12.5. Monitoring virtual machine health

Procedure

1. Customize a YAML configuration file to create an HTTP liveness probe, using the following code block as an example. In this example:

   • You configure a probe using spec.livenessProbe.httpGet, which queries port 1500 of the virtual machine instance, after an initial delay of 120 seconds.
   • The virtual machine instance installs and runs a minimal HTTP server on port 1500 using cloud-init.
   注意

   The timeoutSeconds value must be lower than the periodSeconds value. The timeoutSeconds default value is 1. The periodSeconds default value is 10.

   apiVersion: kubevirt.io/v1alpha3
   kind: VirtualMachineInstance
   metadata:
     labels:
       special: vmi-fedora
     name: vmi-fedora
   spec:
     domain:
       devices:
         disks:
         - disk:
             bus: virtio
           name: containerdisk
         - disk:
             bus: virtio
           name: cloudinitdisk
       resources:
         requests:
           memory: 1024M
     livenessProbe:
       initialDelaySeconds: 120
       periodSeconds: 20
       httpGet:
         port: 1500
       timeoutSeconds: 10
     terminationGracePeriodSeconds: 0
     volumes:
     - name: containerdisk
       registryDisk:
         image: kubevirt/fedora-cloud-registry-disk-demo
     - cloudInitNoCloud:
         userData: |-
           #cloud-config
           password: fedora
           chpasswd: { expire: False }
           bootcmd:
             - setenforce 0
             - dnf install -y nmap-ncat
             - systemd-run --unit=httpserver nc -klp 1500 -e '/usr/bin/echo -e HTTP/1.1 200 OK\\n\\nHello World!'
       name: cloudinitdisk

2. Create the VirtualMachineInstance by running the following command:

   $ oc create -f <file name>.yaml

Procedure

1. Customize a YAML configuration file to create an TCP liveness probe, using this code block as an example. In this example:

   • You configure a probe using spec.livenessProbe.tcpSocket, which queries port 1500 of the virtual machine instance, after an initial delay of 120 seconds.
   • The virtual machine instance installs and runs a minimal HTTP server on port 1500 using cloud-init.
   注意

   The timeoutSeconds value must be lower than the periodSeconds value. The timeoutSeconds default value is 1. The periodSeconds default value is 10.

   apiVersion: kubevirt.io/v1alpha3
   kind: VirtualMachineInstance
   metadata:
     labels:
       special: vmi-fedora
     name: vmi-fedora
   spec:
     domain:
       devices:
         disks:
         - disk:
             bus: virtio
           name: containerdisk
         - disk:
             bus: virtio
           name: cloudinitdisk
       resources:
         requests:
           memory: 1024M
     livenessProbe:
       initialDelaySeconds: 120
       periodSeconds: 20
       tcpSocket:
         port: 1500
       timeoutSeconds: 10
     terminationGracePeriodSeconds: 0
     volumes:
     - name: containerdisk
       registryDisk:
         image: kubevirt/fedora-cloud-registry-disk-demo
     - cloudInitNoCloud:
         userData: |-
           #cloud-config
           password: fedora
           chpasswd: { expire: False }
           bootcmd:
             - setenforce 0
             - dnf install -y nmap-ncat
             - systemd-run --unit=httpserver nc -klp 1500 -e '/usr/bin/echo -e HTTP/1.1 200 OK\\n\\nHello World!'
       name: cloudinitdisk

2. Create the VirtualMachineInstance by running the following command:

   $ oc create -f <file name>.yaml

Procedure

1. Customize a YAML configuration file to create a readiness probe. Readiness probes are configured in a similar manner to liveness probes. However, note the following differences in this example:

   • Readiness probes are saved using a different spec name. For example, you create a readiness probe as spec.readinessProbe instead of as spec.livenessProbe.<type-of-probe>.
   • When creating a readiness probe, you optionally set a failureThreshold and a successThreshold to switch between ready and non-ready states, should the probe succeed or fail multiple times.
   注意

   The timeoutSeconds value must be lower than the periodSeconds value. The timeoutSeconds default value is 1. The periodSeconds default value is 10.

   apiVersion: kubevirt.io/v1alpha3
   kind: VirtualMachineInstance
   metadata:
     labels:
       special: vmi-fedora
     name: vmi-fedora
   spec:
     domain:
       devices:
         disks:
         - disk:
             bus: virtio
           name: containerdisk
         - disk:
             bus: virtio
           name: cloudinitdisk
       resources:
         requests:
           memory: 1024M
     readinessProbe:
       httpGet:
         port: 1500
       initialDelaySeconds: 120
       periodSeconds: 20
       timeoutSeconds: 10
       failureThreshold: 3
       successThreshold: 3
     terminationGracePeriodSeconds: 0
     volumes:
     - name: containerdisk
       registryDisk:
         image: kubevirt/fedora-cloud-registry-disk-demo
     - cloudInitNoCloud:
         userData: |-
           #cloud-config
           password: fedora
           chpasswd: { expire: False }
           bootcmd:
             - setenforce 0
             - dnf install -y nmap-ncat
             - systemd-run --unit=httpserver nc -klp 1500 -e '/usr/bin/echo -e HTTP/1.1 200 OK\\n\\nHello World!'
       name: cloudinitdisk

2. Create the VirtualMachineInstance by running the following command:

   $ oc create -f <file name>.yaml