Azure WebApp - version controlled configuration/user data deployed separately from app - azure

Question

I've developed an WebApp (API) which is hosted in Azure & uses VSTS for CI/CD/version control.
I'd like to give the customer (owner) of this API the ability to update various configuration/data files under wwwroot, however I'd like those files to be under version control (source of truth - a separate repository to the API source code). Creating/Updating/Deleting one of those files in the repository should cause the file to be uploaded/removed in the WebApp (in a folder under wwwroot).
Modifying (creating/deleting) one of these files should not trigger a full redeployment (of the WebApp)
How can I achieve this? So far I've thought about a VSTS release pipeline for a GIT artefact however I couldn't see a low-friction way to make the changes in the Azure webapp (KUDU API seems a bit complex and heavy-handed)
**EDIT: ** Sample PowerShell script to sync Configuration files in WebApp w/ a build-artefact (PUT/DELETE only invoked when necessary).
# The idea behind this script is to synchronize the configuration files on the server with what's in the repo, only updating files where necessary
param (
[string]$resourceGroupName = "XXX",
[Parameter(Mandatory=$true)][string]$webAppName,
[Parameter(Mandatory=$true)][string]$latestConfigFilesPath
)
function Get-AzureRmWebAppPublishingCredentials($resourceGroupName, $webAppName, $slotName = $null) {
if ([string]::IsNullOrWhiteSpace($slotName)) {
$resourceType = "Microsoft.Web/sites/config"
$resourceName = "$webAppName/publishingcredentials"
} else {
$resourceType = "Microsoft.Web/sites/slots/config"
$resourceName = "$webAppName/$slotName/publishingcredentials"
}
$publishingCredentials = Invoke-AzureRmResourceAction -ResourceGroupName $resourceGroupName -ResourceType $resourceType -ResourceName $resourceName -Action list -ApiVersion 2015-08-01 -Force
return $publishingCredentials
}
function Get-KuduApiAuthorisationHeaderValue($resourceGroupName, $webAppName, $slotName = $null) {
$publishingCredentials = Get-AzureRmWebAppPublishingCredentials $resourceGroupName $webAppName $slotName
return ("Basic {0}" -f [Convert]::ToBase64String([Text.Encoding]::ASCII.GetBytes(("{0}:{1}" -f $publishingCredentials.Properties.PublishingUserName, $publishingCredentials.Properties.PublishingPassword))))
}
function Get-KuduInode($kuduHref) {
return Invoke-RestMethod -Uri $kuduHref `
-Headers #{"Authorization"=$kuduApiAuthorisationToken;"If-Match"="*"} `
-Method GET `
-ContentType "application/json"
}
function Get-AllFilesUnderKuduHref($kuduHref) {
$result = #()
$inodes = (Get-KuduInode $kuduHref)
Foreach ($inode in $inodes) {
if ($inode.mime -eq "inode/directory") {
$result += (Get-AllFilesUnderKuduHref $inode.href)
} else {
$result += $inode.href
}
}
return $result
}
function Get-LocalPathForUri([System.Uri]$uri) {
$latestConfigFilesUri = [System.Uri]$latestConfigFilesPath
$localFileUri = [System.Uri]::new($latestConfigFilesUri, $uri)
return $localFileUri.LocalPath
}
function Get-RemoteUri([System.Uri]$uri) {
return [System.Uri]::new($configurationHref, $uri)
}
function Files-Identical($uri) {
$localFilePath = Get-LocalPathForUri $uri
$localFileHash = Get-FileHash $localFilePath -Algorithm MD5
# Download the remote file so that we can calculate the hash. It doesn't matter that it doesn't get cleaned up, this is running on a temporary build server anyway.
$temporaryFilePath = "downloded_kudu_file"
$remoteFileUri = [System.Uri]::new($configurationHref, $uri)
Invoke-RestMethod -Uri $remoteFileUri `
-Headers #{"Authorization"=$kuduApiAuthorisationToken;"If-Match"="*"} `
-Method GET `
-OutFile $temporaryFilePath `
-ContentType "multipart/form-data"
$remoteFileHash = Get-FileHash $temporaryFilePath -Algorithm MD5
return $remoteFileHash.Hash -eq $localFileHash.Hash
}
function CalculateRelativePath([System.Uri]$needle, [System.Uri]$haystack) {
return $haystack.MakeRelativeUri($needle).ToString();
}
function Put-File([System.Uri]$uri) {
Write-Host "Uploading file $uri"
$localFilePath = Get-LocalPathForUri $uri
$remoteFileUri = Get-RemoteUri $uri
Invoke-RestMethod -Uri $remoteFileUri `
-Headers #{"Authorization"=$kuduApiAuthorisationToken;"If-Match"="*"} `
-Method PUT `
-InFile $localFilePath `
-ContentType "multipart/form-data"
}
function Delete-File([System.Uri]$uri) {
Write-Host "Deleting file $uri"
$remoteFileUri = Get-RemoteUri $uri
Invoke-RestMethod -Uri $remoteFileUri `
-Headers #{"Authorization"=$kuduApiAuthorisationToken;"If-Match"="*"} `
-Method DELETE `
}
# Script begins here
$configurationHref = [System.Uri]"https://$webAppName.scm.azurewebsites.net/api/vfs/site/wwwroot/Configuration/"
$kuduApiAuthorisationToken = Get-KuduApiAuthorisationHeaderValue -resourceGroupName $resourceGroupName -webAppName $webAppName
$filenamesOnServer = Get-AllFilesUnderKuduHref $configurationHref $kuduApiAuthorisationToken | % { $configurationHref.MakeRelativeUri($_).OriginalString }
Write-Host "Files currently on server" $filenamesOnServer
$filesCurrentlyInRepo = Get-ChildItem -Path $latestConfigFilesPath -Recurse -File
$filenamesInRepo = $filesCurrentlyInRepo | Select-Object -ExpandProperty FullName | % { CalculateRelativePath $_ $latestConfigFilesPath}
Write-Host "Files currently in repo" $filenamesInRepo
$intersection = $filenamesOnServer | ?{$filenamesInRepo -contains $_}
Write-Host "Intersection: " $intersection
$onlyOnServer = $filenamesOnServer | ?{-Not($filenamesInRepo -contains $_)}
$onlyInRepo = $filenamesInRepo | ?{-Not($filenamesOnServer -contains $_)}
Write-Host "Only on server" $onlyOnServer
Write-Host "Only in repo" $onlyInRepo
Write-Host
Foreach ($uri in $onlyInRepo) {
Put-File $uri
}
Foreach ($uri in $onlyOnServer) {
Delete-File $uri
}
Foreach ($uri in $intersection) {
if (-Not (Files-Identical $uri)) {
Write-Host "Configuration file $uri needs updating"
Put-File $uri
} else {
Write-Host "Configuration file $uri is identical, skipping"
}
}
Write-Host "Sync complete"

Answer 1

With Azure App Service deploy task, you can upload files to app service, but can’t delete files (Uncheck Publish using Web Deploy optioin and specify the folder path in Package or folder input box).
So, the better way is using Kudu API to delete/upload files during build/release.
There is the thread and a blog about using Kudu API:
How to access Kudu in Azure using power shell script
Interacting with Azure Web Apps Virtual File System using PowerShell and the Kudu API