adds urfave/cli/v2 flag parser

providers/cliflag/cliflag.go

@@ -0,0 +1,118 @@
+// Package cliflag implements a koanf.Provider that reads commandline
+// parameters as conf maps using ufafe/cli flag.
+package cliflag
+
+import (
+	"strings"
+
+	"github.com/knadh/koanf/maps"
+	"github.com/urfave/cli/v2"
+)
+
+// CliFlag implements a cli.Flag command line provider.
+type CliFlag struct {
+	ctx   *cli.Context
+	delim string
+}
+
+// Provider returns a commandline flags provider that returns
+// a nested map[string]interface{} of environment variable where the
+// nesting hierarchy of keys are defined by delim. For instance, the
+// delim "." will convert the key `parent.child.key: 1`
+// to `{parent: {child: {key: 1}}}`.
+func Provider(f *cli.Context, delim string) *CliFlag {
+	return &CliFlag{
+		ctx:   f,
+		delim: delim,
+	}
+}
+
+// Read reads the flag variables and returns a nested conf map.
+func (p *CliFlag) Read() (map[string]interface{}, error) {
+	out := make(map[string]interface{})
+
+	// Get command lineage (from root to current command)
+	lineage := p.ctx.Lineage()
+	if len(lineage) > 0 {
+		// Build command path and process flags for each level
+		var cmdPath []string
+		for i := len(lineage) - 1; i >= 0; i-- {
+			cmd := lineage[i]
+			if cmd.Command == nil {
+				continue
+			}
+			cmdPath = append(cmdPath, cmd.Command.Name)
+			prefix := strings.Join(cmdPath, p.delim)
+			p.processFlags(cmd.Command.Flags, prefix, out)
+		}
+	}
+
+	if p.delim == "" {
+		return out, nil
+	}
+
+	return maps.Unflatten(out, p.delim), nil
+}
+
+func (p *CliFlag) processFlags(flags []cli.Flag, prefix string, out map[string]interface{}) {
+	for _, flag := range flags {
+		name := flag.Names()[0]
+		if p.ctx.IsSet(name) {
+			value := p.getFlagValue(name)
+			if value != nil {
+				// Build the full path for the flag
+				fullPath := name
+				if prefix != "global" {
+					fullPath = prefix + p.delim + name
+				}
+
+				p.setNestedValue(fullPath, value, out)
+			}
+		}
+	}
+}
+
+// setNestedValue sets a value in the nested configuration structure
+func (p *CliFlag) setNestedValue(path string, value interface{}, out map[string]interface{}) {
+	parts := strings.Split(path, p.delim)
+	current := out
+
+	// Navigate/create the nested structure
+	for i := 0; i < len(parts)-1; i++ {
+		if _, exists := current[parts[i]]; !exists {
+			current[parts[i]] = make(map[string]interface{})
+		}
+		current = current[parts[i]].(map[string]interface{})
+	}
+
+	// Set the final value
+	current[parts[len(parts)-1]] = value
+}
+
+// getFlagValue extracts the typed value from the flag
+func (p *CliFlag) getFlagValue(name string) interface{} {
+	switch {
+	case p.ctx.IsSet(name):
+		switch {
+		case p.ctx.String(name) != "":
+			return p.ctx.String(name)
+		case p.ctx.StringSlice(name) != nil:
+			return p.ctx.StringSlice(name)
+		case p.ctx.Int(name) != 0:
+			return p.ctx.Int(name)
+		case p.ctx.Int64(name) != 0:
+			return p.ctx.Int64(name)
+		case p.ctx.IntSlice(name) != nil:
+			return p.ctx.IntSlice(name)
+		case p.ctx.Float64(name) != 0:
+			return p.ctx.Float64(name)
+		case p.ctx.Bool(name):
+			return p.ctx.Bool(name)
+		case p.ctx.Duration(name).String() != "0s":
+			return p.ctx.Duration(name)
+		default:
+			return p.ctx.Generic(name)
+		}
+	}
+	return nil
+}

providers/cliflag/cliflag_test.go

@@ -0,0 +1,65 @@
+package cliflag
+
+import (
+	"fmt"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"github.com/urfave/cli/v2"
+)
+
+func TestCliFlag(t *testing.T) {
+	cliApp := cli.App{
+		Name: "testing",
+		Action: func(ctx *cli.Context) error {
+			p := Provider(ctx, ".")
+			x, err := p.Read()
+			require.NoError(t, err)
+			require.NotEmpty(t, x)
+
+			fmt.Printf("x: %v\n", x)
+
+			return nil
+		},
+		Flags: []cli.Flag{
+			cli.HelpFlag,
+			cli.VersionFlag,
+			&cli.StringFlag{
+				Name:    "test",
+				Usage:   "test flag",
+				Value:   "test",
+				Aliases: []string{"t"},
+				EnvVars: []string{"TEST_FLAG"},
+			},
+		},
+		Commands: []*cli.Command{
+			{
+				Name:        "x",
+				Description: "yeah yeah testing",
+				Action: func(ctx *cli.Context) error {
+					p := Provider(ctx, "")
+					x, err := p.Read()
+					require.NoError(t, err)
+					require.NotEmpty(t, x)
+					return nil
+				},
+				Flags: []cli.Flag{
+					cli.HelpFlag,
+					cli.VersionFlag,
+					&cli.StringFlag{
+						Name:     "lol",
+						Usage:    "test flag",
+						Value:    "test",
+						Required: true,
+						EnvVars:  []string{"TEST_FLAG"},
+					},
+				},
+			},
+		},
+	}
+
+	x := append([]string{"testing", "--test", "gf", "x", "--lol", "dsf"}, os.Args...)
+	err := cliApp.Run(append(x, os.Environ()...))
+	require.NoError(t, err)
+}

providers/cliflag/go.mod

@@ -0,0 +1,20 @@
+module github.com/knadh/koanf/v2/providers/cliflag
+
+go 1.21.5
+
+require (
+	github.com/knadh/koanf/maps v0.1.1
+	github.com/stretchr/testify v1.9.0
+	github.com/urfave/cli/v2 v2.27.5
+)
+
+require (
+	github.com/cpuguy83/go-md2man/v2 v2.0.5 // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/mitchellh/copystructure v1.2.0 // indirect
+	github.com/mitchellh/reflectwalk v1.0.2 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/russross/blackfriday/v2 v2.1.0 // indirect
+	github.com/xrash/smetrics v0.0.0-20240521201337-686a1a2994c1 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)

providers/cliflag/go.sum

@@ -0,0 +1,24 @@
+github.com/cpuguy83/go-md2man/v2 v2.0.5 h1:ZtcqGrnekaHpVLArFSe4HK5DoKx1T0rq2DwVB0alcyc=
+github.com/cpuguy83/go-md2man/v2 v2.0.5/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/knadh/koanf/maps v0.1.1 h1:G5TjmUh2D7G2YWf5SQQqSiHRJEjaicvU0KpypqB3NIs=
+github.com/knadh/koanf/maps v0.1.1/go.mod h1:npD/QZY3V6ghQDdcQzl1W4ICNVTkohC8E73eI2xW4yI=
+github.com/mitchellh/copystructure v1.2.0 h1:vpKXTN4ewci03Vljg/q9QvCGUDttBOGBIa15WveJJGw=
+github.com/mitchellh/copystructure v1.2.0/go.mod h1:qLl+cE2AmVv+CoeAwDPye/v+N2HKCj9FbZEVFJRxO9s=
+github.com/mitchellh/reflectwalk v1.0.2 h1:G2LzWKi524PWgd3mLHV8Y5k7s6XUvT0Gef6zxSIeXaQ=
+github.com/mitchellh/reflectwalk v1.0.2/go.mod h1:mSTlrgnPZtwu0c4WaC2kGObEpuNDbx0jmZXqmk4esnw=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/russross/blackfriday/v2 v2.1.0 h1:JIOH55/0cWyOuilr9/qlrm0BSXldqnqwMsf35Ld67mk=
+github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
+github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
+github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+github.com/urfave/cli/v2 v2.27.5 h1:WoHEJLdsXr6dDWoJgMq/CboDmyY/8HMMH1fTECbih+w=
+github.com/urfave/cli/v2 v2.27.5/go.mod h1:3Sevf16NykTbInEnD0yKkjDAeZDS0A6bzhBH5hrMvTQ=
+github.com/xrash/smetrics v0.0.0-20240521201337-686a1a2994c1 h1:gEOO8jv9F4OT7lGCjxCBTO/36wtF6j2nSip77qHd4x4=
+github.com/xrash/smetrics v0.0.0-20240521201337-686a1a2994c1/go.mod h1:Ohn+xnUBiLI6FVj/9LpzZWtj1/D6lUovWYBkxHVV3aM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=