Deploying BrickChat to Databricks Apps

First: Gather Required Information

Before proceeding, always ask the user these questions using AskUserQuestion:

1. App Name: "What is the name of your Databricks App?" (Default: brickchat)
2. Databricks Profile: "Which Databricks CLI profile should be used?" (e.g., DEFAULT, 9cefok, or other configured profile)

Store responses as <APP_NAME> and <PROFILE> for use in all commands below.

All databricks commands must include --profile <PROFILE>.

Second: Check if App Exists

BEFORE any deployment steps, check if the app exists:

databricks apps get <APP_NAME> --profile <PROFILE>

If the app does NOT exist (error: "does not exist or is deleted"):

1. Inform the user: "The app '<APP_NAME>' doesn't exist. I'll create it now."
2. Create the app:

``bash databricks apps create <APP_NAME> --description "BrickChat - AI Chat Application" --profile <PROFILE> ``

1. Wait for creation to complete before proceeding

If the app EXISTS: Proceed directly to deployment workflow.

Overview

Deploy BrickChat (Flutter WASM frontend + FastAPI backend) to Databricks Apps. The deployment folder contains all files needed for a self-contained deployment.

Prerequisites

• Databricks CLI installed and configured (databricks auth login)
• Flutter SDK installed
• Access to Databricks workspace with Apps enabled
• Environment secrets configured in Databricks (first deployment only)

Deployment Workflow

digraph deployment {
    rankdir=TB;
    "Gather info (app name, profile)" -> "Check app exists";
    "Check app exists" -> "App exists?" [shape=diamond];
    "App exists?" -> "Create app" [label="no"];
    "App exists?" -> "Update deployment files" [label="yes"];
    "Create app" -> "Update deployment files";
    "Update deployment files" -> "Upload to workspace";
    "Upload to workspace" -> "Deploy from workspace";
    "Deploy from workspace" -> "Verify deployment";
}

Step 1: Update Deployment Files

Option A: Use the update script

cd deployment
./update_deployment.sh

Option B: Manual steps

# Build Flutter WASM
flutter build web --wasm

# Copy frontend (note: deployment expects build/, not build/web/)
rm -rf deployment/build
mkdir -p deployment/build
cp -r build/web/* deployment/build/

# Copy backend files
cp backend/app.py deployment/
cp backend/database.py deployment/
cp backend/auth.py deployment/
cp backend/routers/* deployment/routers/

# Update requirements
cd backend && uv pip freeze > ../deployment/requirements.txt

IMPORTANT: After copying app.py, verify build paths match:

• deployment/app.py should reference build/ (not build/web/)
• backend/app.py references build/web/ or ../build/web/
• See Troubleshooting section if frontend doesn't load

Step 2: Configure Secrets (First Deployment Only)

Secrets are referenced in app.yaml using valueFrom:

Configure in Databricks workspace settings or via CLI.

Step 3: Local Testing

cd deployment
cp .env.example .env  # Edit with your values
uv pip install -r requirements.txt
uv run uvicorn app:app --host 0.0.0.0 --port 8000

Verify at http://localhost:8000:

• Frontend loads correctly
• Health check: curl http://localhost:8000/health
• Chat functionality works

Step 4: Upload to Databricks Workspace

IMPORTANT: The databricks apps deploy command requires a workspace path, not a local path. You must upload local files to the workspace first.

Why not databricks sync? The databricks sync command respects .gitignore, which excludes build/ folders. Using databricks workspace import-dir bypasses .gitignore and uploads all files directly.

Replace <YOUR_EMAIL> with the user's Databricks email (can be found from databricks apps get output under creator field).

Step 4a: Clear existing workspace folder (if updating)

# Delete old deployment from workspace to ensure clean state
databricks workspace delete /Workspace/Users/<YOUR_EMAIL>/brickchat --recursive --profile <PROFILE>

Note: This command may fail if the folder doesn't exist yet - that's fine for first deployments.

Step 4b: Upload deployment folder

# Upload deployment folder directly (bypasses .gitignore)
databricks workspace import-dir ./deployment /Workspace/Users/<YOUR_EMAIL>/brickchat --profile <PROFILE> --overwrite

Verify upload:

databricks workspace list /Workspace/Users/<YOUR_EMAIL>/brickchat --profile <PROFILE>

You should see app.py, app.yaml, build/, routers/, etc.

Step 5: Deploy from Workspace

# Deploy from the workspace path (NOT local path)
databricks apps deploy <APP_NAME> --source-code-path /Workspace/Users/<YOUR_EMAIL>/brickchat --profile <PROFILE>

Common mistake: Using --source-code-path ./deployment will fail with "must be a valid workspace path" error.

For subsequent updates:

1. Run the delete command (Step 4a) - optional but recommended for clean state
2. Run the import-dir command (Step 4b) again
3. Run the deploy command again

Step 6: Verify Deployment

# Check app status
databricks apps get <APP_NAME> --profile <PROFILE>

# View logs (if needed)
databricks apps logs <APP_NAME> --profile <PROFILE>

Success indicators:

• app_status.state: RUNNING
• compute_status.state: ACTIVE
• active_deployment.status.state: SUCCEEDED
• url: The app URL will be displayed

Quick Reference

Troubleshooting

"Source code path must be a valid workspace path" error

This happens when using a local path with databricks apps deploy. Solution:

1. First upload files to workspace: databricks workspace import-dir ./deployment /Workspace/Users/<EMAIL>/brickchat --profile <PROFILE> --overwrite
2. Then deploy from workspace path: databricks apps deploy <APP_NAME> --source-code-path /Workspace/Users/<EMAIL>/brickchat --profile <PROFILE>

Build folder not uploaded (databricks sync respects .gitignore)

If using databricks sync, the build/ folder is skipped because it's in .gitignore. Solution: Use databricks workspace import-dir instead, which ignores .gitignore and uploads all files directly.

"App does not exist or is deleted" error

Create the app first:

databricks apps create <APP_NAME> --description "BrickChat - AI Chat Application" --profile <PROFILE>

Wait for creation to complete before deploying.

App won't start

• Check logs: databricks apps logs <APP_NAME> --profile <PROFILE>
• Verify secrets are configured in Databricks workspace
• Ensure database is accessible from Databricks

Frontend not loading

• Verify deployment/build/ contains Flutter WASM files (including index.html)
• Check that index.html exists in build directory
• Rebuild: flutter build web --wasm

Build path mismatch (common issue)

When copying app.py from backend/ to deployment/, the build paths may differ:

After copying backend files, verify deployment/app.py uses correct paths:

# Deployment should check for build/ not build/web/
if os.path.exists("build/index.html"):  # Correct for deployment

Use /debug/info endpoint to diagnose:

curl http://localhost:8000/debug/info

This shows which paths exist and helps identify mismatches.

API errors

• Check DATABRICKSTOKEN and DATABRICKSBASE_URL are correct
• Verify model endpoint is accessible
• Review logs for specific error messages

CORS issues (local dev)

• Backend has CORS enabled for all origins in development
• For production, configure specific allowed origins

Key Files