicks{}
+		if ms, ok := args["max"]; ok {
+			m, _ := strconv.ParseFloat(ms[0], 64)
+			p.Y.Max = m
+		}
+		p.Legend.Top = true
+
+		sums := make([]float64, len(data[0].Values))
+
+		plotters := make([]plot.Plotter, len(data))
+		var nextColor int
+		colors := plotutil.SoftColors
+		for i, res := range data {
+			var points plotter.XYs
+			for j, d := range res.Values {
+				value := d.Value
+				if stacked {
+					value += sums[j]
+				}
+				points = append(points, plotter.XY{
+					float64(d.Time.Unix()),
+					value,
+				})
+				sums[j] += d.Value
+			}
+
+			l, _, err := plotter.NewLinePoints(points)
+			if err != nil {
+				w.WriteHeader(400)
+				w.Write([]byte(fmt.Sprintf("%v", err)))
+				return
+			}
+			if stacked {
+				l.FillColor = colors[nextColor]
+				if i != len(data) - 1 {
+					l.Color = color.RGBA{0, 0, 0, 0}
+				}
+			} else {
+				l.Color = colors[nextColor]
+			}
+			nextColor += 1
+			if nextColor >= len(colors) {
+				nextColor = 0
+			}
+			plotters[i] = l
+			p.Legend.Add(res.Metric, l)
+		}
+		for i := len(plotters) - 1; i >= 0; i-- {
+			p.Add(plotters[i])
+		}
+
+		writer, err := p.WriterTo(width, height, "svg")
+		if err != nil {
+			w.WriteHeader(400)
+			w.Write([]byte(fmt.Sprintf("%v", err)))
+			return
+		}
+
+		w.Header().Add("Content-Type", "image/svg+xml")
+		writer.WriteTo(w)
+	})
+
+	addr := ":8142"
+	if len(os.Args) > 2 {
+		addr = os.Args[2]
+	}
+	log.Printf("Listening on %s", addr)
+	http.ListenAndServe(addr, router)
+}
+
+type dateTicks struct{}
+// Ticks computes the default tick marks, but inserts commas
+// into the labels for the major tick marks.
+func (dateTicks) 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)
+		tm := time.Unix(int64(d), 0)
+		tks[i].Label = tm.Format("15:04:05")
+	}
+	return tks
+}