Eppo Server-Side SDK

4.4.1 verified Mon Apr 27 auth: no python

Server-side Python SDK for Eppo's feature flagging and experimentation platform. Current version 4.4.1, requires Python >=3.8. Follows semantic versioning; minor releases may introduce breaking changes.

pip install eppo-server-sdk

Common errors

error TypeError: __init__() got an unexpected keyword argument 'api_key' ↓

cause Using old positional argument pattern with new Configuration-based constructor.

fix

Wrap api_key in Configuration: EppoClient(Configuration(api_key='...'))

error AttributeError: 'EppoClient' object has no attribute 'get_boolean_assignment' ↓

cause Method removed in v4.0.0.

fix

Use client.get_assignment() and compare result to expected variant string.

Warnings

breaking In v4.0.0, the constructor changed from positional arguments to a Configuration object. Old code using EppoClient(api_key='...') will fail. ↓

fix Use EppoClient(Configuration(api_key='...')).

breaking v4.0.0 removed synchronous methods; get_assignment is now the only method. Methods like get_boolean_assignment no longer exist. ↓

fix Use get_assignment with expected_variant or check assignment value manually.

gotcha The client is not thread-safe. Do not share a single EppoClient instance across threads without external locking. ↓

fix Create separate client instances per thread or use a thread-safe wrapper.

gotcha Configuration caching may cause stale flag evaluations if not configured properly. Default cache TTL is 300 seconds. ↓

fix Set cache_ttl_seconds in Configuration to control refresh interval.

Imports

EppoClient

wrong

from eppo import EppoClient

correct

from eppo_client import EppoClient

Incorrect module path

Quickstart

Initialize EppoClient with API key and get a flag assignment.

from eppo_client import EppoClient, Configuration

client = EppoClient(
    Configuration(
        api_key=os.environ.get('EPPO_API_KEY', '')
    )
)
assignment = client.get_assignment(
    subject_key='user-1',
    flag_key='my-flag',
    subject_attributes={'age': 30}
)
print(assignment)