Add Langchain hook to common ai provider

providers/common/ai/docs/hooks/langchain.rst

@@ -0,0 +1,111 @@
+ .. Licensed to the Apache Software Foundation (ASF) under one
+    or more contributor license agreements.  See the NOTICE file
+    distributed with this work for additional information
+    regarding copyright ownership.  The ASF licenses this file
+    to you under the Apache License, Version 2.0 (the
+    "License"); you may not use this file except in compliance
+    with the License.  You may obtain a copy of the License at
+
+ ..   http://www.apache.org/licenses/LICENSE-2.0
+
+ .. Unless required by applicable law or agreed to in writing,
+    software distributed under the License is distributed on an
+    "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+    KIND, either express or implied.  See the License for the
+    specific language governing permissions and limitations
+    under the License.
+
+.. _howto/hook:langchain:
+
+``LangChainHook``
+=================
+
+Use :class:`~airflow.providers.common.ai.hooks.langchain.LangChainHook`
+to bridge Airflow connections to LangChain model constructors.  The hook
+extracts credentials from an Airflow connection and returns configured
+LangChain model objects (``ChatOpenAI``, ``OpenAIEmbeddings``).
+
+The hook reuses the ``pydanticai`` connection type, so users configure a
+single connection for PydanticAI operators, LlamaIndex operators, and
+LangChain tasks.
+
+.. seealso::
+    :ref:`Connection configuration <howto/connection:pydanticai>`
+
+Basic Usage
+-----------
+
+Use the hook in a ``@task`` function to get a configured chat model:
+
+.. code-block:: python
+
+    from airflow.providers.common.ai.hooks.langchain import LangChainHook
+
+    @task
+    def run_chain(query: str) -> str:
+        hook = LangChainHook(llm_conn_id="pydanticai_default", llm_model="gpt-4o")
+        llm = hook.get_chat_model()
+
+        from langchain_core.prompts import ChatPromptTemplate
+        from langchain_core.output_parsers import StrOutputParser
+
+        prompt = ChatPromptTemplate.from_template("Summarize: {query}")
+        chain = prompt | llm | StrOutputParser()
+        return chain.invoke({"query": query})
+
+Embedding Models
+----------------
+
+Use :meth:`~LangChainHook.get_embedding_model` for embeddings.  A
+separate ``embed_conn_id`` can be used when embedding and chat models
+use different API keys:
+
+.. code-block:: python
+
+    hook = LangChainHook(
+        llm_conn_id="chat_conn",
+        embed_conn_id="embed_conn",
+        embed_model="text-embedding-3-large",
+        llm_model="gpt-4o",
+    )
+    embeddings = hook.get_embedding_model()
+    chat_model = hook.get_chat_model()
+
+Connection Configuration
+------------------------
+
+The hook reads credentials from the Airflow connection:
+
+- **password** -- API key (passed as ``api_key`` to model constructors)
+- **host** -- Base URL (passed as ``base_url``; optional, for custom
+  endpoints or Ollama)
+
+Parameters
+----------
+
+.. list-table::
+   :header-rows: 1
+   :widths: 25 15 60
+
+   * - Parameter
+     - Default
+     - Description
+   * - ``llm_conn_id``
+     - ``pydanticai_default``
+     - Airflow connection ID for the LLM provider.
+   * - ``embed_conn_id``
+     - ``None`` (falls back to ``llm_conn_id``)
+     - Separate connection for embeddings.
+   * - ``embed_model``
+     - ``text-embedding-3-small``
+     - Embedding model name.
+   * - ``llm_model``
+     - ``None``
+     - Chat model name.  Required for ``get_chat_model()``.
+
+Dependencies
+------------
+
+Install the ``langchain`` extra to use this hook::
+
+    pip install apache-airflow-providers-common-ai[langchain]

providers/common/ai/provider.yaml

@@ -48,6 +48,9 @@ integrations:
   - integration-name: MCP Server
     external-doc-url: https://modelcontextprotocol.io/
     tags: [ai]
+  - integration-name: LangChain
+    external-doc-url: https://python.langchain.com/
+    tags: [ai]
 
 hooks:
   - integration-name: Pydantic AI
@@ -56,6 +59,9 @@ hooks:
   - integration-name: MCP Server
     python-modules:
       - airflow.providers.common.ai.hooks.mcp
+  - integration-name: LangChain
+    python-modules:
+      - airflow.providers.common.ai.hooks.langchain
 
 plugins:
   - name: hitl_review

providers/common/ai/pyproject.toml

@@ -95,6 +95,10 @@ dependencies = [
 "common.sql" = [
     "apache-airflow-providers-common-sql"
 ]
+"langchain" = [
+    "langchain>=1.0.0",
+    "langchain-openai>=0.3.0",
+]
 
 [dependency-groups]
 dev = [