feat: add local quickstart (#232)

This is a continuation of #218, which add a local quickstart for running
Toolbox with Python and LangGraph.

---------

Co-authored-by: Twisha Bansal <twishabansal@google.com>
Co-authored-by: Anubhav Dhawan <anubhav756@gmail.com>

docs/en/getting-started/local_quickstart.md

@@ -0,0 +1,284 @@
+---
+title: "Local Quickstart"
+type: docs
+weight: 2
+description: >
+  How to get started running Toolbox locally with Python and PostgreSQL. 
+
+---
+
+## Before you begin
+
+This guide assumes you have already done the following: 
+
+1. Installed [Python 3.9+][install-python]
+1. Installed [PostgreSQL 16+ and the `psql` client][install-postgres]
+1. Completed [setup for `langchain-vertexai` package][install-vertexai] (or are
+   comfortable switching the example to a different LLM model)
+
+
+[install-python]: https://wiki.python.org/moin/BeginnersGuide/Download
+[install-postgres]: https://www.postgresql.org/download/
+[install-vertexai]: https://python.langchain.com/docs/integrations/llms/google_vertex_ai_palm/#setup
+
+## Step 1: Set up your database
+
+In this section, we will create a database, insert some data that needs to be
+access by our agent, and create a database user for Toolbox to connect with. 
+
+1. Connect to postgres using the `psql` command:
+
+    ```bash
+    psql -U postgres
+    ```
+
+    Here, `postgres` denotes the default postgres superuser.
+
+1. Create a new database and a new user:
+
+    ```sql
+      CREATE USER toolbox_user WITH PASSWORD 'my-password';
+
+      CREATE DATABASE toolbox_db;
+      GRANT ALL PRIVILEGES ON DATABASE toolbox_db TO toolbox_user;
+
+      ALTER DATABASE toolbox_db OWNER TO toolbox_user;
+    ```
+
+    > **_NOTE:_**  For a real application, it's best to follow the principle of
+    > least permission and only grant the privileges your application needs. 
+
+1. End the database session:
+
+    ```bash
+    \q
+    ```
+
+1. Connect to your database with your new user:
+
+    ```bash
+    psql -U toolbox_user -d toolbox_db
+    ```
+
+1. Create a table using the following command:
+
+    ```sql
+    CREATE TABLE hotels(
+      id            INTEGER NOT NULL PRIMARY KEY,
+      name          VARCHAR NOT NULL,
+      location      VARCHAR NOT NULL,
+      price_tier    VARCHAR NOT NULL,
+      checkin_date  DATE    NOT NULL,
+      checkout_date DATE    NOT NULL,
+      booked        BIT     NOT NULL
+    );
+    ```
+
+1. Insert data into the table.
+
+    ```sql
+    INSERT INTO hotels(id, name, location, price_tier, checkin_date, checkout_date, booked)
+    VALUES 
+      (1, 'Hilton Basel', 'Basel', 'Luxury', '2024-04-22', '2024-04-20', B'0'),
+      (2, 'Marriott Zurich', 'Zurich', 'Upscale', '2024-04-14', '2024-04-21', B'0'),
+      (3, 'Hyatt Regency Basel', 'Basel', 'Upper Upscale', '2024-04-02', '2024-04-20', B'0'),
+      (4, 'Radisson Blu Lucerne', 'Lucerne', 'Midscale', '2024-04-24', '2024-04-05', B'0'),
+      (5, 'Best Western Bern', 'Bern', 'Upper Midscale', '2024-04-23', '2024-04-01', B'0'),
+      (6, 'InterContinental Geneva', 'Geneva', 'Luxury', '2024-04-23', '2024-04-28', B'0'),
+      (7, 'Sheraton Zurich', 'Zurich', 'Upper Upscale', '2024-04-27', '2024-04-02', B'0'),
+      (8, 'Holiday Inn Basel', 'Basel', 'Upper Midscale', '2024-04-24', '2024-04-09', B'0'),
+      (9, 'Courtyard Zurich', 'Zurich', 'Upscale', '2024-04-03', '2024-04-13', B'0'),
+      (10, 'Comfort Inn Bern', 'Bern', 'Midscale', '2024-04-04', '2024-04-16', B'0');
+    ```
+
+1. End the database session:
+
+    ```bash
+    \q
+    ```
+
+
+## Step 2: Install and configure Toolbox
+
+In this section, we will download Toolbox, configure our tools in a
+`tools.yaml`, and then run the Toolbox server.
+
+1. Download the latest version of Toolbox as a binary:
+
+    > **_NOTE:_**  Use the [correct binary][install-toolbox] corresponding to
+    > your OS and CPU architecture.
+
+    ```bash
+    export OS="linux/amd64" # one of linux/amd64, darwin/arm64, darwin/amd64, or windows/amd64
+    curl -O https://storage.googleapis.com/genai-toolbox/v0.0.5/$OS/toolbox
+    ```
+
+    [install-toolbox]: https://github.com/googleapis/genai-toolbox/releases
+
+1. Make the binary executable:
+
+    ```bash
+    chmod +x toolbox
+    ```
+
+1. Write the following into a `tools.yaml` file. Be sure to update any fields
+   such as `user`, `password`, or `database` that you may have customized in the
+   previous step.
+
+    ```yaml
+    sources:
+      my-pg-source:
+        kind: postgres
+        host: 127.0.0.1
+        port: 5432
+        database: toolbox_db
+        user: toolbox_user
+        password: my-password
+    tools:
+      # Define the 5 tools we want our agent to have
+      # for more info on tools check out the "Resources" section of the docs
+      search-hotels-by-name:
+        kind: postgres-sql
+        source: my-pg-source
+        description: Search for hotels based on name.
+        parameters:
+          - name: name
+            type: string
+            description: The name of the hotel.
+        statement: SELECT * FROM hotels WHERE name ILIKE '%' || $1 || '%';
+      search-hotels-by-location:
+        kind: postgres-sql
+        source: my-pg-source
+        description: Search for hotels based on location.
+        parameters:
+          - name: location
+            type: string
+            description: The location of the hotel.
+        statement: SELECT * FROM hotels WHERE location ILIKE '%' || $1 || '%';
+      book-hotel:
+        kind: postgres-sql
+        source: my-pg-source
+        description: >-
+          Book a hotel by its ID. Returns a message indicating whether the hotel was
+          successfully booked or not.
+        parameters:
+          - name: hotel_id
+            type: string
+            description: The ID of the hotel to book.
+        statement: UPDATE hotels SET booked = B'1' WHERE id = $1;
+      update-hotel:
+        kind: postgres-sql
+        source: my-pg-source
+        description: >-
+          Update a hotel's check-in and check-out dates by its ID. Returns a message
+          indicating  whether the hotel was successfully updated or not.
+        parameters:
+          - name: hotel_id
+            type: string
+            description: The ID of the hotel to update.
+          - name: checkin_date
+            type: string
+            description: The new check-in date of the hotel.
+          - name: checkout_date
+            type: string
+            description: The new check-out date of the hotel.
+        statement: >-
+          UPDATE hotels SET checkin_date = CAST($2 as date), checkout_date = CAST($3
+          as date) WHERE id = $1;
+      cancel-hotel:
+        kind: postgres-sql
+        source: my-pg-source
+        description: Cancel a hotel by its ID.
+        parameters:
+          - name: hotel_id
+            type: string
+            description: The ID of the hotel to cancel.
+        statement: UPDATE hotels SET booked = B'0' WHERE id = $1;
+    ```
+
+1. Run the Toolbox server, pointing to the `tools.yaml` file created earlier:
+
+    ```bash
+    ./toolbox --tools_file "tools.yaml"
+    ```
+
+## Step 3: Connect your agent to Toolbox
+
+In this section, we will write and run a LangGraph agent that will load the Tools
+from Toolbox.
+
+1. In a new terminal,install the `toolbox_langchain_sdk` package.
+
+    > **_NOTE:_** toolbox_langchain_sdk package is not yet published to PyPi.
+    > Install it directly from the git repo instead:
+    >
+    > ```bash
+    > pip install -e "git+https://github.com/googleapis/genai-toolbox#egg=toolbox-langchain-sdk&subdirectory=sdks/langchain"
+    > ```
+
+    ```bash
+    pip install toolbox-langchain-sdk
+    ```
+
+1. Install other required dependencies:
+
+    ```bash
+    pip install langgraph langchain-google-vertexai
+    ```
+
+1. Create a new file named `langgraph_hotel_agent.py` and copy the following code to 
+   create a [LangGraph agent][langgraph-agent], based on their [Hotels example][langchain-hotels]:
+
+    ```python
+    import asyncio
+
+    from langgraph.prebuilt import create_react_agent
+    from langchain_google_vertexai import ChatVertexAI
+    from langgraph.checkpoint.memory import MemorySaver
+    
+    from toolbox_langchain_sdk import ToolboxClient
+
+    prompt = """
+      You're a helpful hotel assistant. You handle hotel searching, booking and
+      cancellations. When the user searches for a hotel, mention it's name, id, 
+      location and price tier. Always mention hotel ids while performing any 
+      searches. This is very important for any operations. For any bookings or 
+      cancellations, please provide the appropriate confirmation. Be sure to update 
+      checkin or checkout dates if mentioned by the user.
+      Don't ask for confirmations from the user.
+    """
+    
+    queries = [
+        "Find hotels in Basel with Basel in it's name.",
+        "Can you book the Hilton Basel for me?",
+        "Oh wait, this is too expensive. Please cancel it and book the Hyatt Regency instead.",
+        "My check in dates would be from April 10, 2024 to April 19, 2024.",
+    ]
+
+    async def main():
+        # TODO(reader): replace this with another model if needed
+        model = ChatVertexAI(model_name="gemini-pro")
+        
+        # Load the tools from the Toolbox server
+        client = ToolboxClient("http://127.0.0.1:5000")
+        tools = await client.load_toolset()
+
+        agent = create_react_agent(model, tools, checkpointer=MemorySaver())
+
+        config = {"configurable": {"thread_id": "thread-1"}}
+        for query in queries:
+            inputs = {"messages": [("user", prompt + query)]}
+            response = await agent.ainvoke(inputs, stream_mode="values", config=config)
+            print(response["messages"][-1].content)
+
+    asyncio.run(main())
+    ```
+
+    [langgraph-agent]:https://langchain-ai.github.io/langgraph/reference/prebuilt/#langgraph.prebuilt.chat_agent_executor.create_react_agent
+    [langchain-hotels]: https://langchain-ai.github.io/langgraph/tutorials/customer-support/customer-support/#hotels
+
+1. Run your agent, and observe the results:
+
+    ```sh
+    python langgraph_hotel_agent.py
+    ```