logging#Config: Fix Options can no longer be parsed by go-yaml

Previously, commit ccf002a introduced `UnmarshalText()` to allow `Options` to
be parsed by the `env` package. With this change, the `go-yaml` package detects
that `Options` should be decoded by that unmarshaller [1, 2]. However, since
`Options` is not a text type, `go-yaml` does not use the unmarshaller [3],
resulting in unmarshalling failures [4]. This change implements
`UnmarshalYAML()` on `Options`, which is tried before `UnmarshalText()` [5],
restoring unmarshalling functionality.

Additionally, it's essential that `Options` is no longer inlined within
`Config`, ensuring that `UnmarshalYAML()` receives only the relevant `options`
section instead of the entire YAML.  Interestingly, this used to work
previously.

[1] https://github.com/goccy/go-yaml/blob/v1.12.0/decode.go#L703
[2] https://github.com/goccy/go-yaml/blob/v1.12.0/decode.go#L833
[3] https://github.com/goccy/go-yaml/blob/v1.12.0/decode.go#L788
[4] https://github.com/goccy/go-yaml/blob/v1.12.0/decode.go#L818
[5] https://github.com/goccy/go-yaml/blob/v1.12.0/decode.go#L763

Author: lippserd

logging/config.go

@@ -39,15 +39,27 @@ func (o *Options) UnmarshalText(text []byte) error {
 	return nil
 }
 
+// UnmarshalYAML implements yaml.InterfaceUnmarshaler to allow Options to be parsed go-yaml.
+func (o *Options) UnmarshalYAML(unmarshal func(any) error) error {
+	optionsMap := make(map[string]zapcore.Level)
+
+	if err := unmarshal(&optionsMap); err != nil {
+		return err
+	}
+
+	*o = optionsMap
+
+	return nil
+}
+
 // Config defines Logger configuration.
 type Config struct {
 	// zapcore.Level at 0 is for info level.
 	Level  zapcore.Level `yaml:"level" env:"LEVEL" default:"0"`
 	Output string        `yaml:"output" env:"OUTPUT"`
 	// Interval for periodic logging.
 	Interval time.Duration `yaml:"interval" env:"INTERVAL" default:"20s"`
-
-	Options `yaml:"options" env:"OPTIONS"`
+	Options  Options       `yaml:"options" env:"OPTIONS"`
 }
 
 // SetDefaults implements defaults.Setter to configure the log output if it is not set: