Configuring Amazon S3

You can utilize the Amazon S3 storage service for storing your website files even though the website is hosted on-premise, on your own server.

File name case

Unlike standard Windows file systems, the Amazon S3 storage is case-sensitive. To ensure consistent behavior, Kentico automatically converts all file and folder names to lower case when processing files on Amazon S3.

Configuring Kentico to use Amazon S3

  1. Make sure that you have your Amazon S3 account set up and and that you have created at least one bucket.

  2. Add the following key into the appSettings section of your project’s web.config.

     <add key="CMSExternalStorageName" value="amazon" />
  3. Add the following key to specifiy the bucket that you want to use to store files. Replace the value with the name of the bucket.

     <add key="CMSAmazonBucketName"  value="YourBucketName" />
  4. Specify the ID of your Amazon access key by inserting the following key:

     <add key="CMSAmazonAccessKeyID" value="YourKey" />
  5. Specify the Amazon access key by adding the following key:

     <add key="CMSAmazonAccessKey" value="YourSecret" />

After you save your web.config, Kentico starts storing files in the specified Amazon S3 bucket.

Additional website settings

When configuring this type of storage, keep in mind that the website itself must be configured to store files in the file system rather than in the database only. In Settings -> System -> Files enable the Store files in file system option.

It is also recommended to enable Redirect files to disk in Settings -> System -> Performance. This means that files will be requested from the Amazon S3 account rather than from the database (if possible).

You can configure the following optional settings:



Sample Value


Path to a local directory that the system uses to store temporary files. If you do not specify a value, the provider use the default operating system temporary directory.

 <add key="CMSAmazonTempPath" value="C:\Windows\Temp" />


Path to a local directory where the provider stores cached files. If you do not use this setting, the system creates a directory in the default operating system temporary directory.

<add key="CMSAmazonCachePath" value="C:\Cache" />


Allows you to change the default endpoint, for example when you want to use CloudFront CDN.

The default endpoint address is http://<yourbucketname>

<add key="CMSAmazonEndPoint" value="" />


Specifies whether files uploaded to Amazon S3 through Kentico are accessible for public users.

The default value is true if you specify an endpoint. If no endpoint is specified, the default value is false.

<add key="CMSAmazonPublicAccess" value="true"/> 

Storing files in different buckets

By default, the system stores files in a single bucket. However, the built-in Amazon S3 storage provider allows you to map sections of the file system to different buckets.

  1. Open the Kentico web project in Visual Studio (using the WebSite.sln or WebApp.sln file).
  2. Create a new class in the App_Code folder (or CMSApp_AppCode -> Old_App_Code on web application projects).
  3. Extend the CMSModuleLoader partial class.
  4. Create a new class inside CMSModuleLoader that inherits from CMSLoaderAttribute.
  5. Add the attribute defined by the internal class before the definition of the CMSModuleLoader partial class.
  6. Override the Init method inside the attribute class:
    • Create a new instance of the Amazon S3 storage provider.
    • Specify the target bucket using the CustomRootPath property of the provider.
    • (Optional) You can specify whether you want the bucket to be publicly accessible using the PublicExternalFolderObject property of the provider. True means the bucket is publicly accessible.
    • Map a directory to the provider. This is the directory that you want to store in the bucket.

using CMS.IO;
using CMS.Base;

public partial class CMSModuleLoader
    private class CustomStorageAttribute : CMSLoaderAttribute
        /// <summary>
        /// The system executes the Init method of the CMSModuleLoader attributes when the application starts.
        /// </summary>
        public override void Init()
            // Creates a new StorageProvider instance
            AbstractStorageProvider mediaProvider = new StorageProvider("Amazon", "CMS.AmazonStorage");

            // Specifies the target bucket
            mediaProvider.CustomRootPath = "mymediabucket";

            // Makes the bucket publicly accessible
            mediaProvider.PublicExternalFolderObject = true;

            // Maps a directory to the provider
            StorageHelper.MapStoragePath("~/MySite/Media/", mediaProvider);

  1. Save the file. If your project is installed in the web application format, rebuild the solution.