appsettings.Development.json

cs

public class InjectorData
    {
        public static void RegisterServices(IConfiguration Configuration, IServiceCollection services)
        {
            //Database
            string conn = Configuration.GetConnectionString("SQLDatabase");
            var username = Environment.GetEnvironmentVariable("username");
            var password = Environment.GetEnvironmentVariable("password");
            var host = Environment.GetEnvironmentVariable("HOST");
            conn = $"Host={host};User ID={username};Password={password};{conn}";
            
            if (string.IsNullOrEmpty(username) || string.IsNullOrEmpty(password) || string.IsNullOrEmpty(host))
            {
              throw new ArgumentNullException("conn");
            }
            .
            .
            .
        }
    }

json

{
  "ConnectionStrings": {
    "SQLDatabase": "Port=5432;Database=Nome-do-banco;Persist Security Info=False;TrustServerCertificate=False;"
  },
  "Logging": {
    "Debug": {
      "LogLevel": {
        "Default": "Trace"
      }
    }
  }
}