Connecting to the Server

Once you have the Luna server up and running, you are ready to create a client connection.

First, you need to know the address (host:port) where the server is running. This document will assume the values 127.0.0.1:9001, but these can be replaced with your server address in actual code.

Default Connection

The following code snippet connects to the server and queries its version. It uses our recommended default setup, expecting the server to be listening on a TLS encrypted connection.

package main

import (
	"context"
	"fmt"
	"log"

	"github.com/cobaltspeech/sdk-luna/grpc/go-luna"
)

const serverAddr = "127.0.0.1:9001"

func main() {
	client, err := luna.NewClient(serverAddr)
	if err != nil {
		log.Fatal(err)
	}

	// Be sure to close the client when we are done with it.
	defer client.Close()

	version, err := client.Version(context.Background()).Version
	if err != nil {
		log.Fatal(err)
	}

	fmt.Println(version)
}

from luna.client import LunaClient

client = LunaClient(service_address="localhost:9001")
version = client.Version().version
print("Luna version {}".format(version))

// File - main.cpp

#include "luna_client.h"

#include <iostream>
#include <string>

const char* serverAddr = "127.0.0.1:9001";

int main(int argc, char *argv[])
{
	LunaClient client(serverAddr, true);
	std::string version = client.lunaVersion();
	std::cout << "Luna version: " << version << std::endl;

	return 0;
}

Insecure Connection

It is sometimes required to connect to Luna server without TLS enabled (during debugging, for example). Note that if the server has TLS enabled, attempting to connect with an insecure client will fail.

To create an insecure connection, do the following when creating the client:

client, err := luna.NewClientWithInsecure(serverAddr)

client = LunaClient.with_insecure(service_address="localhost:9001")

LunaClient client(serverAddr, false);

Client Authentication

In our recommended default setup, TLS is enabled in the gRPC setup, and when connecting to the server, clients validate the server’s SSL certificate to make sure they are talking to the right party. This is similar to how “https” connections work in web browsers.

In some setups, it may be desired that the server should also validate clients connecting to it and only respond to the ones it can verify. If your Luna server is configured to do client authentication, you will need to present the appropriate certificate and key when connecting to it.

Please note that in the client-authentication mode, the client will still also verify the server’s certificate, and therefore this setup uses mutually authenticated TLS. This can be done with:

// certfile is a path to the ssl certificate file
certfile="/path/to/cert.pem"
client, err := luna.NewClientWithCertFile(serverAddr, certfile)

# certfile is a path to the ssl certificate file
certfile="/path/to/cert.pem"
client = LunaClient.with_cert_file(service_address="localhost:9001",
                                   certfile=certfile)

// Currently unsupported in C++.