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Using service accounts in applications

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:

Group Description

system:serviceaccounts

Includes all service accounts in the system.

system:serviceaccounts:<project>

Includes all service accounts in the specified project.

Each service account automatically contains two secrets:

  • An API token

  • Credentials for the OpenShift Container Registry

The generated API token and registry credentials do not expire, but you can revoke them by deleting the secret. When you delete the secret, a new one is automatically generated to take its place.

Default service accounts

Your OpenShift Container Platform cluster contains default service accounts for cluster management and generates more service accounts for each project.

Default cluster service accounts

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

Service account Description

replication-controller

Assigned the system:replication-controller role

deployment-controller

Assigned the system:deployment-controller role

build-controller

Assigned the system:build-controller role. Additionally, the build-controller service account is included in the privileged security context constraint to create privileged build pods.

Default project service accounts and roles

Three service accounts are automatically created in each project:

Service account Usage

builder

Used by build pods. It is given the system:image-builder role, which allows pushing images to any imagestream in the project using the internal Docker registry.

The builder service account is not created if the Build cluster capability is not enabled.

deployer

Used by deployment pods and given the system:deployer role, which allows viewing and modifying replication controllers and pods in the project.

The deployer service account is not created if the DeploymentConfig cluster capability is not enabled.

default

Used to run all other pods unless they specify a different service account.

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 image registry.

Automatically generated image pull secrets

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

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.

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    2         2d
default    2         2d
deployer   2         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

    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:	     <none>
Image pull secrets:  robot-dockercfg-qzbhb
Mountable secrets:   robot-dockercfg-qzbhb
Tokens:              robot-token-f4khf
Events:              <none>