Azure Insights: Linux server patching; VNet Gateway; Subscription references

August 29 2022

Microsoft Azure pros discuss updating Management Center and Arc to manage Linux server patching, deploying ExpressRoute with a VNet Gateway, and pulling Azure subscription references.

Updating Management Center and Arc to manage Linux server patching

Matthew Quickenden, writing on Crying Cloud, looked into a situation where a customer wants to redeploy some on-prem servers to a Kubernetes cluster. To do this, users can navigate to the MAAS portal, and review the different systems ready to use. After selecting the OS, a user can paste in an Azure Arc connected script, and begin a deployment.

He shared a reference Linux bash script, generated in Azure portal with the onboarding agent. Users may want to tag servers and lock them. The servers will be added to Azure portal as Arc servers.

“This method could be used to manage systems in any other cloud system, bringing the management of Linux patching into the Azure control plane. This is a small window into what can be done using Azure Arc to help with operational activities in a Hybrid cloud environment,” he wrote.

Deploying ExpressRoute with a VNet Gateway

Chris Pietschmann, writing on Build5Nines, explained that Microsoft offers private connections between Azure datacenters or on-prem datacenters with ExpressRoute, with connections bought through a service provider. When resources are connected to a VNet, Virtual Network Gateway needs to be deployed for ExpressRoute to work.

ExpressRoute circuit is the term for an ExpressRoute connection. A Public IP is used for a VNet Gateway. The peering location is not actually an Azure region, but rather the location of the ExpressRoute Service Providers network exchange. Pietschmann explained how to enable private peering, how to deploy a VNet resource, and the Terraform code for a Public IP address.

“If the Azure ExpressRoute circuit hasn’t been fully provisioned yet, then the deployment of the Azure Virtual Network Gateway will error, and the error message returned from the azurerm Terraform Provider is a little cryptic as to what it really means. [Error: ID was missing the `virtualNetworkGateways` element is the error you would expect to see],” he wrote.

Pulling Azure subscription references

Also on Build5Nines, Chris Pietschmann looked into how to get an Azure subscription reference with Terraform. A reference could be the name of a resource or the ID attributes of a subscription, commonly used with the azurerm Terraform Provider to manage resources. He showed a simple data block to reference a current Azure subscription.

Notice the data azurerm_subscription block doesn’t define any attributes to specify the Azure Subscription to reference. This is because the azurerm_subscription type will automatically grab the Azure Subscription ID set by the default azurerm Terraform Provider on the project. This makes the block extremely simple to define.

Alternatively, users can set the subscription ID attribute to tell the Terraform Provider which of several Azure subscriptions to reference. Users will need to replace the default string of placeholder zeroes with the Azure subscription GUID for the reference to work.

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