Managing Auto Creation of Database or Message Broker Resources in the Critter Stack vNext

If you’d prefer to start with more context, skip to the section named “Why is this important?”.

To set up the problem I’m hoping to address in this post, there are several settings across both Marten and Wolverine that need to be configured for the most optimal possible functioning between development, testing, and deployment time — but yet, some of these settings are done different ways today or have to be done independently for both Marten and Wolverine.

Below is a proposed configuration approach for Marten, Wolverine, and future “Critter” tools with the Marten 8 / Wolverine 4 “Critter Stack 2025” wave of releases:

        var builder = Host.CreateApplicationBuilder();
        
        // This would apply to both Marten, Wolverine, and future critters....
        builder.Services.AddJasperFx(x =>
        {
            // This expands in importance to be the master "AutoCreate"
            // over every resource at runtime and not just databases
            // So this would maybe take the place of AutoProvision() in Wolverine world too
            x.Production.AutoCreate = AutoCreate.None;
            x.Production.GeneratedCodeMode = TypeLoadMode.Static;
            x.Production.AssertAllPreGeneratedTypesExist = true;
            
            // Just for completeness sake, but these are the defaults
            x.Development.AutoCreate = AutoCreate.CreateOrUpdate;
            x.Development.GeneratedCodeMode = TypeLoadMode.Dynamic;

            // Unify the Marten/Wolverine/future critter application assembly
            // Default will always be the entry assembly
            x.ApplicationAssembly = typeof(Message1).Assembly;
        });
        
        // keep bootstrapping...

If you’ve used either Marten or Wolverine for production usages, you know that you probably want to turn off the dynamic code generation at production time, and you might choose to also turn off the automatic database migrations for both Marten and Wolverine in production (or not, I’ve been surprised how many folks are happy to just let the tools manage database schemas).

The killer problem for us today, is that the settings above have to be configured independently for both Marten and Wolverine — and as a bad coincidence, I just chatted with someone on Discord who got burned by this as I was starting this post. Grr.

Even worse, the syntactical options for disabling automatic database management for Wolverine’s envelope storage tables is a little different syntax altogether. And then just to make things more fun — and please cut the Critter Stack community and I some slack because all of this evolved over years — the “auto create / migrate / evolve” functionality for like Rabbit MQ queues/exchanges/bindings or Kafka topics is “opt in” instead of “opt out” like the automatic database migrations are with a completely different syntax and naming than either the Marten or Wolverine tables as shown with the AutoProvision() option below:

using var host = await Host.CreateDefaultBuilder()
    .UseWolverine(opts =>
    {
        opts.UseRabbitMq(rabbit => { rabbit.HostName = "localhost"; })
            // I'm declaring an exchange, a queue, and the binding
            // key that we're referencing below.
            // This is NOT MANDATORY, but rather just allows Wolverine to
            // control the Rabbit MQ object lifecycle
            .DeclareExchange("exchange1", ex => { ex.BindQueue("queue1", "key1"); })

            // This will direct Wolverine to create any missing Rabbit MQ exchanges,
            // queues, or binding keys declared in the application at application
            // start up time
            .AutoProvision();

        opts.PublishAllMessages().ToRabbitExchange("exchange1");
    }).StartAsync();

I’m not married to the syntax per se, but my proposal is that:

• Every possible type of “stateful resource” (database configurations or message brokers or whatever we might introduce in the future) by default follows the AutoCreate settings in one place, which for right now is in the AddJasperFx() method (should this be named something else? ConfigureJasperFx(), ConfigureCritterStack() ????
• You can override this at either the Marten or Wolverine levels, or within Wolverine, maybe you use the default behavior for the application for all database management, but turn down Azure Service Bus to AutoCreate.None.
• We’ll use the AutoCreate enumeration that originated in Marten, but will now move down to a lower level shared library to define the level for each resource
• All resource types will have a default setting of AutoCreate.CreateOrUpdate, even message brokers. This is to move the tools into more of a “it just works” out of the box developer experience. This will make the usage of AutoProvision() in Wolverine unnecessary unless you want to override the AutoCreate settings
• We deprecate the OptimizeArtifactWorkflow() mechanisms that never really caught on, and instead let folks just set potentially different settings for “Development” vs “Production” time, and let the tools apply the right settings based on the IHostEnvironment.Environment name so you don’t have to clutter up your code with too many ugly if (builder.Environment.IsDevelopment() ... calls.

Just for some context, the AutoCreate values are below:

public enum AutoCreate
{
    /// <summary>
    ///     Will drop and recreate tables that do not match the Marten configuration or create new ones
    /// </summary>
    All,

    /// <summary>
    ///     Will never destroy existing tables. Attempts to add missing columns or missing tables
    /// </summary>
    CreateOrUpdate,

    /// <summary>
    ///     Will create missing schema objects at runtime, but will not update or remove existing schema objects
    /// </summary>
    CreateOnly,

    /// <summary>
    ///     Do not recreate, destroy, or update schema objects at runtime. Will throw exceptions if
    ///     the schema does not match the Marten configuration
    /// </summary>
    None
}

For longstanding Critter Stack users, we’ll absolutely keep:

• The existing “stateful resource” model, including the resources command line helper for setting up or tearing down resource dependencies
• The existing db-* command line tooling
• The IServiceCollection.AddResourceSetupOnStartup() method for forcing all resources (databases and broker objects) to be correctly built out on application startup
• The existing Marten and Wolverine settings for configuring the AutoCreate levels, but these will be marked as [Obsolete]
• The existing Marten and Wolverine settings for configuring the code generation TypeLoadMode, but the default values will come from the AddJasperFx() options and the Marten or Wolverine options will be marked as [Obsolete]

Why is this important?

An important part of building, deploying, and maintaining an enterprise system with server side tooling like the “Critter Stack” (Marten, Wolverine, and their smaller sibling Weasel that factors quite a bit into this blog post) is dealing with creating or migrating database schema objects or message broker resources so that your application can function as expected against its infrastructure dependencies.

As any of you know who have ever walked into the development of an existing enterprise system, it’s often challenging to get your local development environment configured for that system — and that can frequently cause you days and I’ve even seen weeks of delay. What if instead you could simply start fresh with a clean clone of the code repository and be up and running very quickly?

If you pick up Marten for the first time today, spin up a brand new PostgreSQL database where you have full admin rights, and write this code it would happily work without you doing any explicit work to migrate the new PostgreSQL database:

public class Customer
{
    public Guid Id { get; set; }

    // We'll use this later for some "logic" about how incidents
    // can be automatically prioritized
    public Dictionary<IncidentCategory, IncidentPriority> Priorities { get; set; }
        = new();

    public string? Region { get; set; }

    public ContractDuration Duration { get; set; }
}

public record ContractDuration(DateOnly Start, DateOnly End);

public enum IncidentCategory
{
    Software,
    Hardware,
    Network,
    Database
}

public enum IncidentPriority
{
    Critical,
    High,
    Medium,
    Low
}

await using var store = DocumentStore
    .For("Host=localhost;Port=5432;Database=marten_testing;Username=postgres;password=postgres");

var customer = new Customer
{
    Duration = new ContractDuration(new DateOnly(2023, 12, 1), new DateOnly(2024, 12, 1)),
    Region = "West Coast",
    Priorities = new Dictionary<IncidentCategory, IncidentPriority>
    {
        { IncidentCategory.Database, IncidentPriority.High }
    }
};

// IDocumentSession is Marten's unit of work 
await using var session = store.LightweightSession();
session.Store(customer);
await session.SaveChangesAsync();

// Marten assigned an identity for us on Store(), so 
// we'll use that to load another copy of what was 
// just saved
var customer2 = await session.LoadAsync<Customer>(customer.Id);

// Just making a pretty JSON printout
Console.WriteLine(JsonConvert.SerializeObject(customer2, Formatting.Indented));

Instead, with its default settings, Marten is able to quietly check if its underlying database has all the necessary database tables, functions, sequences, and schemas for whatever it needs roughly when it needs it for the first time. The whole point of this functionality is to ensure that a new developer coming into your project for the very first time can quickly clone your repository, and be up and running either the whole system or even just integration tests that hit the database immediately because Marten is able to “auto-migrate” database changes for you so you can just focus on getting work done.

Great, right? Except that sometimes you certainly wouldn’t want this “auto-migration” business going. Maybe because the system doesn’t have permissions, or maybe just to make the system spin up faster without the overhead of calculating the necessity of a migration step (it’s not cheap, especially for something like a Serverless usage where you depend on fast cold starts). Either way, you’d like to be able to turn that off at production time with the assumption that you’re applying database changes beforehand (which the Critter Stack has worlds of tools to help with as well), so you’ll turn off the default behavior something like the following with Marten 7 and before:

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddMarten(opts =>
    {
        // Other configuration...

        // In production, let's turn off all the automatic database
        // migration stuff
        if (builder.Environment.IsProduction())
        {
            opts.AutoCreateSchemaObjects = AutoCreate.None;
        }
    })
    // Add background projection processing
    .AddAsyncDaemon(DaemonMode.HotCold)
    // This is a mild optimization
    .UseLightweightSessions();

Wolverine uses the same underlying Weasel helper library to make automatic database migrations that Marten does, and works similarly, but disabling the automatic database setup is different for reasons I don’t remember:

using var host = await Host.CreateDefaultBuilder()
    .UseWolverine(opts =>
    {
        // Disable automatic database migrations for message
        // storage
        opts.AutoBuildMessageStorageOnStartup = false;
    }).StartAsync();

Wolverine can do similar automatic management of Rabbit MQ, Azure Service Bus, AWS SQS, Kafka, Pulsar, or Google Pubsub objects at runtime, but in this case you have to explicitly “opt in” to that automatic management through the fluent interface registration of a message broker like this sample using Google Pubsub:

        var host = await Host.CreateDefaultBuilder()
            .UseWolverine(opts =>
            {
                opts.UsePubsub("your-project-id")

                    // Let Wolverine create missing topics and subscriptions as necessary
                    .AutoProvision()

                    // Optionally purge all subscriptions on application startup.
                    // Warning though, this is potentially slow
                    .AutoPurgeOnStartup();
            }).StartAsync();