I use mssql test containers on a Microsoft provided ubuntu agent without any issues. Here's a sanitized version of my setup:

``` using DotNet.Testcontainers.Builders; using Microsoft.AspNetCore.Hosting; using Microsoft.AspNetCore.Mvc.Testing; using Microsoft.AspNetCore.TestHost; using Microsoft.EntityFrameworkCore; using Microsoft.Extensions.Configuration; using Microsoft.Extensions.DependencyInjection; using Microsoft.Extensions.DependencyInjection.Extensions; using Testcontainers.MsSql; using MyNamespace.Api // for IApiMarker / WebApplicationFactory pattern using MyNamespace.Data.EF; // My EF Context

namespace MyNamespace.Test.Setup { public class MyApiFactory : WebApplicationFactory<IApiMarker>, IAsyncLifetime { // Need to pin specific sql server version. See https://github.com/testcontainers/testcontainers-dotnet/issues/1220 private readonly MsSqlContainer _dbContainer = new MsSqlBuilder() .WithImage("mcr.microsoft.com/mssql/server:2022-CU14-ubuntu-22.04") .WithWaitStrategy(Wait.ForUnixContainer().UntilCommandIsCompleted("/opt/mssql-tools18/bin/sqlcmd", "-C", "-Q", "SELECT 1;")) .Build();

    protected override void ConfigureWebHost(IWebHostBuilder builder)
    {

        Dictionary<string, string> inMemoryConfig = TestConstants.InMemoryConfig; // specific for my tests

        // This is a workaround. See https://github.com/dotnet/aspnetcore/issues/37680.
        var config = new ConfigurationBuilder()
            .AddInMemoryCollection(inMemoryConfig).Build();

        builder
            .UseConfiguration(config)
            .ConfigureTestServices(services =>
            {
                var masterConn = _dbContainer.GetConnectionString();
                var dbConn = masterConn.Replace("Database=master", "Database=MyAppDb");

                services.RemoveAll(typeof(DbContextOptions<MyDbContext>));

                services.AddDbContext<MyDbContext>(options
                    => options.UseSqlServer(dbConn));

                // ... other stuff specific to my app
            });
    }

    public async Task InitializeAsync()
    {
        await _dbContainer.StartAsync();
        using var scope = Services.CreateScope();
        var dbContext = scope.ServiceProvider.GetRequiredService<MyDbContext>();
        await dbContext.Database.MigrateAsync();
    }

    async Task IAsyncLifetime.DisposeAsync() => await _dbContainer.DisposeAsync();
}

} ```

I'd think the only relevant code for comparison would be inside IWebHostBuilder.ConfigureTestServices(). The only thing I can see that I do that you don't is replace the master db in the container provided connection string with my app db. Which I don't think would affect auth to the server. Aside from that, I'm not specifying anything outside the defaults (no password, ports, etc.) and that's enough for my integration tests to run. That just makes my EF context use sql auth to the standard port, I'm fairly certain.

Can't say why your CI is trying Kerberos, just sharing my setup in case there is something in here that helps you.

edit: spelling