---
title: "Client.connect(address [,params]) | Grafana k6 documentation"
description: "Opens a connection to a gRPC server; will block until a connection is made or a connection error is thrown."
---

> For a curated documentation index, see [llms.txt](/llms.txt). For the complete documentation index, see [llms-full.txt](/llms-full.txt).

# Client.connect(address \[,params])

Opens a connection to a gRPC server; will block until a connection is made or a connection error is thrown. Cannot be called during the [`init` phase](/docs/k6/latest/using-k6/test-lifecycle/).

See [Client.close()](/docs/k6/latest/javascript-api/k6-net-grpc/client/client-close/) to close the connection.

Expand table

| Parameter         | Type   | Description                                                                                                                                                                                                                                                                                                                                                                                                                    |
|-------------------|--------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| address           | string | The address of the gRPC server. Should be in the form: `host:port` with no protocol prefix e.g. `grpc.k6.io:443`. The host must be a literal IP address, or a host name that can be resolved to IP addresses. The port must be a literal port number or a service name e.g. `:443` or `:https`. If the host is a literal IPv6 address it must be enclosed in square brackets, as in `[2001:db8::1]:80` or `[fe80::1%zone]:80`. |
| params (optional) | object | [ConnectParams](#connectparams) object containing additional connect parameters.                                                                                                                                                                                                                                                                                                                                               |

## ConnectParams

Expand table

| Name                            | Type            | Description                                                                                                                                                                          |
|---------------------------------|-----------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `ConnectParams.plaintext`       | bool            | If `true` will connect to the gRPC server using plaintext i.e. insecure. Defaults to `false` i.e. secure via TLS.                                                                    |
| `ConnectParams.reflect`         | boolean         | Whether to use the [gRPC server reflection protocol](https://github.com/grpc/grpc/blob/master/doc/server-reflection.md) when connecting.                                             |
| `ConnectParams.reflectMetadata` | object          | Object with key-value pairs representing custom metadata the user would like to add to the reflection request.                                                                       |
| `ConnectParams.timeout`         | string / number | Connection timeout to use. Default timeout is `"60s"`.  <br />The type can also be a number, in which case k6 interprets it as milliseconds, e.g., `60000` is equivalent to `"60s"`. |
| `ConnectParams.maxReceiveSize`  | number          | Sets the maximum message size in bytes the client can receive. Defaults to `grpc-go` default, which is 4MB.                                                                          |
| `ConnectParams.maxSendSize`     | number          | Sets the maximum message size in bytes the client can send. Defaults to `grpc-go` default, which is approximately 2GB.                                                               |
| `ConnectParams.tls` (optional)  | object          | [TLS](#tls) settings of the connection. Defaults to `null`.                                                                                                                          |

## TLS

TLS settings of the connection. If not defined, the main TLS config from options will be used.

Expand table

| Name           | Type           | Description                                           |
|----------------|----------------|-------------------------------------------------------|
| `tls.cert`     | string         | PEM formatted client certificate.                     |
| `tls.key`      | string         | PEM formatted client private key.                     |
| `tls.password` | string         | Password for decrypting the client’s private key.     |
| `tls.cacerts`  | string / array | PEM formatted strings of the certificate authorities. |

### Examples

JavaScript ![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy

```javascript
import grpc from 'k6/net/grpc';

const client = new grpc.Client();

export default () => {
  client.connect('localhost:8080');
};
```

JavaScript ![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy

```javascript
import grpc from 'k6/net/grpc';

const client = new grpc.Client();

export default () => {
  client.connect('localhost:8080', { plaintext: true });
};
```

JavaScript ![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy

```javascript
import grpc from 'k6/net/grpc';
import { check } from 'k6';
import { SharedArray } from 'k6/data';
import exec from 'k6/execution';

// note: the services in this example don't exist. If you would like
// to run this example, make sure to replace the URLs, and
// the cacerts, cert, key, and password variables.
const grpcArgs = new SharedArray('grpc', () => {
  // Using SharedArray here so that not every VU gets a copy of every certificate a key
  return [
    {
      host: 'foo1.grpc-quickpizza.grafana.com:443',
      plaintext: false,
      params: {
        tls: {
          cacerts: [open('cacerts0.pem')],
          cert: open('cert0.pem'),
          key: open('key0.pem'),
        },
      },
    },
    {
      host: 'foo2.grpc-quickpizza.grafana.com:443',
      params: {
        plaintext: false,
        tls: {
          cacerts: open('cacerts1.pem'),
          cert: open('cert1.pem'),
          key: open('key1.pem'),
          password: 'cert1-passphrase',
        },
      },
    },
  ];
});

const client = new grpc.Client(null, 'quickpizza.proto');

export default () => {
  if (__ITER === 0) {
    // Take one config and use it for this one VU
    const grpcArg = grpcArgs[exec.vu.idInTest % grpcArgs.length];
    client.connect(grpcArg.host, grpcArg.params);
  }

  const response = client.invoke('quickpizza.GRPC/Status');

  check(response, {
    'status is OK': (r) => r && r.status === grpc.StatusOK,
  });

  console.log(JSON.stringify(response.message));
};
```