Run Migrations Handler Usage

[toddjudd]

Hey! Awesome template.

I'm trying to use some of this applying it to an app bootstrapped with create-t3-app. I'm struggling to understand the prisma sst setup though. I've pulled over the network, layer, database, and databaseMigrations stacks. but I'm failing to understand migration stack. the migrationFunction constructor references a src/repo/runMigrations.handler which doesn't exist. Is this file generated, or should it be created in advance? What's it's purpose?

const migrationFunction = new Function(this, 'MigrationScriptLambda', {
      vpc,
      enableLiveDev: false,
      handler: 'src/repo/runMigrations.handler',
      layers: [migrationLayer],
      copyFiles: [
        { from: 'prisma/schema.prisma' },
        { from: 'prisma/migrations' },
        { from: 'prisma/schema.prisma', to: 'src/repo/schema.prisma' },
        { from: 'prisma/migrations', to: 'src/repo/migrations' },
        { from: 'package.json', to: 'src/package.json' },
      ],

      nodejs: {
        format: 'cjs',
        esbuild: { external: [...(migrationLayer.externalModules || [])] },
      },
      timeout: '3 minutes',
      environment: {
        DB_SECRET_ARN: dbSecretsArn,
      },
    });