Configuration determines how your application behaves across environments. Poor configuration management leads to security vulnerabilities, deployment failures, and debugging nightmares.
Configuration Sources
Priority (highest to lowest):
1. Command-line arguments
2. Environment variables
3. Config files (environment-specific)
4. Config files (default)
5. Hardcoded defaults
Rule: Higher priority sources override lower ones
Environment Variables
Basic Setup
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Type-Safe Access
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Layered Configuration
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Feature Flags
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Secrets Management
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Configuration Validation
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Runtime Configuration
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Best Practices
DO:
✓ Validate configuration at startup
✓ Use typed configuration objects
✓ Separate secrets from config
✓ Use environment-specific configs
✓ Document all configuration options
✓ Provide sensible defaults
DON'T:
✗ Hardcode configuration values
✗ Commit secrets to version control
✗ Use process.env throughout code
✗ Mix configuration with business logic
✗ Require restarts for all config changes
Conclusion
Configuration management is infrastructure for your application. Invest in validation, type safety, and clear separation between environments.
Good configuration is invisible—it just works across all environments.