Simple ActionFilter demonstrating adding CacheControl headers in Episerver Content Delivery Api

ContentDeliveryApiCacheActionFilter.cs

using EPiServer.ContentApi.Controllers;
using EPiServer.ContentApi.Search.Controllers;
using System;
using System.Linq;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Web.Http.Filters;

namespace Alloy.Business
{
    public class ContentDeliveryApiCacheActionFilter : ActionFilterAttribute, IFilter
    {
        private static readonly Type[] contentDeliveryApiControllers = new Type[]
        {
            typeof(ContentApiController),
            typeof(ContentApiSearchController),
            typeof(SiteDefinitionApiController)
        };

        public override void OnActionExecuted(HttpActionExecutedContext context)
        {
            if (IsContentDeliveryApiRequest(context) && context.Response.IsSuccessStatusCode)
            {
                var requestIsAnonymous = !context.Request.GetRequestContext().Principal.Identity.IsAuthenticated;

                if (requestIsAnonymous)
                {
                    context.Response.Headers.CacheControl = new CacheControlHeaderValue()
                    {
                        Public = true,
                        MaxAge = new TimeSpan(1, 0, 0, 0),
                    };
                }
            }

            base.OnActionExecuted(context);

        }

        private bool IsContentDeliveryApiRequest(HttpActionExecutedContext context)
        {
            var controllerType = context.ActionContext.ControllerContext.ControllerDescriptor.ControllerType;

            return contentDeliveryApiControllers.Contains(controllerType);
        }
    }

}