Is there a way to run EF Core RC2 tools from published DLL?
Unfortunately EF Core migration s*cks, a lot... I have seen tons of solutions for this but lets do a list of them. So here is what you can do to run and deploy EF migrations without Visual Studio. None of the below is perfect solution all have some caveats:
- Use EF Core Tools here is a link to the official MS site which explains how to install and use it.
- Pros: MS official tool. Supported in all version of .NET Core.
- Cons: It seems like the successor of EF6 "Migrate.exe". But it is not! Currently it is not possible to use this tool without the actual source code (.csproj). Which is not really a good fit for Live/Prod deployments. Usually you don't have C# projects on your DB Server.
- dotnet exec I have tried to make sense of the huge amount of poorly documented parameters. And failed to run migrations until found this script. The name suggest .NET core 2.1 but I have used it with 3.0 and worked. UPDATE: did not run it with .NET 5
- Pros: It can be used like EF6 "migrate.exe". Finally migration works without the source code. And most probably this is the only way to do migration from script and using an Assembly.
- Cons: Very hard to set up the script, and easy to miss one parameter. Not really documented solution and might change .NET Core version to version. Also most probably you will need to change your code as well. You have to implement
IDesignTimeDbContextFactory<DbContext>interface in order to make it work. Also make sure you have EF.dll and Microsoft.EntityFrameworkCore.Design.dll on your deploy server. The linked script is looking for those in numerous folders. Best is to copy it during build from your .nuget folders to your artifact. Sounds complicated, yes it is... But linked script helps a lot.
- Add EF migration to your Startup.cs or any point where your code start running and has access to a DBContext. Use
dbContext.Database.Migrate();
- Pros: Migrations happens automatically every time and nothing else had to be done.
- Cons: Migrations happens automatically every time... The problem you might don't want to that happen. Also it will run on every App start. So your startup time will be very bad.
- Custom app. It is similar to the previous solution (point 3.). So you use .NET code to run migration. But instead of putting it into your app you should create a small console app and call migrate in that one. You have to build this app and put into the Artifact to run it during the deployment.
- Pros: No script involved. You can call it any time in your deployment pipeline. So your real app startup time not suffers from it.
- Cons: You have to maintain, build and package an application just to do EF Core migrations.
- If you are using Azure Devops for deploy, you can use extension like this. Or just search Azure Devops Marketplace for one.
- Pros: it should work :) Haven't tried any of them and don't know what they do. (I'm pretty sure they are also using 'dotnet exec' point 2.)
- Cons: Not everyone can have access to Live/Prod from Azure Devops.
- Generate SQL script: If none of the above works you can generate a migration SQL and run it later. Run EF tool with "script" param:
dotnet ef migrations script --output <pathAndFile>.sql --context <DbContextName> --idempotent. The output is an SQL file which can be executed manually or by a script in CI/CD pipeline.
- Pros: it is perfect solution if you don't have access or schema change rights to prod DB only DBAs. You can provide DBAs with a "safe and secure" SQL file to run...
- Cons: very important to emphasize this solution must run in working dir where your
.csprojfile is. So it requires source code! Also you have to change your code a bit. Need to implementIDesignTimeDbContextFactory<DbContext>.
UPDATE: In .NET 5 there is some improvements. It is now easier to implement and make use of IDesignTimeDbContextFactory but most importantly Microsoft fixed this bug. Now it is possible to pass an SQL connection string as args. So if you implemented IDesignTimeDbContextFactory<T> it is simple to use it with .NET CLI and EF tool:
dotnet ef database update --context <DbContextName> --project "**/<ProjectName>.csproj" -- "<SQL connection will be passed into args[0]>"
Also important to emphasize this works only with .NET 5 and requires source code as well! You can also use it with Option 6 (generate SQL script).
Second annoying issue once implemented IDesignTimeDbContextFactory<T> this will be discovered by ALL ef commands (even commands run from Visual Studio during development). If you require SQL connection string from args[0] you have to pass it in during development migrations add or for any other ef command!
Sorry the list got very long. But hope it helps.
I ended up in the same problem on a project but for several reasons I don't want migrations to run automatically on application boot.
To solve it I updated Program.cs to take two arguments (full code is listed below)
--ef-migrate, to apply all pending migrations, and--ef-migrate-check, to validate if all migrations have been applied
If arguments are present then the EF actions are applied and the program exits, otherwise the web application is launched.
Please note that it depends on the Microsoft.Extensions.CommandLineUtils package to ease the command line parsing.
For octopus deploy one can then publish the package twice to seperate locations - one for running migrations and the other for webhosting. In our case, we added a "post deploy powershell script" with the content
$env:ASPNETCORE_ENVIRONMENT="#{Octopus.Environment.Name}"
dotnet example-app.dll --ef-migrate
In a docker context it would work perfectly too
docker run -it "example-app-container" dotnet example-app.dll --ef-migrate
Full Program.cs excluding namespace and usings:
//Remember to run: dotnet add package Microsoft.Extensions.CommandLineUtils
public class Program
{
public static void Main(string[] args)
{
var commandLineApplication = new CommandLineApplication(false);
var doMigrate = commandLineApplication.Option(
"--ef-migrate",
"Apply entity framework migrations and exit",
CommandOptionType.NoValue);
var verifyMigrate = commandLineApplication.Option(
"--ef-migrate-check",
"Check the status of entity framework migrations",
CommandOptionType.NoValue);
commandLineApplication.HelpOption("-? | -h | --help");
commandLineApplication.OnExecute(() =>
{
ExecuteApp(args, doMigrate, verifyMigrate);
return 0;
});
commandLineApplication.Execute(args);
}
private static void ExecuteApp(string[] args, CommandOption doMigrate, CommandOption verifyMigrate)
{
Console.WriteLine("Loading web host");
//
// Please note that this webHostBuilder below is from an older
// dotnet core version. Newer dotnet cores have a simplified version
// Use that instead and just take the command line parsing stuff with you
var webHost = new WebHostBuilder()
.UseKestrel()
.UseContentRoot(Directory.GetCurrentDirectory())
.UseIISIntegration()
.UseStartup<Startup>()
.Build();
if (verifyMigrate.HasValue() && doMigrate.HasValue())
{
Console.WriteLine("ef-migrate and ef-migrate-check are mutually exclusive, select one, and try again");
Environment.Exit(2);
}
if (verifyMigrate.HasValue())
{
Console.WriteLine("Validating status of Entity Framework migrations");
using (var serviceScope = webHost.Services.GetRequiredService<IServiceScopeFactory>().CreateScope())
{
using (var context = serviceScope.ServiceProvider.GetService<DatabaseContext>())
{
var pendingMigrations = context.Database.GetPendingMigrations();
var migrations = pendingMigrations as IList<string> ?? pendingMigrations.ToList();
if (!migrations.Any())
{
Console.WriteLine("No pending migratons");
Environment.Exit(0);
}
Console.WriteLine("Pending migratons {0}", migrations.Count());
foreach (var migration in migrations)
{
Console.WriteLine($"\t{migration}");
}
Environment.Exit(3);
}
}
}
if (doMigrate.HasValue())
{
Console.WriteLine("Applyting Entity Framework migrations");
using (var serviceScope = webHost.Services.GetRequiredService<IServiceScopeFactory>().CreateScope())
{
using (var context = serviceScope.ServiceProvider.GetService<DatabaseContext>())
{
context.Database.Migrate();
Console.WriteLine("All done, closing app");
Environment.Exit(0);
}
}
}
// no flags provided, so just run the webhost
webHost.Run();
}
}
There is an extremely useful post with a solution to this problem here.
It worked for me (I had to tweak the commands a little bit, but it gave me a good basis to start).
In sum: you can replicate the dotnet ef database update command by passing the ef.dll (e.g. directly from your nuget folder (or from somewhere else if you don’t have nuget, since you are on a prod machine..)) with your .dll containing the migrations with some additional parameters (see below) to dotnet.exe (or the linux equivalent).
For completeness here is the .cmd (also from the blogpost!)
set EfMigrationsNamespace=%1
set EfMigrationsDllName=%1.dll
set EfMigrationsDllDepsJson=%1.deps.json
set DllDir=%cd%
set PathToNuGetPackages=%USERPROFILE%\.nuget\packages
set PathToEfDll=%PathToNuGetPackages%\microsoft.entityframeworkcore.tools.dotnet\1.0.0\tools\netcoreapp1.0\ef.dll
dotnet exec --depsfile .\%EfMigrationsDllDepsJson% --additionalprobingpath %PathToNuGetPackages% %PathToEfDll% database update --assembly .\%EfMigrationsDllName% --startup-assembly .\%EfMigrationsDllName% --project-dir . --content-root %DllDir% --data-dir %DllDir% --verbose --root-namespace %EfMigrationsNamespace%
(A bash version if this cmd is in the blogpost)
Btw. this approach was also mentioned in many github issues: https://github.com/aspnet/EntityFramework.Docs/issues/328 https://github.com/aspnet/EntityFramework.Docs/issues/180
ps: I found this in the blog of Ben Day, so all credit goes to Ben!