Add message for FeatureUnavailableException #3402

eliykat · 2023-11-02T05:30:39Z

Type of change

- [ ] Bug fix
- [ ] New feature development
- [x] Tech debt (refactoring, code cleanup, dependency upgrades, etc)
- [ ] Build/deploy pipeline (DevOps)
- [ ] Other

Objective

Add a separate message for FeatureUnavailableException to help with debugging, both while developing and if a customer stumbles across it in prod.

As noted in the xml comment, it is not intended that a user ever sees this; it indicates that we've messed up our client-side feature flagging logic. However, that is helpful to know!

Code changes

file.ext: Description of what was changed and why

Before you submit

Please check for formatting errors (dotnet format --verify-no-changes) (required)
If making database changes - make sure you also update Entity Framework queries and/or migrations
Please add unit tests where it makes sense to do so (encouraged but not required)
If this change requires a documentation update - notify the documentation team
If this change has particular deployment requirements - notify the DevOps team

bitwarden-bot · 2023-11-02T06:01:25Z

Checkmarx One – Scan Summary & Details – 194d714b-cac6-40ff-a64a-6fd8438e728e

No New Or Fixed Issues Found

withinfocus

You can still move to NotFoundObjectResult per our discussion if you'd like too. I see a few good ideas at https://stackoverflow.com/questions/20139621/how-do-i-return-notfound-ihttpactionresult-with-an-error-message-or-exception.

withinfocus · 2023-11-02T13:57:24Z

src/Api/Utilities/ExceptionHandlerFilterAttribute.cs

@@ -82,6 +82,11 @@ public override void OnException(ExceptionContext context)
            errorMessage = "Resource not found.";
            context.HttpContext.Response.StatusCode = 404;
        }
+        else if (exception is FeatureUnavailableException)
+        {
+            errorMessage = "This feature is not available.";


🎨 If you want a custom message you can just put this in the exception class below -- set its Message via the base constructor.

This handler is to override messages, results, etc. for exceptions we don't own.

Not sure this is right - we own NotFoundException, for example, and many others in this if...else if block.

The message given to the constructor will still be included in the error response if it's running in dev mode: https://github.com/bitwarden/server/blob/feature-unavailable-exception-improvements/src/Api/Utilities/ExceptionHandlerFilterAttribute.cs#L133-L141. But this provides a guaranteed user-appropriate message for production use.

This does suggest that these properties should just be on the custom Exception object though; this long if...else if block is basically polymorphic behaviour.

I am unsure how far to go in this PR in refactoring this class, or what direction it even needs to go in. (Part of a larger problem where we routinely throw in the service layer for control flow.)

NotFoundException is ours from inheritance yes, but I mean it has a way to set the message on the base. Why not keep FeatureUnavailableException inheriting that and inside that class set the static "This feature is not available." message; FeatureUnavailableException stays parameterless in its constructor.

The status code will still be set.

…-exception-improvements

withinfocus · 2023-11-22T15:50:40Z

src/Api/Utilities/ExceptionHandlerFilterAttribute.cs

@@ -82,6 +82,11 @@ public override void OnException(ExceptionContext context)
            errorMessage = "Resource not found.";
            context.HttpContext.Response.StatusCode = 404;
        }
+        else if (exception is FeatureUnavailableException)


❌ The current state of this PR has FeatureUnavailableException unused.

It's still used in CollectionsController and CollectionAuthorizationHandler. We've used those as guards at the top of feature-flagged methods, e.g.

if (flagEnabled) { callnewMethod(); } public void newMethod() { // just to make sure noone calls this accidentally... if (!flagEnabled) { throw FeatureUnavailableException(); } // etc etc }

That is maybe overkill and misuse of the exception. What do you think? Maybe we should just remove this use of it and rely on unit testing instead, then we don't need the exception at all.

If your approach to set the result is working well I think it's best to use it everywhere and drop any inconsistent usages.

withinfocus · 2023-11-22T15:52:44Z

src/Core/Utilities/RequireFeatureAttribute.cs

@@ -30,7 +31,7 @@ public override void OnActionExecuting(ActionExecutingContext context)

        if (!featureService.IsEnabled(_featureFlagKey, currentContext))
        {
-            throw new FeatureUnavailableException();
+            context.Result = new NotFoundObjectResult("This feature is unavailable.");


❓ If this setting of the result is acceptable to our middleware and everything works as expected we'd be complete with this change here, but per previous comments it isn't in our situation right? If we can make it move that way that's great, but I thought we need an exception to throw.

I've tested this and confirm that it returns a 404 error with the message. It also short-circuits any remaining action filters (docs).

I thought you were suggesting that we use a NotFoundObjectResult instead of throwing an exception (for the reasons discussed in #architecture, i.e. exceptions are expensive and maybe our current pattern is not a great one). This change would start moving us in this direction, although at the expense of mixing patterns.

If we mix patterns but this is the recommended way and we'd eventually want to move everything to it, I support the mixing.

withinfocus · 2023-11-22T15:53:10Z

test/Core.Test/Utilities/RequireFeatureAttributeTests.cs

+        // Assert
+        Assert.IsType<NotFoundObjectResult>(context.Result);
+        var result = (NotFoundObjectResult)context.Result;
+        Assert.Contains("This feature is unavailable", (string)result.Value);


❓ Do we need to assert error messages in tests?

It's our current practice. In this case (for example), it ensures that the NotFoundObjectResult is the one I expect and not for some other reason (a false negative).

eliykat · 2024-07-12T02:25:26Z

This is pretty old by this point and has never come up again, so I'm leaving it be.

Add message for FeatureUnavailableException

f3c2f29

eliykat requested a review from a team as a code owner November 2, 2023 05:30

withinfocus requested changes Nov 2, 2023

View reviewed changes

eliykat added 2 commits November 22, 2023 13:14

Merge remote-tracking branch 'origin/master' into feature-unavailable…

a9025d8

…-exception-improvements

Return NotFoundObjectResult instead of throwing exception

8f76c70

eliykat requested a review from withinfocus November 22, 2023 03:54

eliykat added 2 commits November 22, 2023 14:11

Update tests

4cfebd9

Make error wording consistent

328b0c2

withinfocus requested changes Nov 22, 2023

View reviewed changes

eliykat marked this pull request as draft April 17, 2024 01:40

eliykat closed this Jul 12, 2024

eliykat deleted the feature-unavailable-exception-improvements branch July 12, 2024 02:25

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Add message for FeatureUnavailableException #3402

Add message for FeatureUnavailableException #3402

eliykat commented Nov 2, 2023

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eliykat commented Jul 12, 2024

Add message for FeatureUnavailableException #3402

Add message for FeatureUnavailableException #3402

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eliykat commented Nov 2, 2023

Type of change

Objective

Code changes

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No New Or Fixed Issues Found

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eliykat commented Jul 12, 2024

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