I am trying to use the excellent Azure blob storage providere from https://our.umbraco.org/projects/collaboration/umbracofilesystemprovidersazure/

However I want to get the connectionString from a file named /AppSettings.config to make it possible to have control over the keys in source control.

<?xml version="1.0"?>
<FileSystemProviders>

  <!-- Media -->
  <Provider alias="media" type="Our.Umbraco.FileSystemProviders.Azure.AzureBlobFileSystem, Our.Umbraco.FileSystemProviders.Azure">
    <Parameters>
        <add key="containerName" value="media"/>
        <add key="rootUrl" value="https://xx.blob.core.windows.net/"/>
        <add key="connectionString"
            value=System.Configuration.ConfigurationManager.AppSettings["AzureFilesConnectionString"]/>
        <!--
        Optional configuration value determining the maximum number of days to cache items in the browser.
        Defaults to 365 days.
      -->
        <add key="maxDays" value="365"/>
    </Parameters>
  </Provider>

</FileSystemProviders>

And the AppSettings.config

<appSettings>
  <!-- Azure File blob connection string-->
  <add key="AzureFilesConnectionString" value="xxx" />
  <!-- SendGrid-->
  <add key="mailAccount" value="My mail account." />
  <add key="mailPassword" value="My mail password." />
  <!-- Google -->
  <add key="GoogleClientID" value="1.apps.googleusercontent.com" />
  <add key="GoogleClientSecret" value="My Google client secret." />
</appSettings>