New flag: --no-colors (disables colored output) (#2507)

Co-authored-by: Jeffrey Cafferata <jeffrey@jcid.nl>
Co-authored-by: Tom Limoncelli <tlimoncelli@stackoverflow.com>

commands/commands.go

@@ -12,6 +12,8 @@ import (
 	"github.com/StackExchange/dnscontrol/v4/pkg/js"
 	"github.com/StackExchange/dnscontrol/v4/pkg/printer"
 	"github.com/urfave/cli/v2"
+
+	"github.com/fatih/color"
 )
 
 // categories of commands
@@ -68,6 +70,12 @@ func Run(v string) int {
 			Destination: &diff2.EnableDiff2,
 			Value:       true,
 		},
+		&cli.BoolFlag{
+			Name:        "no-colors",
+			Usage:       "Disable colors",
+			Destination: &color.NoColor,
+			Value:       false,
+		},
 	}
 	sort.Sort(cli.CommandsByName(commands))
 	app.Commands = commands

documentation/SUMMARY.md

@@ -8,6 +8,7 @@
 * [Examples](examples.md)
 * [Migrating zones to DNSControl](migrating.md)
 * [TypeScript autocomplete and type checking](typescript.md)
+* [Disabling Colors](colors.md)
 
 ## Language Reference
 

documentation/colors.md

@@ -0,0 +1,27 @@
+# Colors support
+
+DNSControl is using colors on both its console and notification outputs, to
+denote changes, such as during preview or push events.
+
+This is on by default in all interactive prompts supporting colors. See below on
+how to bypass it.
+
+## Disable colors
+
+There are cases that we might need to disable colored output, such as in certain
+CI environments or particular notification mechanisms that don't support ANSI color
+codes.
+
+In order to do so, a global `--no-colors` command option is provided, which when
+set `--no-colors=true`, will disable colors globally.
+
+## (Force) Enable colors
+
+If color support is not correctly detected, providing `--no-colors=false` would
+force-enable coloring, bypassing modules TTY detection.
+
+## Force colors in CI environments
+
+Some CI environments, while supporting colors, fail autodetection, such as GHA.
+In that case, colors can be forcibly enabled via `--no-colors=false` or by setting
+a `CI` env variable to `true` (if not autoset).