An example of a bundle that creates a Databricks App backed by Lakebase database instance

knowledge_base/app_with_database/.gitignore

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+.databricks/
+build/
+dist/
+__pycache__/
+*.egg-info
+.venv/

knowledge_base/app_with_database/README.md

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+# Databricks app with OLTP database
+
+This example demonstrates how to define a Databricks app backed by 
+an OLTP Postgres   in a Databricks Asset Bundle.
+
+It includes and deploys an example application that uses Python and Dash and a database instance.
+When application is started it provisions its own schema and demonstration data in the OLTP database.
+
+For more information about Databricks Apps see the [documentation](https://docs.databricks.com/aws/en/dev-tools/databricks-apps).
+For more information about Databricks database instances see the [documentation](https://docs.databricks.com/aws/en/oltp/).
+
+## Prerequisites
+
+* Databricks CLI v0.267.0 or above
+
+## Usage
+
+1. Deploy the bundle:
+```
+databricks bundle deploy -t dev
+```
+Please note that after this bundle gets deployed, the database instance starts running immediately, which incurs cost.
+
+2. Run the app:
+```
+databricks bundle run my_app
+```
+
+3. Open the app:
+Run the following command to navigate to the deployed app in your browser:
+```
+databricks bundle open my_app
+```
+
+Alternatively, run `databricks bundle summary` to display its URL.
+
+4. Query the app data:
+
+Run the following command to display the data generated by the app:
+```
+databricks psql example-database-instance -- --dbname example_database -c "select * from holidays.holiday_requests"
+```
+
+5. Explore the app data:
+   Run the following command to navigate to the Unity Catalog in your browser:
+```
+databricks bundle open my_catalog
+```
+
+## Clean up
+To remove the provisioned resources run 
+```
+databricks bundle destroy
+```

knowledge_base/app_with_database/app/app.py

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+from dash import Dash
+from layout import make_app_layout
+from callbacks import register_callbacks
+
+app = Dash(__name__, title="Holiday Request Manager", suppress_callback_exceptions=True)
+app.layout = make_app_layout()
+register_callbacks(app)
+
+if __name__ == "__main__":
+    app.run(debug=True)

knowledge_base/app_with_database/app/app.yml

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+command: ["python", "app.py"]

knowledge_base/app_with_database/app/callbacks.py

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+from dash import Input, Output, State, callback_context
+from lakebase_connector import get_holiday_requests, update_request_status
+import pandas as pd
+
+
+def register_callbacks(app):
+    @app.callback(
+        Output("holiday-table", "data"),
+        [
+            Input("refresh-interval", "n_intervals"),
+            Input("submit-action", "n_clicks"),
+            Input("action-feedback", "children"),
+        ],
+    )
+    def refresh_table(n_intervals, n_clicks, action_feedback):
+        holiday_request_df = get_holiday_requests()
+        return holiday_request_df.to_dict("records")
+
+    @app.callback(
+        [
+            Output("action-feedback", "children"),
+            Output("action-radio", "value"),
+            Output("manager-comment", "value"),
+        ],
+        Input("submit-action", "n_clicks"),
+        State("holiday-table", "selected_rows"),
+        State("holiday-table", "data"),
+        State("action-radio", "value"),
+        State("manager-comment", "value"),
+        prevent_initial_call=True,
+    )
+    def submit_holiday_request_review(
+        n_clicks, selected_row_nr, table_data, selected_action, manager_comment
+    ):
+        if (selected_action is None) | (selected_row_nr is None):
+            return "Please select a request and approve/decline."
+        row_idx = selected_row_nr[0]
+        selected_row = table_data[row_idx]
+        request_id = selected_row["request_id"]
+
+        update_request_status(
+            request_id=request_id, status=selected_action, comment=manager_comment
+        )
+        return f"You {selected_action.lower()} request {request_id}.", None, ""

knowledge_base/app_with_database/app/lakebase_connector.py

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+import os
+
+import pandas as pd
+from databricks.sdk import WorkspaceClient
+from sqlalchemy import create_engine, event, text
+
+workspace_client = WorkspaceClient()
+user = workspace_client.current_user.me().user_name
+
+postgres_username = user
+postgres_host = os.getenv("PGHOST")
+postgres_port = os.getenv("PGPORT")
+postgres_database = os.getenv("PGDATABASE")
+
+print("postgres_username", postgres_username)
+print("postgres_host", postgres_host)
+print("postgres_port", postgres_port)
+print("postgres_database", postgres_database)
+
+postgres_pool = create_engine(
+    f"postgresql+psycopg://{postgres_username}:@{postgres_host}:{postgres_port}/{postgres_database}"
+)
+
+
+@event.listens_for(postgres_pool, "do_connect")
+def provide_token(dialect, conn_rec, cargs, cparams):
+    """Provide the App's OAuth token. Caching is managed by WorkspaceClient"""
+    cparams["password"] = workspace_client.config.oauth_token().access_token
+
+
+def get_holiday_requests():
+    """
+    Fetch all holiday requests from the database.
+
+    Returns:
+        pd.DataFrame: DataFrame containing holiday requests.
+    """
+    df = pd.read_sql_query("SELECT * FROM holidays.holiday_requests;", postgres_pool)
+    return df
+
+
+def update_request_status(request_id, status, comment):
+    """Update the status and manager note for a specific holiday request."""
+    with postgres_pool.begin() as conn:
+        conn.execute(
+            text("""
+                 UPDATE holidays.holiday_requests
+                 SET status = :status, manager_note = :comment
+                 WHERE request_id = :request_id
+                 """),
+            {"status": status, "comment": comment or "", "request_id": request_id},
+        )
+
+
+def initialize_schema():
+    with postgres_pool.begin() as conn:
+        # create schema:
+        conn.execute(text("""CREATE SCHEMA IF NOT EXISTS holidays"""))
+        print("schema created (or already exists)")
+        # grant privileges
+        conn.execute(text("""GRANT USAGE ON SCHEMA holidays TO PUBLIC"""))
+        conn.execute(
+            text("""GRANT SELECT ON ALL TABLES IN SCHEMA holidays TO PUBLIC""")
+        )
+        print("Read permissions granted to all users")
+
+        # Create the table within the schema:
+        conn.execute(
+            text("""
+                CREATE TABLE IF NOT EXISTS holidays.holiday_requests (
+                  request_id SERIAL PRIMARY KEY,
+                  employee_name VARCHAR(255) NOT NULL,
+                  start_date DATE NOT NULL,
+                  end_date DATE NOT NULL,
+                  status VARCHAR(50) NOT NULL,
+                  manager_note TEXT
+                )
+            """)
+        )
+        print("table created (or already exists)")
+        # Insert demo values:
+        conn.execute(
+            text("""
+                INSERT INTO holidays.holiday_requests (employee_name, start_date, end_date, status, manager_note)
+                VALUES
+                    ('Joe', '2025-08-01', '2025-08-20', 'Pending', ''),
+                    ('Suzy', '2025-07-22', '2025-07-25', 'Pending', ''),
+                    ('Charlie', '2025-08-01', '2025-08-05', 'Pending', '')
+            """)
+        )
+        print("demo data is inserted")
+
+
+initialize_schema()

knowledge_base/app_with_database/app/layout.py

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+from dash import html, dcc, dash_table
+
+
+def make_app_layout():
+    return html.Div(
+        [
+            html.H1("Holiday Request Manager", className="main-title"),
+            html.P(
+                "Review, approve, or decline holiday requests from your team.",
+                className="subtitle",
+            ),
+            dash_table.DataTable(
+                id="holiday-table",
+                columns=[
+                    {"name": "Request ID", "id": "request_id"},
+                    {"name": "Employee", "id": "employee_name"},
+                    {"name": "Start Date", "id": "start_date"},
+                    {"name": "End Date", "id": "end_date"},
+                    {"name": "Status", "id": "status"},
+                    {"name": "Manager Comment", "id": "manager_note"},
+                ],
+                data=[],
+                row_selectable="single",
+                style_table={
+                    "margin": "24px 0",
+                    "width": "100%",
+                    "borderRadius": "8px",
+                    "overflow": "hidden",
+                },
+                style_cell={
+                    "textAlign": "center",
+                    "fontFamily": "Lato, Arial, sans-serif",
+                    "fontSize": "1rem",
+                },
+                style_header={
+                    "backgroundColor": "#1B5162",
+                    "color": "white",
+                    "fontWeight": "bold",
+                    "fontSize": "1.05rem",
+                },
+                style_data_conditional=[
+                    {
+                        "if": {"filter_query": '{status} = "Approved"'},
+                        "backgroundColor": "#d4edda",
+                        "color": "#155724",
+                    },
+                    {
+                        "if": {"filter_query": '{status} = "Declined"'},
+                        "backgroundColor": "#f8d7da",
+                        "color": "#721c24",
+                    },
+                ],
+            ),
+            html.Div(
+                [
+                    html.H3("Action", className="section-title"),
+                    dcc.RadioItems(
+                        id="action-radio",
+                        options=[
+                            {"label": "Approve", "value": "Approved"},
+                            {"label": "Decline", "value": "Declined"},
+                        ],
+                        className="action-radio",
+                    ),
+                    dcc.Textarea(
+                        id="manager-comment",
+                        placeholder="Add a comment (optional)...",
+                        className="manager-comment",
+                    ),
+                    html.Button(
+                        "Submit", id="submit-action", n_clicks=0, className="submit-btn"
+                    ),
+                    html.Div(id="action-feedback", className="feedback"),
+                ],
+                className="action-panel",
+            ),
+            dcc.Interval(id="refresh-interval", interval=10 * 1000, n_intervals=0),
+        ],
+        className="container",
+    )

knowledge_base/app_with_database/app/requirements.txt

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+databricks-sdk>=0.60.0
+pandas
+psycopg[binary]
+psycopg-pool
+sqlalchemy==2.0.41
+dash

knowledge_base/app_with_database/databricks.yml

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+# This is a Databricks asset bundle definition for app_with_database.
+bundle:
+  name: app_with_database_example
+
+include:
+  - resources/*.yml
+
+targets:
+  dev:
+    default: true
+    mode: development

knowledge_base/app_with_database/resources/myapp.app.yml

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+resources:
+  apps:
+    my_app:
+      name: "app-with-database"
+      source_code_path: ../app
+      description: "A Dash app that uses an OLTP Database"
+      # The resources which this app has access to:
+      resources:
+        - name: "app-db"
+          description: "A database for the app to be able to connect to and query"
+          database:
+            database_name: ${resources.database_catalogs.my_catalog.database_name}
+            instance_name: ${resources.database_catalogs.my_catalog.database_instance_name}
+            permission: "CAN_CONNECT_AND_CREATE"

knowledge_base/app_with_database/resources/mydb.database.yml

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+resources:
+  database_instances:
+   my_instance:
+     name: example-database-instance
+     capacity: CU_1
+  database_catalogs:
+    my_catalog:
+      database_instance_name: ${resources.database_instances.my_instance.name}
+      database_name: "example_database"
+      name: example_database_catalog
+      create_database_if_not_exists: true