xposer

Xpose your functions as microservices over arbitrary channels using standardized logging and configuration


Keywords
microservice, function, wrapper, exposer
License
Other
Install
pip install xposer==1.0.1

Documentation

xposer

Unified handler logic exposition with simple configuration management and integrated logging to Kafka.

Configuration

Environment variable XPOSER_CONFIG defines from where to load the config file. This can be overridden using --config command line argument

Configuration filenames

Environment variables must follow the same structure and naming as found in the configuration_xx_yy.yaml examples

Prefixes

Pydantic settings utilize prefixes (xp is the global configurations prefix)

Overriding precedence

Configuration precedence: pydantic settings -> overridden by environment -> overridden by command line So in the default config model we have foo = Field('bar') So if you have in your config.yaml a variable ('xp_' prefix is mandatory!) xp_foo = 'baz' it will be overridden with the environment variable XP_FOO = 'bak' and also will be overridden from the command line variable (it's case insensitive) --xp_foo= 'bang' or --XP_FOO='bang'

Downstream configurations

There is basically one process for attaining and loading configurations, however based on prefixes and configuration objects (pydantic) its possible to map variables from the configuration object for multiple levels: global level: prefix 'xp_' mapping location: core/configuration_model.py application level: prefix is your choice

By default, all configuration parameter is loaded to global configuration object. If something does not have a counterpart in the main configuration object, it will loiter there with the xp_ prefix unprocessed So if you provide an xp_mysettings_custom_param = 'foobar'in the configuration (or Environment or CLI arg), the global configuration object, that is accessible from the Context.config will hold that parameter and value.

Whenever you have your own pydantic settings object named MYSETTINGS, that you want to be defined in your config.yaml, environment or command line, you can do it like:

  • lets say your application has a sample config model, create a shallow copy of the keys, app_config_defaults = SampleAppHTTPConfigModel.model_construct(_validate=False)

  • Merge the ctx.config values but not all, only those which match to SampleAppHTTPConfigModel fields (prefixing with ' app_fast_logic') app_config_merged = Configurator.mergePrefixedAttributes(app_config_defaults, ctx.config, 'xp_mysettings_')

  • Validate your model to make sure all fits app_config_merged.model_validate(app_config_merged)

so your app_config_merged will contain custom_param = 'foobar'

Asyncio and Threading

Xposer creates a main loop and through creating XPTask it creates a new thread and runs the required entry point fn of the XPControllers start services

Controllers

An XPController is a small component that responsible to initialize the services and your core application logic/pkgs The XPController must be implemented by the developer XPController has two main implementable method:

@abstractmethod async def startXPController(self) -> None:

@abstractmethod async def tearDownXPController(self) -> None:

both must be implemented keeping mind that the XPController is running within its own thread and is responsible for the graceful shutdown of its internal business logic

Exceptions

async/await

async/await exceptions must be caught inline using try/catch

non awaited tasks

loop.create_task(...) exceptions caught loop exception handlers these tasks are not gathered and possibly run forever

threaded tasks/processes

threaded functions are always awaited and exceptions are routed to the main thread using threadsafe Queue.queue passed downstream using explicit Context propagation

Examples and container samples in the sample_app folder.