Stop EF Core creating expensive Azure SQL Database configurations on start up & auto connection string builder based on Git branch

ConnectionStringBuilder.cs

using Enis.Domain.Abstractions.StartupServices;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;

public interface IConnectionStringBuilder
{
	string GetApplicationConnectionString();
}

public class ConnectionStringBuilder : IConnectionStringBuilder
{
	private readonly IConfiguration _configuration;
	private readonly IHostingEnvironment _hostingEnvironment;
	private readonly IGitBranchFinder _gitBranchFinder;

	public ConnectionStringBuilder(IConfiguration configuration, IHostingEnvironment hostingEnvironment, IGitBranchFinder gitBranchFinder)
	{
		_configuration = configuration;
		_hostingEnvironment = hostingEnvironment;
		_gitBranchFinder = gitBranchFinder;
	}

	public string GetApplicationConnectionString()
	{
		string connString = _configuration.GetConnectionString("YOUR_CONNECTION_STRING_APPSETTING"); ;

		// If no connection string set in Environment Variables or app setttings, and running locally, guess with branch:
		if (connString == null && _hostingEnvironment.IsEnvironment("Local"))
		{
			connString = GetDevelopmentDatabaseConnectionString();
		}

		return connString;
	}

	private string GetDevelopmentDatabaseConnectionString()
	{
		string branchNameLastPart = _gitBranchFinder.GetBranchNameLastPart();
		string password = _configuration.GetValue<string>("YOUR_DEV_SQL_SERVER_PASSWORD")
		return 
			$"Server=tcp:[*your Azure SQL Server*].database.windows.net,1433;Initial Catalog=[*your dev DB prefix convention*]-{branchNameLastPart};Persist Security Info=False;User ID=[*your-user-id*];Password={password};MultipleActiveResultSets=False;Encrypt=True;TrustServerCertificate=False;Connection Timeout=30;";            
	}
}

DevelopmentDatabaseCreator.cs

using System.Data.SqlClient;
using System.Linq;


public interface IDevelopmentDatabaseCreator
{
	void CreateDevelopmentDatabase(string connectionString);
}


public class DevelopmentDatabaseCreator : IDevelopmentDatabaseCreator
{
	public void CreateDevelopmentDatabase(string connectionString)
	{
		var builder = new SqlConnectionStringBuilder(connectionString);
		string dbToCreate = builder.InitialCatalog;

		string masterDbConnectionString = connectionString.Replace(dbToCreate, "master"); // Ideally would use the SqlConnectionStringBuilder to just replace the db name with master, but when the ConnectionString property is called on the builder it always returns a connection string with a DataSource=... property instead of Server=..., which for some reason doesn't work on Azure

		using (var conn = new SqlConnection(masterDbConnectionString))
		{
			conn.Open();
			using (var command = new SqlCommand())
			{
				command.Connection = conn;
				CheckDbName(dbToCreate); // You can't use parameters when using SQL DDL like CREATE DATABASE, so have to validate SQL manually
				command.CommandTimeout = 60;
				command.CommandText = $@" 

				IF NOT EXISTS (SELECT * FROM sys.databases WHERE name = '{dbToCreate}')
				BEGIN
					CREATE DATABASE [{dbToCreate}] (
					MAXSIZE=2 GB,
					EDITION='Standard',
					SERVICE_OBJECTIVE='S0') 
				END";

				command.ExecuteNonQuery();
			}
		}
	}

	private void CheckDbName(string dbName)
	{
		if (dbName.Any(c => !(Char.IsLetterOrDigit(c) || c == '-')))
		{
			throw new Exception("DB name is invalid");
		}
	}
}

GitBranchFinder.cs

using System;
using System.Diagnostics;

public interface IGitBranchFinder
{
	string GetFullBranchName();
	string GetBranchNameLastPart();
}

public class GitBranchFinder : IGitBranchFinder
{
	public string GetFullBranchName()
	{
		ProcessStartInfo startInfo = new ProcessStartInfo("git.exe");

		startInfo.UseShellExecute = false;
		startInfo.WorkingDirectory = Environment.CurrentDirectory;
		startInfo.RedirectStandardInput = true;
		startInfo.RedirectStandardOutput = true;
		startInfo.Arguments = "rev-parse --abbrev-ref HEAD";

		using (var process = new Process())
		{
			process.StartInfo = startInfo;
			process.Start();

			string branchname = process.StandardOutput.ReadLine();

			return branchname;
		}
	}

	public string GetBranchNameLastPart()
	{
		string fullBranchName = GetFullBranchName();
		return fullBranchName.Contains("/") ? fullBranchName.Remove(0, fullBranchName.LastIndexOf('/') + 1) : fullBranchName;
	}
}

Startup.cs

public class Startup
{
	public Startup(IConfiguration configuration, IHostingEnvironment appEnv)
	{
		_configuration = configuration;
		_currentEnvironment = appEnv;
	}

	public IConfiguration _configuration;

	private IHostingEnvironment _currentEnvironment { get; set; }

	// This method gets called by the runtime. Use this method to add services to the container.
	public void ConfigureServices(IServiceCollection services)
	{
		
		//Startup services
		services.AddSingleton<IHostingEnvironment>(_currentEnvironment);
		services.AddTransient<IConnectionStringBuilder, ConnectionStringBuilder>();
		services.AddTransient<IGitBranchFinder, GitBranchFinder>();
		services.AddTransient<IDevelopmentDatabaseCreator, DevelopmentDatabaseCreator>();

		var sp = services.BuildServiceProvider();

		var connectionStringBuilder = sp.GetService<IConnectionStringBuilder>();
		var connString = connectionStringBuilder.GetApplicationConnectionString();
		

		services.AddDbContext<AppDbContext>(o =>
			o.UseSqlServer(
				connString
			));
		

	}


	// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
	public void Configure(IApplicationBuilder app, AppDbContext dbContext, IDevelopmentDatabaseCreator devDatabaseCreator, IConnectionStringBuilder connectionStringBuilder)
	{
		// ...after the rest of your app configuration:
		if(_currentEnvironment.IsDevelopment() || _currentEnvironment.IsEnvironment("Local")) 
		{
			var connString = connectionStringBuilder.GetApplicationConnectionString();
			devDatabaseCreator.CreateDevelopmentDatabase(connString); 
		}
		
		dbContext.Database.Migrate();
		
	}
}