Unexpected Feature Flags refresh behaviour for 6.0.1

[danyltsiv]

When we upgrade AppConfiguration package from 5.1.0 to 6.0.1 for ASP.NET Core app it starts working very unexpectedly in terms of Feature Flags refresh.
With feature flags setup like this:
Feature1 (label=null): true
Feature1 (label=env1): false
In env1, once the app starts all works correctly and we get FALSE, until the first refresh happens, then the non-labeled value overrides the labeled and since then we always get TRUE.
This does not happen on 5.1.0.

Setup code:

configurationBuilder.AddAzureAppConfiguration(options =>
            {
                options.Connect(appConfigUrl);

                // Since Azure App Configuration API allows to load values filtering by 5 keys max,
                // there are a bunch of configuration providers registered, every of it loads next portion of 5 values
                foreach (var keysString in keysStrings)
                {
                    options
                        .Select(keysString)
                        .Select(keysString, label);
                }

                options
                    .ConfigureKeyVault(vaultOptions =>
                    {
                        vaultOptions.SetCredential(credentials);
                    })
                    .ConfigureRefresh(refresh =>
                    {
                        refresh
                            .Register(sentinelKey, label, true)
                            .SetCacheExpiration(TimeSpan.FromSeconds(reloadInterval));
                    })
                    .UseFeatureFlags(featureFlagsOptions =>
                    {
                        featureFlagsOptions
                            .Select(KeyFilter.Any)
                            .Select(KeyFilter.Any, label);

                        featureFlagsOptions.CacheExpirationInterval = TimeSpan.FromSeconds(reloadInterval);
                    });
            });

Also, worth mentioning that we call UseAzureAppConfiguration at the beginning of Startup.cs, so that we don't have issues like here: microsoft/FeatureManagement-Dotnet#201 (at some point we had, but fixed by moving it to top as well).

This happens with no interaction with Feature Flags on portal, so seems like no relations to #317

[amerjusupovic]

Hi @danyltsiv, the bug in #317 shouldn't be exclusive to those who use the portal. From what you described, the pull request linked in that issue (#404) should resolve this issue as well. I can look more into why this happened while upgrading from 5.1.0 to see if there's anything you can do to work around this at the moment, but this should be fixed in the next major release.

[zhiyuanliang-ms]

@amerjusupovic Has the bug been fixed now? Is it safe to close this issue?

[amerjusupovic]

The team couldn't come to an agreement on the approach in the original PR I mentioned, and the newest PR to add collection monitoring for key-values here should solve this. I can probably close #404 once the new PR I mentioned gets further along.

[danyltsiv]

Hello @amerjusupovic :)
Sorry to disturb you, but we still have occurrences of non-labeled feature flags overriding labeled ones from time to time. It happens randomly for a short period of time, then disappears.
I assume the new PR is about to fix that as well as the original?
Is it possible for the PR to be merged in the near future? Or when should we expect it? :)

Thanks!

[amerjusupovic]

@danyltsiv Hello! Our current plan is to merge and release this in about a month, but I can't say for certain. The PR is part of a couple changes that we are prioritizing for that timeline. Yes, it should remove any existing bugs related to the incorrect label overriding an existing label. In your example, if two flags exist for a key, only the one with a label should appear.