Add Langchain hook to common ai provider

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

@@ -0,0 +1,51 @@
+ .. 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.
+
+Common AI Hooks
+===============
+
+The common-ai provider ships hooks that bridge an Airflow connection to a specific
+LLM framework's model objects. Each hook is a thin adapter: it reads credentials and
+config from the connection, then returns native framework objects (a ``pydantic_ai``
+``Agent`` / ``Model``, a LangChain ``BaseChatModel`` or ``Embeddings``, an MCP client,
+...). Operators and ``@task`` decorators in this provider use these hooks internally.
+
+Choosing a hook
+---------------
+
+.. list-table::
+   :header-rows: 1
+   :widths: 25 75
+
+   * - Hook
+     - When to use
+   * - :class:`~airflow.providers.common.ai.hooks.pydantic_ai.PydanticAIHook`
+     - Default for ``common.ai`` operators (``LLMOperator``, ``AgentOperator``,
+       ``LLMBranchOperator``, ...). Returns a pydantic-ai ``Agent`` / ``Model``.
+   * - :class:`~airflow.providers.common.ai.hooks.langchain.LangChainHook`
+     - Direct LangChain access for tasks that compose ``Runnable``\\s, use the
+       LangChain agent surface, or need LangChain-native chat / embedding model
+       objects. Independent of the pydantic-ai-backed operators.
+
+Hook guides
+-----------
+
+.. toctree::
+    :maxdepth: 1
+    :glob:
+
+    *

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

@@ -0,0 +1,174 @@
+ .. 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 an Airflow connection to `LangChain <https://python.langchain.com/>`__
+chat and embedding models. The hook reads credentials (API key, optional base
+URL) from the connection and returns configured LangChain model objects via
+two universal entry-point functions:
+
+- ``langchain.chat_models.init_chat_model`` for chat models, dispatching to
+  the right vendor based on the ``provider:name`` prefix.
+- ``langchain.embeddings.init_embeddings`` for embedding models, same
+  dispatch story.
+
+The hook owns its own ``langchain`` connection type so the UI is honest about
+which framework a connection configures.
+
+Chat model usage
+----------------
+
+Pass ``llm_model`` to the constructor (or set ``extra["model"]`` on the
+connection) and call ``get_chat_model()``:
+
+.. exampleinclude:: /../../ai/src/airflow/providers/common/ai/example_dags/example_langchain_hook.py
+    :language: python
+    :start-after: [START howto_hook_langchain_chat]
+    :end-before: [END howto_hook_langchain_chat]
+
+The returned model is a LangChain ``BaseChatModel``, so it composes with the
+rest of LangChain's runnable surface
+(``ChatPromptTemplate`` / ``StrOutputParser`` / ``RunnableSequence`` / ...).
+
+Supported chat providers
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+Any model identifier accepted by
+`langchain.chat_models.init_chat_model <https://python.langchain.com/api_reference/langchain/chat_models/langchain.chat_models.base.init_chat_model.html>`__
+works out of the box. Common identifiers:
+
+- ``openai:gpt-4o``, ``openai:gpt-4o-mini`` -- requires ``langchain-openai``
+- ``anthropic:claude-3-7-sonnet`` -- requires ``langchain-anthropic``
+- ``groq:llama-3.3-70b-versatile`` -- requires ``langchain-groq``
+- ``mistralai:mistral-large-latest`` -- requires ``langchain-mistralai``
+- ``ollama:llama3`` -- requires ``langchain-ollama`` (point ``host`` at the Ollama URL)
+- ``deepseek:deepseek-chat`` -- requires ``langchain-deepseek``
+
+Cloud providers with non-standard auth (AWS Bedrock, Google Vertex AI, Azure
+OpenAI) are not covered by the ``api_key`` + ``base_url`` surface here and are
+deferred to per-vendor hooks (mirroring the pydantic-ai cloud-auth subclass
+pattern).
+
+Embedding model usage
+---------------------
+
+Pass ``embed_model`` to the constructor (or set ``extra["embed_model"]`` on
+the connection) and call ``get_embedding_model()``:
+
+.. exampleinclude:: /../../ai/src/airflow/providers/common/ai/example_dags/example_langchain_hook.py
+    :language: python
+    :start-after: [START howto_hook_langchain_embedding]
+    :end-before: [END howto_hook_langchain_embedding]
+
+The same hook instance can serve both chat and embedding models when both
+identifiers are set:
+
+.. exampleinclude:: /../../ai/src/airflow/providers/common/ai/example_dags/example_langchain_hook.py
+    :language: python
+    :start-after: [START howto_hook_langchain_chat_and_embedding]
+    :end-before: [END howto_hook_langchain_chat_and_embedding]
+
+Supported embedding providers
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The hook passes ``api_key`` and (optional) ``base_url`` from the connection to
+`langchain.embeddings.init_embeddings <https://reference.langchain.com/python/langchain/embeddings/base/init_embeddings>`__.
+Providers whose embedding classes accept this kwarg shape work directly:
+
+- ``openai:text-embedding-3-small``, ``openai:text-embedding-3-large`` -- requires ``langchain-openai``
+- ``openai:<model>`` against an OpenAI-compatible endpoint (point ``host`` at
+  Ollama / vLLM / LM Studio) -- requires ``langchain-openai``
+
+``init_embeddings`` advertises more providers (Cohere, Mistral AI, HuggingFace,
+Bedrock, Vertex AI, Azure OpenAI, ...), but their embedding classes expect
+provider-specific credential kwargs (``cohere_api_key``, AWS auth chain, GCP
+service-account, ...) rather than the generic ``api_key`` / ``base_url`` this
+hook forwards. Those are deferred to per-vendor subclasses mirroring the
+pydantic-ai pattern (``PydanticAIBedrockHook`` / ``PydanticAIVertexHook`` /
+``PydanticAIAzureHook``).
+
+Different connections for chat and embeddings
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+If chat and embeddings live on different API keys (e.g. premium chat key vs
+free-tier embeddings key), pass an explicit ``embed_conn_id``. When unset it
+falls back to ``llm_conn_id``, so the common one-provider case stays simple:
+
+.. exampleinclude:: /../../ai/src/airflow/providers/common/ai/example_dags/example_langchain_hook.py
+    :language: python
+    :start-after: [START howto_hook_langchain_different_conns]
+    :end-before: [END howto_hook_langchain_different_conns]
+
+Connection Configuration
+------------------------
+
+The hook reads credentials from the Airflow connection of type ``langchain``:
+
+- **password** -- API key (passed as ``api_key`` to ``init_chat_model`` and
+  ``init_embeddings``).
+- **host** -- Optional base URL (passed as ``base_url``; useful for custom
+  OpenAI-compatible endpoints, Ollama, vLLM).
+- **extra** JSON -- ``{"model": "openai:gpt-4o", "embed_model": "openai:text-embedding-3-small"}``
+  to set default chat and embedding model identifiers on the connection.
+
+Parameters
+----------
+
+.. list-table::
+   :header-rows: 1
+   :widths: 25 25 50
+
+   * - Parameter
+     - Default
+     - Description
+   * - ``llm_conn_id``
+     - ``langchain_default``
+     - Airflow connection ID for the LLM provider.
+   * - ``embed_conn_id``
+     - ``None`` (falls back to ``llm_conn_id``)
+     - Optional separate Airflow connection ID for the embedding provider.
+       Useful when chat and embeddings live on different API keys; in the
+       common one-provider case, leave unset and the hook reuses ``llm_conn_id``.
+   * - ``llm_model``
+     - ``None`` (falls back to ``extra["model"]`` on the connection)
+     - Chat model identifier in ``provider:name`` form, e.g. ``openai:gpt-4o``.
+       Only required when calling ``get_chat_model()``.
+   * - ``embed_model``
+     - ``None`` (falls back to ``extra["embed_model"]`` on the connection)
+     - Embedding model identifier in ``provider:name`` form, e.g.
+       ``openai:text-embedding-3-small``. Only required when calling
+       ``get_embedding_model()``.
+
+Dependencies
+------------
+
+Install the ``langchain`` extra to use this hook::
+
+    pip install apache-airflow-providers-common-ai[langchain]
+
+That extra installs only ``langchain`` itself, since the framework is
+vendor-agnostic. Install the LangChain integration package for whichever
+provider(s) you intend to use:
+
+- ``langchain-openai`` -- OpenAI and OpenAI-compatible endpoints (Ollama, vLLM)
+- ``langchain-anthropic`` -- Anthropic
+- ``langchain-groq``, ``langchain-mistralai``, ``langchain-deepseek``, ``langchain-ollama``, ...

providers/common/ai/docs/index.rst

@@ -36,7 +36,7 @@
 
     Connection types <connections/pydantic_ai>
     MCP connection <connections/mcp>
-    Hooks <hooks/pydantic_ai>
+    Hooks <hooks/index>
     Toolsets <toolsets>
     Operators <operators/index>
     HITL Review <hitl_review>

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
@@ -313,6 +319,39 @@ connection-types:
           type:
             - string
             - 'null'
+  - hook-class-name: airflow.providers.common.ai.hooks.langchain.LangChainHook
+    hook-name: "LangChain"
+    connection-type: langchain
+    ui-field-behaviour:
+      hidden-fields:
+        - schema
+        - port
+        - login
+      relabeling:
+        password: API Key
+      placeholders:
+        host: "https://api.openai.com/v1 (optional, for custom endpoints / Ollama)"
+    conn-fields:
+      model:
+        label: Chat Model
+        description: >
+          Chat model in provider:name format dispatched via
+          langchain.chat_models.init_chat_model
+          (e.g. openai:gpt-4o, anthropic:claude-3-7-sonnet).
+        schema:
+          type:
+            - string
+            - 'null'
+      embed_model:
+        label: Embedding Model
+        description: >
+          Embedding model in provider:name format dispatched via
+          langchain.embeddings.init_embeddings
+          (e.g. openai:text-embedding-3-small, cohere:embed-english-v3.0).
+        schema:
+          type:
+            - string
+            - 'null'
 
 operators:
   - integration-name: Common AI

providers/common/ai/pyproject.toml

@@ -95,6 +95,9 @@ dependencies = [
 "common.sql" = [
     "apache-airflow-providers-common-sql"
 ]
+"langchain" = [
+    "langchain>=1.0.0",
+]
 
 [dependency-groups]
 dev = [
@@ -107,7 +110,8 @@ dev = [
     # Additional devel dependencies (do not remove this line and add extra development dependencies)
     "sqlglot>=30.0.0",
     "pydantic-ai-slim[mcp]",
-    "apache-airflow-providers-common-sql[datafusion]"
+    "apache-airflow-providers-common-sql[datafusion]",
+    "langchain>=1.0.0",
 ]
 
 # To build docs: