Chapter 2. Configuring Red Hat High Availability clusters on Microsoft Azure

Procedure

1. Ensure you are an Administrator or Owner for the Microsoft Azure subscription. You need this authorization to create an Azure AD application.

2. Log in to your Azure account.

   $ az login

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3. Enter the following command to create the Azure AD Application. To use your own password, add the --password option to the command. Ensure that you create a strong password.

   $ az ad sp create-for-rbac --name _FencingApplicationName_ --role owner --scopes "/subscriptions/_SubscriptionID_/resourceGroups/_MyResourseGroup_"

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   Example:

   [clouduser@localhost ~] $ az ad sp create-for-rbac --name FencingApp --role owner --scopes "/subscriptions/2586c64b-xxxxxx-xxxxxxx-xxxxxxx/resourceGroups/azrhelclirsgrp"
   Retrying role assignment creation: 1/36
   Retrying role assignment creation: 2/36
   Retrying role assignment creation: 3/36
   {
     "appId": "1a3dfe06-df55-42ad-937b-326d1c211739",
     "displayName": "FencingApp",
     "name": "http://FencingApp",
     "password": "43a603f0-64bb-482e-800d-402efe5f3d47",
     "tenant": "77ecefb6-xxxxxxxxxx-xxxxxxx-757a69cb9485"
   }

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4. Save the following information before proceeding. You need this information to set up the fencing agent.

   • Azure AD Application ID
   • Azure AD Application Password
   • Tenant ID
   • Microsoft Azure Subscription ID

Procedure

1. Register the VM with Red Hat.

   $ sudo -i
   # subscription-manager register --auto-attach

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2. Disable all repositories.

   # subscription-manager repos --disable=*

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3. Enable the RHEL 7 Server and RHEL 7 Server HA repositories.

   # subscription-manager repos --enable=rhel-7-server-rpms
   # subscription-manager repos --enable=rhel-ha-for-rhel-7-server-rpms

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4. Update all packages.

   # yum update -y

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5. Reboot if the kernel is updated.

   # reboot

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6. Install pcs, pacemaker, fence agent, resource agent, and nmap-ncat.

   # yum install -y pcs pacemaker fence-agents-azure-arm resource-agents nmap-ncat

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Procedure

1. The user hacluster was created during the pcs and pacemaker installation in the previous section. Create a password for hacluster on all cluster nodes. Use the same password for all nodes.

   # passwd hacluster

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2. Add the high availability service to the RHEL Firewall if firewalld.service is enabled.

   # firewall-cmd --permanent --add-service=high-availability
   # firewall-cmd --reload

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3. Start the pcs service and enable it to start on boot.

   # systemctl enable pcsd.service --now

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Procedure

1. On one of the nodes, enter the following command to authenticate the pcs user hacluster. Specify the name of each node in the cluster.

   # pcs host auth  _hostname1_ _hostname2_ _hostname3_

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   Example:

   [root@node01 clouduser]# pcs host auth node01 node02 node03
   Username: hacluster
   Password:
   node01: Authorized
   node02: Authorized
   node03: Authorized

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2. Create the cluster.

   # pcs cluster setup --name _hostname1_ _hostname2_ _hostname3_

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   Example:

   [root@node01 clouduser]# pcs cluster setup --name newcluster node01 node02 node03
   
   ...omitted
   
   Synchronizing pcsd certificates on nodes node01, node02, node03...
   node02: Success
   node03: Success
   node01: Success
   Restarting pcsd on the nodes in order to reload the certificates...
   node02: Success
   node03: Success
   node01: Success

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Verification steps

1. Enable the cluster.

   # pcs cluster enable --all

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2. Start the cluster.

   # pcs cluster start --all

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   Example:

   [root@node01 clouduser]# pcs cluster enable --all
   node02: Cluster Enabled
   node03: Cluster Enabled
   node01: Cluster Enabled
   
   [root@node01 clouduser]# pcs cluster start --all
   node02: Starting Cluster...
   node03: Starting Cluster...
   node01: Starting Cluster...

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Procedure

1. Identify the available instances that can be fenced.

   # fence_azure_arm -l [appid] -p [authkey] --resourceGroup=[name] --subscriptionId=[name] --tenantId=[name] -o list

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   Example:

   [root@node1 ~]# fence_azure_arm -l XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX -p XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX --resourceGroup=hacluster-rg --subscriptionId=XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX --tenantId=XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX -o list
   node01-vm,
   node02-vm,
   node03-vm,

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2. Create a fence device. Use the pcmk_host_map command to map the RHEL host name to the instance ID.

   # pcs stonith create _clusterfence_ fence_azure_arm login=_AD-Application-ID_ passwd=_AD-passwd_ pcmk_host_map="_pcmk-host-map_ resourcegroup= _myresourcegroup_ tenantid=_tenantid_ subscriptionid=_subscriptionid_

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Verification steps

1. Test the fencing agent for one of the other nodes.

   # pcs stonith fence _azurenodename_

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   Example:

   [root@node01 ~]# pcs stonith fence fenceazure
    Resource: fenceazure (class=stonith type=fence_azure_arm)
     Attributes: login=XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX passwd=XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX pcmk_host_map=nodea:nodea-vm;nodeb:nodeb-vm;nodec:nodec-vm pcmk_reboot_retries=4 pcmk_reboot_timeout=480 power_timeout=240 resourceGroup=rg subscriptionId=XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX tenantId=XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX
     Operations: monitor interval=60s (fenceazure-monitor-interval-60s)
   [root@node01 ~]# pcs stonith
    fenceazure     (stonith:fence_azure_arm):      Started nodea

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2. Check the status to verify the node started.

   # watch pcs status

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   Example:

   [root@node01 ~]# watch pcs status
    fenceazure     (stonith:fence_azure_arm):      Started nodea

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Procedure

1. Create a basic load balancer. Select Internal load balancer, the Basic SKU, and Dynamic for the type of IP address assignment.
2. Create a backend address pool. Associate the backend pool to the availability set created while creating Azure resources in HA. Do not set any target network IP configurations.
3. Create a health probe. For the health probe, select TCP and enter port 61000. You can use a TCP port number that does not interfere with another service. For certain HA product applications, for example, SAP HANA and SQL Server, you may need to work with Microsoft to identify the correct port to use.
4. Create a load balancer rule. To create the load balancing rule, use the default values that are prepopulated. Ensure to set Floating IP (direct server return) to Enabled.

Procedure

1. Enter the Azure id command to view the Azure load balancer resource agent description. This shows the options and default operations for this agent.

   # pcs resource describe _azure-id_

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2. Create an Ipaddr2 resource for managing the IP on the node.

   # pcs resource create _resource-id_ IPaddr2 ip=_virtual/floating-ip_ cidr_netmask=_virtual/floating-mask_ --group _group-id_ nic=_network-interface_ op monitor interval=30s

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   Example:

   [root@node01 ~]# pcs resource create ClusterIP ocf:heartbeat:IPaddr2 ip=172.16.66.99 cidr_netmask=24 --group CloudIP nic=eth0 op monitor interval=30s

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3. Configure the load balancer resource agent.

   # pcs resource create _resource-loadbalancer-name_ azure-lb port=_port-number_ --group _cluster-resources-group_

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Procedure

1. Create a shared block volume using the Azure command az disk create.

   $ az disk create -g resource_group -n shared_block_volume_name --size-gb disk_size --max-shares number_vms -l location

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   For example, the following command creates a shared block volume named shared-block-volume.vhd in the resource group sharedblock within the Azure Availability Zone westcentralus.

   $ az disk create -g sharedblock-rg -n shared-block-volume.vhd --size-gb 1024 --max-shares 3 -l westcentralus
   
   {
     "creationData": {
       "createOption": "Empty",
       "galleryImageReference": null,
       "imageReference": null,
       "sourceResourceId": null,
       "sourceUniqueId": null,
       "sourceUri": null,
       "storageAccountId": null,
       "uploadSizeBytes": null
     },
     "diskAccessId": null,
     "diskIopsReadOnly": null,
     "diskIopsReadWrite": 5000,
     "diskMbpsReadOnly": null,
     "diskMbpsReadWrite": 200,
     "diskSizeBytes": 1099511627776,
     "diskSizeGb": 1024,
     "diskState": "Unattached",
     "encryption": {
       "diskEncryptionSetId": null,
       "type": "EncryptionAtRestWithPlatformKey"
     },
     "encryptionSettingsCollection": null,
     "hyperVgeneration": "V1",
     "id": "/subscriptions/12345678910-12345678910/resourceGroups/sharedblock-rg/providers/Microsoft.Compute/disks/shared-block-volume.vhd",
     "location": "westcentralus",
     "managedBy": null,
     "managedByExtended": null,
     "maxShares": 3,
     "name": "shared-block-volume.vhd",
     "networkAccessPolicy": "AllowAll",
     "osType": null,
     "provisioningState": "Succeeded",
     "resourceGroup": "sharedblock-rg",
     "shareInfo": null,
     "sku": {
       "name": "Premium_LRS",
       "tier": "Premium"
     },
     "tags": {},
     "timeCreated": "2020-08-27T15:36:56.263382+00:00",
     "type": "Microsoft.Compute/disks",
     "uniqueId": "cd8b0a25-6fbe-4779-9312-8d9cbb89b6f2",
     "zones": null
   }

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2. Verify that you have created the shared block volume using the Azure command az disk show.

   $ az disk show -g resource_group -n shared_block_volume_name

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   For example, the following command shows details for the shared block volume shared-block-volume.vhd within the resource group sharedblock-rg.

   $ az disk show -g sharedblock-rg -n shared-block-volume.vhd
   
   {
     "creationData": {
       "createOption": "Empty",
       "galleryImageReference": null,
       "imageReference": null,
       "sourceResourceId": null,
       "sourceUniqueId": null,
       "sourceUri": null,
       "storageAccountId": null,
       "uploadSizeBytes": null
     },
     "diskAccessId": null,
     "diskIopsReadOnly": null,
     "diskIopsReadWrite": 5000,
     "diskMbpsReadOnly": null,
     "diskMbpsReadWrite": 200,
     "diskSizeBytes": 1099511627776,
     "diskSizeGb": 1024,
     "diskState": "Unattached",
     "encryption": {
       "diskEncryptionSetId": null,
       "type": "EncryptionAtRestWithPlatformKey"
     },
     "encryptionSettingsCollection": null,
     "hyperVgeneration": "V1",
     "id": "/subscriptions/12345678910-12345678910/resourceGroups/sharedblock-rg/providers/Microsoft.Compute/disks/shared-block-volume.vhd",
     "location": "westcentralus",
     "managedBy": null,
     "managedByExtended": null,
     "maxShares": 3,
     "name": "shared-block-volume.vhd",
     "networkAccessPolicy": "AllowAll",
     "osType": null,
     "provisioningState": "Succeeded",
     "resourceGroup": "sharedblock-rg",
     "shareInfo": null,
     "sku": {
       "name": "Premium_LRS",
       "tier": "Premium"
     },
     "tags": {},
     "timeCreated": "2020-08-27T15:36:56.263382+00:00",
     "type": "Microsoft.Compute/disks",
     "uniqueId": "cd8b0a25-6fbe-4779-9312-8d9cbb89b6f2",
     "zones": null
   }

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3. Create three network interfaces using the Azure command az network nic create. Run the following command three times using a different <nic_name> for each.

   $ az network nic create -g resource_group -n nic_name --subnet subnet_name --vnet-name virtual_network --location location --network-security-group network_security_group --private-ip-address-version IPv4

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   For example, the following command creates a network interface with the name shareblock-nodea-vm-nic-protected.

   $ az network nic create -g sharedblock-rg -n sharedblock-nodea-vm-nic-protected --subnet sharedblock-subnet-protected --vnet-name sharedblock-vn --location westcentralus --network-security-group sharedblock-nsg --private-ip-address-version IPv4

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4. Create three virtual machines and attach the shared block volume using the Azure command az vm create. Option values are the same for each VM except that each VM has its own <vm_name>, <new_vm_disk_name>, and <nic_name>.

   $ az vm create -n vm_name -g resource_group --attach-data-disks shared_block_volume_name --data-disk-caching None --os-disk-caching ReadWrite --os-disk-name new-vm-disk-name --os-disk-size-gb disk_size --location location --size virtual_machine_size --image image_name --admin-username vm_username --authentication-type ssh --ssh-key-values ssh_key --nics -nic_name_ --availability-set availability_set --ppg proximity_placement_group

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   For example, the following command creates a virtual machine named sharedblock-nodea-vm.

   $ az vm create -n sharedblock-nodea-vm -g sharedblock-rg --attach-data-disks shared-block-volume.vhd --data-disk-caching None --os-disk-caching ReadWrite --os-disk-name sharedblock-nodea-vm.vhd --os-disk-size-gb 64 --location westcentralus --size Standard_D2s_v3 --image /subscriptions/12345678910-12345678910/resourceGroups/sample-azureimagesgroupwestcentralus/providers/Microsoft.Compute/images/sample-azure-rhel-7.0-20200713.n.0.x86_64 --admin-username sharedblock-user --authentication-type ssh --ssh-key-values @sharedblock-key.pub --nics sharedblock-nodea-vm-nic-protected --availability-set sharedblock-as --ppg sharedblock-ppg
   
   {
     "fqdns": "",
     "id": "/subscriptions/12345678910-12345678910/resourceGroups/sharedblock-rg/providers/Microsoft.Compute/virtualMachines/sharedblock-nodea-vm",
     "location": "westcentralus",
     "macAddress": "00-22-48-5D-EE-FB",
     "powerState": "VM running",
     "privateIpAddress": "198.51.100.3",
     "publicIpAddress": "",
     "resourceGroup": "sharedblock-rg",
     "zones": ""
   }

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Verification steps

1. For each VM in your cluster, verify that the block device is available by using the SSH command with your VM <ip_address>.

   # ssh ip_address "hostname ; lsblk -d | grep ' 1T '"

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   For example, the following command lists details including the host name and block device for the VM IP 198.51.100.3.

   # ssh 198.51.100.3 "hostname ; lsblk -d | grep ' 1T '"
   
   nodea
   sdb    8:16   0    1T  0 disk

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2. Use the SSH command to verify that each VM in your cluster uses the same shared disk.

   # ssh _ip_address_s "hostname ; lsblk -d | grep ' 1T ' | awk '{print \$1}' | xargs -i udevadm info --query=all --name=/dev/{} | grep '^E: ID_SERIAL='"

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   For example, the following command lists details including the host name and shared disk volume ID for the instance IP address 198.51.100.3.

   # ssh 198.51.100.3 "hostname ; lsblk -d | grep ' 1T ' | awk '{print \$1}' | xargs -i udevadm info --query=all --name=/dev/{} | grep '^E: ID_SERIAL='"
   
   nodea
   E: ID_SERIAL=3600224808dd8eb102f6ffc5822c41d89

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