fix(config): change config schema to allow regex based matches

BREAKING CHANGE: this changes configuration schema for custom label values, it provides more flexibility when setting custom labels and also prevents '*' special wildcard value from conflicting with labels, since '*' is a valid label value.

Fixes #537

docs/CONFIGURATION.md

@@ -329,7 +329,11 @@ labels:
   color:
     static: list of strings
     unique: list of strings
-    custom: dict
+    custom:
+      foo:
+        - value: string
+          value_re: string
+          color: string
   keep: list of strings
   strip: list of strings
 ```
@@ -343,14 +347,20 @@ labels:
   in the UI.
 - `color:custom` - nested map of label names and value with colors - this allows
   to configure a set of labels with custom predefined colors applied to them
-  rather than generated. Colors can be defined as RGB or HEX values.
-  Value is a mapping with `label name` -> `label value` -> `color`, see examples
-  below. Wildcard values (`*`) are allowed to provide a fallback custom color,
-  which can also be used instead of `color:static` option. Wildcard options
-  are evaluated after exact matches, so it's possible to mix explicit and
-  wildcard values.
+  rather than generated. Value is a mapping with `label name` ->
+  `list of dicts`, each dict object allows setting:
+
+  - `value` - the exact value of the label to match against
+  - `value_re` - Go compatible
+    [regular expression](https://golang.org/pkg/regexp/) to match against
+  - `color`: color to apply if either `value` or `value_re` matches
+
+  Either `value` or `value_re` is required, both can be set in which case
+  `value` with be tested first. Entries are evaluated in the order they appear
+  in the config file.
   Note: this option is not available via environment variables, you can only set
   it via the config file.
+
 - `keep` - list of allowed labels, if empty all labels are allowed.
 - `strip` - list of ignored labels.
 
@@ -394,27 +404,39 @@ labels:
   color:
     custom:
       "@alertmanager":
-        prod: "#e6e"
+        - value: prod
+          color: "#e6e"
       severity:
-        info: "#87c4e0"
-        warning: "#ffae42"
-        critical: "#ff220c"
+        - value: info
+          color: "#87c4e0"
+        - value: warning
+          color: "#ffae42"
+        - value: critical
+          color: "#ff220c"
 ```
 
-Example with a wildcard value, `info`, `warning` and `critical` will get colors
-as below, but any value not matching those 3 values will use the color from `*`:
+Example with a regex value, `info`, `warning` and `critical` will get colors
+as below, but any value not matching those 3 values will use the color from
+`.*`:
 
 ```YAML
 labels:
   color:
     custom:
       severity:
-        "*": "#736598"
-        info: "#87c4e0"
-        warning: "#ffae42"
-        critical: "#ff220c"
+        - value: info
+          color: "#87c4e0"
+        - value: warning
+          color: "#ffae42"
+        - value: critical
+          color: "#ff220c"
+        - value_re: ".*"
+          color: "#736598"
 ```
 
+Note: be sure to set fallback values at the end of the list, so they're only
+evaluated if there's no exact value match
+
 Defaults:
 
 ```YAML

internal/config/config.go

@@ -5,6 +5,7 @@ import (
 	"bytes"
 	"io/ioutil"
 	"os"
+	"regexp"
 	"strings"
 	"time"
 
@@ -146,7 +147,7 @@ func (config *configSchema) Read() {
 	config.Grid.Sorting.Order = v.GetString("grid.sorting.order")
 	config.Grid.Sorting.Reverse = v.GetBool("grid.sorting.reverse")
 	config.Grid.Sorting.Label = v.GetString("grid.sorting.label")
-	config.Labels.Color.Custom = map[string]map[string]string{}
+	config.Labels.Color.Custom = CustomLabelColors{}
 	config.Labels.Color.Static = v.GetStringSlice("labels.color.static")
 	config.Labels.Color.Unique = v.GetStringSlice("labels.color.unique")
 	config.Labels.Keep = v.GetStringSlice("labels.keep")
@@ -175,6 +176,19 @@ func (config *configSchema) Read() {
 	if err != nil {
 		log.Fatal(err)
 	}
+	for labelName, customColors := range config.Labels.Color.Custom {
+		for i, customColor := range customColors {
+			if customColor.Value == "" && customColor.ValueRegex == "" {
+				log.Fatalf("Custom label color for '%s' is missing 'value' or 'value_re'", labelName)
+			}
+			if customColor.ValueRegex != "" {
+				config.Labels.Color.Custom[labelName][i].CompiledRegex, err = regexp.Compile(customColor.ValueRegex)
+				if err != nil {
+					log.Fatalf("Failed to parse custom color regex rule '%s' for '%s' label: %s", customColor.ValueRegex, labelName, err)
+				}
+			}
+		}
+	}
 
 	err = v.UnmarshalKey("grid.sorting.customValues.labels", &config.Grid.Sorting.CustomValues.Labels)
 	if err != nil {
@@ -203,7 +217,6 @@ func (config *configSchema) Read() {
 			log.Fatal(err)
 		}
 
-		config.Labels.Color.Custom = raw.Labels.Color.Custom
 		config.Grid.Sorting.CustomValues.Labels = raw.Grid.Sorting.CustomValues.Labels
 	}
 

internal/config/models.go

@@ -1,6 +1,9 @@
 package config
 
-import "time"
+import (
+	"regexp"
+	"time"
+)
 
 type alertmanagerConfig struct {
 	Name    string
@@ -11,7 +14,7 @@ type alertmanagerConfig struct {
 		CA                 string
 		Cert               string
 		Key                string
-		InsecureSkipVerify bool `yaml:"insecureSkipVerify"`
+		InsecureSkipVerify bool `yaml:"insecureSkipVerify"  mapstructure:"insecureSkipVerify"`
 	}
 	Headers map[string]string
 }
@@ -21,6 +24,15 @@ type jiraRule struct {
 	URI   string
 }
 
+type CustomLabelColor struct {
+	Value         string         `yaml:"value" mapstructure:"value"`
+	ValueRegex    string         `yaml:"value_re" mapstructure:"value_re"`
+	CompiledRegex *regexp.Regexp `yaml:"-" mapstructure:"-"`
+	Color         string         `yaml:"color" mapstructure:"color"`
+}
+
+type CustomLabelColors map[string][]CustomLabelColor
+
 type configSchema struct {
 	Alertmanager struct {
 		Interval time.Duration
@@ -50,14 +62,14 @@ type configSchema struct {
 			Label        string
 			CustomValues struct {
 				Labels map[string]map[string]int
-			} `yaml:"customValues"`
+			} `yaml:"customValues" mapstructure:"customValues"`
 		}
 	}
 	Labels struct {
 		Keep  []string
 		Strip []string
 		Color struct {
-			Custom map[string]map[string]string
+			Custom CustomLabelColors
 			Static []string
 			Unique []string
 		}

internal/transform/color_test.go

@@ -1,6 +1,7 @@
 package transform_test
 
 import (
+	"regexp"
 	"testing"
 
 	"github.com/prymitive/karma/internal/config"
@@ -10,7 +11,7 @@ import (
 
 type colorTest struct {
 	uniqueLabels []string
-	customLabels map[string]map[string]string
+	customLabels config.CustomLabelColors
 	labels       map[string]string
 	colors       map[string]string
 }
@@ -56,8 +57,10 @@ var colorTests = []colorTest{
 		},
 	},
 	{
-		customLabels: map[string]map[string]string{
-			"node": map[string]string{"localhost": "#fff"},
+		customLabels: config.CustomLabelColors{
+			"node": []config.CustomLabelColor{
+				config.CustomLabelColor{Value: "localhost", Color: "#fff"},
+			},
 		},
 		labels: map[string]string{
 			"node": "localhost",
@@ -67,8 +70,10 @@ var colorTests = []colorTest{
 		},
 	},
 	{
-		customLabels: map[string]map[string]string{
-			"node": map[string]string{"localhost": "not a color"},
+		customLabels: config.CustomLabelColors{
+			"node": []config.CustomLabelColor{
+				config.CustomLabelColor{Value: "localhost", Color: "not a valid color"},
+			},
 		},
 		labels: map[string]string{
 			"node": "localhost",
@@ -76,8 +81,21 @@ var colorTests = []colorTest{
 		colors: map[string]string{},
 	},
 	{
-		customLabels: map[string]map[string]string{
-			"node": map[string]string{"*": "#123"},
+		customLabels: config.CustomLabelColors{
+			"node": []config.CustomLabelColor{
+				config.CustomLabelColor{ValueRegex: ".*", Color: "#123"},
+			},
+		},
+		labels: map[string]string{
+			"node": "localhost",
+		},
+		colors: map[string]string{"node": "localhost"},
+	},
+	{
+		customLabels: config.CustomLabelColors{
+			"node": []config.CustomLabelColor{
+				config.CustomLabelColor{Value: "foo", ValueRegex: ".*", Color: "#123"},
+			},
 		},
 		labels: map[string]string{
 			"node": "localhost",
@@ -91,9 +109,19 @@ func TestColorLabel(t *testing.T) {
 		config.Config.Labels.Color.Unique = testCase.uniqueLabels
 		config.Config.Labels.Color.Custom = testCase.customLabels
 		colorStore := models.LabelsColorMap{}
+
+		for key, rules := range testCase.customLabels {
+			for i, rule := range rules {
+				if rule.ValueRegex != "" {
+					testCase.customLabels[key][i].CompiledRegex = regexp.MustCompile(rule.ValueRegex)
+				}
+			}
+		}
+
 		for key, value := range testCase.labels {
 			transform.ColorLabel(colorStore, key, value)
 		}
+
 		for key, value := range testCase.colors {
 			if label, found := colorStore[key]; found {
 				if _, found := label[value]; !found {

internal/transform/colors.go

@@ -69,18 +69,16 @@ func ColorLabel(colorStore models.LabelsColorMap, key string, val string) {
 	// first handle custom colors
 	_, ok := config.Config.Labels.Color.Custom[key]
 	if ok {
-		// try matching both key and value
-		customColor, found := config.Config.Labels.Color.Custom[key][val]
-		if found {
-			parseCustomColor(colorStore, key, val, customColor)
-			return
-		}
+		for _, colorRule := range config.Config.Labels.Color.Custom[key] {
+			if colorRule.Value == val {
+				parseCustomColor(colorStore, key, val, colorRule.Color)
+				return
+			}
 
-		// if not found try matching key and wildcard (*)
-		customColor, found = config.Config.Labels.Color.Custom[key]["*"]
-		if found {
-			parseCustomColor(colorStore, key, val, customColor)
-			return
+			if colorRule.CompiledRegex != nil && colorRule.CompiledRegex.MatchString(val) {
+				parseCustomColor(colorStore, key, val, colorRule.Color)
+				return
+			}
 		}
 	}