I was using gopkg.in/yaml.v2 to unmarshal a .yaml file into a struct and couldn’t find a solution to unmarshal an url string into url.URL.

Trying to just use url.URL  fails with:

Error initializing configuration: yaml: 
unmarshal errors:\n  line 54:
cannot unmarshal !!str `http://...` into url.URL

This is because, url.URL doesn’t adhere to yaml.v2.Unmarshaler interface.

So here is my solution, feel free to copy paste it!

type YAMLURL struct {
	*url.URL
}

func (j *YAMLURL) UnmarshalYAML(unmarshal func(interface{}) error) error {
	var s string
	err := unmarshal(&s)
	if err != nil {
		return err
	}
	url, err := url.Parse(s)
	j.URL = url
	return err
}

And here is how to use it:

type Config struct{
    url YAMLURL `yaml:"url"`
}

Thanks for reading!