Overview

Get cost estimation, prompt and completion sampling, error tracking, performance metrics, and more out of LangChain Python library requests using Datadog metrics, APM, and logs.

Setup

Installation

1. Enable APM and StatsD in your Datadog Agent. For example, in Docker:

docker run -d --cgroupns host \
              --pid host \
              -v /var/run/docker.sock:/var/run/docker.sock:ro \
              -v /proc/:/host/proc/:ro \
              -v /sys/fs/cgroup/:/host/sys/fs/cgroup:ro \
              -e DD_API_KEY=<DATADOG_API_KEY> \
              -p 127.0.0.1:8126:8126/tcp \
              -p 127.0.0.1:8125:8125/udp \
              -e DD_DOGSTATSD_NON_LOCAL_TRAFFIC=true \
              -e DD_APM_ENABLED=true \
              gcr.io/datadoghq/agent:latest

2. Install the Datadog APM Python library.

pip install ddtrace>=1.17

3. Prefix your LangChain Python application command with ddtrace-run.

DD_SERVICE="my-service" DD_ENV="staging" DD_API_KEY=<DATADOG_API_KEY> ddtrace-run python <your-app>.py

Note: If the Agent is using a non-default hostname or port, be sure to also set DD_AGENT_HOST, DD_TRACE_AGENT_PORT, or DD_DOGSTATSD_PORT.

See the APM Python library documentation for more advanced usage.

Configuration

See the APM Python library documentation for all the available configuration options.

Log Prompt & Completion Sampling

To enable log prompt and completion sampling, set the DD_LANGCHAIN_LOGS_ENABLED=1 environment variable. By default, 10% of traced requests will emit logs containing the prompts and completions.

To adjust the log sample rate, see the APM library documentation.

Note: Logs submission requires DD_API_KEY to be specified when running ddtrace-run.

Validation

Validate that the APM Python library can communicate with your Agent using:

ddtrace-run --info

You should see the following output:

    Agent error: None

Debug Logging

Pass the --debug flag to ddtrace-run to enable debug logging.

ddtrace-run --debug

This displays any errors sending data:

ERROR:ddtrace.internal.writer.writer:failed to send, dropping 1 traces to intake at http://localhost:8126/v0.5/traces after 3 retries ([Errno 61] Connection refused)
WARNING:ddtrace.vendor.dogstatsd:Error submitting packet: [Errno 61] Connection refused, dropping the packet and closing the socket
DEBUG:ddtrace.contrib._trace_utils_llm.py:sent 2 logs to 'http-intake.logs.datadoghq.com'

Data Collected

Metrics

Events

The LangChain integration does not include any events.

Service Checks

The LangChain integration does not include any service checks.

Troubleshooting

Need help? Contact Datadog support.