Mastering Kubernetes - Second Edition

Secrets

Secrets are small objects that contain sensitive information, such as credentials and tokens. They are stored in etcd, are accessible by the Kubernetes API server, and can be mounted as files into pods (using dedicated secret volumes that piggyback on regular data volumes) that need access to them. The same secret can be mounted into multiple pods. Kubernetes itself creates secrets for its components, and you can create your own secrets. Another approach is to use secrets as environment variables. Note that secrets in a pod are always stored in memory (tmpfs, in the case of mounted secrets) for better security.