start-redis-in-c#

// in startup.cs
using StackExchange.Redis;

public void ConfigureServices(IServiceCollection services)
{
  ConfigurationOptions options = new ConfigurationOptions()
  {
    EndPoints = { { "remote.server.url", 6380 } },
    Ssl = true,
    Password = "password"
  };
  ConnectionMultiplexer connection = ConnectionMultiplexer.ConnectAsync(options).GetAwaiter().GetResult();
  IDatabase db = connection.GetDatabase();
  services.AddScoped<IDatabase>(_ => db);
}

// in namespace
using StackExchange.Redis;

namespace MyProject.MyNamespace
{
  public interface IRedisService
  {
    Task<string> HandleRedisKey(RedisKey key, string val);
  }
  public class MyClass : IRedisService
  {
    private readonly IDatabase db;
    public MyClass(IDatabase db)
    {
      this.db = db;
    }
    public async Task<string> HandleRedisKey(RedisKey key, string val)
    {
      RedisValue redisValue = await db.StringGetAsync(key);
      if (redisValue.HasValue)
      {
        return redisValue;
      }
      else
      {
        db.StringSet(key, val);
        return val;
      }
    }
  }
}