Add Streamlit support to Python Extensions (Experimental)

examples/python/CommunityToolkit.Aspire.Hosting.Python.Extensions.AppHost/Program.cs

@@ -6,4 +6,7 @@
 builder.AddUvApp("uvapp", "../uv-api", "uv-api")
     .WithHttpEndpoint(env: "PORT");
 
+builder.AddStreamlitApp("streamlitapp", "../streamlit-api", "app.py")
+    .WithHttpEndpoint(env: "PORT");
+
 builder.Build().Run();

examples/python/streamlit-api/.gitignore

@@ -0,0 +1,3 @@
+.venv/
+__pycache__/
+*.pyc

examples/python/streamlit-api/.python-version

@@ -0,0 +1 @@
+3.12

examples/python/streamlit-api/README.md

@@ -0,0 +1,57 @@
+# Streamlit API Example
+
+This is a simple Streamlit application that demonstrates how to run Streamlit apps in Aspire using the Python Extensions.
+
+## Prerequisites
+
+- Python 3.12 or later
+- .NET 8.0 or later
+- Streamlit package
+
+## Setup
+
+1. Create a virtual environment:
+   ```bash
+   python -m venv .venv
+   ```
+
+2. Activate the virtual environment:
+   - On Windows:
+     ```bash
+     .venv\Scripts\activate
+     ```
+   - On macOS/Linux:
+     ```bash
+     source .venv/bin/activate
+     ```
+
+3. Install dependencies:
+   ```bash
+   pip install streamlit
+   ```
+
+## Running the App
+
+The app can be run as part of the Aspire AppHost project or standalone.
+
+### Run with Aspire
+
+Navigate to the AppHost project and run:
+```bash
+dotnet run
+```
+
+### Run Standalone
+
+From this directory, run:
+```bash
+streamlit run app.py
+```
+
+## About the App
+
+This is a basic Streamlit app that demonstrates:
+- Simple text display
+- Environment variable reading (PORT)
+- Session state management
+- Interactive buttons

examples/python/streamlit-api/app.py

@@ -0,0 +1,18 @@
+import streamlit as st
+import os
+
+st.title("Hello, Aspire!")
+
+st.write("This is a simple Streamlit app running in Aspire.")
+
+port = os.environ.get("PORT", "8501")
+st.write(f"Running on port: {port}")
+
+# Add a simple counter
+if "counter" not in st.session_state:
+    st.session_state.counter = 0
+
+if st.button("Click me!"):
+    st.session_state.counter += 1
+
+st.write(f"Button clicked {st.session_state.counter} times")

examples/python/streamlit-api/pyproject.toml

@@ -0,0 +1,12 @@
+[project]
+name = "streamlit-api"
+version = "0.1.0"
+description = "Test project for streamlit-api"
+requires-python = ">=3.12"
+dependencies = [
+    "streamlit>=1.40.0",
+]
+
+[build-system]
+requires = ["hatchling"]
+build-backend = "hatchling.build"

src/CommunityToolkit.Aspire.Hosting.Python.Extensions/README.md

@@ -3,6 +3,7 @@
 Provides extensions methods and resource definitions for the .NET Aspire AppHost to extend the support for Python applications. Current support includes:
 - Uvicorn
 - Uv
+- Streamlit
 
 ## Getting Started
 
@@ -36,6 +37,15 @@ var uvicorn = builder.AddUvApp("uvapp", "../uv-api", "uv-api")
     .WithHttpEndpoint(env: "PORT");
 ```
 
+### Streamlit example usage
+
+Then, in the _Program.cs_ file of your AppHost project, define a Streamlit resource, then call `Add`:
+
+```csharp
+var streamlit = builder.AddStreamlitApp("streamlitapp", "../streamlit-api", "app.py")
+    .WithHttpEndpoint(env: "PORT");
+```
+
 ## Additional Information
 
 https://learn.microsoft.com/dotnet/aspire/community-toolkit/hosting-python-extensions

src/CommunityToolkit.Aspire.Hosting.Python.Extensions/StreamlitAppHostingExtension.cs

@@ -0,0 +1,81 @@
+using Aspire.Hosting.ApplicationModel;
+using CommunityToolkit.Aspire.Utils;
+
+namespace Aspire.Hosting;
+
+/// <summary>
+/// Provides extension methods for adding Streamlit applications to an <see cref="IDistributedApplicationBuilder"/>.
+/// </summary>
+public static class StreamlitAppHostingExtension
+{
+    /// <summary>
+    /// Adds a Streamlit application to the distributed application builder.
+    /// </summary>
+    /// <param name="builder">The distributed application builder.</param>
+    /// <param name="name">The name of the Streamlit application.</param>
+    /// <param name="projectDirectory">The directory of the project containing the Streamlit application.</param>
+    /// <param name="scriptPath">The path to the Python script to be run by Streamlit.</param>
+    /// <param name="args">Optional arguments to pass to the Streamlit command.</param>
+    /// <returns>An <see cref="IResourceBuilder{StreamlitAppResource}"/> for the Streamlit application resource.</returns>
+    /// <exception cref="ArgumentNullException">Thrown if <paramref name="builder"/> is null.</exception>
+    /// <exception cref="ArgumentException">Thrown if <paramref name="name"/> or <paramref name="scriptPath"/> is null or empty.</exception>
+    public static IResourceBuilder<StreamlitAppResource> AddStreamlitApp(
+        this IDistributedApplicationBuilder builder,
+        [ResourceName] string name,
+        string projectDirectory,
+        string scriptPath,
+        params string[] args)
+    {
+        return builder.AddStreamlitApp(name, projectDirectory, scriptPath, ".venv", args);
+    }
+
+    private static IResourceBuilder<StreamlitAppResource> AddStreamlitApp(
+        this IDistributedApplicationBuilder builder,
+        string name,
+        string projectDirectory,
+        string scriptPath,
+        string virtualEnvironmentPath,
+        params string[] args)
+    {
+        ArgumentNullException.ThrowIfNull(builder);
+        ArgumentException.ThrowIfNullOrWhiteSpace(name);
+        ArgumentException.ThrowIfNullOrWhiteSpace(scriptPath);
+
+        string wd = projectDirectory ?? Path.Combine("..", name);
+
+        var normalizedAppHostDirectory = PathNormalizer.NormalizePathForCurrentPlatform(builder.AppHostDirectory);
+        var normalizedWd = PathNormalizer.NormalizePathForCurrentPlatform(wd);
+        projectDirectory = PathNormalizer.NormalizePathForCurrentPlatform(Path.Combine(normalizedAppHostDirectory, normalizedWd));
+
+        var projectResource = new StreamlitAppResource(name, projectDirectory);
+
+        return builder.AddResource(projectResource)
+            .WithEnvironment(context =>
+            {
+                // Streamlit uses STREAMLIT_SERVER_PORT instead of PORT, so map PORT to STREAMLIT_SERVER_PORT
+                if (context.EnvironmentVariables.TryGetValue("PORT", out var portValue))
+                {
+                    context.EnvironmentVariables["STREAMLIT_SERVER_PORT"] = portValue;
+                }
+            })
+            .WithArgs(context =>
+            {
+                AddProjectArguments(scriptPath, args, context);
+            });
+    }
+
+    private static void AddProjectArguments(string scriptPath, string[] scriptArgs, CommandLineArgsCallbackContext context)
+    {
+        context.Args.Add("run");
+        context.Args.Add(scriptPath);
+
+        // Add --server.headless to run without browser opening
+        context.Args.Add("--server.headless");
+        context.Args.Add("true");
+
+        foreach (var arg in scriptArgs)
+        {
+            context.Args.Add(arg);
+        }
+    }
+}

src/CommunityToolkit.Aspire.Hosting.Python.Extensions/StreamlitAppResource.cs

@@ -0,0 +1,11 @@
+using Aspire.Hosting.Python;
+
+namespace Aspire.Hosting.ApplicationModel;
+
+/// <summary>
+/// Represents a Streamlit application.
+/// </summary>
+/// <param name="name">The name of the resource.</param>
+/// <param name="workingDirectory">The working directory for streamlit.</param>
+public class StreamlitAppResource(string name, string workingDirectory)
+    : PythonAppResource(name, "streamlit", workingDirectory), IResourceWithServiceDiscovery;

tests/CommunityToolkit.Aspire.Hosting.Python.Extensions.Tests/AppHostTests.cs

@@ -8,6 +8,7 @@ public class AppHostTests(AspireIntegrationTestFixture<Projects.CommunityToolkit
     [Theory(Skip = "To be reviewed with https://github.com/CommunityToolkit/Aspire/issues/917")]
     [InlineData("uvicornapp")]
     [InlineData("uvapp")]
+    [InlineData("streamlitapp")]
     public async Task ResourceStartsAndRespondsOk(string appName)
     {
         var httpClient = fixture.CreateHttpClient(appName);

tests/CommunityToolkit.Aspire.Hosting.Python.Extensions.Tests/ResourceCreationTests.cs

@@ -43,6 +43,25 @@ public void DefaultUvApp()
         Assert.Equal(NormalizePathForCurrentPlatform("../../examples/python/uv-api"), resource.WorkingDirectory);
     }
 
+    [Fact]
+    public void DefaultStreamlitApp()
+    {
+        var builder = DistributedApplication.CreateBuilder();
+
+        builder.AddStreamlitApp("streamlitapp", "../../examples/python/streamlit-api", "app.py");
+
+        using var app = builder.Build();
+
+        var appModel = app.Services.GetRequiredService<DistributedApplicationModel>();
+
+        var resource = appModel.Resources.OfType<StreamlitAppResource>().SingleOrDefault();
+
+        Assert.NotNull(resource);
+
+        Assert.Equal("streamlit", resource.Command);
+        Assert.Equal(NormalizePathForCurrentPlatform("../../examples/python/streamlit-api"), resource.WorkingDirectory);
+    }
+
     static string NormalizePathForCurrentPlatform(string path)
     {
         if (string.IsNullOrWhiteSpace(path) == true)