getAuthorizer() method for settings struct

auth.go

func (settings settings) getAuthorizer() (autorest.Authorizer, error) {
	//1.Client Credentials
	if settings.clientSecret != "" {
		config := NewClientCredentialsConfig(settings.clientID, settings.clientSecret, settings.tenantID)
		config.AADEndpoint = settings.environment.ActiveDirectoryEndpoint
		config.Resource = settings.resource
		return config.Authorizer()
	}

	//2. Client Certificate
	if settings.certificatePath != "" {
		config := NewClientCertificateConfig(settings.certificatePath, settings.certificatePassword, settings.clientID, settings.tenantID)
		config.AADEndpoint = settings.environment.ActiveDirectoryEndpoint
		config.Resource = settings.resource
		return config.Authorizer()
	}

	//3. Username Password
	if settings.username != "" && settings.password != "" {
		config := NewUsernamePasswordConfig(settings.username, settings.password, settings.clientID, settings.tenantID)
		config.AADEndpoint = settings.environment.ActiveDirectoryEndpoint
		config.Resource = settings.resource
		return config.Authorizer()
	}

	// 4. MSI
	config := NewMSIConfig()
	config.Resource = settings.resource
	config.ClientID = settings.clientID
	return config.Authorizer()
}