Chapter 11. Configuring IP failover

Procedure

1. Create an IP failover service account:

   $ oc create sa ipfailover

2. Update security context constraints (SCC) for hostNetwork:

   $ oc adm policy add-scc-to-user privileged -z ipfailover
   $ oc adm policy add-scc-to-user hostnetwork -z ipfailover

3. Create a deployment YAML file to configure IP failover:

   Example deployment YAML for IP failover configuration

   apiVersion: apps/v1
   kind: Deployment
   metadata:
     name: ipfailover-keepalived 1
     labels:
       ipfailover: hello-openshift
   spec:
     strategy:
       type: Recreate
     replicas: 2
     selector:
       matchLabels:
         ipfailover: hello-openshift
     template:
       metadata:
         labels:
           ipfailover: hello-openshift
       spec:
         serviceAccountName: ipfailover
         privileged: true
         hostNetwork: true
         nodeSelector:
           node-role.kubernetes.io/worker: ""
         containers:
         - name: openshift-ipfailover
           image: quay.io/openshift/origin-keepalived-ipfailover
           ports:
           - containerPort: 63000
             hostPort: 63000
           imagePullPolicy: IfNotPresent
           securityContext:
             privileged: true
           volumeMounts:
           - name: lib-modules
             mountPath: /lib/modules
             readOnly: true
           - name: host-slash
             mountPath: /host
             readOnly: true
             mountPropagation: HostToContainer
           - name: etc-sysconfig
             mountPath: /etc/sysconfig
             readOnly: true
           - name: config-volume
             mountPath: /etc/keepalive
           env:
           - name: OPENSHIFT_HA_CONFIG_NAME
             value: "ipfailover"
           - name: OPENSHIFT_HA_VIRTUAL_IPS 2
             value: "1.1.1.1-2"
           - name: OPENSHIFT_HA_VIP_GROUPS 3
             value: "10"
           - name: OPENSHIFT_HA_NETWORK_INTERFACE 4
             value: "ens3" #The host interface to assign the VIPs
           - name: OPENSHIFT_HA_MONITOR_PORT 5
             value: "30060"
           - name: OPENSHIFT_HA_VRRP_ID_OFFSET 6
             value: "0"
           - name: OPENSHIFT_HA_REPLICA_COUNT 7
             value: "2" #Must match the number of replicas in the deployment
           - name: OPENSHIFT_HA_USE_UNICAST
             value: "false"
           #- name: OPENSHIFT_HA_UNICAST_PEERS
             #value: "10.0.148.40,10.0.160.234,10.0.199.110"
           - name: OPENSHIFT_HA_IPTABLES_CHAIN 8
             value: "INPUT"
           #- name: OPENSHIFT_HA_NOTIFY_SCRIPT 9
           #  value: /etc/keepalive/mynotifyscript.sh
           - name: OPENSHIFT_HA_CHECK_SCRIPT 10
             value: "/etc/keepalive/mycheckscript.sh"
           - name: OPENSHIFT_HA_PREEMPTION 11
             value: "preempt_delay 300"
           - name: OPENSHIFT_HA_CHECK_INTERVAL 12
             value: "2"
           livenessProbe:
             initialDelaySeconds: 10
             exec:
               command:
               - pgrep
               - keepalived
         volumes:
         - name: lib-modules
           hostPath:
             path: /lib/modules
         - name: host-slash
           hostPath:
             path: /
         - name: etc-sysconfig
           hostPath:
             path: /etc/sysconfig
         # config-volume contains the check script
         # created with `oc create configmap keepalived-checkscript --from-file=mycheckscript.sh`
         - configMap:
             defaultMode: 0755
             name: keepalived-checkscript
           name: config-volume
         imagePullSecrets:
           - name: openshift-pull-secret 13

   1

   The name of the IP failover deployment.

   2

   The list of IP address ranges to replicate. This must be provided. For example, 1.2.3.4-6,1.2.3.9.

   3

   The number of groups to create for VRRP. If not set, a group is created for each virtual IP range specified with the OPENSHIFT_HA_VIP_GROUPS variable.

   4

   The interface name that IP failover uses to send VRRP traffic. By default, eth0 is used.

   5

   The IP failover pod tries to open a TCP connection to this port on each VIP. If connection is established, the service is considered to be running. If this port is set to 0, the test always passes. The default value is 80.

   6

   The offset value used to set the virtual router IDs. Using different offset values allows multiple IP failover configurations to exist within the same cluster. The default offset is 0, and the allowed range is 0 through 255.

   7

   The number of replicas to create. This must match spec.replicas value in IP failover deployment configuration. The default value is 2.

   8

   The name of the iptables chain to automatically add an iptables rule to allow the VRRP traffic on. If the value is not set, an iptables rule is not added. If the chain does not exist, it is not created, and Keepalived operates in unicast mode. The default is INPUT.

   9

   The full path name in the pod file system of a script that is run whenever the state changes.

   10

   The full path name in the pod file system of a script that is periodically run to verify the application is operating.

   11

   The strategy for handling a new higher priority host. The default value is preempt_delay 300, which causes a Keepalived instance to take over a VIP after 5 minutes if a lower-priority master is holding the VIP.

   12

   The period, in seconds, that the check script is run. The default value is 2.

   13

   Create the pull secret before creating the deployment, otherwise you will get an error when creating the deployment.

Procedure

1. Create the desired script and create a config map to hold it. The script has no input arguments and must return 0 for OK and 1 for fail.

   The check script, mycheckscript.sh:

   #!/bin/bash
       # Whatever tests are needed
       # E.g., send request and verify response
   exit 0

2. Create the config map:

   $ oc create configmap mycustomcheck --from-file=mycheckscript.sh

3. Add the script to the pod. The defaultMode for the mounted config map files must able to run by using oc commands or by editing the deployment configuration. A value of 0755, 493 decimal, is typical:

   $ oc set env deploy/ipfailover-keepalived \
       OPENSHIFT_HA_CHECK_SCRIPT=/etc/keepalive/mycheckscript.sh

   $ oc set volume deploy/ipfailover-keepalived --add --overwrite \
       --name=config-volume \
       --mount-path=/etc/keepalive \
       --source='{"configMap": { "name": "mycustomcheck", "defaultMode": 493}}'

   Note

   The oc set env command is whitespace sensitive. There must be no whitespace on either side of the = sign.

   Tip

   You can alternatively edit the ipfailover-keepalived deployment configuration:

   $ oc edit deploy ipfailover-keepalived

       spec:
         containers:
         - env:
           - name: OPENSHIFT_HA_CHECK_SCRIPT  1
             value: /etc/keepalive/mycheckscript.sh
   ...
           volumeMounts: 2
           - mountPath: /etc/keepalive
             name: config-volume
         dnsPolicy: ClusterFirst
   ...
         volumes: 3
         - configMap:
             defaultMode: 0755 4
             name: customrouter
           name: config-volume
   ...

   1

   In the spec.container.env field, add the OPENSHIFT_HA_CHECK_SCRIPT environment variable to point to the mounted script file.

   2

   Add the spec.container.volumeMounts field to create the mount point.

   3

   Add a new spec.volumes field to mention the config map.

   4

   This sets run permission on the files. When read back, it is displayed in decimal, 493.

   Save the changes and exit the editor. This restarts ipfailover-keepalived.

Procedure

1. Optional: Identify and delete any check and notify scripts that are stored as config maps:

   1. Identify whether any pods for IP failover use a config map as a volume:

      $ oc get pod -l ipfailover \
        -o jsonpath="\
      {range .items[?(@.spec.volumes[*].configMap)]}
      {'Namespace: '}{.metadata.namespace}
      {'Pod:       '}{.metadata.name}
      {'Volumes that use config maps:'}
      {range .spec.volumes[?(@.configMap)]}  {'volume:    '}{.name}
        {'configMap: '}{.configMap.name}{'\n'}{end}
      {end}"

      Example output

      Namespace: default
      Pod:       keepalived-worker-59df45db9c-2x9mn
      Volumes that use config maps:
        volume:    config-volume
        configMap: mycustomcheck

   2. If the preceding step provided the names of config maps that are used as volumes, delete the config maps:

      $ oc delete configmap <configmap_name>

2. Identify an existing deployment for IP failover:

   $ oc get deployment -l ipfailover

   Example output

   NAMESPACE   NAME         READY   UP-TO-DATE   AVAILABLE   AGE
   default     ipfailover   2/2     2            2           105d

3. Delete the deployment:

   $ oc delete deployment <ipfailover_deployment_name>

4. Remove the ipfailover service account:

   $ oc delete sa ipfailover

5. Run a job that removes the IP tables rule that was added when IP failover was initially configured:

   1. Create a file such as remove-ipfailover-job.yaml with contents that are similar to the following example:

      apiVersion: batch/v1
      kind: Job
      metadata:
        generateName: remove-ipfailover-
        labels:
          app: remove-ipfailover
      spec:
        template:
          metadata:
            name: remove-ipfailover
          spec:
            containers:
            - name: remove-ipfailover
              image: quay.io/openshift/origin-keepalived-ipfailover:4.10
              command: ["/var/lib/ipfailover/keepalived/remove-failover.sh"]
            nodeSelector:
              kubernetes.io/hostname: <host_name>  <.>
            restartPolicy: Never

      <.> Run the job for each node in your cluster that was configured for IP failover and replace the hostname each time.

   2. Run the job:

      $ oc create -f remove-ipfailover-job.yaml

      Example output

      job.batch/remove-ipfailover-2h8dm created