Use Blazor gateway CLI during development by javiercn · Pull Request #19432 · microsoft/aspire

Javier Calvarro Nelson (javiercn) · 2026-08-17T10:25:00Z

Description

Standalone Blazor WebAssembly apps now use the official Blazor Gateway CLI during local development instead of launching Aspire's generated file-based gateway. This keeps development aligned with the ASP.NET Core gateway implementation while preserving the existing AddBlazorGateway API, project resource/dashboard experience, endpoints, certificates, telemetry, and client resource relationships.

The run-mode project resource is launched as a process through:

dotnet tool exec Microsoft.AspNetCore.Components.Gateway.Cli --version 11.0.0-preview.7.26381.103 --yes -- ...

The CLI version is centrally pinned and requires the .NET 11 Preview 7 SDK or later. Publish behavior intentionally retains the generated Gateway.cs and its existing SDK 10 runtime image.

The standalone WASM client now targets .NET 11 Preview 7 and enables the SDK's canonical SPA fallback contract:

<TargetFramework>net11.0</TargetFramework>
<StaticWebAssetSpaFallbackEnabled>true</StaticWebAssetSpaFallbackEnabled>

Aspire removes SDK-generated or legacy fallback endpoints before adding one path-prefixed identity fallback using the canonical {**fallback:nonfile} route and string Order="2147483647". The same transformation is used during publish. Existing net10 clients retain the SDK 10 publish image, while net11 clients use the Preview 7 SDK image.

The built-in gateway also suppresses the obsolete Gateway.cs source display while retaining its ProjectResource model shape.

User-facing usage

The existing C# API is unchanged:

var blazorApp = builder.AddBlazorWasmApp("app", "../Blazor/Blazor.csproj");

builder.AddBlazorGateway("gateway")
    .WithBlazorClientApp(blazorApp);

Validation

All 82 Aspire.Hosting.Blazor.Tests passed.
All 8 ResourceSourceViewModel dashboard model cases passed.
SDK 10 AppHost restore/build succeeds without warnings or errors.
SDK 11 Preview 7 client restore/build succeeds without warnings or errors.
The SDK-generated manifest contains identity and compressed {**fallback:nonfile} endpoints with string order.
Aspire's transformed development and publish manifests contain exactly one prefixed identity fallback with no content-encoding selector.
Playwright validates configuration JSON, weather/time service discovery, OTLP proxying, rendered UI, no browser console errors, and dashboard source suppression.
A live run uses an SDK 10 AppHost/services with the project-scoped SDK 11 client and gateway CLI.

Fixes # (issue)

Checklist

Is this feature complete?
- Yes. Ready to ship.
- No. Follow-up changes expected.
Are you including unit tests for the changes and scenario tests if relevant?
- Yes
- No
Did you add public API?
- Yes
  - If yes, did you have an API Review for it?
    - Yes
    - No
  - Did you add <remarks /> and <code /> elements on your triple slash comments?
    - Yes
    - No
- No
Does the change make any security assumptions or guarantees?
- Yes
  - If yes, have you done a threat model and had a security review?
    - Yes
    - No
- No

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

github-actions · 2026-08-17T10:25:54Z

🚀 Dogfood this PR with:

⚠️ WARNING: Do not do this without first carefully reviewing the code of this PR to satisfy yourself it is safe.

curl -fsSL https://raw.githubusercontent.com/microsoft/aspire/main/eng/scripts/get-aspire-cli-pr.sh | bash -s -- 19432

Or

Run remotely in PowerShell:

iex "& { $(irm https://raw.githubusercontent.com/microsoft/aspire/main/eng/scripts/get-aspire-cli-pr.ps1) } 19432"

Copilot

Pull request overview

Moves run-mode Blazor gateways to the official CLI while retaining the generated gateway for publishing.

Changes:

Configures dotnet tool exec with SDK validation.
Preserves project-resource behavior and publish output.
Adds tests, dependency metadata, and sample documentation.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
`tests/Aspire.Hosting.Blazor.Tests/AddBlazorGatewayTests.cs`	Tests run and publish behavior.
`src/Aspire.Hosting.Blazor/BlazorGatewayExtensions.cs`	Launches the CLI during development.
`src/Aspire.Hosting.Blazor/Aspire.Hosting.Blazor.csproj`	Stamps the CLI version.
`playground/BlazorStandalone/README.md`	Documents CLI-based development.
`playground/BlazorStandalone/BlazorStandalone.AppHost/BlazorStandalone.AppHost.csproj`	Adds the Dotnet hosting reference.
`eng/Versions.props`	Pins the CLI package version.
`eng/Version.Details.xml`	Records dependency provenance.

+        Assert.Contains("FROM mcr.microsoft.com/dotnet/sdk:10.0 AS build", dockerfile);
+        Assert.Contains("COPY Gateway.cs .", dockerfile);
+        Assert.Contains("RUN dotnet publish Gateway.cs -c Release -o /app/publish", dockerfile);
+        Assert.Contains("FROM mcr.microsoft.com/dotnet/aspnet:10.0", dockerfile);
+        Assert.Contains("COPY --from=build /app/publish .", dockerfile);


+                    Command = "dotnet",
+                    WorkingDirectory = builder.AppHostDirectory
+                })
+                .WithAnnotation(new ProjectLaunchArgsOverrideAnnotation(["run"]))


Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

github-actions · 2026-08-17T11:32:20Z

Retrying the failed CI jobs for this pull request from the CI run attempt. The rerun is being tracked in the rerun attempt.

Copilot

Pull request overview

Copilot reviewed 11 out of 11 changed files in this pull request and generated 1 comment.

Suppressed comments (1)

src/Aspire.Hosting.Blazor/BlazorGatewayExtensions.cs:37

The public API documentation omits the new run-mode prerequisite. Callers relying on IntelliSense will only learn that AddBlazorGateway now requires .NET 11 Preview 7 after validation fails; document the minimum SDK here as well as in the playground README.

    /// During development the gateway runs from the official .NET tool. The file-based app
    /// shipped with this package remains the publish implementation.

+                    Command = "dotnet",
+                    WorkingDirectory = builder.AppHostDirectory


Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

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Adam Ratzman (adamint) · 2026-08-17T22:20:58Z

does this break aspire runs in vs code?

Javier Calvarro Nelson (javiercn) · 2026-08-18T09:49:40Z

does this break aspire runs in vs code?

Have not explicitly tried VS Code, but how would it break it? (Dashboard works fine)

Use Blazor gateway CLI during development

cfaf3fe

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot AI balanced review requested due to automatic review settings August 17, 2026 10:25

github-actions Bot added the needs-area-label An area label is needed to ensure this gets routed to the appropriate area owners label Aug 17, 2026

Copilot started reviewing on behalf of Javier Calvarro Nelson (javiercn) August 17, 2026 10:26 View session

Copilot AI reviewed Aug 17, 2026

View reviewed changes

Fix Blazor gateway development routing

448c78a

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot AI review requested due to automatic review settings August 17, 2026 11:25

Copilot started reviewing on behalf of Javier Calvarro Nelson (javiercn) August 17, 2026 11:34 View session

Copilot AI reviewed Aug 17, 2026

View reviewed changes

Comment thread src/Aspire.Hosting.Blazor/BlazorGatewayExtensions.cs

Comment on lines +63 to +64

Command = "dotnet",

WorkingDirectory = builder.AppHostDirectory

Align Blazor gateway with SDK fallback

057247a

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot AI review requested due to automatic review settings August 17, 2026 13:29

Copilot started reviewing on behalf of Javier Calvarro Nelson (javiercn) August 17, 2026 13:35 View session

Copilot AI reviewed Aug 17, 2026

github-actions Bot mentioned this pull request Aug 18, 2026

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Use Blazor gateway CLI during development - #19432

Use Blazor gateway CLI during development#19432
Javier Calvarro Nelson (javiercn) wants to merge 3 commits into
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Javier Calvarro Nelson (javiercn) commented Aug 17, 2026 •

edited

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		WorkingDirectory = builder.AppHostDirectory

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Description

User-facing usage

Validation

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Javier Calvarro Nelson (javiercn) commented Aug 17, 2026 •

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