Readiness check
A readiness check is a health probe that determines whether a running service or workload is prepared to receive requests or traffic.
Kubernetes in Action, Second Edition
A readiness endpoint is an application-provided HTTP endpoint that reports whether the application is ready to serve requests.
- How it is used
- Prevents Services from forwarding requests to Pods before their applications can handle them.
- How deep it goes
- Develops HTTP response rules and a database-backed handler alongside probe settings, while leaving the application's readiness criterion to its developer.
- Examples
- Uses a switchable file check, a quote-serving path, and a database-connection HTTP handler to show different readiness criteria.
- What you can do after
- Build it from scratch as an HTTP handler that checks a required database connection and returns a success or failure response.
Read how Kubernetes in Action, Second Edition explains readiness check →
Kubernetes for Developers
A readiness probe is a health test that determines whether an application instance is ready to receive user traffic.
- How it is used
- Controls which Kubernetes Pod replicas receive Service traffic during startup, dependency failures, and updates.
- How deep it goes
- Explains probe behavior, HTTP configuration, endpoint design, dependency tests, and delayed recovery from prolonged unreadiness.
- Examples
- Uses a three-replica web service, an HTTP Deployment probe, a database query, and a rollout comparison.
- What you can do after
- Operate/configure it by adding an HTTP readiness probe and an endpoint that reports whether the application can serve traffic.
Read how Kubernetes for Developers explains readiness check →
Machine Learning Platform Engineering
A periodic check that determines whether a workload is ready to receive traffic.
- How it is used
- Determines whether a deployed model-serving pod can receive incoming traffic.
- How deep it goes
- Defines periodic /readyz polling and operational readiness, while deferring custom endpoint implementation.
- Examples
- Uses the /readyz endpoint and BentoML’s built-in Kubernetes observability endpoints as concrete examples.
- What you can do after
- Operate/configure BentoML services with Kubernetes readiness probes for traffic eligibility and pod observability.
Read how Machine Learning Platform Engineering explains readiness check →
Quarkus in Action
A readiness probe is a Kubernetes health check that determines whether a container is ready to receive traffic.
- How it is used
- Uses Kubernetes readiness probes to withhold traffic from applications that cannot currently process requests.
- How deep it goes
- Explains failure semantics, HTTP endpoints, automatic JDBC checks, Dev UI inspection, and a database outage demonstration.
- Examples
- Demonstrates an Inventory service, MySQL through Dev Services, the Quarkus Dev UI, health JSON, and a stopped database container.
- What you can do after
- Operate/configure Quarkus health monitoring and diagnose readiness failures through endpoints, Dev UI, and database status.
Learn Docker in a Month of Lunches, Second Edition
A readiness probe is a Kubernetes container probe that determines whether a Pod should receive traffic from a Service.
- How it is used
- Controls whether a Pod remains available through a Service while Kubernetes rolls out or maintains an application.
- How deep it goes
- Explains probe types, timing, endpoint removal, and a runnable Deployment configuration, but does not detail probe thresholds.
- Examples
- Uses an HTTP GET request to /healthz every five seconds in a numbers-api Deployment.
- What you can do after
- Operate/configure readiness behavior through Deployment YAML and verify Pod status with kubectl.
Read how Learn Docker in a Month of Lunches, Second Edition explains readiness check →
Spring in Action, Sixth Edition
A readiness probe is a Kubernetes health check that determines whether an application instance is prepared to receive traffic.
- How it is used
- Uses Kubernetes traffic gating to keep uninitialized application instances out of service.
- How deep it goes
- Explains startup behavior, distinguishes readiness from liveness, and shows Spring Boot and Kubernetes configuration.
- Examples
- Shows application.yml probe enablement, Actuator readiness responses, and a Kubernetes Deployment readinessProbe.
- What you can do after
- Apply it via Spring Boot Actuator and Kubernetes HTTP probes to control when instances receive traffic.
Read how Spring in Action, Sixth Edition explains readiness check →
Bootstrapping Microservices, Second Edition: With Docker, Kubernetes, GitHub Actions, and Terraform
A Kubernetes readiness probe is a health check that indicates whether a container or application instance is ready to receive traffic.
- How it is used
- Uses Kubernetes traffic gating to keep microservices unavailable until startup and upstream dependencies are ready.
- How deep it goes
- Explains readiness alongside liveness and demonstrates HTTP configuration, but does not detail endpoint implementation.
- Examples
- Uses a gateway Deployment calling /ready and /alive over HTTP, plus a history service waiting for RabbitMQ.
- What you can do after
- Operate/configure Kubernetes Deployments with HTTP readiness and liveness probes for dependency-aware service availability.
Related concepts
- Kubernetesused by · Kubernetes is an open-source platform for orchestrating and automating the deployment, scaling, and management of containerized workloads across computing clusters.
- health checkkind of · A health check is an assessment or probe that determines whether a system, service, or component is functioning acceptably according to defined criteria.
- liveness checkcontrasts with · A liveness check is an automated health test that determines whether a running workload remains functional or should be restarted.
- TCP socket probeincludes · A TCP socket probe is a Kubernetes container probe that checks whether a TCP connection can be established on a specified port.
- http get probeincludes · An HTTP GET probe is a Kubernetes liveness-check mechanism that sends an HTTP GET request to a specified path and port in a container and succeeds for a non-error response.
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