github.com/Unleash/unleash-client-go (go): Package unleash is a client library for connecting to an Unleash feature toggle server.  See https://github.com/Unleash/unleash for more information.  The API is very simple. The main functions of interest are Initialize and IsEnabled. Calling Initialize will create a default client and if a listener is supplied, it will start the sync loop. Internally the client consists of two components. The first is the repository which runs in a separate Go routine and polls the server to get the latest feature toggles. Once the feature toggles are fetched, they are stored by sending the data to an instance of the Storage interface which is responsible for storing the data both in memory and also persisting it somewhere. The second component is the metrics component which is responsible for tracking how often features were queried and whether or not they were enabled. The metrics components also runs in a separate Go routine and will occasionally upload the latest metrics to the Unleash server. The client struct creates a set of channels that it passes to both of the above components and it uses those for communicating asynchronously. It is important to ensure that these channels get regularly drained to avoid blocking those Go routines. There are two ways this can be done.  The first and perhaps simplest way to "drive" the synchronization loop in the client is to provide a type that implements one or more of the listener interfaces. There are 3 interfaces and you can choose which ones you should implement:  If you are only interesting in tracking errors and warnings and don't care about any of the other signals, then you only need to implement the ErrorListener and pass this instance to WithListener(). The DebugListener shows an example of implementing all of the listeners in a single type.  If you would prefer to have control over draining the channels yourself, then you must not call WithListener(). Instead, you should read all of the channels continuously inside a select. The WithInstance example shows how to do this. Note that all channels must be drained, even if you are not interested in the result.  The following examples show how to use the client in different scenarios.  ExampleCustomStrategy demonstrates using a custom strategy.   ExampleSimpleUsage demonstrates the simplest way to use the unleash client.   ExampleWithInstance demonstrates how to create the client manually instead of using the default client. It also shows how to run the event loop manually.
Keywords: feature|feature-flags|feature-management|feature-toggles|go|hacktoberfest|toggles|unleash