What do startup probes do in Kubernetes?

Startup probes in Kubernetes are specifically designed to determine if an application has successfully started. During the startup phase of an application, it may take some time for the application to become ready to handle requests. Startup probes help in identifying when the application is fully initialized and ready to serve traffic.

When a startup probe is configured, Kubernetes uses it to check if the application has successfully started. If the probe fails, Kubernetes can take appropriate actions, such as restarting the container, until the application is confirmed to be running. This mechanism is particularly helpful for applications that require a considerable amount of time to initialize before they can accept traffic, allowing Kubernetes to manage their state appropriately.

The other choices describe concepts that do not align with the primary function of startup probes. For instance, checking application performance and monitoring network traffic pertain more to different types of probes or monitoring tools in a Kubernetes environment. Meanwhile, running continuously throughout the application lifecycle is characteristic of liveness or readiness probes rather than startup probes. These differences highlight the specific and targeted role of startup probes in ensuring applications are ready before they begin accepting workloads.