Kubernetes Cluster Configuration Concepts
Internal
Secrets
A secret is a mechanism, backed by a Kubernetes API resource, that allows applications running on a Kubernetes cluster to safely manage, store and access security-sensitive information such as passwords, OAuth tokens and ssh keys. This mechanism provides a better alternative to placing that information in a container image or in the pod metadata. An individual secret contains a small amount of data, limited to 1 MiB - this is to discourage creation of very large secrets that would exhaust API server and kubelet memory. Entire multi-line configuration files can be exposed as secrets.
A Secret instance contains two maps: "data", which is used to store arbitrary key/value pairs, where the values are base64-encoded string, and "stringData", which is a field provided for convenience that allows to provide secret data as unencoded fields.
Secrets are consumed by applications, and they can be exposed to pods in two ways:
- As files in dedicated volumes mounted in the pod.
- As environment variables exposed to containers in the pod.
A pod must explicitly reference a secret in its manifest to access it. If that does not happen, the system will not initialize the infrastructure that exposes the information to the pod.
Secrets can also be used by other parts of the system, without being directly exposed to pods.
Secret Types
Opaque
kubernetes.io/service-account-token
Accessible on pods as /var/run/secrets/kubernetes.io/serviceaccount.