aio-service-caller 0.1.4

An async service invocation framework with registry, discovery, load balancing, and declarative HTTP client features.

Aio Service Caller

A lightweight and high-performance asynchronous service invocation framework for Python, providing service registration, discovery, load balancing, and declarative HTTP client capabilities.

1. Features

• 🔍 Service Discovery: Built-in Nacos integration for automatic service registration and discovery
• ⚖️ Load Balancing: Multiple strategies included (round robin, random, weighted random, weighted round robin)
• 🔌 Interceptor Mechanism: Spring-style interceptors supporting pre-request, post-response, and exception handling
• 🚀 High Performance Async I/O: Powered by aiohttp with connection pooling for efficient HTTP requests

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2. Installation

pip install aio-service-caller[config]

The optional config extra automatically installs yamlpyconfig. It is recommended to use yamlpyconfig to load service registry, discovery, and caller configuration from local configuration files combined with environment variables.

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3. Quick Start

3.1. Add configuration

Create a config file such as application.yaml or application-{profile}.yaml inside your config directory (e.g., /config):

For details about yamlpyconfig, refer to the documentation.

# Service caller settings
service-caller:
  # Supported load balancer types: round_robin, random, weight_round_robin, weight_random
  lb-type: round_robin           # Load balancer type
  connection-timeout: 6          # Connection timeout in seconds
  read-timeout: 6                # Read timeout in seconds
  connection-pool-size: 100      # Connection pool size

# Nacos configuration
app-registry:
  nacos:
    server-addr: "192.168.30.36:9090"   # Nacos server address
    namespace: "dev"                    # Optional namespace
    cluster: "DEFAULT"                  # Optional cluster
    group: "DEFAULT_GROUP"              # Default group name
    ip: "127.0.0.1"                     # Local service IP
    port: 9999                          # Local service port
    app-name: "my-app"                  # Application name
    username: "nacos"                   # Optional username
    password: "Y789uioJKL"              # Optional password
    weight: 1.0                         # Service instance weight

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3.2. Create ServiceManager and call other services in the cluster

Creating a ServiceManager serves two purposes:

1. Automatically registers the current service to Nacos using the provided configuration
2. Allows you to call other service instances registered under the same namespace (real HTTP requests are handled internally via aiohttp)

Example:

@pytest.mark.asyncio
async def test_get_service_instances_with_nacos(self):
    # Load configuration
    async with ConfigManager("./") as config_manager:
        # Creating the ServiceManager automatically registers the current service into Nacos
        async with ServiceManager(
            config_manager=config_manager,
            interceptors=[LoggingInterceptor(), AuthInterceptor(token="123456"), MetricsInterceptor()]
        ) as manager:

            # Option 1: Directly get the parsed result
            result = await manager.get("other-app", "/hello")
            assert result == {"status": "OK"}

            # Option 2: Get the raw aiohttp response object
            async with manager.raw_get("other-app", "/hello") as response:
                assert response.status == 200
                result = await response.json()
                assert result == {"status": "OK"}

You may pass any argument supported by aiohttp (except method and url) to the request— such as headers, params, data, json, timeout, etc.

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3.3. Custom Interceptors

When using ServiceManager, interceptors will be executed at the appropriate time during the call lifecycle. You can implement your own interceptors and pass them via the interceptors parameter to implement custom behavior.

Example: a logging interceptor

class LoggingInterceptor(IServiceInterceptor):
    """Logging interceptor"""

    def __init__(self, log_request: bool = True, log_response: bool = True):
        """
        Args:
            log_request: Whether to log request details
            log_response: Whether to log response info
        """
        self.log_request = log_request
        self.log_response = log_response

    @property
    def name(self) -> str:
        return "LoggingInterceptor"

    async def before_request(self, context: RequestContext) -> None:
        """Log before sending the request"""
        if self.log_request:
            logger.info(
                f"→ {context.method} {context.service_name}{context.path} | "
                f"Headers: {context.kwargs.get('headers', {})} | "
                f"Params: {context.kwargs.get('params', {})}"
            )

    async def after_response(self, context: RequestContext) -> None:
        """Log after receiving the response"""
        if self.log_response and context.response:
            logger.info(
                f"← {context.method} {context.service_name}{context.path} | "
                f"Resolved URL: {context.resolved_url} | "
                f"Status: {context.response.status} | "
                f"Duration: {context.duration:.3f}s | "
                f"Size: {len(str(context.result)) if context.result else 0} bytes"
            )

    async def handle_exception(self, context: RequestContext) -> None:
        """Log when an exception occurs"""
        if context.exception:
            logger.error(
                f"✗ {context.method} {context.service_name}{context.path} | "
                f"Exception: {context.exception} | "
                f"Duration: {context.duration:.3f}s"
            )

    @property
    def order(self) -> int:
        return 99999

Another example: adding authentication headers before the request is sent

class AuthInterceptor(IServiceInterceptor):
    """Authentication interceptor"""

    def __init__(self, token: str, header_name: str = "Authorization", prefix: str = "Bearer "):
        """
        Args:
            token: Authentication token
            header_name: HTTP header key
            prefix: Token prefix
        """
        self.token = token
        self.header_name = header_name
        self.prefix = prefix

    @property
    def name(self) -> str:
        return "AuthInterceptor"

    async def before_request(self, context: RequestContext) -> None:
        """Add auth headers before request"""
        if "headers" not in context.kwargs:
            context.kwargs["headers"] = {}

        context.kwargs["headers"][self.header_name] = f"{self.prefix}{self.token}"

    async def after_response(self, context: RequestContext) -> None:
        """Handle authentication-related responses"""
        if context.response and context.response.status == 401:
            logger.warning(f"Authentication failed for {context.service_name}{context.path}")

    async def handle_exception(self, context: RequestContext) -> None:
        """Authentication exception handling"""
        pass  # Let upper layers handle the error

Interceptor execution order is determined by the order property. Default is 0, and smaller values execute earlier.

Notes on Interceptors:

1. Interceptors with the same name will only be added once. Any subsequent interceptor with the same name will be ignored.
2. You can manually add or remove interceptors through the following three methods of service_manager:
   • add_interceptor(interceptor: IServiceInterceptor): Add an interceptor.
   • remove_interceptor(name: str): Remove an interceptor by its name.
   • clear_interceptors(): Remove all interceptors.