Configurable features

In the context of this framework, configurables are entities that designate what properties of the microservice can be dynamically set and configurators are strategies that, on service startup, collects the required properties from the environment.

Currently, the available confugurators are:

  • gemstone.config.configurator.CommandLineConfigurator - collects values from the command line arguments

In order to specify configurables for the microservice, you have to provide set the gemstone.MicroService.configurables attribute to a list of Configurable objects.

Configurators are specified in the gemstone.MicroService.configurators attribute. On service startup, each configurator tries to extract the required values from the environment in the order they are defined.

In order to trigger the configurators, you need to explicitly call the gemstone.MicroService.configure() method before calling gemstone.MicroService.start()

Defining configurators

Configurators are defined in the gemstone.MicroService.configurators class attribute.

class ExampleService(gemstone.MicroService):
    # ...
    configurators = [
    # ...

Defining configurables

Configurables are defined in the gemstone.MicroService.configurables class attribute.

class ExampleService(gemstone.MicroService):
    # ...
    configurables = [
        gemstone.config.Configurable("port", template=lambda x: int(x)),
                                     template=lambda x: [RedisDiscoveryStrategy(a) for a in x.split(",")]),
    # ...

In the example above, we defined 4 configurables:

  • gemstone.config.Configurable("port", template=lambda x: int(x)) the --port command-line argument will be casted to int and assigned to gemstone.MicroService.port
  • gemstone.config.Configurable("host") the --host command-line argument assigned to