How to Use the Command 'az serial-console' (with Examples)

The az serial-console command is part of the Azure Command-Line Interface (CLI), commonly referred to as az. This command is specifically designed to connect to the serial console of a virtual machine hosted within Microsoft’s Azure cloud platform. The serial console is a powerful tool that allows administrators and developers to troubleshoot and manage virtual machines at a low level, bypassing issues related to the standard remote access methods.

Use Case 1: Connect to a Serial Console

Code:

az serial-console connect --resource-group Resource_Group_Name --name Virtual_Machine_Name

Motivation:

Connecting to the serial console of a virtual machine is an essential task for system administrators and developers who need to perform low-level diagnostics or troubleshooting. When a virtual machine cannot be accessed through traditional means, such as Remote Desktop Protocol (RDP) or Secure Shell (SSH), the serial console provides a critical alternative. It allows direct access to the machine’s boot process and system logs, which can be crucial for identifying and resolving configuration errors, kernel panics, or other boot-time issues.

Explanation:

• az: This is the Azure CLI command, which provides a variety of tools for managing Azure resources. The az command is the starting point for executing any Azure CLI commands.

• serial-console: This specifies that the CLI operation pertains to the serial console. It indicates that the subsequent command should apply to Azure’s serial console service.

• connect: This argument tells the Azure CLI to establish a connection to the serial console of the specified virtual machine. It initiates the communication session between your local machine and the virtual machine’s console.

• --resource-group Resource_Group_Name: The --resource-group flag is used to specify the Azure resource group that contains the virtual machine. Resource groups in Azure are collections of resources that share the same lifecycle, permissions, and policies. Resource_Group_Name should be replaced with the actual name of your resource group.

• --name Virtual_Machine_Name: This flag specifies the exact name of the virtual machine to which you want to connect via the serial console. Virtual_Machine_Name is a placeholder for your virtual machine’s name in Azure.

Example output:

Opening serial console for VM 'Virtual_Machine_Name' in resource group 'Resource_Group_Name'.
Connected to serial console. Use <Ctrl>-] to disconnect.

Use Case 2: Terminate the Connection

Code:

<Ctrl>-]

Motivation:

Terminating a connection to the serial console is often necessary after performing required maintenance or troubleshooting tasks on a virtual machine. Disconnecting in a timely manner is a good practice as it helps in preserving network resources and ensures security by not leaving open connections unnecessarily. Knowing how to cleanly and efficiently terminate a session is an important aspect of managing virtual machines and their associated resources.

Explanation:

• <Ctrl>-]: This keyboard shortcut is used to terminate the active serial console session. It is a built-in mechanism provided by the Azure CLI for gracefully disconnecting from the console. This command ensures that the console session is ended securely without leaving it open or potentially exposed.

Example output:

Serial console session terminated.

Conclusion:

The az serial-console command is an indispensable tool for those tasked with managing virtual machines on Azure. By providing direct access to the serial console, it allows for in-depth diagnostics and problem-solving that aren’t possible through standard access methods. Using the command to both connect and terminate a session ensures that the user can efficiently manage their virtual machines and address issues at a foundational level. The examples provided demonstrate the simplicity and efficacy of these commands in practical scenarios.