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Use an external Redis-compatible cache in Azure API Management

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APPLIES TO: All API Management tiers

In addition to utilizing the built-in cache, Azure API Management allows for caching responses in an external Redis-compatible cache, such as Azure Cache for Redis.

Using an external cache allows you to overcome a few limitations of the built-in cache:

  • Avoid having your cache periodically cleared during API Management updates
  • Have more control over your cache configuration
  • Cache more data than your API Management tier allows
  • Use caching with the Consumption tier of API Management
  • Enable caching in the API Management self-hosted gateway

For more detailed information about caching, see API Management caching policies and Custom caching in Azure API Management.

Bring your own cache to APIM

What you'll learn:

  • Add an external cache in API Management

Prerequisites

To complete this tutorial, you need to:

Create Azure Cache for Redis

This section explains how to create an Azure Cache for Redis in Azure. If you already have an Azure Cache for Redis, or another Redis-compatible cache within or outside of Azure, you can skip to the next section.

  1. To create a cache, sign in to the Azure portal and select Create a resource.

    Create a resource is highlighted in the left navigation pane.

  2. On the New page, select Databases and then select Azure Cache for Redis.

    On New, Databases is highlighted, and Azure Cache for Redis is highlighted.

  3. On the New Redis Cache page, configure the settings for your new cache.

    Setting Choose a value Description
    Subscription Drop down and select your subscription. The subscription under which to create this new Azure Cache for Redis instance.
    Resource group Drop down and select a resource group, or select Create new and enter a new resource group name. Name for the resource group in which to create your cache and other resources. By putting all your app resources in one resource group, you can easily manage or delete them together.
    DNS name Enter a unique name. The cache name must be a string between 1 and 63 characters that contain only numbers, letters, or hyphens. The name must start and end with a number or letter, and can't contain consecutive hyphens. Your cache instance's host name is <DNS name>.redis.cache.windows.net.
    Location Drop down and select a location. Select a region near other services that use your cache.
    Cache type Drop down and select a tier. The tier determines the size, performance, and features that are available for the cache. For more information, see Azure Cache for Redis Overview.

  4. Select the Networking tab or select the Networking button at the bottom of the page.

  5. In the Networking tab, select your connectivity method.

  6. Select the Next: Advanced tab or select the Next: Advanced button on the bottom of the page to see the Advanced tab.

    Screenshot showing the Advanced tab in the working pane and the available option to select.

    • For Basic or Standard caches, toggle the selection for a non-TLS port. You can also select if you want to enable Microsoft Entra Authentication.
    • For a Premium cache, configure the settings for non-TLS port, clustering, managed identity, and data persistence. You can also select if you want to enable Microsoft Entra Authentication.

  7. Select the Next: Tags tab or select the Next: Tags button at the bottom of the page.

  8. Optionally, in the Tags tab, enter the name and value if you wish to categorize the resource.

  9. Select Review + create. You're taken to the Review + create tab where Azure validates your configuration.

  10. After the green Validation passed message appears, select Create.

It takes a while for a cache to create. You can monitor progress on the Azure Cache for Redis Overview page. When Status shows as Running, the cache is ready to use.

Deploy Redis cache to Kubernetes

For a self-hosted gateway, caching requires an external cache. For caching to be effective, a self-hosted gateway and the cache it relies on must be located close to each other to minimize lookup and store latencies. Deploying a Redis cache into the same Kubernetes cluster or in a separate cluster nearby are the best options. Learn how to deploy Redis cache to a Kubernetes cluster.

Add an external cache

Follow the steps below to add an external Redis-compatible cache in Azure API Management. You can limit the cache to a specific gateway in your API Management instance.

Screenshot that shows how to add an external Azure Cache for Redis in Azure API Management.

Use from setting

The Use from setting in the configuration specifies the location of your API Management instance that will use the cache. Select one of the following:

  • The Azure region where the API Management instance is hosted (or one of the configured locations, if you have a multi-region deployment)

  • A self-hosted gateway location

  • Default, to configure the cache as the default for all gateway locations in the API Management instance

    A cache used for Default will be overridden by a cache used for a specific matching region or location.

    For example, consider an API Management instance that's hosted in the East US, Southeast Asia, and West Europe regions. There are two caches configured, one for Default and one for Southeast Asia. In this example, API Management in Southeast Asia will use its own cache, while the other two regions will use the Default cache entry.

Note

You can configure the same external cache for more than one API Management instance. The API Management instances can be in the same or different regions. When sharing the cache for more than one instance, you must select Default in the Use from setting.

Add an Azure Cache for Redis from the same subscription

  1. Browse to your API Management instance in the Azure portal.
  2. Select the External cache tab from the menu on the left.
  3. Select the + Add button.
  4. Select your cache in the Cache instance dropdown field.
  5. Select Default or specify the desired region in the Use from dropdown field.
  6. Select Save.

Add a Redis-compatible cache hosted outside of the current Azure subscription or Azure in general

  1. Browse to your API Management instance in the Azure portal.
  2. Select the External cache tab from the menu on the left.
  3. Select the + Add button.
  4. Select Custom in the Cache instance dropdown field.
  5. Select Default or specify the desired region in the Use from dropdown field.
  6. Provide your Azure Cache for Redis (or Redis-compatible cache) connection string in the Connection string field.
  7. Select Save.

Add a Redis cache to a self-hosted gateway

  1. Browse to your API Management instance in the Azure portal.
  2. Select the External cache tab from the menu on the left.
  3. Select the + Add button.
  4. Select Custom in the Cache instance dropdown field.
  5. Specify the desired self-hosted gateway location or Default in the Use from dropdown field.
  6. Provide your Redis cache connection string in the Connection string field.
  7. Select Save.

Use the external cache

After adding a Redis-compatible cache, configure caching policies to enable response caching, or caching of values by key, in the external cache.

For a detailed example, see Add caching to improve performance in Azure API Management.

Next steps