Feature Toggle Pattern Should:

• Default to safe. So if the configuration is missing, the feature defaults to the safer of the two options.
• Have a value that is easily accessible, within a configuration file.
  • At runtime we should be able to change the value in the configuration file.
  • Deployment tools can access the value in the configuration file so that test can have a different value to production. Therefore there is no need to have a different batch in source control.

Example

An example of the Feature Toggle Pattern implemented within the Startup class of Monolith Application. This example also shows the inversion of control pattern.

var useCustomerManagerAPI = Configuration.GetValue_a_m_p_;_lt;bool_a_m_p_;_gt;("UseCustomerManagerAPI");

if (useCustomerManagerAPI)
{
    services.AddSingleton_a_m_p_;_lt;IBankAccountRepository, BankAccountRepositoryService_a_m_p_;_gt; ();
    services.AddSingleton_a_m_p_;_lt;ICustomerRepository, CustomerRepositoryService_a_m_p_;_gt; ();
}
else
{
    services.AddSingleton_a_m_p_;_lt;IBankAccountRepository, BankAccountRepository_a_m_p_;_gt; ();
    services.AddSingleton_a_m_p_;_lt;ICustomerRepository, CustomerRepository_a_m_p_;_gt; ();
}