Clean up your Azure Container Registry

Azure Container Registry is one way to privately publish docker images and use these in your Azure resources. You might observe that over time, your used storage goes up and up even though you store just a few images. This is due to some dangling image layers that are no longer in use but still count against your storage limit. To get rid of these, I use this small powershell script: $registry = "name-of-your-registry" $repositories = az acr repository list --name $registry --output tsv $manifestsToDelete = $repositories | ForEach-Object -Parallel { Write-Host "Check ${_}" $manifests = (az acr repository show-manifests --name ${using:registry} --repository $_ --query "[?tags[0]==null].digest" -o tsv) -split "`n" foreach ($manifest in $manifests -split "`n") { "${_}@${manifest}" } } -ThrottleLimit 10 Write-Host "Total manifests to delete: $($manifestsToDelete.Count)" $manifestsToDelete | ForEach-Object -Parallel { az acr repository delete --name ${using:registry} --image $_ --yes } -ThrottleLimit 20 Just fill in the name of your registry. The script will then list the repositories (your images) and find the manifests to delete. Finally, it will delete the manifests (in parallel, to speed up the process).

Apr 4, 2025 - 18:28

Azure Container Registry is one way to privately publish docker images and use these in your Azure resources.

You might observe that over time, your used storage goes up and up even though you store just a few images. This is due to some dangling image layers that are no longer in use but still count against your storage limit.

To get rid of these, I use this small powershell script:

$registry = "name-of-your-registry"
$repositories = az acr repository list --name $registry --output tsv

$manifestsToDelete = $repositories | ForEach-Object -Parallel {
    Write-Host "Check ${_}"
    $manifests = (az acr repository show-manifests --name ${using:registry} --repository $_ --query "[?tags[0]==null].digest" -o tsv) -split "`n"
    foreach ($manifest in $manifests -split "`n") { "${_}@${manifest}" }
} -ThrottleLimit 10

Write-Host "Total manifests to delete: $($manifestsToDelete.Count)"

$manifestsToDelete | ForEach-Object -Parallel {
    az acr repository delete --name ${using:registry} --image $_ --yes
} -ThrottleLimit 20

Just fill in the name of your registry. The script will then list the repositories (your images) and find the manifests to delete.

Finally, it will delete the manifests (in parallel, to speed up the process).