CreateConnectionString.cs

var host = Configuration.GetValue<string>("host");
var database = Configuration.GetValue<string>("database");
var port = Configuration.GetValue<string>("port");
var username = Configuration.GetValue<string>("username");
var password = Configuration.GetValue<string>("password");

var connectionString =
    $"Server={host},{port};Database={database};User={username};Password={password};";

services.AddDbContext<ProductsContext>(options =>
    options.UseSqlServer(connectionString));