Generate OpenAPI documents on build throws DirectoryNotFoundException when application calls 'Directory.SetCurrentDirectory(AppContext.BaseDirectory)'

[wu-yafeng]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

Generate OpenAPI documents on build (dotnet build) throws DirectoryNotFoundException when application called Directory.SetCurrentDirectory(AppContext.BaseDirectory)

Expected Behavior

No exception thrown.

Steps To Reproduce

dotnet new webapi -n test-webapi
cd .\test-webapi\
dotnet add package Microsoft.Extensions.ApiDescription.Server

open Program.cs and insert Directory.SetCurrentDirectory(AppContext.BaseDirectory) at first line.

dotnet build

Exceptions (if any)

test-webapi 失败，出现 9 错误 (1.3) → bin\Debug\net9.0\test-webapi.dll
C:\Users\xxxxx.nuget\packages\microsoft.extensions.apidescription.server\9.0.3\build\Microsoft.Extensions.ApiDescription.Server.targets(68,5): error : System.IO.DirectoryNotFoundException: Could not find a part of the path 'C:\Users\xxxxxx\source\repos\xxx\test-webapi\bin\Debug\net9.0\obj\test-webapi.OpenApiFiles.cache'.

.NET Version

9.0.200

Anything else?

Backgrounds:

I have a webapi that run as windows services and access Sqlite database. The connection string is configured in appsettings.json like Data Source=./mydb.db.

The database file is always stored in C:/Windows/System32 due to application is running under system process.

Call Directory.SetCurrentDirectory(AppContext.BaseDirectory) so that database file willbe saved at application content directory.

[martincostello]

The OpenAPI build tooling has to execute your application to retrieve the OpenAPI document, so it will also execute anything your application does on startup.

The best approach is to detect that scenario in some way (for example the value of ASPNETCORE_ENVIRONMENT or some other environment variable, or through configuration) and avoid doing the operation that causes the exception, or change the configuration so it behaves differently in that scenario.

[qfyra]

Many of the things you usually do in Program.cs will cause this issue during build. It's not a fringe issue, it happens often. It's high time Microsoft addresses it properly, "by design" or not, because this issue isn't gonna go away on its own. The community has already supplied Microsoft with plenty of reproducible examples.

[martincostello]

I agree this is a bit of a pit of failure, but there are ways to unblock usage.

The issues are mostly fundamental to the way the tool is designed (i.e. it has to run your code to get the document, it's not possible to do statically) so I don't think there's much that can be done here as a "bug fix".

I'm sure @captainsafia has plenty of ideas on how to move this forward in .NET 10 and beyond. There's various conversation on the topic of the OpenAPI tool in #57044.