Chapter 5. Configuring Service Accounts

When a person uses the OpenShift Enterprise CLI or web console, their API token authenticates them to the OpenShift Enterprise API. However, when a regular user’s credentials are not available, it is common for components to make API calls independently. For example:

Service accounts provide a flexible way to control API access without sharing a regular user’s credentials.

Every service account has an associated user name that can be granted roles, just like a regular user. The user name is derived from its project and name:

system:serviceaccount:<project>:<name>

For example, to add the view role to the robot service account in the top-secret project:

$ oc policy add-role-to-user view system:serviceaccount:top-secret:robot

Every service account is also a member of two groups:

For example, to allow all service accounts in all projects to view resources in the top-secret project:

$ oc policy add-role-to-group view system:serviceaccounts -n top-secret

To allow all service accounts in the managers project to edit resources in the top-secret project:

$ oc policy add-role-to-group edit system:serviceaccounts:managers -n top-secret

Service accounts authenticate to the API using tokens signed by a private RSA key. The authentication layer verifies the signature using a matching public RSA key.

To enable service account token generation, update the serviceAccountConfig stanza in the /etc/origin/master/master-config.yml file on the master to specify a privateKeyFile (for signing), and a matching public key file in the publicKeyFiles list:

serviceAccountConfig:
  ...
  masterCA: ca.crt 1
  privateKeyFile: serviceaccounts.private.key 2
  publicKeyFiles:
  - serviceaccounts.public.key 3
  - ...

Service accounts are required in each project to run builds, deployments, and other pods. The managedNames setting in the /etc/origin/master/master-config.yml file on the master controls which service accounts are automatically created in every project:

serviceAccountConfig:
  ...
  managedNames: 1
  - builder 2
  - deployer 3
  - default 4
  - ...

All service accounts in a project are given the system:image-puller role, which allows pulling images from any image stream in the project using the internal container registry.

Several infrastructure controllers run using service account credentials. The following service accounts are created in the OpenShift Enterprise infrastructure project (openshift-infra) at server start, and given the following roles cluster-wide:

To configure the project where those service accounts are created, set the openshiftInfrastructureNamespace field in in the /etc/origin/master/master-config.yml file on the master:

policyConfig:
  ...
  openshiftInfrastructureNamespace: openshift-infra

Set the limitSecretReferences field in the /etc/origin/master/master-config.yml file on the master to true to require pod secret references to be whitelisted by their service accounts. Set its value to false to allow pods to reference any secret in the project.

serviceAccountConfig:
  ...
  limitSecretReferences: false