The twelve‑factor app stores configuration in environment variables, which are easy to change between deploys without altering any code. In a twelve‑factor app, environment variables are granular controls, each fully orthogonal to others. They are never grouped as "environments" but instead independently managed for each deploy.
Local log files quickly become unmanageable and risk consumption of disk space. Production systems must route structured logs (preferably in JSON format) to a centralized log management platform such as the ELK Stack (Elasticsearch, Logstash, Kibana), Datadog, or AWS CloudWatch. This allows operations teams to query, filter, and trace errors across distributed microservices. Application Performance Monitoring (APM) production-settings
