Azure CORS Variable Allowed Origins - azure

Question

Whenever a new release pipeline is ran in Azure DevOps, the URL Is changed.. currently my ARM template has a hard-coded URL which can be annoying to keep on adding in manually.
"cors": {
"allowedOrigins": [
"[concat('https://',parameters('storage_account_name'),'.z10.web.core.windows.net')]"
}
The only thing that changes is the 10 part in the z10 so essentially i want it to be something like
[concat('https://',parameters('storage_account_name'),'.z', '*', '.web.core.windows.net')] I dont know if something like that is valid but essentially its so that the cors policy will accept the URL regardless of the z number.

Answer 1

Basically speaking this is not possible, because of the CORS standard (see docs).
which allows only for exact origins, wildcard, or null.
For instance, ARM for Azure Storage is also following this pattern allowing you to put a list of exact origins or a wildcard (see ARM docs)
However, if you know your website name, in your ARM you can receive the full host and use it in your CORS:
"[reference(resourceId('Microsoft.Web/sites', parameters('SiteName')), '2018-02-01').defaultHostName]"
The same with a static website (which is your case I guess) if you know the storage account name:
"[reference(concat('Microsoft.Storage/storageAccounts/', variables('storageAccountName')), '2019-06-01', 'Full').properties.primaryEndpoints.web]"
Advance reference output manipulation
Answering on comment - if you would like to replace some characters in the output from the reference function the easiest way is to use build-in replace function (see docs)
In case you need a more advanced scenario I am pasting my solution by introducing a custom function which is removing https:// and / from the end so https://contonso.com/ is transformed to contonso.com:
"functions": [
{
"namespace": "lmc",
"members": {
"replaceUri": {
"parameters": [
{
"name": "uriString",
"type": "string"
}
],
"output": {
"type": "string",
"value": "[replace(replace(parameters('uriString'), 'https://',''), '/','')]"
}
}
}
}
],
# ...(some code)...
"resources": [
# ... (some resource)...:
"properties": {
"hostName": "[lmc.replaceUri(reference(variables('storageNameCdn')).primaryEndpoints.blob)]"
}
]