Add support for graphTemplates

- Implement support for template argument for /render handler.
  Template file can be specified as graphTemplates parameter.
  It supports yaml and toml files, but not the 'ini' style conf
- Make colors to look like in graphite-web in PR graphite-project/graphite-web#2239
- Allow to redefined default colors (see carbonapi.example.yaml/toml for examples)

Fixes #163

CHANGES.md

@@ -16,6 +16,10 @@ CHANGELOG
 **Master**
  - [Fix] `lineWidth` param is not working
  - [Fix] Support `&` in metric name
+ - [Fix] default colors for png and svg are now defined as in graphite-web after https://github.com/graphite-project/graphite-web/pull/2239 
+ - [Improvement] You can override default colors through config
+ - [Improvement] It's now possible to specify 'template=' option to png or svg renders. It will use templates that's specified by 'graphTemplates' option in config. Template config format is not compatible with graphite-web though and uses either toml or yaml. Options naming is also different and follows URL override style.
+ - [Code] Minor API changes in expr/png: MarshalPNGRequest and MarshalSVGRequest now requires to specify template.
 
 **0.9.2**
  - [Improvement] "pipe" function chaining syntax. Same way as in https://github.com/graphite-project/graphite-web/pull/2042 (thx. to @lomik)

carbonapi.example.toml

@@ -11,6 +11,7 @@ maxBatchSize = 100
 pidFile = ""
 sendGlobsAsIs = false
 tz = ""
+graphTemplates = "graphTemplates.example.toml"
 
 [cache]
 defaultTimeoutSec = 60
@@ -38,6 +39,14 @@ file = "carbonapi.log"
 level = "info"
 logger = ""
 
+[defaultColors]
+red = "c80032"
+green = "00c800"
+blue = "6464ff"
+darkred = "ff0000"
+darkgreen = "00ff0"
+darkblue = "0000ff"
+
 [upstreams]
 backends = ["http://10.0.0.1:8080", "http://10.0.0.2:8080", "http://192.168.0.100:8080", "http://192.168.0.200:8080", "http://192.168.1.212:8080"]
 buckets = 10

carbonapi.example.yaml

@@ -89,11 +89,9 @@ upstreams:
     # "http://host:port" array of instances of carbonserver stores
     # This is the *ONLY* config element in this section that MUST be specified.
     backends:
-        - "http://10.0.0.1:8080"
-        - "http://10.0.0.2:8080"
-        - "http://192.168.0.100:8080"
-        - "http://192.168.0.200:8080"
-        - "http://192.168.1.212:8080"
+        - "http://127.0.0.2:8080"
+        - "http://127.0.0.3:8080"
+        - "http://127.0.0.4:8080"
 
     carbonsearch:
         # Instance of carbonsearch backend
@@ -108,7 +106,15 @@ upstreams:
 # If not zero, enabled cache for find requests
 # This parameter controls when it will expire (in seconds)
 # Default: 600 (10 minutes)
+graphTemplates: graphTemplates.example.yaml
 expireDelaySec: 10
+defaultColors:
+      "red": "c80032"
+      "green": "00c800"
+      "blue": "6464ff"
+      "darkred": "ff0000"
+      "darkgreen": "00ff0"
+      "darkblue": "0000ff"
 logger:
     - logger: ""
       file: "stderr"

expr/png/cairo.go

@@ -713,12 +713,12 @@ func MarshalPNG(params PictureParams, results []*types.MetricData) []byte {
 	return marshalCairo(params, results, cairoPNG)
 }
 
-func MarshalSVGRequest(r *http.Request, results []*types.MetricData) []byte {
-	return marshalCairo(GetPictureParams(r, results), results, cairoSVG)
+func MarshalSVGRequest(r *http.Request, results []*types.MetricData, templateName string) []byte {
+	return marshalCairo(GetPictureParamsWithTemplate(r, templateName, results), results, cairoSVG)
 }
 
-func MarshalPNGRequest(r *http.Request, results []*types.MetricData) []byte {
-	return marshalCairo(GetPictureParams(r, results), results, cairoPNG)
+func MarshalPNGRequest(r *http.Request, results []*types.MetricData, templateName string) []byte {
+	return marshalCairo(GetPictureParamsWithTemplate(r, templateName, results), results, cairoPNG)
 }
 
 func marshalCairo(p PictureParams, results []*types.MetricData, backend cairoBackend) []byte {
@@ -855,6 +855,7 @@ func marshalCairo(p PictureParams, results []*types.MetricData, backend cairoBac
 
 func drawGraph(cr *cairoSurfaceContext, params *Params, results []*types.MetricData) {
 	var minNumberOfPoints, maxNumberOfPoints int32
+
 	params.secondYAxis = false
 
 	params.startTime = -1

expr/png/graphutil.go

@@ -3,6 +3,7 @@ package png
 import (
 	"image/color"
 	"strconv"
+	"strings"
 )
 
 func getBool(s string, def bool) bool {
@@ -52,12 +53,61 @@ func getInt(s string, def int) int {
 	return int(n)
 }
 
+func string2RGBA(clr string) color.RGBA {
+	if c, ok := colors[clr]; ok {
+		return c
+	}
+	c, err := hexToRGBA(clr)
+	if err != nil {
+		return color.RGBA{0, 0, 0, 255}
+	}
+	return *c
+}
+
+// https://code.google.com/p/sadbox/source/browse/color/hex.go
+// hexToRGBA converts an Hex string to a RGB triple.
+func hexToRGBA(h string) (*color.RGBA, error) {
+	var r, g, b uint8
+	if len(h) > 0 && h[0] == '#' {
+		h = h[1:]
+	}
+
+	if len(h) == 3 {
+		h = h[:1] + h[:1] + h[1:2] + h[1:2] + h[2:] + h[2:]
+	}
+
+	alpha := byte(255)
+
+	if len(h) == 6 {
+		if rgb, err := strconv.ParseUint(string(h), 16, 32); err == nil {
+			r = uint8(rgb >> 16)
+			g = uint8(rgb >> 8)
+			b = uint8(rgb)
+		} else {
+			return nil, err
+		}
+	}
+
+	if len(h) == 8 {
+		if rgb, err := strconv.ParseUint(string(h), 16, 32); err == nil {
+			r = uint8(rgb >> 24)
+			g = uint8(rgb >> 16)
+			b = uint8(rgb >> 8)
+			alpha = uint8(rgb)
+		} else {
+			return nil, err
+		}
+	}
+
+	return &color.RGBA{r, g, b, alpha}, nil
+}
+
 var colors = map[string]color.RGBA{
 	// Graphite default colors
 	"black":     {0x00, 0x00, 0x00, 0xff},
 	"white":     {0xff, 0xff, 0xff, 0xff},
-	"blue":      {0x64, 0x64, 0xff, 0xff},
-	"green":     {0x00, 0xc8, 0x00, 0xff},
+	"blue":      {0x00, 0x00, 0xff, 0xff},
+	"green":     {0x00, 0xff, 0x00, 0xff},
 	"red":       {0xff, 0x00, 0x00, 0xff},
 	"yellow":    {0xff, 0xff, 0x00, 0xff},
 	"orange":    {0xff, 0xa5, 0x00, 0xff},
@@ -71,8 +121,8 @@ var colors = map[string]color.RGBA{
 	"pink":      {0xff, 0x64, 0x64, 0xff},
 	"gold":      {0xc8, 0xc8, 0x00, 0xff},
 	"rose":      {0xc8, 0x96, 0xc8, 0xff},
-	"darkblue":  {0x00, 0x00, 0xff, 0xff},
-	"darkgreen": {0x00, 0xff, 0x00, 0xff},
+	"darkblue":  {0x00, 0x21, 0x73, 0xff},
+	"darkgreen": {0x00, 0xc8, 0x00, 0xff},
 	"darkred":   {0xc8, 0x00, 0x32, 0xff},
 	"darkgray":  {0x6f, 0x6f, 0x6f, 0xff},
 	"darkgrey":  {0x6f, 0x6f, 0x6f, 0xff},
@@ -159,3 +209,14 @@ var colors = map[string]color.RGBA{
 	"lightyellow":          {0xff, 0xff, 0xe0, 0xff},
 	"ivory":                {0xff, 0xff, 0xf0, 0xff},
 }
+
+func SetColor(name, rgba string) error {
+	color, err := hexToRGBA(rgba)
+	if err != nil {
+		return err
+	}
+
+	name = strings.ToLower(name)
+	colors[name] = *color
+	return nil
+}