Building

lttle.cloud provides automatic image building for your applications using Nixpacks, eliminating the need to manually create and manage Docker images. When you specify a build configuration in your machine or app resources, the CLI automatically builds and pushes container images to lttle.cloud's registry during deployment.

How Building Works

When you run lttle deploy, the CLI:

1. Detects Resources: Scans your deployment files for machines or apps with build configurations
2. Builds Images: Uses Nixpacks or Docker to build container images locally
3. Pushes Images: Automatically pushes built images to lttle.cloud's private registry
4. Updates Resources: Replaces the build configuration with the pushed image reference
5. Deploys: Proceeds with normal deployment using the built images

Build Configuration

The build field supports three modes:

Auto Build

The simplest option - automatically detects your application type and builds accordingly:

machine:
  name: my-app
  build: auto
  resources:
    cpu: 1
    memory: 256

Options Build

Provides more control over the build process:

machine:
  name: my-app
  build:
    options:
      dir: ./backend # Build directory (default: ".")
      name: my-backend # Image name (default: auto-generated)
      tag: v1.0.0 # Image tag (default: "latest")
      image: custom/name # Full image reference (overrides name/tag)
  resources:
    cpu: 1
    memory: 256

Property	Type	Default	Description
dir	string	"."	Directory to build from
name	string	auto	Image name (generates UUID if not specified)
tag	string	"latest"	Image tag
image	string	auto	Full image reference (overrides all other options)

Docker Build

For projects with existing Dockerfiles:

machine:
  name: my-app
  build:
    docker:
      context: . # Build context (default: ".")
      dockerfile: Dockerfile.prod # Dockerfile path (default: "Dockerfile")
      name: my-docker-app # Image name (default: auto-generated)
      tag: production # Image tag (default: "latest")
      image: myregistry.com/my-app:v1.0.0 # Full image reference (overrides name/tag)
      args: # Build arguments
        NODE_ENV: production
        API_VERSION: v2
  resources:
    cpu: 1
    memory: 256

Property	Type	Default	Description
context	string	"."	Docker build context directory
dockerfile	string	"Dockerfile"	Path to Dockerfile
name	string	auto	Image name (generates UUID if not specified)
tag	string	"latest"	Image tag
image	string	auto	Full image reference (overrides all other options)
args	object	none	Docker build arguments

Nixpacks Integration

lttle.cloud uses Nixpacks for automatic builds, which provides zero-configuration support for many languages and frameworks.

Supported Languages

Nixpacks automatically detects and builds applications for:

• Node.js - Detects package.json, supports npm/yarn/pnpm
• Python - Detects requirements.txt, Pipfile, pyproject.toml
• Go - Detects go.mod, builds static binaries
• Rust - Detects Cargo.toml, optimized release builds
• Java - Detects Maven (pom.xml) or Gradle (build.gradle)
• Ruby - Detects Gemfile, supports Bundler
• PHP - Detects composer.json, includes common extensions
• Clojure - Detects project.clj or build.clj Learn more
• C#/.NET - Detects .csproj, .sln files
• Elixir - Detects mix.exs, supports Phoenix
• And many more - See Nixpacks Language Support for the complete list

Language-Specific Examples

Node.js Application

app:
  name: web-app
  build: auto
  resources:
    cpu: 1
    memory: 512
  expose:
    web:
      port: 3000
      external:
        protocol: https

Nixpacks will:

• Detect package.json
• Install dependencies with npm/yarn/pnpm
• Build the application if a build script exists
• Start with npm start or the start script

Python Application

machine:
  name: api-server
  build: auto
  resources:
    cpu: 1
    memory: 256
  environment:
    PORT: "8000"

Nixpacks will:

• Detect requirements.txt, Pipfile, or pyproject.toml
• Install Python and dependencies
• Start with detected entry point or python main.py

Go Application

machine:
  name: go-service
  build:
    options:
      dir: ./cmd/server
  resources:
    cpu: 1
    memory: 128

Nixpacks will:

• Detect go.mod
• Build a static binary
• Create minimal container image

Nixpacks Configuration

You can customize Nixpacks behavior with a nixpacks.toml file:

nixpacks.toml

[variables]
NODE_VERSION = "18"
NPM_CONFIG_PRODUCTION = "false"

[phases.setup]
nixPkgs = ["nodejs-18_x", "yarn"]

[phases.build]
cmds = [
  "yarn install --frozen-lockfile",
  "yarn build"
]

[start]
cmd = "yarn start"

Place this file in your project root or build directory. The CLI will automatically detect and use it.

Build Process

Local Building

When you run lttle deploy, builds happen locally on your machine:

lttle deploy

Building image for default/my-app
Auto-build using providers: node
Pushing image for default/my-app → registry.lttle.cloud/tenant/my-app:abc123
Successfully built and pushed image for default/my-app
Successfully deployed app: default/my-app

Build Output

Use --debug-build to see detailed build information:

lttle deploy --debug-build

Building image for default/my-app
Generated image reference: registry.lttle.cloud/tenant/my-app:abc123
Building image for path: ./
Auto-build using providers: node
Build summary:
  setup    │ apt-get update && apt-get install -y nodejs npm
  install  │ npm ci
  build    │ npm run build
  start    │ npm start
Generated docker file:
  FROM ubuntu:jammy
  # ... dockerfile content ...
Docker build output:
  # ... build logs ...
Successfully built and pushed image for default/my-app

Build Cache

Builds are cached by default for faster subsequent deployments. Disable caching with:

lttle deploy --no-build-cache

Common Build Patterns

Monorepo Applications

Build specific applications within a monorepo:

# Frontend app
app:
  name: frontend
  build:
    options:
      dir: ./apps/web
  resources:
    cpu: 1
    memory: 512

---
# Backend API
app:
  name: backend
  build:
    options:
      dir: ./apps/api
  resources:
    cpu: 1
    memory: 256

Multi-Stage Docker Builds

Use Docker builds for complex scenarios:

machine:
  name: production-app
  build:
    docker:
      dockerfile: Dockerfile.prod
      args:
        ENVIRONMENT: production
        BUILD_VERSION: "1.2.3"
  resources:
    cpu: 2
    memory: 1024

Dockerfile.prod

FROM node:18-alpine AS builder
WORKDIR /app
COPY package*.json ./
RUN npm ci --only=production

FROM node:18-alpine AS runtime
ARG ENVIRONMENT
ARG BUILD_VERSION
ENV NODE_ENV=${ENVIRONMENT}
ENV VERSION=${BUILD_VERSION}
WORKDIR /app
COPY --from=builder /app/node_modules ./node_modules
COPY . .
EXPOSE 3000
CMD ["npm", "start"]

Custom Build Commands

Override the default start command:

machine:
  name: custom-app
  build: auto
  command:
    - node
    - --experimental-modules
    - server.mjs
  resources:
    cpu: 1
    memory: 256

Troubleshooting

Build Failures

If your build fails:

1. Check supported languages: Ensure your project is supported by Nixpacks
2. Use debug mode: Run with --debug-build to see detailed logs
3. Verify build directory: Ensure the dir option points to the correct location
4. Check dependencies: Make sure all required files (package.json, requirements.txt, etc.) are present

Common Issues

No compatible providers found:

No compatible providers found for auto-build. Check the documentation for auto-build supported targets.

• Ensure your project has the required files for language detection
• Consider using Docker build mode instead

Dockerfile not found:

Dockerfile not found

• Verify the dockerfile path in Docker build configuration
• Ensure the Dockerfile exists in the specified location

Build context issues:

• Make sure the context directory exists and contains necessary files
• Check that paths are relative to your deployment file location

Getting Help

For build-related issues:

• Check the Nixpacks documentation for language-specific guidance
• Use --debug-build flag to get detailed build logs
• Verify your project structure matches the expected patterns for your language

Best Practices

Image Optimization

• Use .dockerignore: Exclude unnecessary files from build context
• Minimize dependencies: Only install required packages
• Use specific versions: Pin language and dependency versions for reproducible builds

Build Configuration

• Environment-specific builds: Use different build configurations for development/production
• Consistent naming: Use descriptive names and tags for images
• Version tagging: Tag images with version numbers for better tracking

Security

• Minimal base images: Nixpacks uses optimized base images
• No secrets in builds: Use environment variables for runtime secrets, not build arguments
• Regular updates: Keep dependencies updated for security patches