Foundry Hosting integration automatically deploys capabilityHosts subresource, no clear way to disable it

[hansmbakker]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

Referencing existing Foundry resource and project resource automatically deploys a capabilityHosts subresource and hangs until it is deployed.

I found ClearDefaultRoleAssignments to prevent role deployments (also an annoying one) but there is no clear way to disable the capabilityHosts deployment.

Expected Behavior

Referencing existing resources should not start deploying things. Especially not without confirmation by the user.

Steps To Reproduce

Have an existing Foundry resource with an existing project.

Add Aspire.Hosting.Foundry 13.5.4-preview.1.26464.4 to your project

Run

var existingFoundryName = builder.AddParameter("existingFoundryName");
var existingFoundryProject = builder.AddParameter("existingFoundryProject");
var existingFoundryResourceGroup = builder.AddParameter("existingFoundryResourceGroup");

var foundry = builder.AddFoundry("foundry")
    .AsExisting(existingFoundryName, existingFoundryResourceGroup)
    .ClearDefaultRoleAssignments();

var foundryProject = foundry.AddProject("foundry-project")
    .AsExisting(existingFoundryProject, existingFoundryResourceGroup);

Exceptions (if any)

No response

Aspire doctor output

Anything else?

No response

[hansmbakker]

In general, it is weird that AsExisting starts deploying stuff.

[joperezr]

🤖 Aspire triage pass — 2026-09-16 16:20 UTC

Area: area-deployment, area-integrations
Kind: bug
Repro: yes-minimal — see lines 17–38 of the issue body
Affected version(s): 13.5.4-preview.1.26464.4 (latest: 13.5.4)
Severity: S2 — referencing existing Foundry resources unexpectedly provisions a subresource and blocks deployment, with no documented opt-out

Urgency: 🟡 vNext — recommend milestone 13.6
Reason: meaningful, actionable product bug for the active release train; there is no evidence that it requires servicing

Suggested owner(s): Sébastien Ros (@sebastienros) (score 13), backup Mitch Denny (@mitchdenny) (score 10)
Evidence:

• sebastienros merged [release/13.5] Pin Polyglot API surface #19864, [release/13.5] Pin C# API surface #19866, and Restore hosted agent ATS compatibility #18980 touching Foundry in area-integrations (last 45d)
• sebastienros closed aspire destroy fails to uninstall Helm release for AKS deployments #19206 as completed in area-integrations
• mitchdenny merged Add portable volume path environment variables #19404, Fix Kubernetes values for embedded environment parameters #19429, and Fix Kubernetes hostname publishing and routing #19430 in area-deployment and closed [Failing test]: Aspire.Deployment.EndToEnd.Tests.AzureResourceScopeDeploymentTests.DeployExistingServiceBusWithResourceGroupAndSubscriptionScope #19173 and Deployment E2E: AKS/Kubernetes tests fail due to Azure compute quota/capacity in centralus #18933 as completed

Confidence: medium
Needs human?: no