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Constrain port replacers to URL contexts only

Description

Port replacers in template.json were performing global replacements, corrupting numeric values in generated files. For example, interval: 5000 in bootstrap.bundle.js would become interval: 5126 when a random port was assigned.

Added onlyIf: [{"after": "localhost:"}] constraint to kestrelHttpPortReplacer and kestrelHttpsPortReplacer symbols:

"kestrelHttpPortReplacer": {
  "type": "generated",
  "generator": "coalesce",
  "parameters": {
    "sourceVariableName": "kestrelHttpPort",
    "fallbackVariableName": "kestrelHttpPortGenerated"
  },
  "replaces": "5000",
  "onlyIf": [{
    "after": "localhost:"
  }]
}

Applied to all web project templates:

• BlazorWeb-CSharp, ComponentsWebAssembly-CSharp
• StarterWeb-CSharp/FSharp, WebApi-CSharp/FSharp, WebApiAot-CSharp
• RazorPagesWeb-CSharp, EmptyWeb-CSharp/FSharp, GrpcService-CSharp

Replacement now occurs only in launchSettings.json URLs, preserving all other numeric values.

Original prompt

Problem

When creating a Blazor project using dotnet new blazorwasm -o projectname, the port number replacement is incorrectly modifying the bootstrap.bundle.js file. Specifically, Default$b.interval at line 1131 in projectname/wwwroot/lib/bootstrap/dist/js/bootstrap.bundle.js is being set to the same value as the port number in launchSettings.json.

This is happening because the kestrelHttpPortReplacer and kestrelHttpsPortReplacer symbols in template.json are configured to replace 5500 and 5501 globally across all files, without restricting the replacement to only occur in the context of localhost: URLs.

See issue: dotnet/sdk#48811

Solution

Add onlyIf constraints to the port replacer symbols to ensure they only perform replacements when the port number is preceded by localhost:. This approach is already used successfully in the dotnet/extensions templates.

In src/ProjectTemplates/Web.ProjectTemplates/content/BlazorWeb-CSharp/.template.config/template.json, modify the following symbols:

kestrelHttpPortReplacer

Change from:

"kestrelHttpPortReplacer": {
  "type": "generated",
  "generator": "coalesce",
  "parameters": {
    "sourceVariableName": "kestrelHttpPort",
    "fallbackVariableName": "kestrelHttpPortGenerated"
  },
  "replaces": "5500"
},

To:

"kestrelHttpPortReplacer": {
  "type": "generated",
  "generator": "coalesce",
  "parameters": {
    "sourceVariableName": "kestrelHttpPort",
    "fallbackVariableName": "kestrelHttpPortGenerated"
  },
  "replaces": "5500",
  "onlyIf": [{
    "after": "localhost:"
  }]
},

kestrelHttpsPortReplacer

Change from:

"kestrelHttpsPortReplacer": {
  "type": "generated",
  "generator": "coalesce",
  "parameters": {
    "sourceVariableName": "kestrelHttpsPort",
    "fallbackVariableName": "kestrelHttpsPortGenerated"
  },
  "replaces": "5501"
},

To:

"kestrelHttpsPortReplacer": {
  "type": "generated",
  "generator": "coalesce",
  "parameters": {
    "sourceVariableName": "kestrelHttpsPort",
    "fallbackVariableName": "kestrelHttpsPortGenerated"
  },
  "replaces": "5501",
  "onlyIf": [{
    "after": "localhost:"
  }]
},

Notes

• The after: "localhost:" constraint works for both the standard localhost:5500 and the .dev.localhost:5500 (LocalhostTld) formats, since both end with localhost:.
• This is the same pattern used in the dotnet/extensions AI template: https://github.com/dotnet/extensions/blob/7978e87e466ba6b7369fd68cafde4a82fe7c7e5b/src/ProjectTemplates/Microsoft.Extensions.AI.Templates/templates/AIChatWeb-CSharp/.template.config/template.json

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Pull request overview

This PR constrains Kestrel port replacements in project templates so they only occur in URL contexts, preventing unintended modification of numeric literals (e.g., in bootstrap.bundle.js) when random ports are assigned.

Changes:

• Added onlyIf conditions to kestrelHttpPortReplacer and kestrelHttpsPortReplacer across all relevant web project templates so replacements only occur when the port is preceded by localhost:.
• Left IIS port replacers unchanged (still global), after confirming their literal values (e.g., 8080, 44300) are not used elsewhere in template content.
• Normalized a minor JSON formatting issue in GrpcService-CSharp ("NativeAot": { spacing).

Reviewed changes

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

Show a summary per file

File	Description
src/ProjectTemplates/Web.ProjectTemplates/content/WebApiAot-CSharp/.template.config/template.json	Adds onlyIf on kestrelHttpPortReplacer so HTTP port substitution only happens in localhost: URL contexts for the native AOT Web API template.
src/ProjectTemplates/Web.ProjectTemplates/content/WebApi-FSharp/.template.config/template.json	Constrains both HTTP and HTTPS Kestrel port replacers with onlyIf conditions to avoid global numeric replacements.
src/ProjectTemplates/Web.ProjectTemplates/content/WebApi-CSharp/.template.config/template.json	Mirrors the F# Web API changes for C#, adding onlyIf constraints to Kestrel HTTP/HTTPS port replacers.
src/ProjectTemplates/Web.ProjectTemplates/content/StarterWeb-FSharp/.template.config/template.json	Adds onlyIf to Kestrel HTTP/HTTPS port replacers so only localhost: URLs are affected in the starter F# web template.
src/ProjectTemplates/Web.ProjectTemplates/content/StarterWeb-CSharp/.template.config/template.json	Same onlyIf constraints added for the C# starter web template’s Kestrel HTTP/HTTPS port replacers.
src/ProjectTemplates/Web.ProjectTemplates/content/RazorPagesWeb-CSharp/.template.config/template.json	Restricts Kestrel HTTP/HTTPS port replacements to URL contexts via onlyIf to avoid corrupting other numeric values.
src/ProjectTemplates/Web.ProjectTemplates/content/GrpcService-CSharp/.template.config/template.json	Adds onlyIf to Kestrel HTTP/HTTPS port replacers and tidies JSON spacing for the NativeAot symbol.
src/ProjectTemplates/Web.ProjectTemplates/content/EmptyWeb-FSharp/.template.config/template.json	Constrains Kestrel HTTP/HTTPS port replacers with onlyIf so only localhost: URLs are rewritten in the empty F# template.
src/ProjectTemplates/Web.ProjectTemplates/content/EmptyWeb-CSharp/.template.config/template.json	Same Kestrel HTTP/HTTPS onlyIf constraints applied for the empty C# template.
src/ProjectTemplates/Web.ProjectTemplates/content/ComponentsWebAssembly-CSharp/.template.config/template.json	Adds onlyIf to Kestrel HTTP/HTTPS replacers for the Blazor WebAssembly components template to avoid global numeric replacements.
src/ProjectTemplates/Web.ProjectTemplates/content/BlazorWeb-CSharp/.template.config/template.json	Adds onlyIf to Kestrel HTTP/HTTPS port replacers (the source of the reported issue), constraining replacements to localhost: URLs and preventing corruption of bundled JS numeric literals.

[Copilot]

These new onlyIf constraints change how the template engine performs port substitutions, but there doesn't appear to be a regression test asserting that ports are only replaced in URL contexts (for example, ensuring numeric constants in bootstrap.bundle.js are not modified). Consider adding a template test that generates a Blazor WebAssembly project, reads wwwroot/lib/bootstrap/dist/js/bootstrap.bundle.js, and verifies that known numeric literals (such as the carousel interval value) remain unchanged and do not get replaced with the assigned Kestrel HTTP/HTTPS ports.