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.