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A Giraffe extension that incorporates FSharp.Compiler.Portacode to enable live-updates
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A repo to explore using FSharp.Compiler.Portacode for hot-reloading Giraffe Views

Enabling Giraffe View Hot-Reload in your project

  • Install the giraffe-reload global tool
    • dotnet tool install -g Giraffe.HotReload.Cli::*
  • Invoke the giraffe-reload tool in watch-mode on your project
    • giraffe-reload --watch --webhook:http://localhost:5000/update path/to/project.fsproj
    • If your project runs on another IP or port, change it as appropriate.
    • The /update route is default right now, but can be configured
    • You can run the tool from your project directory and it'll discover your fsproj as well.
  • open the Giraffe.HotReload namespace and use the new UseGiraffeWithHotReload extension method on IApplicationBuilder. You'll likely want to #ifdef this around the DEBUG define, so that you don't allow hot-reloading in production.
  • Use this extension method instead of the normal UseGiraffe one. Check the sample project for an example usage.
  • Launch your project as usual, likely via dotnet run
  • Make edits to your giraffe handler

Enabling static content Hot-Reload in your project

  • Give your webroot folder and all files a name in your fsproj and tell msbuild it will be watchable
    <WebRoot Include="$(MSBuildProjectDirectory)/wwwroot/**/*" />
    <Watch Include="@(WebRoot)" />
  • Tell msbuild to copy these files on builds in your fsproj
    <Content Include="@(WebRoot)">
  • Make an msbuild task for copying these files in your fsproj
  <Target Name="CopyWebroot">
  • Teach ASP.NET Core where your webroot is
  let webroot = "wwwroot"

  • Start a dotnet watch task with this target. Everytime you save, msbuild will now copy this files to the output
$ dotnet watch msbuild /t:CopyWebroot

By default this will watch your webroot folder. If you want to include additional folders, you can add them to StaticFileProviders in the Settings.


The current settings that can be configured are listed below.

  type Settings = {
    /// The route where the hot reload tool should post.
    UpdateRoute : string
    /// The route for the websocket that will refresh the browser.
    WebsocketRefreshRoute : string
    /// The name of the Giraffe HttpHandler member that will be searched for
    WebAppMemberName : string
    /// Static file providers for anything not under webroot
    StaticFileProviders : IFileProvider list
      static member Default = {
        UpdateRoute = "/update"
        WebsocketRefreshRoute = "/ws"
        WebAppMemberName = "webApp"
        StaticFileProviders = []

You can pass these settings to the UseGiraffeWithHotReload as a second argument.

let settings = { Settings.Default with UpdateRoute = "/PleaseSendCodeHere" }


Triggering the auto-reload of your Giraffe app

The code looks for either a static HttpHandler value or a HttpHandler-generating-function called webApp (or another name that you provide in Settings) in your main application code.

If the value webApp: HttpHandler (or another name that you provide in Settings) is found, that value is passed into the HotReload middleware immediately.

If a member of the form webApp: 'dep1 -> ... -> 'depN -> HttpHandler (or another name that you provide in Settings) is found, the parameters are resolved from the HttpContext.RequestServices service locator on your behalf, passed into the function to get the HttpHandler, and then that value is passed into the HotReload middleware.

Log messages for both of these traversal paths will be written to the ASP.Net Core Logging Infrastructure under the Giraffe.HotReload.LiveUpdate.HotReloadGiraffeMiddleware logger name,

Check the samples/ReloadSample/Program.fs file for an example of a function-generating webApp.

WARNING: If your function includes generic parameters it will not work at this time.

Enabling auto-refresh of your page

The new middleware exposes a websocket-friendly connection at localhost:5000/ws, and if you include a simple script like in your root page template every page in your app will support hot-refresh. The important part is the onmessage handler, where the page is refreshed when a message is sent.

var socket = new WebSocket('ws://localhost:5000/ws');
socket.onopen = function(event) {
  console.log('Connection opened');
socket.onmessage = function(event) {
  return false;
socket.onclose = function(event) {
  console.log("connection closed");
socket.onerror = function(error) {
  console.log("error", error);

Running locally from the repo

To test the current set up:

  • cd to the samples/ReloadSample directory
  • run the Giraffe.HotReload.Cli project from that working directory to generate the project options
    • dotnet run --project ../../src/Giraffe.HotReload.Cli/Giraffe.HotReload.Cli.fsproj -- --eval @out.args
    • you may need to ensure that file exists first
  • run the Giraffe.HotReload.Cli project from that working directory in watch mode
    • dotnet run --project ../../src/Giraffe.HotReload.Cli/Giraffe.HotReload.Cli.fsproj -- --watch --webhook:http://localhost:5000/update @out.args
  • run the ReloadSample project
    • dotnet run
  • make changes to the ReloadSample project


MacOS/Linux Windows
Travis Badge Build status
Build History Build History


Stable Prerelease
NuGet Badge NuGet Badge


Make sure the following requirements are installed in your system:

> build.cmd // on windows
$ ./  // on unix

Environment Variables

  • CONFIGURATION will set the configuration of the dotnet commands. If not set it will default to Release.
    • CONFIGURATION=Debug ./ will result in things like dotnet build -c Debug
  • GITHUB_TOKEN will be used to upload release notes and nuget packages to github.
    • Be sure to set this before releasing

Watch Tests

The WatchTests target will use dotnet-watch to watch for changes in your lib or tests and re-run your tests on all TargetFrameworks

./ WatchTests


git add .
git commit -m "Scaffold"
git remote add origin origin
git push -u origin master
paket config add-token "" 4003d786-cc37-4004-bfdf-c4f3e8ef9b3a
  • Create a GitHub OAuth Token

    • You can then set the GITHUB_TOKEN to upload release notes and artifacts to github
    • Otherwise it will fallback to username/password
  • Then update the with a new version, date, and release notes ReleaseNotesHelper

#### 0.2.0 - 2017-04-20
* FEATURE: Does cool stuff!
* BUGFIX: Fixes that silly oversight
  • You can then use the Release target. This will:
    • make a commit bumping the version: Bump version to 0.2.0 and add the release notes to the commit
    • publish the package to nuget
    • push a git tag
./ Release

Code formatting

To format code run the following target

./ FormatCode

This uses Fantomas to do code formatting. Please report code formatting bugs to that repository.

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