Add the LangChain integration (#15229)

* Add LangChain integration

* Rename dashboard jsonfile

* Fix metadata csv

* Remove monitors for now

* Fix manifest

* Address comments

* Display on public website

* Add monitors

* Use proper langchain logo

* Remove openai docs reference

.github/CODEOWNERS

@@ -165,6 +165,10 @@ datadog_checks_base/tests/**/test_db_statements.py  @DataDog/database-monitoring
 /oracle/*.md                                        @DataDog/agent-integrations @DataDog/database-monitoring @DataDog/documentation
 /oracle/manifest.json                               @DataDog/agent-integrations @DataDog/database-monitoring @DataDog/documentation
 
+# APM Integrations
+/langchain/         @DataDog/apm-core-python @DataDog/llm-obs @DataDog/agent-integrations @DataDog/documentation
+/openai/            @DataDog/apm-core-python @DataDog/llm-obs @DataDog/agent-integrations @DataDog/documentation
+
 
 # Windows agent
 datadog_checks_base/datadog_checks/base/checks/win/                  @DataDog/windows-agent @DataDog/agent-integrations

.github/workflows/config/labeler.yml

@@ -253,6 +253,8 @@ integration/kubernetes_state_core:
 - kubernetes_state_core/**/*
 integration/kyototycoon:
 - kyototycoon/**/*
+integration/langchain:
+- langchain/**/*
 integration/lighttpd:
 - lighttpd/**/*
 integration/linkerd:

langchain/CHANGELOG.md

@@ -0,0 +1 @@
+# CHANGELOG - LangChain

langchain/README.md

@@ -0,0 +1,113 @@
+# LangChain
+
+## Overview
+
+Get cost estimation, prompt and completion sampling, error tracking, performance metrics, and more out of [LangChain][1] 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][2] for more advanced usage.
+
+
+### Configuration
+
+See the [APM Python library documentation][3] 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][3].
+
+**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
+
+See [metadata.csv][4] for a list of metrics provided by this integration.
+
+### 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][5].
+
+
+[1]: https://docs.langchain.com/docs/
+[2]: https://ddtrace.readthedocs.io/en/stable/installation_quickstart.html
+[3]: https://ddtrace.readthedocs.io/en/stable/integrations.html#langchain
+[4]: https://github.com/DataDog/integrations-core/blob/master/langchain/metadata.csv
+[5]: https://docs.datadoghq.com/help/