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virtual-machines-common-classic-inject-custom-data.md

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This article describes how to:

  • Inject data into an Azure virtual machine (VM) when it is being provisioned.
  • Retrieve it for both Windows and Linux.
  • Use special tools available on some systems to detect and handle custom data automatically.

Note

This article describes how custom data can be injected by using a VM created with the classic deployment model. To see how to use the Azure Resource Management API, see the example template.

Injecting custom data into your Azure virtual machine

This feature is currently supported only in the Azure Command-Line Interface. Here we create a custom-data.txt file that contains our data, then inject that in to the VM during provisioning. Although you may use any of the options for the azure vm create command, the following example demonstrates one basic approach:

    azure vm create <vmname> <vmimage> <username> <password> \  
    --location "West US" --ssh 22 \  
    --custom-data ./custom-data.txt

Using custom data in the virtual machine

  • If your Azure VM is a Windows-based VM, then the custom data file is saved to %SYSTEMDRIVE%\AzureData\CustomData.bin. Although it was base64-encoded to transfer from the local computer to the new VM, it is automatically decoded and can be opened or used immediately.

    [!NOTE] If the file exists, it is overwritten. The security on the directory is set to System:Full Control and Administrators:Full Control.

  • If your Azure VM is a Linux-based VM, then the custom data file is located in one of the following places depending on your distro. The data may be base64-encoded, so you may need to decode the data first:

    • /var/lib/waagent/ovf-env.xml
    • /var/lib/waagent/CustomData
    • /var/lib/cloud/instance/user-data.txt

Cloud-init on Azure

If your Azure VM is from an Ubuntu or CoreOS image, then you can use CustomData to send a cloud-config to cloud-init. Or if your custom data file is a script, then cloud-init can execute it.

Ubuntu Cloud Images

In most Azure Linux images, you would edit "/etc/waagent.conf" to configure the temporary resource disk and swap file. See Azure Linux Agent user guide for more information.

However, on the Ubuntu Cloud Images, you must use cloud-init to configure the resource disk (that is, the "ephemeral" disk) and swap partition. See the following page on the Ubuntu wiki for more details: AzureSwapPartitions.

Next steps: Using cloud-init

For more information, see the cloud-init documentation for Ubuntu.

Add Role Service Management REST API Reference

Azure Command-line Interface