Integrate the Azure Cosmos DB for Gremlin with Service Connector

Article
02/05/2024

This page shows supported authentication methods and clients, and shows sample code you can use to connect Azure Cosmos DB for Apache Gremlin to other cloud services using Service Connector. You might still be able to connect to Azure Cosmos DB for Gremlin in other programming languages without using Service Connector. This page also shows default environment variable names and values you get when you create the service connection.

Supported compute services

Service Connector can be used to connect the following compute services to Azure Cosmos DB for Apache Gremlin:

Azure App Service
Azure Functions
Azure Container Apps
Azure Spring Apps

Supported authentication types and client types

The table below shows which combinations of client types and authentication methods are supported for connecting your compute service to Azure Cosmos DB for Apache Gremlin using Service Connector. A “Yes” indicates that the combination is supported, while a “No” indicates that it is not supported.

Client type	System-assigned managed identity	User-assigned managed identity	Secret / connection string	Service principal
.NET	Yes	Yes	Yes	Yes
Java	Yes	Yes	Yes	Yes
Node.js	Yes	Yes	Yes	Yes
PHP	Yes	Yes	Yes	Yes
Python	Yes	Yes	Yes	Yes
Go	Yes	Yes	Yes	Yes
None	Yes	Yes	Yes	Yes

This table indicates that all combinations of client types and authentication methods in the table are supported. All client types can use any of the authentication methods to connect to Azure Cosmos DB for Apache Gremlin using Service Connector.

Default environment variable names or application properties and sample code

Use the connection details below to connect your compute services to Azure Cosmos DB for Apache Gremlin. For each example below, replace the placeholder texts <Azure-Cosmos-DB-account>, <database>, <collection or graphs>, <username>, <password>, <resource-group-name>, <subscription-ID>, <client-ID>,<client-secret>, and <tenant-id> with your own information. For more information about naming conventions, check the Service Connector internals article.

System-assigned managed identity

Default environment variable name	Description	Example value
AZURE_COSMOS_LISTKEYURL	The URL to get the connection string	`https://management.azure.com/subscriptions/<subscription-ID>/resourceGroups/<resource-group-name>/providers/Microsoft.DocumentDB/databaseAccounts/<Azure-Cosmos-DB-account>/listKeys?api-version=2021-04-15`
AZURE_COSMOS_SCOPE	Your managed identity scope	`https://management.azure.com/.default`
AZURE_COSMOS_RESOURCEENDPOINT	Your resource endpoint	`https://<Azure-Cosmos-DB-account>.documents.azure.com:443/`
AZURE_COSMOS_HOSTNAME	Your Gremlin Unique Resource Identifier (UFI)	`<Azure-Cosmos-DB-account>.gremlin.cosmos.azure.com`
AZURE_COSMOS_PORT	Connection port	443
AZURE_COSMOS_USERNAME	Your username	`/dbs/<database>/colls/<collection or graphs>`

Sample code

Refer to the steps and code below to connect to Azure Cosmos DB for Gremlin using a system-assigned managed identity.

Install dependencies.

dotnet add package Gremlin.Net
dotnet add package Azure.Identity

Get an access token for the managed identity or service principal using client library Azure.Identity. Use the access token and AZURE_COSMOS_LISTKEYURL to get the password. Get the connection information from the environment variables added by Service Connector and connect to Azure Cosmos DB for Apache Gremlin. When using the code below, uncomment the part of the code snippet for the authentication type you want to use.

using System;
using System.Security.Authentication;
using System.Net.Security;
using System.Net.Http;
using System.Security.Authentication;
using System.Threading.Tasks;
using System;
using Gremlin.Net.Driver;
using Azure.Identity;

var gremlinEndpoint = Environment.GetEnvironmentVariable("AZURE_COSMOS_RESOURCEENDPOINT");
var userName = Environment.GetEnvironmentVariable("AZURE_COSMOS_USERNAME");
var gremlinPort = Int32.Parse(Environment.GetEnvironmentVariable("AZURE_COSMOS_PORT"));
var listKeyUrl = Environment.GetEnvironmentVariable("AZURE_COSMOS_LISTKEYURL");
var scope = Environment.GetEnvironmentVariable("AZURE_COSMOS_SCOPE");

// Uncomment the following lines according to the authentication type.
// For system-assigned identity.
// var tokenProvider = new DefaultAzureCredential();

// For user-assigned identity.
// var tokenProvider = new DefaultAzureCredential(
//     new DefaultAzureCredentialOptions
//     {
//         ManagedIdentityClientId = Environment.GetEnvironmentVariable("AZURE_COSMOS_CLIENTID");
//     }
// );

// For service principal.
// var tenantId = Environment.GetEnvironmentVariable("AZURE_COSMOS_TENANTID");
// var clientId = Environment.GetEnvironmentVariable("AZURE_COSMOS_CLIENTID");
// var clientSecret = Environment.GetEnvironmentVariable("AZURE_COSMOS_CLIENTSECRET");
// var tokenProvider = new ClientSecretCredential(tenantId, clientId, clientSecret);

// Acquire the access token. 
AccessToken accessToken = await tokenProvider.GetTokenAsync(
    new TokenRequestContext(scopes: new string[]{ scope }));

// Get the password.
var httpClient = new HttpClient();
httpClient.DefaultRequestHeaders.Add("Authorization", $"Bearer {accessToken.Token}");
var response = await httpClient.POSTAsync(listKeyUrl);
var responseBody = await response.Content.ReadAsStringAsync();
var keys = JsonConvert.DeserializeObject<Dictionary<string, string>>(responseBody);
var password = keys["primaryMasterKey"];

// Connect to Azure Cosmos DB for Apache Gremlin
var server = new GremlinServer(
    hostname: gremlinEndpoint,
    port: gremlinPort,
    username: userName,
    password: password,
    enableSsl: true
);

using var client = new GremlinClient(
    gremlinServer: server,
    messageSerializer: new Gremlin.Net.Structure.IO.GraphSON.GraphSON2MessageSerializer()
);

Add the following dependencies in your pom.xml file:

<dependency>
  <groupId>org.apache.tinkerpop</groupId>
  <artifactId>gremlin-driver</artifactId>
  <version>3.4.13</version>
</dependency>
<dependency>
    <groupId>com.azure</groupId>
    <artifactId>azure-identity</artifactId>
    <version>1.1.5</version>
</dependency>

Get an access token for the managed identity or service principal using azure-identity. Use the access token and AZURE_COSMOS_LISTKEYURL to get the password. Get the connection information from the environment variables added by Service Connector and connect to Azure Cosmos DB for Apache Gremlin. When using the code below, uncomment the part of the code snippet for the authentication type you want to use.

import org.apache.tinkerpop.gremlin.driver.Client;
import org.apache.tinkerpop.gremlin.driver.Cluster;
import javax.net.ssl.*;
import java.net.InetSocketAddress;
import com.azure.identity.*;
import com.azure.core.credentital.*;
import java.net.http.*;
import java.net.URI;

int gremlinPort = Integer.parseInt(System.getenv("AZURE_COSMOS_PORT"));
String username = System.getenv("AZURE_COSMOS_USERNAME");
String gremlinEndpoint = System.getenv("AZURE_COSMOS_RESOURCEENDPOINT");
String listKeyUrl = System.getenv("AZURE_COSMOS_LISTKEYURL");
String scope = System.getenv("AZURE_COSMOS_SCOPE");

// Uncomment the following lines according to the authentication type.
// For system managed identity.
// DefaultAzureCredential defaultCredential = new DefaultAzureCredentialBuilder().build();

// For user assigned managed identity.
// DefaultAzureCredential defaultCredential = new DefaultAzureCredentialBuilder()
//     .managedIdentityClientId(System.getenv("AZURE_COSMOS_CLIENTID"))
//     .build();

// For service principal.
// ClientSecretCredential defaultCredential = new ClientSecretCredentialBuilder()
//   .clientId(System.getenv("AZURE_COSMOS_CLIENTID"))
//   .clientSecret(System.getenv("AZURE_COSMOS_CLIENTSECRET"))
//   .tenantId(System.getenv("AZURE_COSMOS_TENANTID"))
//   .build();

// Get the access token.
AccessToken accessToken = defaultCredential.getToken(new TokenRequestContext().addScopes(new String[]{ scope })).block();
String token = accessToken.getToken();

// Get the password.
HttpClient client = HttpClient.newBuilder().build();
HttpRequest request = HttpRequest.newBuilder()
    .uri(new URI(listKeyUrl))
    .header("Authorization", "Bearer " + token)
    .POST()
    .build();
HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
JSONParser parser = new JSONParser();
JSONObject responseBody = parser.parse(response.body());
String gremlinPassword = responseBody.get("primaryMasterKey");

// Connect to Azure Cosmos DB for Apache Gremlin
Cluster cluster;
Client client;

cluster = Cluster.addContactPoint(gremlinEndpoint).port(gremlinPort).credentials(username, password).create();

Install dependencies.
```
pip install gremlinpython
```

Use azure-identity to authenticate with the managed identity or service principal and send request to AZURE_COSMOS_LISTKEYURL to get the password. Get the connection information from the environment variables added by Service Connector and connect to Azure Cosmos DB for Apache Gremlin. When using the code below, uncomment the part of the code snippet for the authentication type you want to use.

from gremlin_python.driver import client, serializer
import requests
from azure.identity import ManagedIdentityCredential, ClientSecretCredential

username = os.getenv('AZURE_COSMOS_USERNAME')
endpoint = os.getenv('AZURE_COSMOS_RESOURCEENDPOINT')
port = os.getenv('AZURE_COSMOS_PORT')
listKeyUrl = os.getenv('AZURE_COSMOS_LISTKEYURL')
scope = os.getenv('AZURE_COSMOS_SCOPE')

# Uncomment the following lines according to the authentication type.
# For system-assigned managed identity
# cred = ManagedIdentityCredential()

# For user-assigned managed identity
# managed_identity_client_id = os.getenv('AZURE_COSMOS_CLIENTID')
# cred = ManagedIdentityCredential(client_id=managed_identity_client_id)

# For service principal
# tenant_id = os.getenv('AZURE_COSMOS_TENANTID')
# client_id = os.getenv('AZURE_COSMOS_CLIENTID')
# client_secret = os.getenv('AZURE_COSMOS_CLIENTSECRET')
# cred = ClientSecretCredential(tenant_id=tenant_id, client_id=client_id, client_secret=client_secret)

# Get the password 
session = requests.Session()
token = cred.get_token(scope)
response = session.post(listKeyUrl, headers={"Authorization": "Bearer {}".format(token.token)})
keys_dict = response.json()
password = keys_dict['primaryMasterKey']

# Connect to Azure Cosmos DB for Apache Gremlin.
client = client.Client(
    url=endpoint,
    traversal_source="g",
    username=username,
    password=password,
    message_serializer=serializer.GraphSONSerializersV2d0(),
)

Install dependencies.

go get github.com/Azure/azure-sdk-for-go/sdk/azidentity
go get github.com/go-gremlin/gremlin

In code, get the access token using azidentity, then use it to acquire the password. Get connection information from the environment variable added by Service Connector and connect to Azure Cosmos DB for Apache Gremlin. When using the code below, uncomment the part of the code snippet for the authentication type you want to use.

import (
    "fmt"
    "os"
    "context"
    "log"
    "io/ioutil"
    "encoding/json"

    "github.com/go-gremlin/gremlin"
    "github.com/Azure/azure-sdk-for-go/sdk/azidentity"
)

func main() {
    username = os.Getenv("AZURE_COSMOS_USERNAME")
    endpoint = os.getenv("AZURE_COSMOS_RESOURCEENDPOINT")
    port = os.getenv("AZURE_COSMOS_PORT")
    listKeyUrl = os.Getenv("AZURE_COSMOS_LISTKEYURL")
    scope = os.Getenv("AZUE_COSMOS_SCOPE")

    // Uncomment the following lines according to the authentication type.
    // For system-assigned identity.
    // cred, err := azidentity.NewDefaultAzureCredential(nil)

    // For user-assigned identity.
    // clientid := os.Getenv("AZURE_COSMOS_CLIENTID")
    // azidentity.ManagedIdentityCredentialOptions.ID := clientid
    // options := &azidentity.ManagedIdentityCredentialOptions{ID: clientid}
    // cred, err := azidentity.NewManagedIdentityCredential(options)

    // For service principal.
    // clientid := os.Getenv("AZURE_COSMOS_CLIENTID")
    // tenantid := os.Getenv("AZURE_COSMOS_TENANTID")
    // clientsecret := os.Getenv("AZURE_COSMOS_CLIENTSECRET")
    // cred, err := azidentity.NewClientSecretCredential(tenantid, clientid, clientsecret, &azidentity.ClientSecretCredentialOptions{})

    // Acquire the access token.
    ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
    token, err := cred.GetToken(ctx, policy.TokenRequestOptions{
        Scopes: []string{scope},
    })

    // Acquire the connection string.
    client := &http.Client{}
    req, err := http.NewRequest("POST", listKeyUrl, nil)
    req.Header.Add("Authorization", "Bearer " + token.Token)
    resp, err := client.Do(req)
    body, err := ioutil.ReadAll(resp.Body)
    var result map[string]interface{}
    json.Unmarshal(body, &result)
    password, err := result["primaryMasterKey"];

    auth := gremlin.OptAuthUserPass(username, password)
     client, err := gremlin.NewClient(endpoint, auth)
}

Install dependencies.

npm install gremlin
npm install --save @azure/identity

In code, get the access token using @azure/identity, then use it to acquire the password. Get connection information from the environment variable added by Service Connector and connect to Azure Cosmos DB for Apache Gremlin. When using the code below, uncomment the part of the code snippet for the authentication type you want to use.

import { DefaultAzureCredential,ClientSecretCredential } from "@azure/identity";
import gremlin from 'gremlin'
const axios = require('axios');

let username = process.env.AZURE_COSMOS_USERNAME;
let endoint = process.env.AZURE_COSMOS_RESOURCEENDPOINT;
let port = process.env.AZURE_COSMOS_PORT;
let listKeyUrl = process.env.AZURE_COSMOS_LISTKEYURL;
let scope = process.env.AZURE_COSMOS_SCOPE;

// Uncomment the following lines according to the authentication type.  
// For system-assigned identity.
// const credential = new DefaultAzureCredential();

// For user-assigned identity.
// const clientId = process.env.AZURE_COSMOS_CLIENTID;
// const credential = new DefaultAzureCredential({
//     managedIdentityClientId: clientId
// });

// For service principal.
// const tenantId = process.env.AZURE_COSMOS_TENANTID;
// const clientId = process.env.AZURE_COSMOS_CLIENTID;
// const clientSecret = process.env.AZURE_COSMOS_CLIENTSECRET;

// Acquire the access token.
var accessToken = await credential.getToken(scope);

// Get the password.
const config = {
    method: 'post',
    url: listKeyUrl,
    headers: { 
      'Authorization': `Bearer ${accessToken.token}`
    }
};
const response = await axios(config);
const keysDict = response.data;
const password = keysDict['primaryMasterKey'];

const credentials = new gremlin.driver.auth.PlainTextSaslAuthenticator(
  username,
  password
)

const client = new gremlin.driver.Client(
  endpoint,
  {
    credentials,
    traversalsource: 'g',
    rejectUnauthorized: true,
    mimeType: 'application/vnd.gremlin-v2.0+json'
  }
)

client.open()

Get an access token with a managed identity or a service principal to acquire the primary key of Azure Cosmos DB for Gremlin by calling REST API at AZURE_COSMOS_LISTKEYURL.

$endpoint = getenv('AZURE_COSMOS_RESOURCEENDPOINT');
$username = getenv('AZURE_COSMOS_USERNAME');
$port = getenv('AZURE_COSMOS_PORT');

$db = new Connection([
    'host' => $endpoint,
    'username' => $username,
    'password' => $password,
    'port' => $port,
    'ssl' => TRUE
]);

User-assigned managed identity

Default environment variable name	Description	Example value
AZURE_COSMOS_LISTKEYURL	The URL to get the connection string	`https://management.azure.com/subscriptions/<subscription-ID>/resourceGroups/<resource-group-name>/providers/Microsoft.DocumentDB/databaseAccounts/<Azure-Cosmos-DB-account>/listKeys?api-version=2021-04-15`
AZURE_COSMOS_SCOPE	Your managed identity scope	`https://management.azure.com/.default`
AZURE_COSMOS_RESOURCEENDPOINT	Your resource endpoint	`https://<Azure-Cosmos-DB-account>.documents.azure.com:443/`
AZURE_COSMOS_HOSTNAME	Your Gremlin Unique Resource Identifier (UFI)	`<Azure-Cosmos-DB-account>.gremlin.cosmos.azure.com`
AZURE_COSMOS_PORT	Connection port	443
AZURE_COSMOS_USERNAME	Your username	`/dbs/<database>/colls/<collection or graphs>`
AZURE_CLIENTID	Your client ID	`<client_ID>`

Sample code

Refer to the steps and code below to connect to Azure Cosmos DB for Gremlin using a user-assigned managed identity.

Install dependencies.

dotnet add package Gremlin.Net
dotnet add package Azure.Identity

using System;
using System.Security.Authentication;
using System.Net.Security;
using System.Net.Http;
using System.Security.Authentication;
using System.Threading.Tasks;
using System;
using Gremlin.Net.Driver;
using Azure.Identity;

var gremlinEndpoint = Environment.GetEnvironmentVariable("AZURE_COSMOS_RESOURCEENDPOINT");
var userName = Environment.GetEnvironmentVariable("AZURE_COSMOS_USERNAME");
var gremlinPort = Int32.Parse(Environment.GetEnvironmentVariable("AZURE_COSMOS_PORT"));
var listKeyUrl = Environment.GetEnvironmentVariable("AZURE_COSMOS_LISTKEYURL");
var scope = Environment.GetEnvironmentVariable("AZURE_COSMOS_SCOPE");

// Uncomment the following lines according to the authentication type.
// For system-assigned identity.
// var tokenProvider = new DefaultAzureCredential();

// For user-assigned identity.
// var tokenProvider = new DefaultAzureCredential(
//     new DefaultAzureCredentialOptions
//     {
//         ManagedIdentityClientId = Environment.GetEnvironmentVariable("AZURE_COSMOS_CLIENTID");
//     }
// );

// For service principal.
// var tenantId = Environment.GetEnvironmentVariable("AZURE_COSMOS_TENANTID");
// var clientId = Environment.GetEnvironmentVariable("AZURE_COSMOS_CLIENTID");
// var clientSecret = Environment.GetEnvironmentVariable("AZURE_COSMOS_CLIENTSECRET");
// var tokenProvider = new ClientSecretCredential(tenantId, clientId, clientSecret);

// Acquire the access token. 
AccessToken accessToken = await tokenProvider.GetTokenAsync(
    new TokenRequestContext(scopes: new string[]{ scope }));

// Get the password.
var httpClient = new HttpClient();
httpClient.DefaultRequestHeaders.Add("Authorization", $"Bearer {accessToken.Token}");
var response = await httpClient.POSTAsync(listKeyUrl);
var responseBody = await response.Content.ReadAsStringAsync();
var keys = JsonConvert.DeserializeObject<Dictionary<string, string>>(responseBody);
var password = keys["primaryMasterKey"];

// Connect to Azure Cosmos DB for Apache Gremlin
var server = new GremlinServer(
    hostname: gremlinEndpoint,
    port: gremlinPort,
    username: userName,
    password: password,
    enableSsl: true
);

using var client = new GremlinClient(
    gremlinServer: server,
    messageSerializer: new Gremlin.Net.Structure.IO.GraphSON.GraphSON2MessageSerializer()
);

Add the following dependencies in your pom.xml file:

<dependency>
  <groupId>org.apache.tinkerpop</groupId>
  <artifactId>gremlin-driver</artifactId>
  <version>3.4.13</version>
</dependency>
<dependency>
    <groupId>com.azure</groupId>
    <artifactId>azure-identity</artifactId>
    <version>1.1.5</version>
</dependency>

import org.apache.tinkerpop.gremlin.driver.Client;
import org.apache.tinkerpop.gremlin.driver.Cluster;
import javax.net.ssl.*;
import java.net.InetSocketAddress;
import com.azure.identity.*;
import com.azure.core.credentital.*;
import java.net.http.*;
import java.net.URI;

int gremlinPort = Integer.parseInt(System.getenv("AZURE_COSMOS_PORT"));
String username = System.getenv("AZURE_COSMOS_USERNAME");
String gremlinEndpoint = System.getenv("AZURE_COSMOS_RESOURCEENDPOINT");
String listKeyUrl = System.getenv("AZURE_COSMOS_LISTKEYURL");
String scope = System.getenv("AZURE_COSMOS_SCOPE");

// Uncomment the following lines according to the authentication type.
// For system managed identity.
// DefaultAzureCredential defaultCredential = new DefaultAzureCredentialBuilder().build();

// For user assigned managed identity.
// DefaultAzureCredential defaultCredential = new DefaultAzureCredentialBuilder()
//     .managedIdentityClientId(System.getenv("AZURE_COSMOS_CLIENTID"))
//     .build();

// For service principal.
// ClientSecretCredential defaultCredential = new ClientSecretCredentialBuilder()
//   .clientId(System.getenv("AZURE_COSMOS_CLIENTID"))
//   .clientSecret(System.getenv("AZURE_COSMOS_CLIENTSECRET"))
//   .tenantId(System.getenv("AZURE_COSMOS_TENANTID"))
//   .build();

// Get the access token.
AccessToken accessToken = defaultCredential.getToken(new TokenRequestContext().addScopes(new String[]{ scope })).block();
String token = accessToken.getToken();

// Get the password.
HttpClient client = HttpClient.newBuilder().build();
HttpRequest request = HttpRequest.newBuilder()
    .uri(new URI(listKeyUrl))
    .header("Authorization", "Bearer " + token)
    .POST()
    .build();
HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
JSONParser parser = new JSONParser();
JSONObject responseBody = parser.parse(response.body());
String gremlinPassword = responseBody.get("primaryMasterKey");

// Connect to Azure Cosmos DB for Apache Gremlin
Cluster cluster;
Client client;

cluster = Cluster.addContactPoint(gremlinEndpoint).port(gremlinPort).credentials(username, password).create();

Install dependencies.
```
pip install gremlinpython
```

from gremlin_python.driver import client, serializer
import requests
from azure.identity import ManagedIdentityCredential, ClientSecretCredential

username = os.getenv('AZURE_COSMOS_USERNAME')
endpoint = os.getenv('AZURE_COSMOS_RESOURCEENDPOINT')
port = os.getenv('AZURE_COSMOS_PORT')
listKeyUrl = os.getenv('AZURE_COSMOS_LISTKEYURL')
scope = os.getenv('AZURE_COSMOS_SCOPE')

# Uncomment the following lines according to the authentication type.
# For system-assigned managed identity
# cred = ManagedIdentityCredential()

# For user-assigned managed identity
# managed_identity_client_id = os.getenv('AZURE_COSMOS_CLIENTID')
# cred = ManagedIdentityCredential(client_id=managed_identity_client_id)

# For service principal
# tenant_id = os.getenv('AZURE_COSMOS_TENANTID')
# client_id = os.getenv('AZURE_COSMOS_CLIENTID')
# client_secret = os.getenv('AZURE_COSMOS_CLIENTSECRET')
# cred = ClientSecretCredential(tenant_id=tenant_id, client_id=client_id, client_secret=client_secret)

# Get the password 
session = requests.Session()
token = cred.get_token(scope)
response = session.post(listKeyUrl, headers={"Authorization": "Bearer {}".format(token.token)})
keys_dict = response.json()
password = keys_dict['primaryMasterKey']

# Connect to Azure Cosmos DB for Apache Gremlin.
client = client.Client(
    url=endpoint,
    traversal_source="g",
    username=username,
    password=password,
    message_serializer=serializer.GraphSONSerializersV2d0(),
)

Install dependencies.

go get github.com/Azure/azure-sdk-for-go/sdk/azidentity
go get github.com/go-gremlin/gremlin

import (
    "fmt"
    "os"
    "context"
    "log"
    "io/ioutil"
    "encoding/json"

    "github.com/go-gremlin/gremlin"
    "github.com/Azure/azure-sdk-for-go/sdk/azidentity"
)

func main() {
    username = os.Getenv("AZURE_COSMOS_USERNAME")
    endpoint = os.getenv("AZURE_COSMOS_RESOURCEENDPOINT")
    port = os.getenv("AZURE_COSMOS_PORT")
    listKeyUrl = os.Getenv("AZURE_COSMOS_LISTKEYURL")
    scope = os.Getenv("AZUE_COSMOS_SCOPE")

    // Uncomment the following lines according to the authentication type.
    // For system-assigned identity.
    // cred, err := azidentity.NewDefaultAzureCredential(nil)

    // For user-assigned identity.
    // clientid := os.Getenv("AZURE_COSMOS_CLIENTID")
    // azidentity.ManagedIdentityCredentialOptions.ID := clientid
    // options := &azidentity.ManagedIdentityCredentialOptions{ID: clientid}
    // cred, err := azidentity.NewManagedIdentityCredential(options)

    // For service principal.
    // clientid := os.Getenv("AZURE_COSMOS_CLIENTID")
    // tenantid := os.Getenv("AZURE_COSMOS_TENANTID")
    // clientsecret := os.Getenv("AZURE_COSMOS_CLIENTSECRET")
    // cred, err := azidentity.NewClientSecretCredential(tenantid, clientid, clientsecret, &azidentity.ClientSecretCredentialOptions{})

    // Acquire the access token.
    ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
    token, err := cred.GetToken(ctx, policy.TokenRequestOptions{
        Scopes: []string{scope},
    })

    // Acquire the connection string.
    client := &http.Client{}
    req, err := http.NewRequest("POST", listKeyUrl, nil)
    req.Header.Add("Authorization", "Bearer " + token.Token)
    resp, err := client.Do(req)
    body, err := ioutil.ReadAll(resp.Body)
    var result map[string]interface{}
    json.Unmarshal(body, &result)
    password, err := result["primaryMasterKey"];

    auth := gremlin.OptAuthUserPass(username, password)
     client, err := gremlin.NewClient(endpoint, auth)
}

Install dependencies.

npm install gremlin
npm install --save @azure/identity

import { DefaultAzureCredential,ClientSecretCredential } from "@azure/identity";
import gremlin from 'gremlin'
const axios = require('axios');

let username = process.env.AZURE_COSMOS_USERNAME;
let endoint = process.env.AZURE_COSMOS_RESOURCEENDPOINT;
let port = process.env.AZURE_COSMOS_PORT;
let listKeyUrl = process.env.AZURE_COSMOS_LISTKEYURL;
let scope = process.env.AZURE_COSMOS_SCOPE;

// Uncomment the following lines according to the authentication type.  
// For system-assigned identity.
// const credential = new DefaultAzureCredential();

// For user-assigned identity.
// const clientId = process.env.AZURE_COSMOS_CLIENTID;
// const credential = new DefaultAzureCredential({
//     managedIdentityClientId: clientId
// });

// For service principal.
// const tenantId = process.env.AZURE_COSMOS_TENANTID;
// const clientId = process.env.AZURE_COSMOS_CLIENTID;
// const clientSecret = process.env.AZURE_COSMOS_CLIENTSECRET;

// Acquire the access token.
var accessToken = await credential.getToken(scope);

// Get the password.
const config = {
    method: 'post',
    url: listKeyUrl,
    headers: { 
      'Authorization': `Bearer ${accessToken.token}`
    }
};
const response = await axios(config);
const keysDict = response.data;
const password = keysDict['primaryMasterKey'];

const credentials = new gremlin.driver.auth.PlainTextSaslAuthenticator(
  username,
  password
)

const client = new gremlin.driver.Client(
  endpoint,
  {
    credentials,
    traversalsource: 'g',
    rejectUnauthorized: true,
    mimeType: 'application/vnd.gremlin-v2.0+json'
  }
)

client.open()

Get an access token with a managed identity or a service principal to acquire the primary key of Azure Cosmos DB for Gremlin by calling REST API at AZURE_COSMOS_LISTKEYURL.

$endpoint = getenv('AZURE_COSMOS_RESOURCEENDPOINT');
$username = getenv('AZURE_COSMOS_USERNAME');
$port = getenv('AZURE_COSMOS_PORT');

$db = new Connection([
    'host' => $endpoint,
    'username' => $username,
    'password' => $password,
    'port' => $port,
    'ssl' => TRUE
]);

Connection string

Default environment variable name	Description	Example value
AZURE_COSMOS_HOSTNAME	Your Gremlin Unique Resource Identifier (UFI)	`<Azure-Cosmos-DB-account>.gremlin.cosmos.azure.com`
AZURE_COSMOS_PORT	Connection port	443
AZURE_COSMOS_USERNAME	Your username	`/dbs/<database>/colls/<collection or graphs>`
AZURE_COSMOS_PASSWORD	Your password	`<password>`

Sample code

Refer to the steps and code below to connect to Azure Cosmos DB for Gremlin using a connection string.

Install dependency.
```
dotnet add package Gremlin.Net
```