feat: add toml config support

file_resolvers.go

@@ -0,0 +1,72 @@
+package king
+
+import (
+	"io"
+	"io/ioutil"
+
+	"github.com/BurntSushi/toml"
+	"github.com/alecthomas/kong"
+	"gopkg.in/yaml.v3"
+)
+
+// FileResolver represents a kong fileresolver.
+type FileResolver string
+
+// All supported file resolvers.
+const (
+	YAML FileResolver = "yaml"
+	TOML FileResolver = "toml"
+)
+
+// NewFileResolver creates a new fileresolver.
+func NewFileResolver(f FileResolver) kong.ConfigurationLoader {
+	switch f {
+	case TOML:
+		return tomlResolver
+	default:
+		return yamlResolver
+	}
+}
+
+func yamlResolver(r io.Reader) (kong.Resolver, error) {
+	values := map[string]interface{}{}
+
+	err := yaml.NewDecoder(r).Decode(&values)
+	if err != nil {
+		return nil, err
+	}
+
+	var f kong.ResolverFunc = func(ctx *kong.Context, parent *kong.Path, flag *kong.Flag) (interface{}, error) {
+		raw, ok := values[flag.Name]
+		if !ok {
+			return nil, nil
+		}
+
+		return raw, nil
+	}
+
+	return f, nil
+}
+
+func tomlResolver(r io.Reader) (kong.Resolver, error) {
+	values := map[string]interface{}{}
+
+	data, err := ioutil.ReadAll(r)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := toml.Unmarshal(data, &values); err != nil {
+		return nil, err
+	}
+
+	var f kong.ResolverFunc = func(ctx *kong.Context, parent *kong.Path, flag *kong.Flag) (interface{}, error) {
+		raw, ok := values[flag.Name]
+		if !ok {
+			return nil, nil
+		}
+		return raw, nil
+	}
+
+	return f, nil
+}

go.mod

@@ -3,6 +3,7 @@ module github.com/zbindenren/king
 go 1.15
 
 require (
+	github.com/BurntSushi/toml v0.3.1
 	github.com/alecthomas/kong v0.2.17
 	github.com/kr/text v0.2.0 // indirect
 	github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e // indirect

go.sum

@@ -1,4 +1,6 @@
 cloud.google.com/go v0.34.0/go.mod h1:aQUYkXzVsufM+DwF1aE+0xfcU+56JwCaLick0ClmMTw=
+github.com/BurntSushi/toml v0.3.1 h1:WXkYYl6Yr3qBf1K79EBnL4mak0OimBfB0XUf9Vl28OQ=
+github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/alecthomas/kong v0.2.17 h1:URDISCI96MIgcIlQyoCAlhOmrSw6pZScBNkctg8r0W0=
 github.com/alecthomas/kong v0.2.17/go.mod h1:ka3VZ8GZNPXv9Ov+j4YNLkI8mTuhXyr/0ktSlqIydQQ=
 github.com/alecthomas/template v0.0.0-20160405071501-a0175ee3bccc/go.mod h1:LOuyumcjzFXgccqObfd/Ljyb9UuFJ6TxHnclSeseNhc=

king.go

@@ -15,11 +15,12 @@ const redactChar = `*`
 
 // Config is used to create DefaultOptions.
 type Config struct {
-	Context     context.Context
-	Name        string
-	Description string
-	BuildInfo   *BuildInfo
-	ConfigPaths []string
+	Context      context.Context
+	Name         string
+	Description  string
+	BuildInfo    *BuildInfo
+	ConfigPaths  []string
+	FileResolver FileResolver
 }
 
 func (c Config) pathString() string {
@@ -28,6 +29,10 @@ func (c Config) pathString() string {
 
 // DefaultOptions creates a set of opinionated options.
 func DefaultOptions(c Config) []kong.Option {
+	if c.FileResolver == "" {
+		c.FileResolver = YAML
+	}
+
 	if c.ConfigPaths == nil {
 		c.ConfigPaths = configsForApp(c.Name)
 	}
@@ -53,14 +58,17 @@ func DefaultOptions(c Config) []kong.Option {
 		}),
 		kong.UsageOnError(),
 		kong.Resolvers(EnvResolver()),
-		kong.Configuration(YAML, c.ConfigPaths...),
 		vars,
 	}
 
 	if c.Context != nil {
 		opts = append(opts, bindContext(c.Context))
 	}
 
+	if len(c.ConfigPaths) > 0 {
+		opts = append(opts, kong.Configuration(NewFileResolver(c.FileResolver), c.ConfigPaths...))
+	}
+
 	return opts
 }
 

king_test.go

@@ -107,6 +107,37 @@ override-config: "%s"
 	assert.Equal(t, expected, c)
 }
 
+func TestTOMLResolver(t *testing.T) {
+	cfgValue := "fromConfig"
+	path, cleanUpFile := writeFile(t, []byte(fmt.Sprintf(`from-config="%s"
+override-config="%s"
+`, cfgValue, cfgValue),
+	))
+	defer cleanUpFile()
+
+	expected := cli{
+		FromConfig:     cfgValue,
+		OverrideConfig: cfgValue,
+	}
+
+	cli := cli{}
+	buf := &strings.Builder{}
+	opts := king.DefaultOptions(
+		king.Config{
+			Name:         "test",
+			Description:  "A application to test.",
+			ConfigPaths:  []string{path},
+			FileResolver: king.TOML,
+		},
+	)
+	opts = append(opts, kong.Writers(buf, buf))
+	parser, err := kong.New(&cli, opts...)
+	require.NoError(t, err)
+	_, err = parser.Parse([]string{})
+	require.NoError(t, err)
+	assert.Equal(t, expected, cli)
+}
+
 func TestVersion(t *testing.T) {
 	buf := &strings.Builder{}
 	b, err := king.NewBuildInfo("1.0.0",