requestid

var (
	// MetadataFunc wil be used if user not provide own func to fill metadata
	MetadataFunc = func(ctx context.Context) (context.Context, error) {
		_, ok := metadata.Get(ctx, MetadataKey)
		if ok {
			return ctx, nil
		}
		id, err := uuid.NewRandom()
		if err != nil {
			return ctx, err
		}
		ctx = metadata.Set(ctx, MetadataKey, id.String())
		return ctx, nil
	}
)

var (
	// MetadataKey contains metadata key
	MetadataKey = textproto.CanonicalMIMEHeaderKey("x-request-id")
)