Add flagd Aspire hosting #827

askpt · 2025-09-01T20:29:13Z

Closes #737

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I want to add all of these syncs (https://flagd.dev/concepts/syncs/) but I want this to get merged to add more later on.
For telemetry data, this issue needs to be fixed [FEATURE] flagd should use standard OTel SDK env vars open-feature/flagd#1141

Odonno · 2025-09-02T11:58:44Z

src/CommunityToolkit.Aspire.Hosting.Flagd/FlagdBuilderExtensions.cs

+        return builder.AddResource(resource)
+            .WithImage(FlagdContainerImageTags.Image, FlagdContainerImageTags.Tag)
+            .WithImageRegistry(FlagdContainerImageTags.Registry)
+            .WithHttpEndpoint(port: 8013, targetPort: port, name: FlagdResource.HttpEndpointName)


todo: create a constant FlagdPort

Fixed with f468d42

Odonno · 2025-09-02T12:00:38Z

src/CommunityToolkit.Aspire.Hosting.Flagd/FlagdBuilderExtensions.cs

+        this IDistributedApplicationBuilder builder,
+        [ResourceName] string name,
+        string fileSource,
+        int port = 8013)


todo: the other integration uses int? port = null so that it provides a dynamic port by default, allowing the possibility to override the port only when needed.

yep, should be defaulting to null and leave that to Aspire to assign a port.

Fixed with 6317cd6

Odonno · 2025-09-02T12:01:18Z

src/CommunityToolkit.Aspire.Hosting.Flagd/FlagdBuilderExtensions.cs

+    public static IResourceBuilder<FlagdResource> AddFlagd(
+        this IDistributedApplicationBuilder builder,
+        [ResourceName] string name,
+        string fileSource,


suggestion: if you expect a default value for this, why not set it here?

Suggested change

string fileSource,

string fileSource = "flagd.json",

I am still thinking on what to do here. The main reason is flagd supports multiple sources and at this moment I am limiting just to file system. Thinking on if I should add a minimal working hosting that works with just files or adding now all the possible syncs. Check: https://flagd.dev/concepts/syncs/

Odonno · 2025-09-02T12:04:14Z

src/CommunityToolkit.Aspire.Hosting.Flagd/FlagdBuilderExtensions.cs

+    /// <param name="builder">The resource builder.</param>
+    /// <param name="level">The logging level (debug, info, warn, error).</param>
+    /// <returns>The <see cref="IResourceBuilder{FlagdResource}"/>.</returns>
+    public static IResourceBuilder<FlagdResource> WithLogging(


suggestion: It may be me but I would have expect WithLogLevel(builder, FlagdLogLevel level) with FlagdLogLevel being a specifc enum of possible values.

cc. @aaronpowell

Agreed, an enum would be better as that is more discoverable to the end user.

Alternatively, shouldn't it just inherit the logging level from the standard logger? Is there a reason you'd configure flagd to log a different verbosity level to the whole app?

I am not sure what the default logger would be. If it's like goff, the default log level is INFO. You can still override it within the config file and if needed by the environment variable. I do think that overriding with an env variable like this is the best solution. What did you have in mind?

Fixed with a03c6e0

This was still code from the initial scaffolding the copilot did when I used the agent in this repo to create the structure for this hosting project. Now it is fixed to add extra logging when a flag is evaluated: https://flagd.dev/troubleshooting/

Yeah, I checked and I don't see any possibility to set the log level (like warning or info). It's either DEBUG or not.

I would go for a more generic solution/naming that can be reused for other Hosting integration like goff, I suggest this:

enum FlagdLogLevel { Error = 0, Debug } public static IResourceBuilder<FlagdResource> WithLoglevel( this IResourceBuilder<FlagdResource> builder, FlagdLogLevel logLevel) { // .. return builder.WithEnvironment("FLAGD_DEBUG", logLevel == FlagdLogLevel.Error ? "true" : "false"); }

Even better would be reusing this https://learn.microsoft.com/en-us/dotnet/api/microsoft.extensions.logging.loglevel?view=net-9.0-pp

public static IResourceBuilder<FlagdResource> WithLoglevel( this IResourceBuilder<FlagdResource> builder, LogLevel logLevel) { // .. if (logLevel == LogLevel.Debug) { return builder.WithEnvironment("FLAGD_DEBUG", "true"); } else if (logLevel == LogLevel.Error) { return builder; } else { // throw error as not expected? } }

What do you think @aaronpowell ?

It definitely gives a more .NET-like look and feel. Waiting on feedback to make that change since it feels a design we might want to replicate in other integrations.

Yeah let's go idiomatic with the .NET logging levels. I think that raising an exception if someone uses a log level that's unsupported would be the right way to go as that avoids a false sense of what logging can achieve, and allows for flexibility if flagd adds additional logging levels in the future.

aaronpowell · 2025-09-04T05:28:45Z

examples/flagd/CommunityToolkit.Aspire.Hosting.Flagd.AppHost/Program.cs

+builder.Eventing.Subscribe<AfterResourcesCreatedEvent>(static async (@event, cancellationToken) =>
+    {
+        // When the resources are created, set the OpenFeature provider to use Flagd (debug purposes)
+        await OpenFeature.Api.Instance.SetProviderAsync(new FlagdProvider());
+
+        var flagClient = OpenFeature.Api.Instance.GetClient();
+        var welcomeBanner = await flagClient.GetBooleanDetailsAsync("welcome-banner", false);
+        var backgroundColor = await flagClient.GetStringDetailsAsync("background-color", "000000");
+        var apiVersion = await flagClient.GetStringDetailsAsync("api-version", "0.1");
+    });


Is this for illustrating something specific in the example apphost, or is this the kind of thing that we could roll up into an extension method?

@aaronpowell I am using this as a testing project to see if the integration is working properly. With this I can test a flag evaluation when I start this aspire project.

Ideally, I will add later this Service extension: #800, which will deal with the DI and so on. Similar to what I have here: https://github.com/askpt/openfeature-aspire-welcome/blob/550eb169399da489916ebf9360503df99cf9befe/Todo.ServiceDefaults/Extensions.cs#L32

aaronpowell · 2025-09-04T05:29:26Z

src/CommunityToolkit.Aspire.Hosting.Flagd/FlagdBuilderExtensions.cs

+        this IDistributedApplicationBuilder builder,
+        [ResourceName] string name,
+        string fileSource,
+        int port = 8013)


yep, should be defaulting to null and leave that to Aspire to assign a port.

aaronpowell · 2025-09-04T05:31:02Z

src/CommunityToolkit.Aspire.Hosting.Flagd/FlagdBuilderExtensions.cs

+    /// <param name="builder">The resource builder.</param>
+    /// <param name="level">The logging level (debug, info, warn, error).</param>
+    /// <returns>The <see cref="IResourceBuilder{FlagdResource}"/>.</returns>
+    public static IResourceBuilder<FlagdResource> WithLogging(


Agreed, an enum would be better as that is more discoverable to the end user.

Alternatively, shouldn't it just inherit the logging level from the standard logger? Is there a reason you'd configure flagd to log a different verbosity level to the whole app?

aaronpowell · 2025-09-04T05:32:27Z

tests/CommunityToolkit.Aspire.Hosting.Flagd.Tests/AppHostTests.cs

+    public async Task ResourceStartsAndRespondsCorrectly()
+    {
+        var resourceName = "flagd";
+        await fixture.ResourceNotificationService.WaitForResourceAsync(resourceName).WaitAsync(TimeSpan.FromMinutes(1));
+        var httpClient = fixture.CreateHttpClient(resourceName);
+    }


Is there anything we can assert against on the resource to verify that it's running beyond "it didn't time out"?

I am still implementing this tests and cleanup some code. I am planning on adding a flag evaluation here, similar to what is done in the examples project.

askpt · 2025-10-01T05:59:53Z

@aaronpowell could you please reopen this PR? I am still working on it

src/CommunityToolkit.Aspire.Hosting.Flagd/README.md

Copilot

Pull Request Overview

This PR adds a new .NET Aspire hosting integration for flagd, a feature flag evaluation engine that provides an OpenFeature-compliant backend system. The integration allows developers to easily add flagd containers to their Aspire applications with support for flag configuration files.

Key changes include:

Complete flagd hosting integration with resource definition, builder extensions, and configuration options
Comprehensive test coverage for the new integration
Example application demonstrating flagd usage
Documentation and project configuration updates

Reviewed Changes

Copilot reviewed 16 out of 16 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
`src/CommunityToolkit.Aspire.Hosting.Flagd/FlagdResource.cs`	Defines the FlagdResource class with endpoint references and connection string implementation
`src/CommunityToolkit.Aspire.Hosting.Flagd/FlagdBuilderExtensions.cs`	Provides extension methods for adding flagd to applications with configuration options
`src/CommunityToolkit.Aspire.Hosting.Flagd/FlagdContainerImageTags.cs`	Constants for flagd container image registry, name, and version
`tests/CommunityToolkit.Aspire.Hosting.Flagd.Tests/AddFlagdTests.cs`	Unit tests covering all builder extension methods and resource configuration
`tests/CommunityToolkit.Aspire.Hosting.Flagd.Tests/AppHostTests.cs`	Integration tests verifying flagd functionality with both flagd and OFREP providers
`examples/flagd/CommunityToolkit.Aspire.Hosting.Flagd.AppHost/Program.cs`	Example application showing how to configure flagd with file sync and logging
`examples/flagd/CommunityToolkit.Aspire.Hosting.Flagd.AppHost/flags/flagd.json`	Sample flag configuration file for testing and demonstration
`README.md`	Updated main README to include flagd integration in the toolkit listing

src/CommunityToolkit.Aspire.Hosting.Flagd/README.md

aaronpowell

Once there's the update with the logging design, I think this will be ready to merge in

aaronpowell · 2025-10-13T00:11:56Z

src/CommunityToolkit.Aspire.Hosting.Flagd/FlagdBuilderExtensions.cs

+    /// <param name="builder">The resource builder.</param>
+    /// <param name="level">The logging level (debug, info, warn, error).</param>
+    /// <returns>The <see cref="IResourceBuilder{FlagdResource}"/>.</returns>
+    public static IResourceBuilder<FlagdResource> WithLogging(


Yeah let's go idiomatic with the .NET logging levels. I think that raising an exception if someone uses a log level that's unsupported would be the right way to go as that avoids a false sense of what logging can achieve, and allows for flexibility if flagd adds additional logging levels in the future.

aaronpowell · 2025-10-13T00:17:41Z

@askpt can you add the test project to the list so that the tests are run.

Signed-off-by: André Silva <[email protected]>

…ge examples Signed-off-by: André Silva <[email protected]>

… related tests Signed-off-by: André Silva <[email protected]>

…oint Signed-off-by: André Silva <[email protected]>

…ing level and update related tests Signed-off-by: André Silva <[email protected]>

Signed-off-by: GitHub <[email protected]>

Signed-off-by: André Silva <[email protected]>

…ource configuration Signed-off-by: André Silva <[email protected]>

…d endpoint validation Signed-off-by: André Silva <[email protected]>

…urations Signed-off-by: André Silva <[email protected]>

… removing skip attribute Signed-off-by: André Silva <[email protected]>

…ync method Signed-off-by: André Silva <[email protected]>

Co-authored-by: Copilot <[email protected]>

Updated README to clarify logging configuration and port customization for flagd.

Signed-off-by: André Silva <[email protected]>

…dition and error handling Signed-off-by: André Silva <[email protected]>

…ogLevel for improved clarity and functionality Signed-off-by: André Silva <[email protected]>

askpt · 2025-10-13T07:24:17Z

@askpt can you add the test project to the list so that the tests are run.

@aaronpowell I fixed the test list and the log level suggestion. Should be now good to go 👍

askpt force-pushed the askpt/737-add-flagd-hosting branch from c671d0f to b3cefbc Compare September 2, 2025 06:59

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askpt force-pushed the askpt/737-add-flagd-hosting branch 2 times, most recently from fde75aa to 3fa7e87 Compare September 15, 2025 15:54

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askpt force-pushed the askpt/737-add-flagd-hosting branch from c0171e6 to 85f6924 Compare September 21, 2025 14:23

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askpt force-pushed the askpt/737-add-flagd-hosting branch from 85f6924 to 0dc4471 Compare October 1, 2025 16:09

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askpt marked this pull request as ready for review October 3, 2025 15:32

askpt requested review from Odonno, aaronpowell, Copilot and kylejuliandev October 3, 2025 15:32

Copilot AI reviewed Oct 3, 2025

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Odonno mentioned this pull request Oct 5, 2025

Add WithLogLevel extension method #884

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Add flagd hosting integration with configuration and tests

b6dadb7

Signed-off-by: André Silva <[email protected]>

askpt and others added 20 commits October 13, 2025 08:23

Fix AddFlagd method to correctly set target port for HTTP endpoint

c604625

Signed-off-by: André Silva <[email protected]>

Update README to correct flag configuration file path and enhance usa…

ec99e79

…ge examples Signed-off-by: André Silva <[email protected]>

Refactor AddFlagd method to accept optional port parameter and update…

6432c91

… related tests Signed-off-by: André Silva <[email protected]>

Refactor AddFlagd method to use constant for target port in HTTP endp…

1a34af8

…oint Signed-off-by: André Silva <[email protected]>

Refactor logging configuration in AddFlagd method to use default logg…

a597e40

…ing level and update related tests Signed-off-by: André Silva <[email protected]>

Add tests for flagd provider and assert expected values

ef086c5

Signed-off-by: GitHub <[email protected]>

Add health check endpoint to Flagd resource and builder

1b04555

Signed-off-by: GitHub <[email protected]>

Add OFREP endpoint support to Flagd resource and builder

a40d022

Signed-off-by: André Silva <[email protected]>

Refactor AddFlagd method to use WithBindFileSync for flag configuration

7cb777f

Signed-off-by: André Silva <[email protected]>

Fix documentation for AddFlagd method to include remarks about sync s…

8ebce6b

…ource configuration Signed-off-by: André Silva <[email protected]>

Update AddFlagdTests and AppHostTests to improve resource handling an…

ba0424d

…d endpoint validation Signed-off-by: André Silva <[email protected]>

Add support for OpenFeature.Providers.Ofrep and update related config…

35c60ff

…urations Signed-off-by: André Silva <[email protected]>

Fix Ofrep evaluation test by updating connection string retrieval and…

1e550c2

… removing skip attribute Signed-off-by: André Silva <[email protected]>

Update README to reflect changes in AddFlagd usage with WithBindFileS…

b043e89

…ync method Signed-off-by: André Silva <[email protected]>

Apply suggestion from @Copilot

2cb3e67

Co-authored-by: Copilot <[email protected]>

Clarify logging and port customization in README

60f78ef

Updated README to clarify logging configuration and port customization for flagd.

Add Hosting.Flagd.Tests to integration test matrix

518c086

Signed-off-by: André Silva <[email protected]>

Add WithLoglevel method to configure logging level for flagd

8ea83ca

Signed-off-by: André Silva <[email protected]>

Add tests for WithLoglevel method to validate environment variable ad…

6e646a2

…dition and error handling Signed-off-by: André Silva <[email protected]>

Refactor logging configuration: replace WithLogging method with WithL…

a794065

…ogLevel for improved clarity and functionality Signed-off-by: André Silva <[email protected]>

askpt force-pushed the askpt/737-add-flagd-hosting branch from d74d47a to a794065 Compare October 13, 2025 07:23

askpt requested a review from aaronpowell October 13, 2025 07:24

aaronpowell approved these changes Oct 16, 2025

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Merge branch 'main' into askpt/737-add-flagd-hosting

310e58e

aaronpowell merged commit 757bf85 into CommunityToolkit:main Oct 16, 2025
206 of 207 checks passed

askpt deleted the askpt/737-add-flagd-hosting branch October 16, 2025 08:25

Add flagd Aspire hosting #827

Add flagd Aspire hosting #827

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askpt commented Sep 1, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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askpt commented Oct 1, 2025

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askpt commented Sep 1, 2025 •

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