Tuesday 23 November 2021

Create and Manage Linux VMs with the Azure CLI

 Azure virtual machines provide a fully configurable and flexible computing environment. This tutorial covers basic Azure virtual machine deployment items such as selecting a VM size, selecting a VM image, and deploying a VM. You learn how to:

[!div class="checklist"]

  • Create and connect to a VM
  • Select and use VM images
  • View and use specific VM sizes
  • Resize a VM
  • View and understand VM state

This tutorial uses the CLI within the Azure Cloud Shell, which is constantly updated to the latest version. To open the Cloud Shell, select Try it from the top of any code block.

If you choose to install and use the CLI locally, this tutorial requires that you are running the Azure CLI version 2.0.30 or later. Run az --version to find the version. If you need to install or upgrade, see Install Azure CLI.

Create resource group

Create a resource group with the az group create command.

An Azure resource group is a logical container into which Azure resources are deployed and managed. A resource group must be created before a virtual machine. In this example, a resource group named myResourceGroupVM is created in the eastus region.

az group create --name myResourceGroupVM --location eastus

The resource group is specified when creating or modifying a VM, which can be seen throughout this tutorial.

Create virtual machine

Create a virtual machine with the az vm create command.

When you create a virtual machine, several options are available such as operating system image, disk sizing, and administrative credentials. The following example creates a VM named myVM that runs Ubuntu Server. A user account named azureuser is created on the VM, and SSH keys are generated if they do not exist in the default key location (~/.ssh):

az vm create \
    --resource-group myResourceGroupVM \
    --name myVM \
    --image UbuntuLTS \
    --admin-username azureuser \
    --generate-ssh-keys

It may take a few minutes to create the VM. Once the VM has been created, the Azure CLI outputs information about the VM. Take note of the publicIpAddress, this address can be used to access the virtual machine..

{
  "fqdns": "",
  "id": "/subscriptions/d5b9d4b7-6fc1-0000-0000-000000000000/resourceGroups/myResourceGroupVM/providers/Microsoft.Compute/virtualMachines/myVM",
  "location": "eastus",
  "macAddress": "00-0D-3A-23-9A-49",
  "powerState": "VM running",
  "privateIpAddress": "10.0.0.4",
  "publicIpAddress": "52.174.34.95",
  "resourceGroup": "myResourceGroupVM"
}

Connect to VM

You can now connect to the VM with SSH in the Azure Cloud Shell or from your local computer. Replace the example IP address with the publicIpAddress noted in the previous step.

ssh azureuser@52.174.34.95

Once logged in to the VM, you can install and configure applications. When you are finished, you close the SSH session as normal:

exit

Understand VM images

The Azure marketplace includes many images that can be used to create VMs. In the previous steps, a virtual machine was created using an Ubuntu image. In this step, the Azure CLI is used to search the marketplace for a CentOS image, which is then used to deploy a second virtual machine.

To see a list of the most commonly used images, use the az vm image list command.

az vm image list --output table

The command output returns the most popular VM images on Azure.

Offer          Publisher               Sku                 Urn                                                             UrnAlias             Version
-------------  ----------------------  ------------------  --------------------------------------------------------------  -------------------  ---------
WindowsServer  MicrosoftWindowsServer  2016-Datacenter     MicrosoftWindowsServer:WindowsServer:2016-Datacenter:latest     Win2016Datacenter    latest
WindowsServer  MicrosoftWindowsServer  2012-R2-Datacenter  MicrosoftWindowsServer:WindowsServer:2012-R2-Datacenter:latest  Win2012R2Datacenter  latest
WindowsServer  MicrosoftWindowsServer  2008-R2-SP1         MicrosoftWindowsServer:WindowsServer:2008-R2-SP1:latest         Win2008R2SP1         latest
WindowsServer  MicrosoftWindowsServer  2012-Datacenter     MicrosoftWindowsServer:WindowsServer:2012-Datacenter:latest     Win2012Datacenter    latest
UbuntuServer   Canonical               16.04-LTS           Canonical:UbuntuServer:16.04-LTS:latest                         UbuntuLTS            latest
CentOS         OpenLogic               7.3                 OpenLogic:CentOS:7.3:latest                                     CentOS               latest
openSUSE-Leap  SUSE                    42.2                SUSE:openSUSE-Leap:42.2:latest                                  openSUSE-Leap        latest
RHEL           RedHat                  7.3                 RedHat:RHEL:7.3:latest                                          RHEL                 latest
SLES           SUSE                    12-SP2              SUSE:SLES:12-SP2:latest                                         SLES                 latest
Debian         credativ                8                   credativ:Debian:8:latest                                        Debian               latest
CoreOS         CoreOS                  Stable              CoreOS:CoreOS:Stable:latest                                     CoreOS               latest

A full list can be seen by adding the --all argument. The image list can also be filtered by --publisher or –-offer. In this example, the list is filtered for all images with an offer that matches CentOS.

az vm image list --offer CentOS --all --output table

Partial output:

Offer             Publisher         Sku   Urn                                     Version
----------------  ----------------  ----  --------------------------------------  -----------
CentOS            OpenLogic         6.5   OpenLogic:CentOS:6.5:6.5.201501         6.5.201501
CentOS            OpenLogic         6.5   OpenLogic:CentOS:6.5:6.5.201503         6.5.201503
CentOS            OpenLogic         6.5   OpenLogic:CentOS:6.5:6.5.201506         6.5.201506
CentOS            OpenLogic         6.5   OpenLogic:CentOS:6.5:6.5.20150904       6.5.20150904
CentOS            OpenLogic         6.5   OpenLogic:CentOS:6.5:6.5.20160309       6.5.20160309
CentOS            OpenLogic         6.5   OpenLogic:CentOS:6.5:6.5.20170207       6.5.20170207

To deploy a VM using a specific image, take note of the value in the Urn column, which consists of the publisher, offer, SKU, and optionally a version number to identify the image. When specifying the image, the image version number can be replaced with “latest”, which selects the latest version of the distribution. In this example, the --image argument is used to specify the latest version of a CentOS 6.5 image.

az vm create --resource-group myResourceGroupVM --name myVM2 --image OpenLogic:CentOS:6.5:latest --generate-ssh-keys

Understand VM sizes

A virtual machine size determines the amount of compute resources such as CPU, GPU, and memory that are made available to the virtual machine. Virtual machines need to be sized appropriately for the expected work load. If workload increases, an existing virtual machine can be resized.

VM Sizes

The following table categorizes sizes into use cases.

TypeCommon sizesDescription
General purposeB, Dsv3, Dv3, DSv2, Dv2, Av2, DCBalanced CPU-to-memory. Ideal for dev / test and small to medium applications and data solutions.
Compute optimizedFsv2High CPU-to-memory. Good for medium traffic applications, network appliances, and batch processes.
Memory optimizedEsv3, Ev3, M, DSv2, Dv2High memory-to-core. Great for relational databases, medium to large caches, and in-memory analytics.
Storage optimizedLsv2, LsHigh disk throughput and IO. Ideal for Big Data, SQL, and NoSQL databases.
GPUNV, NVv2, NC, NCv2, NCv3, NDSpecialized VMs targeted for heavy graphic rendering and video editing.
High performanceHOur most powerful CPU VMs with optional high-throughput network interfaces (RDMA).

Find available VM sizes

To see a list of VM sizes available in a particular region, use the az vm list-sizes command.

az vm list-sizes --location eastus --output table

Partial output:

  MaxDataDiskCount    MemoryInMb  Name                      NumberOfCores    OsDiskSizeInMb    ResourceDiskSizeInMb
------------------  ------------  ----------------------  ---------------  ----------------  ----------------------
                 2          3584  Standard_DS1                          1           1047552                    7168
                 4          7168  Standard_DS2                          2           1047552                   14336
                 8         14336  Standard_DS3                          4           1047552                   28672
                16         28672  Standard_DS4                          8           1047552                   57344
                 4         14336  Standard_DS11                         2           1047552                   28672
                 8         28672  Standard_DS12                         4           1047552                   57344
                16         57344  Standard_DS13                         8           1047552                  114688
                32        114688  Standard_DS14                        16           1047552                  229376
                 1           768  Standard_A0                           1           1047552                   20480
                 2          1792  Standard_A1                           1           1047552                   71680
                 4          3584  Standard_A2                           2           1047552                  138240
                 8          7168  Standard_A3                           4           1047552                  291840
                 4         14336  Standard_A5                           2           1047552                  138240
                16         14336  Standard_A4                           8           1047552                  619520
                 8         28672  Standard_A6                           4           1047552                  291840
                16         57344  Standard_A7                           8           1047552                  619520

Create VM with specific size

In the previous VM creation example, a size was not provided, which results in a default size. A VM size can be selected at creation time using az vm create and the --size argument.

az vm create \
    --resource-group myResourceGroupVM \
    --name myVM3 \
    --image UbuntuLTS \
    --size Standard_F4s \
    --generate-ssh-keys

Resize a VM

After a VM has been deployed, it can be resized to increase or decrease resource allocation. You can view the current of size of a VM with az vm show:

az vm show --resource-group myResourceGroupVM --name myVM --query hardwareProfile.vmSize

Before resizing a VM, check if the desired size is available on the current Azure cluster. The az vm list-vm-resize-options command returns the list of sizes.

az vm list-vm-resize-options --resource-group myResourceGroupVM --name myVM --query [].name

If the desired size is available, the VM can be resized from a powered-on state, however it is rebooted during the operation. Use the az vm resize command to perform the resize.

az vm resize --resource-group myResourceGroupVM --name myVM --size Standard_DS4_v2

If the desired size is not on the current cluster, the VM needs to be deallocated before the resize operation can occur. Use the az vm deallocate command to stop and deallocate the VM. Note, when the VM is powered back on, any data on the temp disk may be removed. The public IP address also changes unless a static IP address is being used.

az vm deallocate --resource-group myResourceGroupVM --name myVM

Once deallocated, the resize can occur.

az vm resize --resource-group myResourceGroupVM --name myVM --size Standard_GS1

After the resize, the VM can be started.

az vm start --resource-group myResourceGroupVM --name myVM

VM power states

An Azure VM can have one of many power states. This state represents the current state of the VM from the standpoint of the hypervisor.

Power states

Power StateDescription
StartingIndicates the virtual machine is being started.
RunningIndicates that the virtual machine is running.
StoppingIndicates that the virtual machine is being stopped.
StoppedIndicates that the virtual machine is stopped. Virtual machines in the stopped state still incur compute charges.
DeallocatingIndicates that the virtual machine is being deallocated.
DeallocatedIndicates that the virtual machine is removed from the hypervisor but still available in the control plane. Virtual machines in the Deallocated state do not incur compute charges.
-Indicates that the power state of the virtual machine is unknown.

Find the power state

To retrieve the state of a particular VM, use the az vm get-instance-view command. Be sure to specify a valid name for a virtual machine and resource group.

az vm get-instance-view \
    --name myVM \
    --resource-group myResourceGroupVM \
    --query instanceView.statuses[1] --output table

Output:

ode                DisplayStatus    Level
------------------  ---------------  -------
PowerState/running  VM running       Info

To retrieve the power state of all the VMs in your subscription, use the Virtual Machines - List All API with parameter statusOnly set to true.

Management tasks

During the life-cycle of a virtual machine, you may want to run management tasks such as starting, stopping, or deleting a virtual machine. Additionally, you may want to create scripts to automate repetitive or complex tasks. Using the Azure CLI, many common management tasks can be run from the command line or in scripts.

Get IP address

This command returns the private and public IP addresses of a virtual machine.

az vm list-ip-addresses --resource-group myResourceGroupVM --name myVM --output table

Stop virtual machine

az vm stop --resource-group myResourceGroupVM --name myVM

Start virtual machine

az vm start --resource-group myResourceGroupVM --name myVM

Deleting VM resources

You can delete a VM, but by default this only deletes the VM resource, not the disks and networking resources the VM uses. You can change the default behavior to delete other resources when you delete the VM. For more information, see Delete a VM and attached resources.

Deleting a resource group also deletes all resources contained within, such as the VM, virtual network, and disk. The --no-wait parameter returns control to the prompt without waiting for the operation to complete. The --yes parameter confirms that you wish to delete the resources without an additional prompt to do so.

az group delete --name myResourceGroupVM --no-wait --yes

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