Architecture.md

Architecture

Patron has two basic concepts:

• The Component, which defines a long-running task like a server e.g. HTTP, gRPC, Kafka consumer, etc.
• The Service, which is responsible for running provided components and monitoring them for errors

Component

A Component implements the following interface:

type Component interface {
  Run(ctx context.Context) error  
}

This allows a Service to start and then gracefully shutdown a Component via context cancellation.
The framework distinguishes between two types of components:

• synchronous, which are components that follow the request/response pattern and
• asynchronous, which consume messages from a source but don't respond anything back

The following component implementations are available:

• HTTP (sync)
• gRPC
• RabbitMQ consumer (async)
• Kafka consumer (async)
• AWS SQS (async)

Service

The Service has the role of gluing all the above together:

• setting up logging, metrics and tracing
• setting up a default HTTP component with the following endpoints configured:
  • profiling via pprof
  • liveness check
  • readiness check
• setting up termination by an OS signal
• setting up SIGHUP custom hook if provided by an option
• starting and stopping components
• handling component errors

The service has some default settings which can be changed via environment variables:

• Service HTTP port, for setting the default HTTP components port to 50000 with PATRON_HTTP_DEFAULT_PORT
• Service HTTP read and write timeout, use PATRON_HTTP_READ_TIMEOUT, PATRON_HTTP_WRITE_TIMEOUT respectively. For acceptable values check here.
• Log level, for setting the logger with INFO log level with PATRON_LOG_LEVEL
• Tracing, for setting up jaeger tracing with
  • agent host 0.0.0.0 with PATRON_JAEGER_AGENT_HOST
  • agent port 6831 with PATRON_JAEGER_AGENT_PORT
  • sampler type probabilisticwith PATRON_JAEGER_SAMPLER_TYPE
  • sampler param 0.0 with PATRON_JAEGER_SAMPLER_PARAM, which means that no traces are sent.