Environment Configuration

Introduction

12-factor apps configure via the environment. In Kubernetes that's a ConfigMap + Secret; locally it's .env; in CI it's pipeline variables.

Informative example

# application.yml — env vars with defaults
spring:
  datasource:
    url: ${DB_URL:jdbc:postgresql://localhost:5432/orders}
    username: ${DB_USER:postgres}
    password: ${DB_PASSWORD}      # required, no default

stripe:
  api-key: ${STRIPE_API_KEY}      # secret

Best practices

• Secrets in env vars, never in YAML committed to git.
• Use a secrets manager (Vault, AWS Secrets Manager) — mount as env or files.
• Fail fast on missing required vars at startup.