Configure liveness, readiness, and startup probes for Spring Boot applications (alpha)

This topic tells you how to override the liveness, readiness, and startup probes’ settings for Spring Boot apps in Tanzu Application Platform. You can override the Kubernetes default probe settings in spring-boot-conventions for containers on Tanzu Application Platform.

Caution

This feature is in alpha testing. It is intended for evaluation and test purposes only.

Overview of the probes

Kubernetes provides built-in mechanisms for checking the health and readiness of your Spring Boot apps. By default, Kubernetes uses specific endpoints provided by Spring Boot Actuator for liveness and readiness checks. However, you might need to customize these probes to align them with your app’s specific requirements.

Probe	Function
Liveness	Indicates whether the app is running and responsive. If the probe fails, Kubernetes might restart the container.
Readiness	Indicates whether the app is ready to serve requests. If the probe fails, Kubernetes won’t route traffic to the container.
Startup	Indicates when the app has completed its initialization and is ready to handle traffic. This is especially useful for apps with a slow startup process.

For more information about the probes, see the Kubernetes documentation.

Override the default configurations of the probes

To override the default settings and customize the probes at a cluster level:

1. List the schema for the spring-boot-conventions package by running:

   tanzu package available get spring-boot-conventions.tanzu.vmware.com/VERSION-NUMBER \
   --values-schema --namespace tap-install
   

   Where VERSION-NUMBER is the version of the package listed. For example: 1.7.0.

   For example:

   $ tanzu package available get spring-boot-conventions.tanzu.vmware.com/1.7.0 --values-schema --namespace tap-install
       KEY                                          DEFAULT             TYPE     DESCRIPTION
       autoConfigureActuators                       false               boolean  Enable or disable the automatic configuration of actuators on the TAP platform level
       kubernetes_distribution                                          string   Kubernetes distribution that this package is being installed on. Accepted
                                                                                  values: ['''',''openshift'']
       kubernetes_version                                               string   Optional: The Kubernetes Version. Valid values are '1.24.*', or ''
       livenessProbe.terminationGracePeriodSeconds                      number   configure a grace period for the kubelet to wait  between triggering a shut down
                                                                                  of the failed container, and then forcing the container runtime to stop that
                                                                                  container
       livenessProbe.timeoutSeconds                 1                   number   Number of seconds after which the probe times out
       livenessProbe.failureThreshold                                   number   After a probe fails failureThreshold times in a row, Kubernetes considers that
                                                                                  the overall check has failed
       livenessProbe.initialDelaySeconds            0                   number   Number of seconds after the container has started before liveness probes are
                                                                                  initiated
       livenessProbe.periodSeconds                  10                  number   How often (in seconds) to perform the probe
       livenessProbe.successThreshold               1                   number   Minimum consecutive successes for the probe to be considered successful after
                                                                                  having failed
       readinessProbe.initialDelaySeconds             0                 number   Number of seconds after the container has started before readiness probes are
                                                                                  initiated
       readinessProbe.periodSeconds                   10                number   How often (in seconds) to perform the probe
       readinessProbe.successThreshold                1                 number   Minimum consecutive successes for the probe to be considered successful after
                                                                                  having failed
       readinessProbe.terminationGracePeriodSeconds                     number   configure a grace period for the kubelet to wait between triggering a shut down
                                                                                  of the failed container, and then forcing the container runtime to stop that
                                                                                  container
       readinessProbe.timeoutSeconds                  1                 number   Number of seconds after which the probe times out
       readinessProbe.failureThreshold                                  number   After a probe fails failureThreshold times in a row, Kubernetes considers that
                                                                                  the overall check has failed
       startupProbe.periodSeconds                     10                number   How often (in seconds) to perform the probe
       startupProbe.successThreshold                  1                 number   Minimum consecutive successes for the probe to be considered successful after
                                                                                  having failed
       startupProbe.terminationGracePeriodSeconds                       number   configure a grace period for the kubelet to wait between triggering a shut down
                                                                                  of the failed container, and then forcing the container runtime to stop that
                                                                                  container
       startupProbe.timeoutSeconds                    1                 number   Number of seconds after which the probe times out
       startupProbe.failureThreshold                                    number   After a probe fails failureThreshold times in a row, Kubernetes considers that
                                                                                  the overall check has failed
       startupProbe.initialDelaySeconds               0                 number   Number of seconds after the container has started before probes are initiated
   

2. When you install Spring Boot conventions, provide an entry in the values.yaml file to override the configuration.

   For example:

   springboot_conventions:
     autoConfigureActuators: true
     livenessProbe:
       initialDelaySeconds: 11
       periodSeconds: 12
       timeoutSeconds: 13
       terminationGracePeriodSeconds: 14
     readinessProbe:
       initialDelaySeconds: 15
       periodSeconds: 12
       successThreshold: 3
       failureThreshold: 4
   

3. Install the package by running:

   tanzu package install spring-boot-conventions \
    --package spring-boot-conventions.tanzu.vmware.com \
    --version VERSION-NUMBER \
    --namespace tap-install \
    --values-file values.yaml
   

   Where VERSION-NUMBER is the version of the package to install. For example: 1.7.2.

4. Verify that you installed the package by running:

   tanzu package installed get spring-boot-conventions --namespace tap-install
   

   For example:

   tanzu package installed get spring-boot-conventions -n tap-install
   | Retrieving installation details for spring-boot-conventions...
   NAME:                    spring-boot-conventions
   PACKAGE-NAME:            spring-boot-conventions.tanzu.vmware.com
   PACKAGE-VERSION:         1.7.0
   STATUS:                  Reconcile succeeded
   CONDITIONS:              [{ReconcileSucceeded True  }]
   USEFUL-ERROR-MESSAGE:
   

   Verify that STATUS is Reconcile succeeded

   The Spring Boot convention applies the probe and timeout settings at the cluster level to all Spring Boot and Spring Native workloads.

5. Verify the PodIntent of your workload by ensuring that spec.containers.livenessProbe shows the overridden configuration values propagated through the Spring Boot conventions

   kubectl get podintents.conventions.carto.run tanzu-java-web-app -o yaml
   
   spec:
    containers:
    - env:
      - name: JAVA_TOOL_OPTIONS
        value: -Dmanagement.endpoint.health.probes.add-additional-paths="true" -Dmanagement.endpoint.health.show-details="always"
          -Dmanagement.endpoints.web.base-path="/actuator" -Dmanagement.endpoints.web.exposure.include="*"
          -Dmanagement.health.probes.enabled="true" -Dmanagement.server.port="8081"
          -Dserver.port="8080" -Dserver.shutdown.grace-period="24s"
      image: registry.example.com/app-live-view/test/tanzu-java-web-app-default@sha256:fa822a6585eb1287a817a956f16d77dd391624462a626bf37bbf0f9e89ff7562
      livenessProbe:
        httpGet:
          path: /livez
          port: 8080
          scheme: HTTP
        initialDelaySeconds: 11
        periodSeconds: 12
        terminationGracePeriodSeconds: 14
        timeoutSeconds: 13
      name: workload
      ports:
      - containerPort: 8080
        protocol: TCP
      readinessProbe:
        failureThreshold: 4
        httpGet:
          path: /readyz
          port: 8080
          scheme: HTTP
        initialDelaySeconds: 15
        periodSeconds: 12
        successThreshold: 3
      resources: {}
      securityContext:
        runAsUser: 1000
      startupProbe:
        httpGet:
          path: /startupz
          port: 8080
          scheme: HTTP