VivaVictoria.Chaos 1.1.1-preview

VivaVictoria.Chaos

Universal version migration tool for .NET

Status

version 1.0.0-preview - unstable

Supported platforms:

• .NET Core 3.1
• .NET 5+

Structure

Chaos is simple database-independent migration tool. Independence from the DBMS and the connection method is achieved due to the following mechanism:
base tool class is Chaos, it manages process of migration and requires next components:

• ILogger for logging actions and SQL statements,
• IMigrator for receiving / saving metadata and applying migration scripts,
• IMigrationReader for reading list of migrations stored in MigrationInfo model.

In turn, some IMigrator or IMigrationReader implementations can be dependent on ISettings instance. ISettings provides ConnectionString and default MigrationMode.
MigrationMode is enum describing the migration mode:

• Default - default mode from ISettings
• One - run each migration and save metadata in one migration,
• None - do not use migrations.
  Note: MigrationMode is just recommendation and will be used only if IMigrator and DBMS supports specified mode.

Sample

Simple example with PostgreSQL, ConsoleLogger and Reflection reader:

var services = new ServiceCollection()

//register settings
services.AddTransient<ISettings, Settings>();
//register PostgreSQL or other RDBMS driver
services.RegisterChaosPostgres();
//register ConsoleLogger or other ILogger
services.RegisterChaosConsoleLogger();
            
//add Reflection support with project Assembly
services.RegisterChaosReflection(typeof(Program).Assembly);

Now you can request IChaos service and run migrations.

//build chaos via DI container            
using (var scope = services.BuildServiceProvider())
{
    var chaos = scope.GetRequiredService<IChaos>();
    chaos.Init().Up();
}

Data Race on replicated services

Problem

Let's imagine a situation in which our service is implemented in a Docker container with replication.
In most cases, one of the replicas will start before the others and perform migrations. However, there may be cases when replicas are started simultaneously, or the migration process is too long and several replicas have time to start the migration. In this case, all replicas will receive an error due to the race condition.

Usual solution

Usual solution is running migration as a part of CI/CD pipeline - your CI/CD tool runs migration and then, if database migrated successfully, containers will be updated.

Chaos solution

Chaos provides you possibility to skip migrations if some condition is not met:

using (var scope = services.BuildServiceProvider())
{
    chaos
        .Init(() => !string.IsNullOrEmpty(System.Environment.GetEnvironmentVariable("REPLICA_MASTER")))
        .Up();
}

Now, define environment variable REPLICA_MASTER only on your master replica container. All other replicas will be skipped.
Note: it is not ideal solution, because some of your replicas can be available before database will be migrated and some requests to database may be failed. But if you use blue-green deploy with 'usual' solution you can receive same errors when blue container is still exists and green container runs migrations. Blue container can fail on database requests.

Total nuget packages list

VivaVictoria.Chaos
VivaVictoria.Chaos.Logging
VivaVictoria.Chaos.Logging.Console
VivaVictoria.Chaos.ClickHouse
VivaVictoria.Chaos.Dapper
VivaVictoria.Chaos.PostgreSQL
VivaVictoria.Chaos.SqlServer
VivaVictoria.Chaos.RawSql
VivaVictoria.Chaos.Reflection

Contributing

1. If you creates new project, please follow the following structure:

• Extensions - all static classes with extension methods
• Interfaces - for public project interfaces
• Models - for all models
• Enums - for all enums
• Service implementations and readme.md should be placed in project root

2. Please, throw Exceptions only if you receive fatal error and need to abort migration process.
3. Support readme actuality and create samples for new projects.