Configure Azure VMs auto-firstboot using customData or userData. There is no data merging from these sources, so provide the data via customData or userData, but not both.

Arista Networks recommends using customData as it provides a better security posture because it is available only during VM provisioning and requires sudo access to mount the virtual CDROM.

userData is less secure because it is available via Instance MetaData Service (IMDS) after provisioning and can be queried from the VM without any authorization restrictions.

If sshKey is configured for the admin account during Azure VM provisioning along with auto-firstboot parameters, then it is also configured for the admin user of the DMF Controllers.

The following table lists details of the first boot parameters for the auto-firstboot configuration.

Firstboot Parameters - Required Parameters

Additional Parameters

Networking Parameters

{
"admin_password": "admin_user_password",
"recovery_password": "recovery_user_password"
}

Full List of Parameters

{
"admin-password": "admin_user_password",
"recovery_password": "recovery_user_password",
"hostname": "hostname",
"cluster_name": "cluster name",
"cluster_description": "cluster description",
"ip_stack": "dual-stack",
"ipv4_method": "manual",
"ipv4_address": "10.0.0.3",
"ipv4_prefix-length": "24",
"ipv4_gateway": "10.0.0.1",
"ipv6_method": "manual",
"ipv6_address": "be:ee::1",
"ipv6_prefix-length": "64",
"ipv6_gateway": "be:ee::100",
"dns_servers": [
"10.0.0.101",
"10.0.0.102"
],
"dns_search_domains": [
"dns-search1.com",
"dns-search2.com"
],
"ntp_servers": [
"1.ntp.server.com",
"2.ntp.server.com"
]
}

The following limitations apply to the DANZ Monitoring Fabric (DMF) Controller in Microsoft Azure.

• There is no support for any features specific to Azure-optimized Ubuntu Linux, including Accelerated Networking.

• The DMF Controllers in Azure are only supported on Gen-1 VMs.

• The DMF Controllers in Azure do not support adding the virtual IP address for the cluster.

• There is no support for capture interfaces in Azure.

• DMF ignores the Azure username and password fields.

• There is no support for static IP address assignment that differs from what is configured on the Azure NIC.

• The DMF Controllers are rebooted if the static IP on the NIC is updated.

Please refer to the following resources for more information.

• Azure user data details: https://learn.microsoft.com/en-us/azure/virtual-machines/user-data

• Azure custom data details: https://learn.microsoft.com/en-us/azure/virtual-machines/custom-data

• Azure Gen1 vs Gen2 VMs: https://learn.microsoft.com/en-us/azure/virtual-machines/generation-2

• Azure optimized Ubuntu Linux features: https://ubuntu.com/blog/microsoft-and-canonical-increase-velocity-with-azure-tailored-kernel

• Azure NIC assignment behavior: https://learn.microsoft.com/en-us/troubleshoot/azure/virtual-machines/reset-network-interface-azure-linux-vm

• There are three possible failure modes:

  • VM fails Azure registration.

  • auto-firstboot fails due to a transient error or bug.

  • auto-firstboot parameter validation fails.

• These failures can be debugged by accessing the firstboot logs, after manually booting the VM.
• Azure DMF Controller VMs can be accessed via ssh. Firstboot logs can be accessed using debug bash as shown below:

  dmf-controller-0-vm> debug bash
  admin@dmf-controller-0-vm:~$ less /var/log/floodlight/firstboot/firstboot.log

• For debugging parameter validation errors, access the parameter validation results using debug bash as shown below:

  dmf-controller-0-vm> debug bash
  admin@dmf-controller-0-vm:~$ less /var/lib/floodlight/firstboot/validation-results.json