feat: configure colors of output with env variables

Signed-off-by: mark.barzali <mark.barzali@heureka.group>

README.md

@@ -423,6 +423,30 @@ Flags:
 
 Use "yq [command] --help" for more information about a command.
 ```
+
+## Environment Variables
+
+### Color Customization
+
+You can customize the colors used in YAML output by setting these environment variables:
+
+- `YQ_COLOR_BOOL` - Color for boolean values (default: hi-magenta)
+- `YQ_COLOR_NUMBER` - Color for numeric values (default: hi-magenta)  
+- `YQ_COLOR_MAP_KEY` - Color for map keys (default: cyan)
+- `YQ_COLOR_ANCHOR` - Color for YAML anchors (default: hi-yellow)
+- `YQ_COLOR_ALIAS` - Color for YAML aliases (default: hi-yellow)
+- `YQ_COLOR_STRING` - Color for string values (default: green)
+- `YQ_COLOR_COMMENT` - Color for comments (default: hi-black)
+
+Supported color values: `black`, `red`, `green`, `yellow`, `blue`, `magenta`, `cyan`, `white`, and their `hi-` prefixed variants (e.g., `hi-red`).
+
+Example:
+```bash
+export YQ_COLOR_STRING=red
+export YQ_COLOR_MAP_KEY=hi-blue
+yq -C '.data' file.yaml
+```
+
 ## Known Issues / Missing Features
 - `yq` attempts to preserve comment positions and whitespace as much as possible, but it does not handle all scenarios (see https://github.com/go-yaml/yaml/tree/v3 for details)
 - Powershell has its own...[opinions on quoting yq](https://mikefarah.gitbook.io/yq/usage/tips-and-tricks#quotes-in-windows-powershell)

pkg/yqlib/color_config.go

@@ -0,0 +1,93 @@
+package yqlib
+
+import (
+	"fmt"
+	"github.com/fatih/color"
+	"os"
+)
+
+type ColorConfig struct {
+	Bool    color.Attribute
+	Number  color.Attribute
+	MapKey  color.Attribute
+	Anchor  color.Attribute
+	Alias   color.Attribute
+	String  color.Attribute
+	Comment color.Attribute
+}
+
+func NewColorConfig() *ColorConfig {
+	config := &ColorConfig{
+		Bool:    color.FgHiMagenta,
+		Number:  color.FgHiMagenta,
+		MapKey:  color.FgCyan,
+		Anchor:  color.FgHiYellow,
+		Alias:   color.FgHiYellow,
+		String:  color.FgGreen,
+		Comment: color.FgHiBlack,
+	}
+
+	colorMappings := map[string]*color.Attribute{
+		"YQ_COLOR_BOOL":    &config.Bool,
+		"YQ_COLOR_NUMBER":  &config.Number,
+		"YQ_COLOR_MAP_KEY": &config.MapKey,
+		"YQ_COLOR_ANCHOR":  &config.Anchor,
+		"YQ_COLOR_ALIAS":   &config.Alias,
+		"YQ_COLOR_STRING":  &config.String,
+		"YQ_COLOR_COMMENT": &config.Comment,
+	}
+
+	for envVar, configField := range colorMappings {
+		if colorStr := os.Getenv(envVar); colorStr != "" {
+			if attr, err := parseColorAttribute(colorStr); err == nil {
+				*configField = attr
+			}
+		}
+	}
+
+	return config
+}
+
+// parseColorAttribute converts a color string to a color.Attribute.
+//
+// Supports three types of color specifications:
+// 1. Standard color names: "red", "green", "blue", "yellow", "magenta", "cyan", "white", "black"
+// 2. High-intensity variants: "hi-red", "hi-green", "hi-blue", etc.
+func parseColorAttribute(colorStr string) (color.Attribute, error) {
+	switch colorStr {
+	case "black":
+		return color.FgBlack, nil
+	case "red":
+		return color.FgRed, nil
+	case "green":
+		return color.FgGreen, nil
+	case "yellow":
+		return color.FgYellow, nil
+	case "blue":
+		return color.FgBlue, nil
+	case "magenta":
+		return color.FgMagenta, nil
+	case "cyan":
+		return color.FgCyan, nil
+	case "white":
+		return color.FgWhite, nil
+	case "hi-black":
+		return color.FgHiBlack, nil
+	case "hi-red":
+		return color.FgHiRed, nil
+	case "hi-green":
+		return color.FgHiGreen, nil
+	case "hi-yellow":
+		return color.FgHiYellow, nil
+	case "hi-blue":
+		return color.FgHiBlue, nil
+	case "hi-magenta":
+		return color.FgHiMagenta, nil
+	case "hi-cyan":
+		return color.FgHiCyan, nil
+	case "hi-white":
+		return color.FgHiWhite, nil
+	default:
+		return color.Reset, fmt.Errorf("unknown color: %s", colorStr)
+	}
+}

pkg/yqlib/color_print.go

@@ -19,46 +19,47 @@ func format(attr color.Attribute) string {
 
 func colorizeAndPrint(yamlBytes []byte, writer io.Writer) error {
 	tokens := lexer.Tokenize(string(yamlBytes))
+	config := NewColorConfig()
 	var p printer.Printer
 	p.Bool = func() *printer.Property {
 		return &printer.Property{
-			Prefix: format(color.FgHiMagenta),
+			Prefix: format(config.Bool),
 			Suffix: format(color.Reset),
 		}
 	}
 	p.Number = func() *printer.Property {
 		return &printer.Property{
-			Prefix: format(color.FgHiMagenta),
+			Prefix: format(config.Number),
 			Suffix: format(color.Reset),
 		}
 	}
 	p.MapKey = func() *printer.Property {
 		return &printer.Property{
-			Prefix: format(color.FgCyan),
+			Prefix: format(config.MapKey),
 			Suffix: format(color.Reset),
 		}
 	}
 	p.Anchor = func() *printer.Property {
 		return &printer.Property{
-			Prefix: format(color.FgHiYellow),
+			Prefix: format(config.Anchor),
 			Suffix: format(color.Reset),
 		}
 	}
 	p.Alias = func() *printer.Property {
 		return &printer.Property{
-			Prefix: format(color.FgHiYellow),
+			Prefix: format(config.Alias),
 			Suffix: format(color.Reset),
 		}
 	}
 	p.String = func() *printer.Property {
 		return &printer.Property{
-			Prefix: format(color.FgGreen),
+			Prefix: format(config.String),
 			Suffix: format(color.Reset),
 		}
 	}
 	p.Comment = func() *printer.Property {
 		return &printer.Property{
-			Prefix: format(color.FgHiBlack),
+			Prefix: format(config.Comment),
 			Suffix: format(color.Reset),
 		}
 	}