How do I handle environment variables in Docker?
Pass at runtime with docker run -e VAR=value, or use env_file in docker-compose.yml to load from a .env file. Never bake secrets into the Docker image. Use Docker secrets or AWS Secrets Manager for production.
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More FAQs in dotenv Advanced Techniques in Node.js Variables Expansion, Validation, and Type Casting
Use ${VAR_NAME} syntax. For example, BASE_URL=https://api.yourdomain.com and API_URL=${BASE_URL}/api/v1. When dotenv loads, API_URL becomes https://api.yourdomain.com/api/v1. This avoids duplication.
Use the envalid package. Define a schema with types (str, num, bool, url, email), choices, defaults, and minLength. cleanEnv validates all variables, type-casts them, provides defaults, and throws an error at startup if validation fails.
dotenv-flow automatically loads multiple .env files based on NODE_ENV: .env (base), .env.local (local overrides), .env.${NODE_ENV} (environment-specific), and .env.${NODE_ENV}.local. Later files override earlier ones, providing flexible environment management.
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