You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: internalissuer.go
    path of file: ./repos/caddy/modules/caddytls
    
    the code of the file until where you have to start completion: // Copyright 2015 Matthew Holt and The Caddy Authors
//
// Licensed under the Apache License, Version 2.0 (the "Li
    
func (iss *InternalIssuer) Provision(ctx caddy.Context) error {
	iss.logger = ctx.Logger()

	// set some defaults
	if iss.CA == "" {
		iss.CA = caddypki.DefaultCAID
	}

	// get a reference to the configured CA
	appModule, err := ctx.App("pki")
	if err != nil {
		return err
	}
	pkiApp := appModule.(*caddypki.PKI)
	ca, err := pkiApp.GetCA(ctx, iss.CA)
	if err != nil {
		return err
	}
	iss.ca = ca

	// set any other default values
	if iss.Lifetime == 0 {
		iss.Lifetime = caddy.Duration(defaultInternalCertLifetime)
	}

	return nil
}