From 6c2731071dc9e3ced467d50bf18fa93b645320c4 Mon Sep 17 00:00:00 2001
From: Joseph Milazzo <joseph.v.milazzo@gmail.com>
Date: Wed, 19 Jan 2022 15:03:47 -0800
Subject: [PATCH] Migration Safety (#967)

* Updated EF version

* When we perform a migration, backup the database to temp/migration/VERSION and do it only once in case a migration fails.

* When a migration fails, we will now restore what was corrupted.
---
 API/API.csproj |  6 +++---
 API/Program.cs | 42 ++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 43 insertions(+), 5 deletions(-)

diff --git a/API/API.csproj b/API/API.csproj
index fbf15067e..759f1ae86 100644
--- a/API/API.csproj
+++ b/API/API.csproj
@@ -49,13 +49,13 @@
     <PackageReference Include="MarkdownDeep.NET.Core" Version="1.5.0.4" />
     <PackageReference Include="Microsoft.AspNetCore.Authentication.JwtBearer" Version="6.0.1" />
     <PackageReference Include="Microsoft.AspNetCore.Authentication.OpenIdConnect" Version="6.0.1" />
-    <PackageReference Include="Microsoft.AspNetCore.Identity.EntityFrameworkCore" Version="6.0.0" />
+    <PackageReference Include="Microsoft.AspNetCore.Identity.EntityFrameworkCore" Version="6.0.1" />
     <PackageReference Include="Microsoft.AspNetCore.SignalR" Version="1.1.0" />
-    <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="6.0.0">
+    <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="6.0.1">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
-    <PackageReference Include="Microsoft.EntityFrameworkCore.Sqlite" Version="6.0.0" />
+    <PackageReference Include="Microsoft.EntityFrameworkCore.Sqlite" Version="6.0.1" />
     <PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="6.0.0" />
     <PackageReference Include="Microsoft.IO.RecyclableMemoryStream" Version="2.2.0" />
     <PackageReference Include="NetVips" Version="2.1.0" />
diff --git a/API/Program.cs b/API/Program.cs
index 4ed8ce56a..286a0f0cd 100644
--- a/API/Program.cs
+++ b/API/Program.cs
@@ -62,7 +62,15 @@ namespace API
                 if (pendingMigrations.Any())
                 {
                     logger.LogInformation("Performing backup as migrations are needed. Backup will be kavita.db in temp folder");
-                    directoryService.CopyFileToDirectory(directoryService.FileSystem.Path.Join(directoryService.ConfigDirectory, "kavita.db"), directoryService.TempDirectory);
+                    var migrationDirectory = await GetMigrationDirectory(context, directoryService);
+                    directoryService.ExistOrCreate(migrationDirectory);
+
+                    if (!directoryService.FileSystem.File.Exists(
+                            directoryService.FileSystem.Path.Join(migrationDirectory, "kavita.db")))
+                    {
+                        directoryService.CopyFileToDirectory(directoryService.FileSystem.Path.Join(directoryService.ConfigDirectory, "kavita.db"), migrationDirectory);
+                        logger.LogInformation("Database backed up to {MigrationDirectory}", migrationDirectory);
+                    }
                 }
 
                 await context.Database.MigrateAsync();
@@ -82,12 +90,42 @@ namespace API
             catch (Exception ex)
             {
                 var logger = services.GetRequiredService<ILogger<Program>>();
-                logger.LogCritical(ex, "An error occurred during migration");
+                var context = services.GetRequiredService<DataContext>();
+                var migrationDirectory = await GetMigrationDirectory(context, directoryService);
+
+                logger.LogCritical(ex, "A migration failed during startup. Restoring backup from {MigrationDirectory} and exiting", migrationDirectory);
+                directoryService.CopyFileToDirectory(directoryService.FileSystem.Path.Join(migrationDirectory, "kavita.db"), directoryService.ConfigDirectory);
+
+                return;
             }
 
             await host.RunAsync();
         }
 
+        private static async Task<string> GetMigrationDirectory(DataContext context, IDirectoryService directoryService)
+        {
+            string currentVersion = null;
+            try
+            {
+                currentVersion =
+                    (await context.ServerSetting.SingleOrDefaultAsync(s =>
+                        s.Key == ServerSettingKey.InstallVersion))?.Value;
+            }
+            catch
+            {
+                // ignored
+            }
+
+            if (string.IsNullOrEmpty(currentVersion))
+            {
+                currentVersion = "vUnknown";
+            }
+
+            var migrationDirectory = directoryService.FileSystem.Path.Join(directoryService.TempDirectory,
+                "migration", currentVersion);
+            return migrationDirectory;
+        }
+
         private static IHostBuilder CreateHostBuilder(string[] args) =>
             Host.CreateDefaultBuilder(args)
                 .ConfigureAppConfiguration((hostingContext, config) =>