Chapter 12. Using bound service account tokens

Procedure

1. Configure a pod to use a bound service account token by using volume projection.

   1. Create a file called pod-projected-svc-token.yaml with the following contents:

      apiVersion: v1
      kind: Pod
      metadata:
        name: nginx
      spec:
        securityContext:
          runAsNonRoot: true 1
          seccompProfile:
            type: RuntimeDefault 2
        containers:
        - image: nginx
          name: nginx
          volumeMounts:
          - mountPath: /var/run/secrets/tokens
            name: vault-token
          securityContext:
            allowPrivilegeEscalation: false
            capabilities:
              drop: [ALL]
        serviceAccountName: build-robot 3
        volumes:
        - name: vault-token
          projected:
            sources:
            - serviceAccountToken:
                path: vault-token 4
                expirationSeconds: 7200 5
                audience: vault 6

      1

      Prevents containers from running as root to minimize compromise risks.

      2

      Sets the default seccomp profile, limiting to essential system calls, to reduce risks.

      3

      A reference to an existing service account.

      4

      The path relative to the mount point of the file to project the token into.

      5

      Optionally set the expiration of the service account token, in seconds. The default value is 3600 seconds (1 hour), and this value must be at least 600 seconds (10 minutes). The kubelet starts trying to rotate the token if the token is older than 80 percent of its time to live or if the token is older than 24 hours.

      6

      Optionally set the intended audience of the token. The recipient of a token should verify that the recipient identity matches the audience claim of the token, and should otherwise reject the token. The audience defaults to the identifier of the API server.

      Note

      In order to prevent unexpected failure, OpenShift Dedicated overrides the expirationSeconds value to be one year from the initial token generation with the --service-account-extend-token-expiration default of true. You cannot change this setting.

   2. Create the pod:

      $ oc create -f pod-projected-svc-token.yaml

      The kubelet requests and stores the token on behalf of the pod, makes the token available to the pod at a configurable file path, and refreshes the token as it approaches expiration.

2. The application that uses the bound token must handle reloading the token when it rotates.

   The kubelet rotates the token if it is older than 80 percent of its time to live, or if the token is older than 24 hours.