Development Workflow Guide

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This guide covers how to run, update, and debug applications using dala_dev tooling in your daily development workflow.

Prerequisites

Before starting, ensure you have:

  • Elixir and Mix installed
  • dala_dev dependency added to your project
  • For iOS development: Xcode and Xcode command line tools
  • For Android development: Android SDK and ADB tools
  • A connected device or running emulator/simulator

New to dala? See the Beginner Step-by-Step Guide first.

Running Your App with dala_dev

Quick Start

The fastest way to get your app running on a device:

# Deploy to the first available device/emulator
mix dala.deploy

# List available devices first
mix dala.devices

# Deploy to a specific device
mix dala.deploy --device <device_id>

Development Mode with Hot Reloading

For active development with automatic code pushing:

# Start watch mode - automatically pushes BEAM changes on file save
mix dala.watch

# Watch mode with specific device
mix dala.watch --device <device_id>

# Stop watch mode when done
mix dala.watch_stop

Connecting to a Running App

To connect to a deployed app for interactive development:

# Connect to any running dala app
mix dala.connect

# Connect to specific device
mix dala.connect --device <device_id>

Once connected, you'll have an IEx session on the device where you can:

  • Call functions directly
  • Inspect state
  • Debug issues interactively

Updating Your App

Hot Pushing Changes

For quick updates without full redeployment:

# Push only changed BEAM files (no restart required)
mix dala.push

# Push to specific device
mix dala.push --device <device_id>

Hot push is ideal for:

  • Quick iteration on business logic
  • Fixing bugs without app restart
  • Testing changes immediately

Full Redeployment

When you need a complete rebuild:

# Full deploy rebuilds and reinstalls
mix dala.deploy

# Force reinstall even if version hasn't changed
mix dala.deploy --force

Debugging with dala_dev

Interactive Debugging

# Start interactive debugging session
mix dala.debug

# Debug specific node
mix dala.debug --node <node_name@host>

The debug session provides:

  • Process inspection
  • Message tracing
  • State examination
  • Breakpoint-style debugging

Log Collection

# Stream logs from all devices
mix dala.logs

# Stream logs from specific device
mix dala.logs --device <device_id>

# Filter logs by level
mix dala.logs --level error

# Save logs to file
mix dala.logs --output debug.log

Remote Observer

For advanced Erlang system introspection:

# Launch web-based observer for remote node
mix dala.observer

# Observe specific node
mix dala.observer --node <node_name@host>

The observer provides:

  • Process tree visualization
  • Memory usage analysis
  • ETS table inspection
  • Application supervision tree

Distributed Tracing

# Start distributed tracing
mix dala.trace

# Trace specific modules
mix dala.trace --modules MyApp.Core,MyApp.Web

# Set trace duration
mix dala.trace --duration 60

Crash Dump Analysis

When your app crashes, analyze the crash dump:

# Parse and summarize crash dump
mix dala.crash_dump analyze <dump_file>

# Generate HTML report
mix dala.crash_dump report <dump_file> --output report.html

# Open report in browser
open report.html

Development Dashboard

For a comprehensive web UI:

# Start the development dashboard (localhost:4040)
mix dala.server

# Start full web UI with all features
mix dala.web

The dashboard provides:

  • Device management
  • Log streaming
  • File watching controls
  • Performance metrics
  • Crash dump viewer

Common Development Scenarios

Scenario 1: Quick Bug Fix

# 1. Connect to running app
mix dala.connect --device <id>

# 2. Reproduce and diagnose issue in IEx

# 3. Fix code locally

# 4. Push changes
mix dala.push --device <id>

# 5. Verify fix in connected session

Scenario 2: New Feature Development

# 1. Start watch mode
mix dala.watch --device <id>

# 2. Develop feature with automatic pushes

# 3. Test on device in real-time

# 4. When done, stop watch mode
mix dala.watch_stop

Scenario 3: Performance Investigation

# 1. Start observer for overview
mix dala.observer --node <node>

# 2. Run benchmarks
mix dala.bench --duration 30

# 3. Profile specific code paths
mix dala.trace --modules MyApp.SlowModule

# 4. Generate flame graph
mix dala.profile --function "MyApp.SlowModule.slow_function/2"

Device Management

Listing and Selecting Devices

# List all connected devices and emulators
mix dala.devices

See Beginner Guide for device setup instructions.

Managing Emulators

# List available emulators/simulators
mix dala.emulators

# Launch an emulator
mix dala.emulators launch "Pixel_6_API_33"

# Launch iOS simulator
mix dala.emulators launch "iPhone 14"

# Shutdown emulator
mix dala.emulators shutdown "Pixel_6_API_33"

Screen Capture and Recording

# Take screenshot
mix dala.screen screenshot --device <id> --output screen.png

# Record video (30 seconds)
mix dala.screen record --device <id> --output demo.mp4 --duration 30

# Live screen preview (macOS only)
mix dala.screen preview --device <id>

Diagnosing Issues

Running Doctor

When things aren't working, run diagnostics:

# Diagnose common setup and configuration issues
mix dala.doctor

See Beginner Guide for initial setup.

Checking Configuration

# View current dala.exs configuration
mix dala.config show

# Validate configuration
mix dala.config validate

Cache Management

# Show cache information
mix dala.cache show

# Clear OTP runtime cache
mix dala.cache clear otp

# Clear all caches
mix dala.cache clear all

Best Practices

  1. Use watch mode during development - It saves time with automatic pushes
  2. Connect for debugging - IEx on the device is powerful for investigation
  3. Check logs early - Stream logs when diagnosing issues
  4. Use short device IDs - They're easier to type and remember
  5. Run doctor first - When encountering issues, mix dala.doctor is your friend
  6. Keep dala_dev updated - Regular updates bring fixes and features

Next Steps