Well well. Turns out that when you delete a virtual machine in Azure, the network interface cards (NICs) are not deleted by default. If you create and delete multiple VMs, the unused NICs continue to use the internal IP address leases.

Not only can this be a giant pain if you run out of addresses on your subnet, but it can also be a security concern if that IP address is reserved for a critical service. Either way, it's better to delete unused Azure network interfaces in your account.

This workflow will first look for all Azure network interfaces in a Subscription (or optionally, resource group). Then, it will filter that list for the NICs that aren't attached to a Virtual Machine. Next, it waits for your approval. Finally, once approval has been granted, it will delete the unused NICs. Good job!

For more details, check out our blog post How to Delete Unused Azure Network Interfaces.

Prerequisites

Before you run this workflow, you will need the following:

• An Azure Subscription
• An Azure Service Principal with permissions to manage network interface cards.
• One or more unused Azure Network Interface Cards (NIC).

Configure the workflow

Follow these steps to configure the workflow. Doing this will enable Relay to connect to your Azure account.

You may see a warning that you are missing a required connection. This means you will need to add your Azure credentials as a Connection.

• Click Fill in missing connections or click Settings in the side nav.

• Find the Connection named my-azure-account and click the plus sign (+).

• Fill out the form:

  • Name - You can’t change this with the form. The name is supplied by the YAML. If you wanted to change it you would need to do so in the Code tab.
  • Subscription ID - Enter your Azure Subscription ID
  • Client ID - Enter your Azure Client ID associated with the service principal
  • Tenant ID - Enter your Azure Tenant ID associated with the service principal
  • Secret - Enter your Azure Secret associated with the service principal

TIP If you need help getting your Azure credentials, check out our blog post.

• Click Save

Run the workflow manually

Follow these steps to run this workflow.

• Click Run workflow and wait for the workflow run page to appear.

  

• Supply values for the parameters fields when the modal appears:

  

  • dryRun - true or false
    • true if you dont want to actually delete the resources. Use this to test the workflow and ensure it is behaving as expected.
    • false if you want the resources to be immediately deleted.

WARNING! Be careful setting dryRun to false. Though the workflow comes with an approval step, once approved the resources will be terminated. Please use caution.

Run the workflow on a schedule

Follow these steps to run this workflow on a schedule:

• Un-comment out the included Trigger block in the workflow YAML. You can do this in the Code tab.

TIP: If you're using the Relay code editor, highlight the triggers section and type ⌘ + / (Mac) or Ctrl + / (Windows) to uncomment.

# triggers:
# - name: schedule
#   source:
#     type: schedule
#     schedule: '0 * * * *'
#   binding:
#     parameters:
#       dryRun: true

• Configure the schedule trigger:
  • Supply the run interval in cron format.
  • Configure the following parameter bindings:
    • Specify whether dryRun should be set to true or false.

  binding:
    parameters:
      dryRun: true

• Click Save changes