Dev Mode for Templates

Dev mode enables hot-reloading during template development. Instead of building Docker images on every change, the coordinator reads template files directly from your filesystem.

When to Use Dev Mode

• Rapid iteration - No rebuild needed between code changes
• Live debugging - See changes instantly
• Template development - Writing and testing new templates

How It Works

Normal Mode:  code ──► docker build ──► container ──► output
Dev Mode:     code ──────────────────────────────────► output

Setup

1. Add Dev Configuration

Add a dev section to your cyan.yaml:

username: myuser
name: my-template
description: My template
# ... other fields ...

dev:
  blob_path: ./cyan
  template_url: http://localhost:5550

See Dev Configuration Reference for complete field documentation.

2. Start Template Server

Run your template locally with hot-reload:

cd cyan
bun install
bun run --watch index.ts

cd cyan
pip install -r requirements.txt
python index.py

pip install watchdog
watchmedo auto-restart -d . -p "*.py" -- python index.py

cd cyan
dotnet watch run

3. Run Try with Dev Flag

cyanprint try template . ./output --dev

Development Workflow

Typical Dev Cycle

1. Start the template server locally
2. Run cyanprint try template . ./output --dev
3. Answer the template prompts
4. Review generated output
5. Edit template code
6. Repeat from step 2

Example Session

# Terminal 1: Start template server
cd cyan && bun run --watch index.ts

# Terminal 2: Run try command
cyanprint try template . ./output --dev
# ... answer prompts ...
ls ./output

# Make changes to index.ts
# Server auto-restarts

# Run again
rm -rf ./output
cyanprint try template . ./output --dev

Comparison: Normal vs Dev Mode

Normal Mode

cyanprint try template . ./output

• Builds Docker images
• Full isolation
• Slower iteration
• Tests production-like behavior

Dev Mode

cyanprint try template . ./output --dev

• No Docker build
• Direct filesystem access
• Fast iteration
• Requires local template server

Troubleshooting

Template Server Not Running

Error: Failed to connect to template at http://localhost:5550

Solution: Start your template server before running the try command.

Blob Path Not Found

Error: Blob path does not exist: ./cyan

Solution: Ensure dev.blob_path in cyan.yaml points to the correct directory.

Next Steps

• Dev Configuration - Full dev config reference
• Test Locally - Normal mode testing
• Push to Registry - Publish your template
• Template Reference - Full cyan.yaml specification