Create a Linux image and distribute it to an Azure Compute Gallery by using the Azure CLI

Grein
08/22/2024

Applies to: ✔️ Linux VMs ✔️ Flexible scale sets

In this article, you learn how to use Azure VM Image Builder and the Azure CLI to create an image version in an Azure Compute Gallery (formerly Shared Image Gallery) and then distribute the image globally. You can also create an image version by using Azure PowerShell.

This article uses a sample JSON template to configure the image. The JSON file is at helloImageTemplateforSIG.json.

To distribute the image to an Azure Compute Gallery, the template uses sharedImage as the value for the distribute section of the template.

Register the providers

To use VM Image Builder, you need to register the providers. Check your registration by running the following commands:

az provider show -n Microsoft.VirtualMachineImages -o json | grep registrationState
az provider show -n Microsoft.KeyVault -o json | grep registrationState
az provider show -n Microsoft.Compute -o json | grep registrationState
az provider show -n Microsoft.Storage -o json | grep registrationState
az provider show -n Microsoft.Network -o json | grep registrationState
az provider show -n Microsoft.ContainerInstance -o json | grep registrationState

If the output doesn't say registered, run the following commands:

az provider register -n Microsoft.VirtualMachineImages
az provider register -n Microsoft.Compute
az provider register -n Microsoft.KeyVault
az provider register -n Microsoft.Storage
az provider register -n Microsoft.Network
az provider register -n Microsoft.ContainerInstance

Set variables and permissions

Because you'll be using some pieces of information repeatedly, create some variables to store that information.

VM Image Builder supports creating custom images only in the same resource group as the source-managed image. In the following example, update the resource group name to be the same resource group as your source-managed image.

# Resource group name - ibLinuxGalleryRG in this example
sigResourceGroup=ibLinuxGalleryRG
# Datacenter location - West US 2 in this example
location=westus2
# Additional region to replicate the image to - East US in this example
additionalregion=eastus
# Name of the Azure Compute Gallery - myGallery in this example
sigName=myIbGallery
# Name of the image definition to be created - myImageDef in this example
imageDefName=myIbImageDef
# Reference name in the image distribution metadata
runOutputName=aibLinuxSIG

Create a variable for your subscription ID:

subscriptionID=$(az account show --query id --output tsv)

Create the resource group:

az group create -n $sigResourceGroup -l $location

Create a user-assigned identity and set permissions on the resource group

VM Image Builder uses the provided user-identity to inject the image into an Azure Compute Gallery. In this example, you create an Azure role definition with specific actions for distributing the image. The role definition is then assigned to the user identity.

# Create user-assigned identity for VM Image Builder to access the storage account where the script is stored
identityName=aibBuiUserId$(date +'%s')
az identity create -g $sigResourceGroup -n $identityName

# Get the identity ID
imgBuilderCliId=$(az identity show -g $sigResourceGroup -n $identityName --query clientId -o tsv)

# Get the user identity URI that's needed for the template
imgBuilderId=/subscriptions/$subscriptionID/resourcegroups/$sigResourceGroup/providers/Microsoft.ManagedIdentity/userAssignedIdentities/$identityName

# Download an Azure role-definition template, and update the template with the parameters that were specified earlier
curl https://raw.githubusercontent.com/Azure/azvmimagebuilder/master/solutions/12_Creating_AIB_Security_Roles/aibRoleImageCreation.json -o aibRoleImageCreation.json

imageRoleDefName="Azure Image Builder Image Def"$(date +'%s')

# Update the definition
sed -i -e "s/<subscriptionID>/$subscriptionID/g" aibRoleImageCreation.json
sed -i -e "s/<rgName>/$sigResourceGroup/g" aibRoleImageCreation.json
sed -i -e "s/Azure Image Builder Service Image Creation Role/$imageRoleDefName/g" aibRoleImageCreation.json

# Create role definitions
az role definition create --role-definition ./aibRoleImageCreation.json

# Grant a role definition to the user-assigned identity
az role assignment create \
    --assignee $imgBuilderCliId \
    --role "$imageRoleDefName" \
    --scope /subscriptions/$subscriptionID/resourceGroups/$sigResourceGroup

Create an image definition and gallery

To use VM Image Builder with Azure Compute Gallery, you need to have an existing gallery and image definition. VM Image Builder doesn't create the gallery and image definition for you.

If you don't already have a gallery and image definition to use, start by creating them.

First, create a gallery:

az sig create \
    -g $sigResourceGroup \
    --gallery-name $sigName

Then, create an image definition:

az sig image-definition create \
   -g $sigResourceGroup \
   --gallery-name $sigName \
   --gallery-image-definition $imageDefName \
   --publisher myIbPublisher \
   --offer myOffer \
   --sku 20_04-lts-gen2 \
   --os-type Linux \
   --hyper-v-generation V2 \
   --features SecurityType=TrustedLaunchSupported

Download and configure the JSON file

Download the JSON template and configure it with your variables:

curl https://raw.githubusercontent.com/Azure/azvmimagebuilder/master/quickquickstarts/1_Creating_a_Custom_Linux_Shared_Image_Gallery_Image/helloImageTemplateforSIG.json -o helloImageTemplateforSIG.json
sed -i -e "s/<subscriptionID>/$subscriptionID/g" helloImageTemplateforSIG.json
sed -i -e "s/<rgName>/$sigResourceGroup/g" helloImageTemplateforSIG.json
sed -i -e "s/<imageDefName>/$imageDefName/g" helloImageTemplateforSIG.json
sed -i -e "s/<sharedImageGalName>/$sigName/g" helloImageTemplateforSIG.json
sed -i -e "s/<region1>/$location/g" helloImageTemplateforSIG.json
sed -i -e "s/<region2>/$additionalregion/g" helloImageTemplateforSIG.json
sed -i -e "s/<runOutputName>/$runOutputName/g" helloImageTemplateforSIG.json
sed -i -e "s%<imgBuilderId>%$imgBuilderId%g" helloImageTemplateforSIG.json

Create the image version

In this section you create the image version in the gallery.

Submit the image configuration to the Azure VM Image Builder service:

az resource create \
    --resource-group $sigResourceGroup \
    --properties @helloImageTemplateforSIG.json \
    --is-full-object \
    --resource-type Microsoft.VirtualMachineImages/imageTemplates \
    -n helloImageTemplateforSIG01

Start the image build:

az resource invoke-action \
     --resource-group $sigResourceGroup \
     --resource-type  Microsoft.VirtualMachineImages/imageTemplates \
     -n helloImageTemplateforSIG01 \
     --action Run

It can take a few moments to create the image and replicate it to both regions. Wait until this part is finished before you move on to create a VM.

Create the VM

Create the VM from the image version that was created by VM Image Builder.

az vm create \
  --resource-group $sigResourceGroup \
  --name myAibGalleryVM \
  --admin-username aibuser \
  --location $location \
  --image "/subscriptions/$subscriptionID/resourceGroups/$sigResourceGroup/providers/Microsoft.Compute/galleries/$sigName/images/$imageDefName/versions/latest" \
  --security-type TrustedLaunch \
  --generate-ssh-keys

Connect to the VM via Secure Shell (SSH):

ssh aibuser@<publicIpAddress>

As soon as your SSH connection is established, you should see that the image was customized with a Message of the Day:

*******************************************************
**            This VM was built from the:            **
**      !! AZURE VM IMAGE BUILDER Custom Image !!    **
**         You have just been Customized :-)         **
*******************************************************

Clean up your resources

Note

If you now want to try to recustomize the image version to create a new version of the same image, skip the step outlined here and go to Use VM Image Builder to create another image version.

If you no longer need the resources that were created as you followed the process in this article, you can delete them by doing the following.

This process deletes both the image that you created and all the other resource files. Make sure that you've finished this deployment before you delete the resources.

When you're deleting gallery resources, you need delete all the image versions before you can delete the image definition that was used to create them. To delete a gallery, you first need to have deleted all the image definitions in the gallery.

Delete the VM Image Builder template.

az resource delete \
    --resource-group $sigResourceGroup \
    --resource-type Microsoft.VirtualMachineImages/imageTemplates \
    -n helloImageTemplateforSIG01

Delete permissions assignments, roles, and identity.

az role assignment delete \
    --assignee $imgBuilderCliId \
    --role "$imageRoleDefName" \
    --scope /subscriptions/$subscriptionID/resourceGroups/$sigResourceGroup

az role definition delete --name "$imageRoleDefName"

az identity delete --ids $imgBuilderId

Get the image version that was created by VM Image Builder (it always starts with 0.), and then delete it.

sigDefImgVersion=$(az sig image-version list \
-g $sigResourceGroup \
--gallery-name $sigName \
--gallery-image-definition $imageDefName \
--subscription $subscriptionID --query [].'name' -o json | grep 0. | tr -d '"')
az sig image-version delete \
-g $sigResourceGroup \
--gallery-image-version $sigDefImgVersion \
--gallery-name $sigName \
--gallery-image-definition $imageDefName \
--subscription $subscriptionID

Delete the image definition.

az sig image-definition delete \
-g $sigResourceGroup \
--gallery-name $sigName \
--gallery-image-definition $imageDefName \
--subscription $subscriptionID

Delete the gallery.

az sig delete -r $sigName -g $sigResourceGroup

Delete the resource group.

az group delete -n $sigResourceGroup -y

Next steps

Learn more about Azure Compute Gallery.

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