Load balancing and web farms in nopCommerce

Load balancing is the distribution of a workload across many nodes. It is typically used for balancing HTTP traffic over multiple servers acting together as a web front end.

There are several ways to configure load balancing in nopCommerce:

1. Use cloud-based autoscaling appliances like Microsoft's Azure Web Apps. Please find more about it here.
2. Configure load balancing with IIS web farms. This approach is described below.

We highly recommend you to read this tutorial by Microsoft before you start configuring a web farm for nopCommerce. So Microsoft suggests two ways to build a web farm with IIS servers:

1. Local Content Infrastructure
2. Shared Network Content Infrastructure

nopCommerce supports both ways and handles content replication by using Distributed File System Replication (DFSR) if you use Local Content Infrastructure or uses a central location to manage the content with Shared Network Content Infrastructure.

nopCommerce configuration

First of all, you have to configure the initial settings of your web farm in IIS and add the first instance of your nopCommerce store there. Then, you have to configure a few settings in the nopCommerce admin area to allow nopCommerce to work with web farms:

1. Go to Configuration → Settings → All settings (advanced). Find the mediasettings.useabsoluteimagepath setting and change its value to false

2. Go to Configuration → Settings → App settings and find the Distributed cache configuration tab. Select the Use distributed cache checkbox and choose the option you prefer:

   • Redis. In this case, you just need to enter the Connection string to your Redis server below
   • SQL Server. In this case, you need to prepare a new table in your database using the "sql-cache create" command first. Read more about it in Microsoft docs here. Then fill in the Connection string, Schema name, and Table name fields

3. Since our web farm utilizes Application Request Routing (ARR) to control traffic using a proxy server, select the Use proxy servers checkbox

4. Click the Save button. The nopCommerce application will be restarted.

Web farm configuration

Admin area redirection rule

Since a web farm hosts multiple instances of an application, you need to choose one of the nopCommerce instances as a primary one to avoid file locking. This primary node will process requests from the admin panel.

The rule should look as follows:

<rule name="Admin Area" enabled="true" patternSyntax="ECMAScript" stopProcessing="true">
    <match url="^(admin(/.*)?)$|^(lib_npm/.+)$" />
    <conditions logicalGrouping="MatchAll" trackAllCaptures="false">
        <add input="{HTTP_HOST}" pattern="^admin\.wf\.local$" negate="true" />
    </conditions>
    <action type="Rewrite" url="http://admin.wf.local/{R:0}" />
</rule>

Where admin.wf.local is the address of your primary instance.

Load balancing rules

After you set up the web farm, you need to configure a load balancing rule in the Application Request Routing section. Add the condition that prevents handling requests intended for the primary node (admin area requests in our case):

<rule name="ARR_wf-local_loadbalance" enabled="true" patternSyntax="ECMAScript" stopProcessing="true">
    <match url=".*" ignoreCase="false" />
    <conditions logicalGrouping="MatchAll" trackAllCaptures="false">
        <add input="{PATH_INFO}" pattern="^(/admin(/.*)?)$|^(/lib_npm/.+)$" negate="true" />
    </conditions>
    <action type="Rewrite" url="http://wf-local/{R:0}" />
</rule>

Where wf-local is the web farm name.

You can add the rules we described above in two ways:

1. Include them in the applicationHost.config file (system.webServer/rewrite/globalRules section)
2. Use the URL Rewrite script section in IIS Manager

Note

In some cases, ARR has issues handling URLs of javascript files containing more than one “.” symbol. For example, it can affect minified js-files ending with .min.js. To avoid errors when processing such files, we recommend directly routing these requests to one of the nopCommerce instances. As you can see in the examples above, we do this for the whole lib_npm directory by routing to the primary instance.

When the configuration is finished, add new instances to your web farm.

File replication

When you start the configuration of file replication, please make sure that the following folders of the primary instance are set up to support replication to all other nodes (instances):

• /App_Data
• /Plugins
• /Themes
• /wwwroot

Note

All actions that assume restarting the nopCommerce application (for example, plugin installation, updating of the app settings), require manual restarting of all application pools related to the web farm.