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Chapter 10. Understanding and creating service accounts

10.1. Service accounts overview

A service account is an OpenShift Container Platform account that allows a component to directly access the API. Service accounts are API objects that exist within each project. Service accounts provide a flexible way to control API access without sharing a regular user’s credentials.

When you use the OpenShift Container Platform CLI or web console, your API token authenticates you to the API. You can associate a component with a service account so that they can access the API without using a regular user’s credentials.

For example, service accounts can allow:

  • Replication controllers to make API calls to create or delete pods
  • Applications inside containers to make API calls for discovery purposes
  • External applications to make API calls for monitoring or integration purposes

Each service account’s user name is derived from its project and name: 

system:serviceaccount:<project>:<name>

Every service account is also a member of two groups:

GroupDescription

system:serviceaccounts

Includes all service accounts in the system.

system:serviceaccounts:<project>

Includes all service accounts in the specified project.

10.1.1. Automatically generated image pull secrets

By default, OpenShift Container Platform creates an image pull secret for each service account.

Note

Prior to OpenShift Container Platform 4.16, a long-lived service account API token secret was also generated for each service account that was created. Starting with OpenShift Container Platform 4.16, this service account API token secret is no longer created.

After upgrading to 4.17, any existing long-lived service account API token secrets are not deleted and will continue to function. For information about detecting long-lived API tokens that are in use in your cluster or deleting them if they are not needed, see the Red Hat Knowledgebase article Long-lived service account API tokens in OpenShift Container Platform.

This image pull secret is necessary to integrate the OpenShift image registry into the cluster’s user authentication and authorization system.

However, if you do not enable the ImageRegistry capability or if you disable the integrated OpenShift image registry in the Cluster Image Registry Operator’s configuration, an image pull secret is not generated for each service account.

When the integrated OpenShift image registry is disabled on a cluster that previously had it enabled, the previously generated image pull secrets are deleted automatically.

10.2. Creating service accounts

You can create a service account in a project and grant it permissions by binding it to a role.

Procedure

  1. Optional: To view the service accounts in the current project: 

    $ oc get sa

    Example output

    NAME       SECRETS   AGE
builder    1         2d
default    1         2d
deployer   1         2d

  2. To create a new service account in the current project: 

    $ oc create sa <service_account_name> 1
    1
    To create a service account in a different project, specify -n <project_name>.

    Example output

    serviceaccount "robot" created

    Tip

    You can alternatively apply the following YAML to create the service account: 

    apiVersion: v1
kind: ServiceAccount
metadata:
  name: <service_account_name>
  namespace: <current_project>

  3. Optional: View the secrets for the service account: 

    $ oc describe sa robot

    Example output

    Name:                robot
Namespace:           project1
Labels:              <none>
Annotations:         openshift.io/internal-registry-pull-secret-ref: robot-dockercfg-qzbhb
Image pull secrets:  robot-dockercfg-qzbhb
Mountable secrets:   robot-dockercfg-qzbhb
Tokens:              <none>
Events:              <none>

10.3. Granting roles to service accounts

You can grant roles to service accounts in the same way that you grant roles to a regular user account.

  • You can modify the service accounts for the current project. 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
    Tip

    You can alternatively apply the following YAML to add the role: 

    apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: view
  namespace: top-secret
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: view
subjects:
- kind: ServiceAccount
  name: robot
  namespace: top-secret

  • You can also grant access to a specific service account in a project. For example, from the project to which the service account belongs, use the -z flag and specify the <service_account_name> 

    $ oc policy add-role-to-user <role_name> -z <service_account_name>
    Important

    If you want to grant access to a specific service account in a project, use the -z flag. Using this flag helps prevent typos and ensures that access is granted to only the specified service account.

    Tip

    You can alternatively apply the following YAML to add the role: 

    apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: <rolebinding_name>
  namespace: <current_project_name>
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: <role_name>
subjects:
- kind: ServiceAccount
  name: <service_account_name>
  namespace: <current_project_name>

  • To modify a different namespace, you can use the -n option to indicate the project namespace it applies to, as shown in the following examples.

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

      $ oc policy add-role-to-group view system:serviceaccounts -n my-project
      Tip

      You can alternatively apply the following YAML to add the role: 

      apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: view
  namespace: my-project
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: view
subjects:
- apiGroup: rbac.authorization.k8s.io
  kind: Group
  name: system:serviceaccounts

    • To allow all service accounts in the managers project to edit resources in the my-project project: 

      $ oc policy add-role-to-group edit system:serviceaccounts:managers -n my-project
      Tip

      You can alternatively apply the following YAML to add the role: 

      apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: edit
  namespace: my-project
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: edit
subjects:
- apiGroup: rbac.authorization.k8s.io
  kind: Group
  name: system:serviceaccounts:managers
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