Which resource tracks image versions and triggers deployments when a new image is available?

Which resource tracks image versions and triggers deployments when a new image is available?

• A. ImageStream
• B. BuildConfig
• C. Deployment
• D. Route

Answer: (A)

OpenShift uses an ImageStream to represent container images from registries and to track their versions through tags. When a new image is built and pushed and the image stream’s tag is updated, the system can automatically trigger a deployment to use that new image if the deployment is configured with an imageChange trigger pointing at that image stream tag. This setup decouples image creation from deployment, enabling smooth, automatic rollouts as soon as new images are available. Other resources have different roles: a BuildConfig defines how to build images, a Deployment controls running pods, and a Route exposes the service to the outside world. But the mechanism that monitors image versions and drives deployments in response to new images is the ImageStream.

OpenShift uses an ImageStream to represent container images from registries and to track their versions through tags. When a new image is built and pushed and the image stream’s tag is updated, the system can automatically trigger a deployment to use that new image if the deployment is configured with an imageChange trigger pointing at that image stream tag. This setup decouples image creation from deployment, enabling smooth, automatic rollouts as soon as new images are available. Other resources have different roles: a BuildConfig defines how to build images, a Deployment controls running pods, and a Route exposes the service to the outside world. But the mechanism that monitors image versions and drives deployments in response to new images is the ImageStream.