# Connect to the server

```json metadata
{
  "schema_version": 2,
  "title": "Connect to the server",
  "description": "Connect your Python application to a Redis database",
  "categories": ["docs","develop","stack","oss","rs","rc","oss","kubernetes","clients"],
  "tableOfContents": {"sections":[{"id":"basic-connection","title":"Basic connection"},{"id":"connect-to-a-redis-cluster","title":"Connect to a Redis cluster"},{"id":"connect-to-redis-sentinel","title":"Connect to Redis Sentinel"},{"id":"connect-to-your-production-redis-with-tls","title":"Connect to your production Redis with TLS"}]}

,
  "codeExamples": []
}
```


## Basic connection

Connect to localhost on port 6379:

```js
const redis = new Redis();
```

You can also specify a full set of connection options:

```js
const redis = new Redis({
  port: 6379,
  host: "127.0.0.1",
  username: "default",
  password: "my-password",
  db: 0,
});
```

> [!NOTE]
> ioredis supports [connection URLs](https://redis.io/docs/latest/develop/clients/connection-urls#ioredis-javascript) through the `Redis` constructor.
> A URL can set the host, port, credentials, database, and whether to use TLS,
> so you can use one instead of passing those options separately.

Store and retrieve a simple string.

```js
await redis.set('foo', 'bar');
const value = await redis.get('foo');
console.log(value); // >>> bar
```

## Connect to a Redis cluster

To connect to a Redis cluster, use `Redis.Cluster()`, passing an array of
endpoints.

```js
const redis = new Redis.Cluster([
    {
        host: '127.0.0.1',
        port: 6380,
        password: 'my-password',
        username: 'default',
    },
    {
        host: '127.0.0.1',
        port: 6381,
        password: 'my-other-password',
        username: 'default',
    },
    // ...
]);
```

## Connect to Redis Sentinel

To connect through [Redis Sentinel](https://redis.io/docs/latest/operate/oss_and_stack/management/sentinel),
pass a list of Sentinels in the `sentinels` option and the name of the primary that the
Sentinels monitor in `name`. The client asks the Sentinels for the current primary.

```js
const redis = new Redis({
  sentinels: [
    { host: "localhost", port: 26379 },
    { host: "localhost", port: 26380 },
    { host: "localhost", port: 26381 },
  ],
  name: "mymaster",
});

await redis.set('foo', 'bar');
const value = await redis.get('foo');
console.log(value); // >>> bar
```

The Sentinels and the data nodes have separate credentials. Set `sentinelPassword` (and
`sentinelUsername`, if needed) for the Sentinels, and `username` and `password` for the
primary and replicas:

```js
const redis = new Redis({
  sentinels: [
    { host: "localhost", port: 26379 },
    { host: "localhost", port: 26380 },
    { host: "localhost", port: 26381 },
  ],
  name: "mymaster",
  // Credentials for the Sentinel instances.
  sentinelPassword: "my-sentinel-password",
  // Credentials for the primary and replica data nodes.
  username: "default",
  password: "my-password",
});
```

If the Sentinel password is wrong or missing, the error says that all Sentinels are
unreachable.

By default, ioredis doesn't listen for failover announcements from the Sentinels. After a
failover, the client keeps using the old primary until Sentinel reconfigures it as a
replica and closes the connection. Any writes that the old primary accepts during that time
are lost. Set `failoverDetector: true` to switch to the new primary as soon as the Sentinels
announce it.

To connect to a replica instead of the primary, set `role: "slave"`. The client connects to
one replica, chosen at random. Replication is asynchronous, so a replica can return stale
data.

```js
const replica = new Redis({
  sentinels: [{ host: "localhost", port: 26379 }],
  name: "mymaster",
  role: "slave",
});
```

## Connect to your production Redis with TLS

When you deploy your application, use TLS and follow the [Redis security](https://redis.io/docs/latest/operate/oss_and_stack/management/security) guidelines.

```js
const redis = new Redis({
  host: "localhost",
  //...
  tls: {
    key: readFileSync('./redis_user_private.key'),
    cert: readFileSync('./redis_user.crt'),
    ca: fs.readFileSync('./redis_ca.pem'),
  },
});
```