harness-sdk 1.0.2

Harness Python SDK with instrumentation and plugin architecture

harness-sdk (otel-python-sdk)

Generic Python agent SDK with OpenTelemetry instrumentation and a plugin architecture.

Local development

bash scripts/fetch-vendor.sh
pip install -e ".[dev,anthropic,openai,litellm]"
./scripts/run-unit-tests.sh

Environment variables for SDK configuration use the HA_ prefix (for example HA_SERVICE_NAME, HA_REPORTING_ENDPOINT).

Integration tests (MySQL / PostgreSQL)

cd test/externalServices && docker compose up -d --wait
cd ../..
RUN_SDK_INTEGRATION_TESTS=1 ./scripts/run-unit-tests.sh

CI

GitHub Actions workflows (public repo, ubuntu-latest):

Workflow	Trigger	Purpose
pr_build.yaml	PR + push to main	Build manylinux wheels, lint, pytest (with Docker for DB tests)
publish.yaml	Tag v*.*.*	Build release artifacts and publish to PyPI / TestPyPI
staticanalysis.yaml	PR, main, weekly	Trivy filesystem scan

Publishing to PyPI

1. Configure trusted publishing on PyPI (and TestPyPI for RCs):
   • PyPI: environment pypi, workflow publish.yaml, job publish-pypi
   • TestPyPI: environment testpypi, workflow publish.yaml, job publish-testpypi
2. Create and push a release tag:

   git tag v0.1.0
   git push origin v0.1.0
   

3. Release candidates (v1.0.0-rc.1) publish to TestPyPI only; stable tags publish to PyPI.

Version is taken from the tag (v1.2.3 → 1.2.3) via scripts/build.sh, which updates src/harness_sdk/version.py and pyproject.toml.

Installing

From PyPI (stable releases)

pip install harness-sdk

Optional instrumentation extras:

pip install "harness-sdk[anthropic,openai,litellm]"

From TestPyPI (release candidates)

Tags containing -rc (for example v1.0.0-rc.1) are published only to TestPyPI. Use TestPyPI as the primary index and PyPI as a fallback so dependencies that are not on TestPyPI still resolve:

pip install \
  --index-url https://test.pypi.org/simple/ \
  --extra-index-url https://pypi.org/simple/ \
  "harness-sdk==1.0.0-rc.1"

With optional extras:

pip install \
  --index-url https://test.pypi.org/simple/ \
  --extra-index-url https://pypi.org/simple/ \
  "harness-sdk[anthropic,openai,litellm]==1.0.0-rc.1"

Pin the version to the RC you want (see published files on TestPyPI). The version string matches the tag without the leading v (tag v1.0.0-rc.1 → 1.0.0-rc.1). In a virtualenv or requirements.txt, the same flags apply:

--index-url https://test.pypi.org/simple/
--extra-index-url https://pypi.org/simple/
harness-sdk==1.0.0-rc.1

After install, import and auto-instrument work the same as a PyPI release:

from harness_sdk.agent import Agent

harness-instrument python app.py

Usage

from harness_sdk.agent import Agent

agent = Agent()
agent.instrument()

Auto-instrumentation:

export HA_CONFIG_FILE=/path/to/config.yaml
harness-instrument python app.py

Plugins

The SDK loads extensions via setuptools entry points. Each plugin has a name (the entry-point key). Names are listed in config or environment variables; only installed plugins are loaded, in the order you configure.

Type	Entry-point group	Config key / env
Control	harness_sdk_control_plugin	plugins.control / HA_CONTROL_PLUGINS
Observability	harness_sdk_observability_plugin	plugins.observability / HA_OBSERVABILITY_PLUGINS

Built-in observability plugins (shipped with harness-sdk):

• builtin_pipeline — OTLP export, sampling, exclusion processors
• builtin_span_attributes — service name and configured span attributes

Example agent-config.yaml:

service_name: my-service
reporting:
  endpoint: http://localhost:4318
plugins:
  control:
    - my_policy          # order matters: first plugin runs first
  observability:
    - builtin_pipeline
    - builtin_span_attributes
    - my_exporter        # custom plugin after builtins

Or via environment (comma-separated, same order semantics):

export HA_CONTROL_PLUGINS=my_policy
export HA_OBSERVABILITY_PLUGINS=builtin_pipeline,builtin_span_attributes,my_exporter

Create a control plugin

Control plugins evaluate HTTP/gRPC ingress and GenAI spans. They return a ControlResult (block, headers, span attributes, etc.). Plugins run in config order; the chain stops when one returns block=True.

1. Implement the plugin in your package (see harness_sdk.plugins.control.ControlPlugin):

# my_company_policy/plugin.py
from typing import Any
from opentelemetry.trace import Span
from harness_sdk.plugins.control import ControlResult, ControlPlugin


class MyPolicyPlugin:
    name = "my_policy"
    provides_blocking = True  # set True if this plugin can block requests

    def on_init(self, config: Any) -> None:
        self._config = config

    def evaluate(
        self, span: Span, url: str, headers: dict, body, is_grpc: bool
    ) -> ControlResult:
        result = ControlResult()
        # result.block = True
        # result.response_status_code = 403
        return result

    def evaluate_agent_span(self, span: Span, body: str = "") -> ControlResult:
        return ControlResult()

    def shutdown(self) -> None:
        pass


def factory(config: Any) -> ControlPlugin:
    return MyPolicyPlugin()

2. Register the entry point in your package pyproject.toml:

[project.entry-points.harness_sdk_control_plugin]
my_policy = "my_company_policy.plugin:factory"

(Equivalent in setup.py: entry_points={'harness_sdk_control_plugin': ['my_policy = ...']}.)

3. Install your package in the same environment as the app (pip install my-company-policy).

4. Enable the plugin by name in config or HA_CONTROL_PLUGINS (see above).

For tests or one-off wiring you can also call agent.register_control_plugin(plugin) after Agent() is constructed.

Reference implementation: the Traceable agent ships a control plugin as traceable (traceableai.plugins.traceable_control:factory).

Create an observability plugin

Observability plugins contribute OpenTelemetry SpanProcessor instances to the tracer provider. Processors are registered in config order (each plugin’s create_span_processors may return multiple processors).

1. Implement the plugin (see harness_sdk.plugins.observability.ObservabilityPlugin):

# my_company_telemetry/plugin.py
from typing import Any, List
from opentelemetry.sdk.trace import SpanProcessor
from opentelemetry.sdk.trace.export import ConsoleSpanExporter, SimpleSpanProcessor


class MyExporterPlugin:
    name = "my_exporter"
    priority = 300  # informational; ordering is driven by config list

    def on_init(self, config: Any) -> None:
        self._config = config

    def create_span_processors(self, config: Any) -> List[SpanProcessor]:
        return [SimpleSpanProcessor(ConsoleSpanExporter())]

    def shutdown(self) -> None:
        pass


def factory(config: Any) -> MyExporterPlugin:
    return MyExporterPlugin()

2. Register the entry point:

[project.entry-points.harness_sdk_observability_plugin]
my_exporter = "my_company_telemetry.plugin:factory"

3. Install your package and enable it under plugins.observability or HA_OBSERVABILITY_PLUGINS.

If you omit observability plugins entirely, the SDK defaults to builtin_pipeline and builtin_span_attributes. Custom plugins typically keep those builtins and append your entry after them.

Reference implementations in this repo:

• harness_sdk.plugins.builtin.pipeline
• harness_sdk.plugins.builtin.span_attributes