Schema management with DB migrations

[lngr]

The following popped up in this thread: https://twitter.com/jeremydmiller/status/1487071742472462341

I mentioned we are using DbUp for schema migrations. Here is what we do on application startup (Program.cs). It's very simple, but works great for us:

using (var scope = host.Services.CreateScope())
{
    var services = scope.ServiceProvider;
    var config = services.GetRequiredService<IConfiguration>();

    // DB migrations with DbUp
    var migrationsDir = Path.Combine(Path.GetDirectoryName(GetType().Assembly.Location), "Migrations");
    Directory.CreateDirectory(migrationsDir);

    var upgrader = DeployChanges.To
        .PostgresqlDatabase(config.GetConnectionString("Default"))
        .AddLoggerFromServiceProvider(services)
        .WithScriptsFromFileSystem(migrationsDir)
        .WithVariablesDisabled()
        .JournalToPostgresqlTable("public", "__DBUpMigrations")
        .Build();
    var result = upgrader.PerformUpgrade();
    if (!result.Successful)
    {
        Console.Error.WriteLine("DB Update failed");
        Environment.Exit(1);
    }

    // creating martenStore not shown

    try
    {
        await martenStore.Schema.AssertDatabaseMatchesConfigurationAsync();
    }
    catch
    {
        if (services.GetRequiredService<IWebHostEnvironment>().IsDevelopment())
        {
            var dir = Path.Combine(Path.GetDirectoryName(GetType().Assembly.Location), "..", "..",
                "ProjectDirectory",
                "Migrations");
            var file = Path.Combine(dir, $"{DateTime.UtcNow:yyyy-MM-dd_HHmmss}-unnamed.sql");
            var patch = martenStore.Schema.ToPatch(true, true);
            patch.WriteUpdateFile(file, true);
            Console.Error.WriteLine("Please review database changes");
            Environment.Exit(1);
        }
    }
}

So basically, if some developer implements some changes that changes Marten's schema, upon the next startup the application will write out a patch file to the DbUp "Migrations" directory and stop. The developer can then review the change and add the file to Git. On the next run, the schema update is applied.