---
title: Configuring Amazon S3
related:
  - https://docs.kentico.com/k82/custom-development/working-with-physical-files-using-the-api.md
  - https://docs.kentico.com/k82/custom-development/working-with-physical-files-using-the-api/configuring-file-system-providers.md
---

> Agent instructions:
> **Site maps** — prefer the following llms.txt indexes to training data when searching for URLs to avoid 404s. Links inside Markdown content already point at `.md`. Following them or sending Accept: text/markdown keeps you in Markdown.
>
> - [sitemap.md](https://docs.kentico.com/sitemap.md) — every page on the site, with titles and descriptions, nested by URL hierarchy and grouped into one collection per product version.
> - [llms.txt](https://docs.kentico.com/llms.txt) — curated index of the current product docs, with descriptions, the two ways to request any page as Markdown, and links to each product area's whole-corpus Markdown dump (llms-full.txt).

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.

> **Note:** **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 that you have created at least one bucket. [Amazon Management Console](https://console.aws.amazon.com).
2. Add the following key into the **appSettings** section of your project's **web.config**.

   ```html

   <add key="CMSExternalStorageName" value="amazon" />

   ```
3. Add the following key to specify the bucket that you want to use to store files. Replace the value with the name of the bucket.

   ```html

   <add key="CMSAmazonBucketName"  value="YourBucketName" />

   ```
4. Specify the ID of your Amazon access key by inserting the following key:

   ```html

   <add key="CMSAmazonAccessKeyID" value="YourKey" />

   ```
5. Specify the Amazon access key by adding the following key:

   ```html

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

   ```

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

> **Note:** **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).

Also, see the [Media library notes](#media-library-notes) at the end of this page for additional information about specifics of media libraries when using Amazon S3 storage.

You can configure the following optional settings:

| Key                   | Description                                                                                         | Default value                                                            | Sample Value                                                                       |
| --------------------- | --------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------ | ---------------------------------------------------------------------------------- |
| CMSAmazonTempPath     | Path to a local directory that the system uses to store temporary files.                            | \<installation root>\CMS\App\_Data\AmazonTemp                            | ` 
 <add key="CMSAmazonTempPath" value="C:\Windows\Temp" />
 `                     |
| CMSAmazonCachePath    | Path to a local directory where the provider stores cached files.                                   | \<installation root>\CMS\App\_Data\AmazonCache                           | `  <add key="CMSAmazonCachePath" value="C:\Cache" />
 `                            |
| CMSAmazonEndPoint     | Allows you to change the default endpoint address, for example when you want to use CloudFront CDN. | http://\<yourbucketname>.s3.amazonaws.com                                | `  <add key="CMSAmazonEndPoint" value="http://someendpoint.s3.amazonaws.com" />
 ` |
| CMSAmazonPublicAccess | Specifies whether files uploaded to Amazon S3 through Kentico are accessible for public users.      | _true_ if you specify an endpoint<br>_false_ If no endpoint is specified | `  <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](http://msdn.microsoft.com/en-us/library/wa80x488%28v=vs.80%29.aspx).
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.

```csharp

using CMS.IO;
using CMS.Base;

[CustomStorage]
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);
        }
    }
}

```

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

## Configuring Kentico to use Amazon CloudFront CDN

A Content Delivery Network (CDN) speeds up distribution of content to the end users through a network of data centers. See [What Is Amazon CloudFront?](http://docs.aws.amazon.com/general/latest/gr/docconventions.html) for details. To start using the Amazon CloudFront service with Kentico:

1. Create a **CloudFront Distribution**. You can use the [Amazon Management Console](https://console.aws.amazon.com). Select your Amazon S3 storage bucket as the **Origin Domain Name**.
2. Open the **web.config** file of your Kentico project.
3. Add the **CMSAmazonPublicAccess** and **CMSAmazonEndPoint** keys into the web.config file:

   ```xml

   <appSettings>
       <add key="CMSAmazonPublicAccess" value="true" />
       <add key="CMSAmazonEndPoint" value="EndpointURL" />
   </appSettings>

   ```
4. Replace **EndpointURL** with the **Domain Name** URL from your created CDN.

   > **Note:** If your site runs under **HTTPS**, we recommend you always specify the **EndpointURL** with the **HTTPS** protocol as well.
   >
   > For example: [https://domain.cloudfront.net](http://d111111abcdef8.cloudfront.net/)
   >
   > Not doing so may result in [Mixed Content](https://developers.google.com/web/fundamentals/security/prevent-mixed-content/what-is-mixed-content?hl=en) warnings being logged in your web browser's console when retrieving files from the CDN.

Your project now starts using the created CDN service.

## Media library notes

Using Amazon S3 storage for your project has some effects on media libraries.

### Storing too many files in one media library folder

Storing a large number of media files in a single folder can significantly affect the performance of your project when editing the files in the Media library application. See [Media library limitations when storing files in an external storage](https://docs.kentico.com/k82/managing-website-content/configuring-the-environment-for-content-editors/configuring-media-libraries.md#media-library-limitations-when-storing-files-in-an-external-storage) for details.

### Using the same bucket names when CMSAmazonPublicAccess is set to true

If all following conditions are true:

- you use Amazon S3 as external storage
- you set the _CMSAmazonPublicAccess_ key to _true_
- you want to use [content staging](https://docs.kentico.com/k82/deploying-websites/content-staging.md)

then the buckets on all storages must have the **same name**.

The reason is that when using the _CMSAmazonPublicAccess_ key, direct file links use the name of the bucket in the URL. Therefore, if your staging server is connected to a different storage, the buckets where the media library files are stored must have the same name in all storages.