Configuration Reference

This document provides a comprehensive reference for all configuration options available in Trailer.dev.

Configuration Methods

Trailer.dev can be configured through:

• Environment variables
• Configuration file (YAML)
• Command line flags

Configuration Categories

Server Configuration

• Server URL and port
• Host settings
• Authentication settings
• Security options

Agent Configuration

• Agent type (Docker/Kubernetes)
• Build directory settings
• Deployment name
• Hostname configuration
• Authentication token
• Build context management

Dynamic Configuration

• Host enablement
• Heartbeat intervals
• Reconciliation intervals

Configuration File Structure

The configuration file (config.yaml) supports the following structure:

server:
  url: "http://localhost:8090"
  port: 8090
  host: "0.0.0.0"

agent:
  type: "docker"  # or "kubernetes"
  deployment_name: "default"
  host_name: "host-1"
  build_directory: "/tmp"
  delete_build_context_after_build: true

dynamic:
  host_enabled: true
  heartbeat_interval: "30s"
  reconciliation_interval: "1m"

Environment Variables

Common environment variables:

# Server settings
TRAILER_SERVER_URL=http://localhost:8090
TRAILER_SERVER_PORT=8090
TRAILER_SERVER_HOST=0.0.0.0

# Agent settings
TRAILER_AGENT_TYPE=docker
TRAILER_AGENT_DEPLOYMENT_NAME=default
TRAILER_AGENT_HOST_NAME=host-1
TRAILER_AGENT_BUILD_DIR=/tmp
TRAILER_AGENT_DELETE_BUILD_CONTEXT=true

# Dynamic settings
TRAILER_HOST_ENABLED=true
TRAILER_HEARTBEAT_INTERVAL=30s
TRAILER_RECONCILIATION_INTERVAL=1m

Command Line Flags

Common command line flags:

trailer --server-url http://localhost:8090 \
        --port 8090 \
        --host 0.0.0.0 \
        --agent-type docker \
        --deployment-name default \
        --host-name host-1 \
        --build-dir /tmp \
        --delete-build-context \
        --host-enabled \
        --heartbeat-interval 30s \
        --reconciliation-interval 1m

Configuration Precedence

Configuration options are applied in the following order (later options override earlier ones):

1. Default values
2. Configuration file
3. Environment variables
4. Command line flags

Security Considerations

• Sensitive values like authentication tokens should be provided through environment variables or secure secret management
• Configuration files should have appropriate permissions (readable only by the application user)
• Avoid storing sensitive information in version control

Best Practices

1. Configuration File Location

   • Default: ~/.config/trailer/config.yaml
   • Can be overridden with --config flag

2. Environment Variables

   • Use for sensitive information
   • Use for environment-specific settings
   • Follow the TRAILER_* prefix convention

3. Command Line Flags

   • Use for temporary overrides
   • Use for development/testing
   • Use for one-off configurations

4. Configuration Validation

   • All configuration options are validated at startup
   • Invalid configurations will prevent the application from starting
   • Check logs for configuration errors