Configuration

a2akit reads settings from environment variables prefixed with A2AKIT_. Every setting has a sensible default; explicit constructor parameters always take priority.

Environment Variables

Variable	Default	Description
A2AKIT_BLOCKING_TIMEOUT	30.0	Seconds message:send blocks for a result
A2AKIT_CANCEL_FORCE_TIMEOUT	60.0	Seconds before force-cancel kicks in
A2AKIT_MAX_CONCURRENT_TASKS	(none)	Worker parallelism (None = unlimited)
A2AKIT_MAX_RETRIES	3	Broker retry attempts on worker crash
A2AKIT_BROKER_BUFFER	1000	InMemoryBroker queue depth
A2AKIT_EVENT_BUFFER	200	InMemoryEventBus fan-out buffer per task
A2AKIT_LOG_LEVEL	(unset)	Root a2akit logger level (e.g. DEBUG)

Priority

Settings are resolved in this order (highest priority first):

1. Constructor parameter — explicit values passed to A2AServer()
2. Environment variable — A2AKIT_* prefix
3. Built-in default — hardcoded in Settings

Constructor > Env-Var > Default

Example

Set environment variables:

export A2AKIT_BLOCKING_TIMEOUT=10
export A2AKIT_LOG_LEVEL=DEBUG
export A2AKIT_MAX_CONCURRENT_TASKS=4

Programmatic Override

Use Settings() to override defaults programmatically:

from a2akit import A2AServer, Settings

custom = Settings(blocking_timeout=5.0, max_retries=5)
server = A2AServer(worker=..., agent_card=..., settings=custom)

Settings Class

from pydantic_settings import BaseSettings, SettingsConfigDict


class Settings(BaseSettings):
    model_config = SettingsConfigDict(env_prefix="A2AKIT_")

    blocking_timeout: float = 30.0
    cancel_force_timeout: float = 60.0
    max_concurrent_tasks: int | None = None
    max_retries: int = 3
    broker_buffer: int = 1000
    event_buffer: int = 200
    log_level: str | None = None

The Settings class uses pydantic-settings for automatic environment variable binding.

A2AServer Constructor Parameters

These constructor parameters override Settings values:

Parameter	Settings Field	Description
blocking_timeout_s	blocking_timeout	Blocking timeout in seconds
cancel_force_timeout_s	cancel_force_timeout	Force-cancel timeout
max_concurrent_tasks	max_concurrent_tasks	Worker parallelism

Development vs. Production

For development, the defaults work well. For production, consider:

• Setting A2AKIT_MAX_CONCURRENT_TASKS to limit resource usage
• Reducing A2AKIT_BLOCKING_TIMEOUT for faster client feedback
• Setting A2AKIT_LOG_LEVEL=INFO for structured logging