Task 1.11: Managing Configuration Settings

Summary

Implement configuration management for buylater.email using command-line flags, environment variables, and sensible defaults to make the application more flexible and production-ready.

Motivation

Following Let’s Go Chapter 3.1, we need to move away from hardcoded configuration values (like port 4000) to a flexible configuration system. This will allow easy deployment across different environments and better operational control.

Acceptance Criteria

Add command-line flag support for server address/port configuration
Implement environment variable fallbacks for configuration
Create configuration struct to hold all application settings
Add configuration for template directory paths
Add configuration for static file directory paths
Support debug/production mode configuration
Provide sensible defaults for all configuration options
Update application struct to use configuration
Document all available configuration options

Technical Requirements

Configuration Structure

type config struct {
    port      int
    env       string
    staticDir string
    htmlDir   string
}

Implementation Details

Use Go’s flag package for command-line arguments
Support environment variable overrides
Implement configuration validation
Update main.go to parse and use configuration
Make template and static file paths configurable
Add help text for all configuration options

Dependencies

Task 1.10 completed (HTTP handler interface foundation)

Testing Strategy

Unit Tests

Test configuration parsing with various inputs
Verify default values are applied correctly
Test environment variable precedence

Integration Tests

Application starts with default configuration
Command-line flags override defaults correctly
Environment variables work as expected

Manual Testing

Start server with default settings
Test custom port: go run ./cmd/web -port=8080
Test environment variables: PORT=3000 go run ./cmd/web
Verify help output: go run ./cmd/web -help
Test different environment modes (development/production)

Definition of Done

All acceptance criteria met
All specified tests pass
Code follows project conventions (go fmt, go vet)
Configuration system is well-documented
No hardcoded values remain in application
Environment-specific behavior works correctly
Human verification completed successfully
Git commit created with proper message format

Implementation Notes

Approach

Replace hardcoded values with a flexible configuration system that supports multiple sources (flags, environment, defaults) with proper precedence.

Key Files to Modify

cmd/web/main.go - Add configuration parsing and usage
cmd/web/handlers.go - Update to use configurable paths

Configuration Options

port: Server port (default: 4000)
env: Environment mode (default: “development”)
static-dir: Static files directory (default: “./ui/static”)
html-dir: HTML templates directory (default: “./ui/html”)

Potential Risks

Configuration parsing errors could prevent startup
Path resolution issues in different environments
Environment variable naming conflicts

Success Metrics

Flexible, configurable buylater.email application that can be easily deployed and managed across different environments with proper configuration management.

Blocks: Future deployment and environment-specific configurations
Blocked by: Task 1.10 (needs application struct foundation)
Related: Production deployment and operational management

Implementation Log

Implementation details will be recorded here during development.

Final Verification

Human Tester: [Name]
Date Completed: [YYYY-MM-DD]
Verification Result: [Pass/Fail]
Notes: [Any issues found or additional observations]

task_id: “1.11” title: “Managing Configuration Settings” status: “pending” priority: “high” estimated_effort: “medium” created: “2025-07-24” assigned_to: “pair” related_rfds: “RFD 004”