How to change the default HTTP scaler concurrency (10 requests) to 1000 in .NET Aspire?

Question

I’m using .NET Aspire to orchestrate my services, and everything is deployed to Azure Container Apps.

By default for replication, Container Apps seem to use HTTP scaler with a concurrency target of 10 requests per replica, but I’d like to increase this limit to 1000 requests per replica.

Here’s an example of what I’m doing in my AppHost project:

var webBuilder = builder.AddProject<Project_Web>(ProjectWebResourceName)
    .WithExternalHttpEndpoints()
    .WithHttpHealthCheck("/health")
    .PublishAsAzureContainerApp((infrastructure, app) =>
    {
        app.Template.Scale.MinReplicas = appHostOptions.Web.MinReplicas;
        app.Template.Scale.CooldownPeriod = appHostOptions.Web.CooldownPeriodSeconds;
    });

However, I can’t find where or how to override the HTTP scaler’s concurrency target (default 10). I want to configure it directly through Aspire.

Edward Villarin · Accepted Answer · 2025-10-22 07:17:17Z

-2

using Microsoft.Azure.Provisioning.ContainerApps; // Ensure this namespace is available via NuGet

// ... (other builder configurations)

var webBuilder = builder.AddProject<Project_Web>(ProjectWebResourceName)
    .WithExternalHttpEndpoints()
    .WithHttpHealthCheck("/health")
    .PublishAsAzureContainerApp((infrastructure, app) => // app is ContainerAppResource
    {
        // Basic scale settings
        app.Template.Scale.MinReplicas = appHostOptions.Web.MinReplicas;
        app.Template.Scale.MaxReplicas = appHostOptions.Web.MaxReplicas ?? 10; // Example fallback
        app.Template.Scale.CooldownPeriod = appHostOptions.Web.CooldownPeriodSeconds;

        // Optional: Clear default rules if they interfere
        // app.Template.Scale.Rules.Clear();

        // Add custom HTTP scale rule with increased concurrency
        app.Template.Scale.Rules.Add(new ScaleRule
        {
            Name = "custom-http-rule", // Unique name for the rule
            Http = new HttpScaleRule
            {
                Metadata = new Dictionary<string, string>
                {
                    ["concurrentRequests"] = "1000" // Your desired target
                }
            }
        });
    });

answered Oct 22 at 7:17

Edward Villarin

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1 Comment

Markiian Hoinets Oct 22 at 9:36

No package like Microsoft.Azure.Provisioning.ContainerApps, available only Azure.Provisioning.AppContainers. Also, this syntax is not right, because ScaleRule not proper parameter for Rules.Add() function.

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