Load external references

Use ref to load a field from a URI. Use refFrom when another field contains the URI.

type Config struct {
    PasswordPath string `yaml:"password_path"`
    Password     string `refFrom:"PasswordPath" ref:"env://APP_PASSWORD"`
}

Fuda tries PasswordPath first. When that field has no URI, it falls back to the ref tag.

password_path: file:///run/secrets/db_password

The default resolver supports these URI schemes:

Scheme	Example	Use
file://	file:///run/secrets/db_password	Read a mounted secret or local file.
http://	http://config.internal/token	Read from an HTTP endpoint.
https://	https://config.example.com/token	Read from an HTTPS endpoint.
env://	env://APP_PASSWORD	Read a process environment variable.

file:///absolute/path reads an absolute path. file://relative/path reads a path relative to the process working directory. URI authorities such as file://host/path are not supported. The file:// prefix is matched case-insensitively, so FILE://relative/path behaves the same way. file://C:/x, file://C:\x, and file:///C:/x all read the same Windows drive-form absolute path, resolving to C:\x on Windows. The drive letter is treated as part of the path, not a URI authority.

Set a timeout for network references

Set a timeout when you use http:// or https:// references:

loader, err := fuda.New().
    FromFile("config.yaml").
    WithTimeout(5 * time.Second).
    Build()

Keep source fields before dependent fields

Fuda processes struct fields in declaration order. Declare fields that provide URI template values before the field that uses ref or refFrom.

Next step

Compose a DSN from resolved values.