Use the Credentials tool to call API operations by using Alibaba Cloud SDK for .NET in a secure manner - Alibaba Cloud SDK

When you call API operations to manage cloud resources using Alibaba Cloud SDKs, you must configure valid credential information. The Credentials tool of Alibaba Cloud provides a set of easy-to-use features and supports various types of credentials, including the default credential, AccessKey pairs, and Security Token Service (STS) tokens. The Credentials tool helps you obtain and manage credentials. This topic describes how to configure different types of credentials and the order based on which the Credentials tool obtains the default credential. You can develop a thorough knowledge of configuring and managing credentials in Alibaba Cloud SDKs. This ensures that you can perform operations on cloud resources in an efficient and secure manner.

Background information

A credential is a set of information that is used to prove the identity of a user. When you log on to the system, you must use a valid credential to complete identity authentication. The following types of credentials are commonly used:

The AccessKey pair of an Alibaba Cloud account or a Resource Access Management (RAM) user. An AccessKey pair is permanently valid and consists of an AccessKey ID and an AccessKey secret.
An STS token of a RAM role. An STS token is a temporary credential. You can specify a validity period and access permissions for an STS token. For more information, see What is STS?
A bearer token. It is used for identity authentication and authorization.

Prerequisites

.NET Framework 4.5 or later is installed.
.NET Standard 2.0 or later is installed.
C# 4.0 or later is installed.
Alibaba Cloud SDK V2.0 is installed.

Install the Credentials tool

Run the following command on the .NET CLI to install Alibaba Cloud Credentials for .NET:
```
dotnet add package Aliyun.Credentials
```
Use the NuGet package manager to install Alibaba Cloud Credentials for .NET.
1. Right-click your project in the Solution Explorer panel and select Manage NuGet Packages.
2. On the Browse tab of the NuGet Package Manager panel, enter Aliyun.Credentials in the search box in the upper-left corner.
3. In the search results, select the package whose value of the Authors parameter is Alibaba Cloud and click Install.
We recommend that you use the latest version of Alibaba Cloud Credentials for .NET. This ensures that all credentials are supported.
For information about all released versions of Alibaba Cloud Credentials for .NET, see ChangeLog.txt.

Parameters of the Credentials tool

The parameters of the Credentials tool are defined in the Aliyun.Credentials.Models.Config class. The credential type is specified by the type parameter, which is a required parameter in the configurations. After you determine a credential type, configure parameters based on the credential type. The following table describes the valid values of the type parameter and the parameters supported by each credential type. In the table, a check mark (✓ indicates that the parameter is required, a hyphen (-) indicates that the parameter is optional, and an X mark (×) indicates that the parameter is not supported.

Note

We recommend that you do not use parameters that are not listed in the following table.

Type	access_key	sts	ram_role_arn	ecs_ram_role	oidc_role_arn	credentials_uri	bearer
AccessKeyId: the AccessKey ID.	✓	✓	✓	×	×	×	×
AccessKeySecret: the AccessKey secret.	✓	✓	✓	×	×	×	×
SecurityToken: the Security Token Service (STS) token.	×	✓	-	×	×	×	×
RoleArn: the Alibaba Cloud Resource Name (ARN) of the Resource Access Management (RAM) role.	×	×	✓	×	✓	×	×
roleSessionName: the name of the custom session. The default format is `credentials-csharp-The current timestamp`.	×	×	-	×	-	×	×
RoleName: specifies the name of the RAM role.	×	×	×	-	×	×	×
DisableIMDSv1: specifies whether to forcibly use the security hardening mode (IMDSv2). If you set this parameter to true, the security hardening mode (IMDSv2) is used. Default value: `false`.	×	×	×	-	×	×	×
BearerToken: a bearer token.	×	×	×	×	×	×	✓
Policy: a custom policy.	×	×	-	×	-	×	×
RoleSessionExpiration: the session timeout period. Default value: 3600. Unit: seconds.	×	×	-	×	-	×	×
OidcProviderArn: the ARN of the OpenID Connect (OIDC) identity provider (IdP).	×	×	×	×	✓	×	×
OidcTokenFilePath: the absolute path to the OIDC token.	×	×	×	×	✓	×	×
ExternalId: the external ID of the role, which is used to prevent the confused deputy issue. For more information, see Use external IDs to prevent the confused deputy issue.	×	×	-	×	×	×	×
CredentialsURI: the URI of the credential.	×	×	×	×	×	✓	×
STSEndpoint: the endpoint of STS. VPC endpoints and Internet endpoints are supported. Default value: `sts.aliyuncs.com`. For more information about the valid values, see Endpoints.	×	×	-	×	-	×	×
Timeout: the timeout period of HTTP read requests. Default value: 5000. Unit: milliseconds.	×	×	-	-	-	-	×
ConnectTimeout: the timeout period of HTTP connection requests. Default value: 10000. Unit: milliseconds.	×	×	-	-	-	-	×

Initialize a Credentials client

You can use one of the following methods to initialize a Credentials client as needed:

Important

If you use a plaintext AccessKey pair in a project, the AccessKey pair may be leaked due to improper permission management on the code repository. This may threaten the security of all resources within the account to which the AccessKey pair belongs. We recommend that you store the AccessKey pair in environment variables or configuration files.
We recommend that you initialize the Credentials client in single-instance mode. This mode not only enables the credential caching feature of the SDK, but also effectively prevents traffic control issues and waste of performance resources caused by multiple API calls. For more information, see the Automatic update mechanism of session credentials section of this topic.

Method 1: Use the default credential provider chain

If you do not specify a method to initialize a Credentials client, the default credential provider chain is used. For more information, see Default credential provider chain.

using Aliyun.Credentials.Models;

namespace credentials_demo
{
    class Program
    {
        static void Main(string[] args)
        {
            // Do not specify a value or specify null as the value.
            var credential = new Aliyun.Credentials.Client();
            // var credential = new Aliyun.Credentials.Client(null);
        }
    }
}

Example

The following sample code shows how to call the DescribeRegions operation of Elastic Compute Service (ECS). Before you call this operation, you must install ECS SDK for .NET.

using System;
using Aliyun.Credentials.Models;
using Tea;
using Tea.Utils;

namespace credentials_demo
{
    public class Sample
    {
        static void Main(string[] args)
        {
            // Use the default credential to initialize the Credentials client. 
            Aliyun.Credentials.Client credentialClient = new Aliyun.Credentials.Client(null);

            AlibabaCloud.OpenApiClient.Models.Config ecsConfig = new AlibabaCloud.OpenApiClient.Models.Config();
            // Specify the endpoint of ECS. 
            ecsConfig.Endpoint = "ecs.cn-beijing.aliyuncs.com";
            // Specify the credential. 
            ecsConfig.Credential = credentialClient;
            // Initialize an ECS SDK client. 
            AlibabaCloud.SDK.Ecs20140526.Client escClient = new AlibabaCloud.SDK.Ecs20140526.Client(ecsConfig);
            // Initialize a request to call the DescribeRegions operation. 
            AlibabaCloud.SDK.Ecs20140526.Models.DescribeRegionsRequest describeInstancesRequest = new AlibabaCloud.SDK.Ecs20140526.Models.DescribeRegionsRequest();
            // Initialize the runtime configurations. 
            AlibabaCloud.TeaUtil.Models.RuntimeOptions runtime = new AlibabaCloud.TeaUtil.Models.RuntimeOptions();
            // Call the GetInstance operation and obtain a response. 
            AlibabaCloud.SDK.Ecs20140526.Models.DescribeRegionsResponse response = escClient.DescribeRegionsWithOptions(describeInstancesRequest, runtime);
            Console.WriteLine(response.Body.ToMap());
        }
    }
}

Method 2: Use an AccessKey pair

This method lets you create an AccessKey pair to initialize a Credentials client. For more information, see Create an AccessKey pair.

Warning

An Alibaba Cloud account has full permissions on resources within the account. AccessKey pair leaks of an Alibaba Cloud account pose critical threats to the system.

Therefore, we recommend that you use an AccessKey pair of a RAM user that is granted permissions based on the principle of least privilege (PoLP) to initialize a Credentials client.

using Aliyun.Credentials.Models;

namespace credentials_demo
{
    class Program
    {
        static void Main(string[] args)
        {
            Config config = new Config()
            {
                Type = "access_key",                    
                AccessKeyId = Environment.GetEnvironmentVariable("ALIBABA_CLOUD_ACCESS_KEY_ID"),          
                AccessKeySecret = Environment.GetEnvironmentVariable("ALIBABA_CLOUD_ACCESS_KEY_SECRET")   
            };
            var akCredential = new Aliyun.Credentials.Client(config);

            string accessKeyId = akCredential.GetAccessKeyId();
            string accessSecret = akCredential.GetAccessKeySecret();
            string credentialType = akCredential.GetType();
        }
    }
}

Example

The following sample code shows how to call the DescribeRegions operation of ECS. Before you call this operation, you must install ECS SDK for .NET.

using System;
using Aliyun.Credentials.Models;
using Tea;
using Tea.Utils;

namespace credentials_demo
{
    public class Sample
    {
        static void Main(string[] args)
        {
            // Use an AccessKey pair to initialize a Credentials client. 
            Aliyun.Credentials.Models.Config credentialsConfig = new Aliyun.Credentials.Models.Config()
            {
                // The credential type. 
                Type = "access_key",
                // Obtain the AccessKey ID from an environment variable. 
                AccessKeyId = Environment.GetEnvironmentVariable("ALIBABA_CLOUD_ACCESS_KEY_ID"),
                // Obtain the AccessKey secret from an environment variable. 
                AccessKeySecret = Environment.GetEnvironmentVariable("ALIBABA_CLOUD_ACCESS_KEY_SECRET")
            };
            Aliyun.Credentials.Client credentialClient = new Aliyun.Credentials.Client(credentialsConfig);

            AlibabaCloud.OpenApiClient.Models.Config ecsConfig = new AlibabaCloud.OpenApiClient.Models.Config();
            // Specify the endpoint of ECS. 
            ecsConfig.Endpoint = "ecs.cn-beijing.aliyuncs.com";
            // Specify the credential. 
            ecsConfig.Credential = credentialClient;
            // Initialize an ECS SDK client. 
            AlibabaCloud.SDK.Ecs20140526.Client escClient = new AlibabaCloud.SDK.Ecs20140526.Client(ecsConfig);
            // Initialize a request to call the DescribeRegions operation. 
            AlibabaCloud.SDK.Ecs20140526.Models.DescribeRegionsRequest describeInstancesRequest = new AlibabaCloud.SDK.Ecs20140526.Models.DescribeRegionsRequest();
            // Initialize the runtime configurations. 
            AlibabaCloud.TeaUtil.Models.RuntimeOptions runtime = new AlibabaCloud.TeaUtil.Models.RuntimeOptions();
            // Call the GetInstance operation and obtain a response. 
            AlibabaCloud.SDK.Ecs20140526.Models.DescribeRegionsResponse response = escClient.DescribeRegionsWithOptions(describeInstancesRequest, runtime);
            Console.WriteLine(response.Body.ToMap());
        }
    }
}

Method 3: Use a STS token

This method lets you use a static STS token to initialize a Credentials client. For more information about how to obtain an STS token, see What is STS? The following example shows how to initialize a Credentials client using an STS token. The example does not show how to obtain an STS token.

using Aliyun.Credentials.Models;

namespace credentials_demo
{
    class Program
    {
        static void Main(string[] args)
        {
            Config config = new Config()
            {
                Type = "sts", 
                // Obtain the AccessKey ID from an environment variable. 
                AccessKeyId = Environment.GetEnvironmentVariable("ALIBABA_CLOUD_ACCESS_KEY_ID"),
                // Obtain the AccessKey secret from an environment variable. 
                AccessKeySecret = Environment.GetEnvironmentVariable("ALIBABA_CLOUD_ACCESS_KEY_SECRET"), 
                // Obtain the STS token from an environment variable. 
              	SecurityToken = Environment.GetEnvironmentVariable("<ALIBABA_CLOUD_SECURITY_TOKEN>")
            };
            var stsCredential = new Aliyun.Credentials.Client(config);

            string accessKeyId = stsCredential.GetAccessKeyId();
            string accessSecret = stsCredential.GetAccessKeySecret();
            string credentialType = stsCredential.GetType();
            string securityToken = stsCredential.GetSecurityToken();
        }
    }

Example

The following sample code shows how to call the DescribeRegions operation of ECS. Before you call this operation, you must install ECS SDK for .NET and STS SDK for .NET.

using System;
using Aliyun.Credentials.Models;
using Tea;
using Tea.Utils;

namespace credentials_demo
{
    public class Sample
    {
        static void Main(string[] args)
        {
            // Use an STS token to initialize a Credentials client. 
            Aliyun.Credentials.Models.Config credentialsConfig = new Aliyun.Credentials.Models.Config()
            {
                // The credential type. 
                Type = "sts", 
                // Obtain the AccessKey ID from an environment variable. 
                AccessKeyId = Environment.GetEnvironmentVariable("ALIBABA_CLOUD_ACCESS_KEY_ID"),
                // Obtain the AccessKey secret from an environment variable. 
                AccessKeySecret = Environment.GetEnvironmentVariable("ALIBABA_CLOUD_ACCESS_KEY_SECRET"), 
                // Obtain the STS token from an environment variable. 
              	SecurityToken = Environment.GetEnvironmentVariable("<ALIBABA_CLOUD_SECURITY_TOKEN>")
            };
            Aliyun.Credentials.Client credentialClient = new Aliyun.Credentials.Client(credentialsConfig);

            AlibabaCloud.OpenApiClient.Models.Config ecsConfig = new AlibabaCloud.OpenApiClient.Models.Config();
            // Specify the endpoint of ECS. 
            ecsConfig.Endpoint = "ecs.cn-beijing.aliyuncs.com";
            // Specify the credential. 
            ecsConfig.Credential = credentialClient;
            // Initialize an ECS SDK client. 
            AlibabaCloud.SDK.Ecs20140526.Client escClient = new AlibabaCloud.SDK.Ecs20140526.Client(ecsConfig);
            // Initialize a request to call the DescribeRegions operation. 
            AlibabaCloud.SDK.Ecs20140526.Models.DescribeRegionsRequest describeInstancesRequest = new AlibabaCloud.SDK.Ecs20140526.Models.DescribeRegionsRequest();
            // Initialize the runtime configurations. 
            AlibabaCloud.TeaUtil.Models.RuntimeOptions runtime = new AlibabaCloud.TeaUtil.Models.RuntimeOptions();
            // Call the GetInstance operation and obtain a response. 
            AlibabaCloud.SDK.Ecs20140526.Models.DescribeRegionsResponse response = escClient.DescribeRegionsWithOptions(describeInstancesRequest, runtime);
            Console.WriteLine(response.Body.ToMap());
        }
    }
}

Method 4: Use an AccessKey pair and a RAM role

The underlying logic of this method is to use an STS token to initialize a Credentials client. After you specify the ARN of a RAM role, the Credentials tool can obtain an STS token from STS. You can also use the Policy parameter to limit the permissions of the RAM role.

using Aliyun.Credentials.Models;

namespace credentials_demo
{
    class Program
    {
        static void Main(string[] args)
        {
            Config config = new Config()
            {
                Type = "ram_role_arn",                  
                AccessKeyId = Environment.GetEnvironmentVariable("ALIBABA_CLOUD_ACCESS_KEY_ID"),
                AccessKeySecret = Environment.GetEnvironmentVariable("ALIBABA_CLOUD_ACCESS_KEY_SECRET"),
              	// Specify the ARN of the RAM role that you want your application to assume. You can obtain the value from the ALIBABA_CLOUD_ROLE_ARN environment variable. Example: acs:ram::123456789012****:role/adminrole.
                RoleArn = "<RoleArn>",  
              	// Specify the role session name. You can configure the role session name as the ALIBABA_CLOUD_ROLE_SESSION_NAME environment variable.
                RoleSessionName = "<RoleSessionName>", 
            };
            var arnCredential = new Aliyun.Credentials.Client(config);

            string accessKeyId = arnCredential.GetAccessKeyId();
            string accessSecret = arnCredential.GetAccessKeySecret();
            string credentialType = arnCredential.GetType();
            string securityToken = arnCredential.GetSecurityToken();
        }
    }
}

Example

The following sample code shows how to call the DescribeRegions operation of ECS. Before you call this operation, you must install ECS SDK for .NET.

using System;
using Aliyun.Credentials.Models;
using Tea;
using Tea.Utils;

namespace credentials_demo
{
    public class Sample
    {
        static void Main(string[] args)
        {
            // Use an AccessKey pair and a RAM role to initialize a Credentials client. 
            Aliyun.Credentials.Models.Config credentialsConfig = new Aliyun.Credentials.Models.Config()
            {
                // The credential type. 
                Type = "ram_role_arn",
                // Specify the AccessKey ID. 
                AccessKeyId = Environment.GetEnvironmentVariable("ALIBABA_CLOUD_ACCESS_KEY_ID"),
                // Specify the AccessKey secret. 
                AccessKeySecret = Environment.GetEnvironmentVariable("ALIBABA_CLOUD_ACCESS_KEY_SECRET"),
                // Specify the ARN of the RAM role that you want your application to assume. You can obtain the value from the ALIBABA_CLOUD_ROLE_ARN environment variable. Example: acs:ram::123456789012****:role/adminrole.
                RoleArn = "<RoleArn>",
                // Specify the role session name. You can configure the role session name as the ALIBABA_CLOUD_ROLE_SESSION_NAME environment variable.
                RoleSessionName = "<RoleSessionName>",
            };
            Aliyun.Credentials.Client credentialClient = new Aliyun.Credentials.Client(credentialsConfig);

            AlibabaCloud.OpenApiClient.Models.Config ecsConfig = new AlibabaCloud.OpenApiClient.Models.Config();
            // Specify the endpoint of ECS. 
            ecsConfig.Endpoint = "ecs.cn-beijing.aliyuncs.com";
            // Specify the credential. 
            ecsConfig.Credential = credentialClient;
            // Initialize an ECS SDK client. 
            AlibabaCloud.SDK.Ecs20140526.Client escClient = new AlibabaCloud.SDK.Ecs20140526.Client(ecsConfig);
            // Initialize a request to call the DescribeRegions operation. 
            AlibabaCloud.SDK.Ecs20140526.Models.DescribeRegionsRequest describeInstancesRequest = new AlibabaCloud.SDK.Ecs20140526.Models.DescribeRegionsRequest();
            // Initialize the runtime configurations. 
            AlibabaCloud.TeaUtil.Models.RuntimeOptions runtime = new AlibabaCloud.TeaUtil.Models.RuntimeOptions();
            // Call the GetInstance operation and obtain a response. 
            AlibabaCloud.SDK.Ecs20140526.Models.DescribeRegionsResponse response = escClient.DescribeRegionsWithOptions(describeInstancesRequest, runtime);
            Console.WriteLine(response.Body.ToMap());
        }
    }
}

Method 5: Use the RAM role of an ECS instance

ECS instances and elastic container instances can be assigned RAM roles. Programs that run on the instances can use the Credentials tool to automatically obtain an STS token for the RAM role. The STS token can be used to initialize the Credentials client.

By default, the Credentials tool accesses the metadata server of ECS in security hardening mode (IMDSv2). If an exception is thrown, the Credentials tool switches to the normal mode (IMDSv1). You can also configure the disableIMDSv1 parameter or the ALIBABA_CLOUD_IMDSV1_DISABLE environment variable to specify the exception handling logic. Valid values:

false (default): The Credentials tool continues to obtain the access credential in normal mode (IMDSv1).
true: The exception is thrown and the Credentials tool continues to obtain the access credential in security hardening mode (IMDSv2).

Your instance configuration determines whether the instance metadata server supports IMDSv2.

In addition, you can specify ALIBABA_CLOUD_ECS_METADATA_DISABLED=true to disable access from the Credentials tool to the metadata server of ECS.

Note

If you obtain an STS token in security hardening mode (IMDSv2), make sure that the version of the Credentials tool is 1.4.2 or later.
For more information about how to obtain the metadata of an ECS instance, see Obtain instance metadata.
For more information about how to attach a RAM role to an ECS instance, see the "Create an instance RAM role and attach the instance RAM role to an ECS instance" section of the Instance RAM roles topic. For more information about how to attach a RAM role to an elastic container instance, see the "Assign the instance RAM role to an elastic container instance" section of the Use an instance RAM role by calling API operations topic.

using Aliyun.Credentials.Models;

namespace credentials_demo
{
    class Program
    {
        static void Main(string[] args)
        {
            var config = new Config()
            {
                Type = "ecs_ram_role",
              	// Optional. Specify the name of the RAM role of the ECS instance. You can obtain the value from the ALIBABA_CLOUD_ECS_METADATA environment variable. If you do not specify this parameter, the value is automatically obtained. We recommend that you specify this parameter to reduce the number of requests.
                RoleName = "<RoleName>" 
            };
            # Default value: false. This parameter is optional. true: The security hardening mode (IMDSv2) is forcibly used. false: The system preferentially attempts to obtain the access credential in security hardening mode (IMDSv2). If the attempt fails, the system switches to the normal mode (IMDSv1) to obtain access credentials.
            // config.DisableIMDSv1 = true;
            
            var ecsCredential = new Aliyun.Credentials.Client(config);

            string accessKeyId = ecsCredential.GetAccessKeyId();
            string accessSecret = ecsCredential.GetAccessKeySecret();
            string credentialType = ecsCredential.GetType();
            string securityToken = ecsCredential.GetSecurityToken();
        }
    }
}

Example

The following sample code shows how to call the DescribeRegions operation of ECS. Before you call this operation, you must install ECS SDK for .NET.

using System;
using Aliyun.Credentials.Models;
using Tea;
using Tea.Utils;

namespace credentials_demo
{
    public class Sample
    {
        static void Main(string[] args)
        {
            // Use the RAM role of an ECS instance to initialize a Credentials client. 
            Aliyun.Credentials.Models.Config credentialsConfig = new Aliyun.Credentials.Models.Config()
            {
                // The credential type. 
                Type = "ecs_ram_role",
              	// Optional. Specify the name of the RAM role of the ECS instance. You can obtain the value from the ALIBABA_CLOUD_ECS_METADATA environment variable. If you do not specify this parameter, the value is automatically obtained. We recommend that you specify this parameter to reduce the number of requests.
                RoleName = "<RoleName>"
            };
            Aliyun.Credentials.Client credentialClient = new Aliyun.Credentials.Client(credentialsConfig);

            AlibabaCloud.OpenApiClient.Models.Config ecsConfig = new AlibabaCloud.OpenApiClient.Models.Config();
            // Specify the endpoint of ECS. 
            ecsConfig.Endpoint = "ecs.cn-beijing.aliyuncs.com";
            // Specify the credential. 
            ecsConfig.Credential = credentialClient;
            // Initialize an ECS SDK client. 
            AlibabaCloud.SDK.Ecs20140526.Client escClient = new AlibabaCloud.SDK.Ecs20140526.Client(ecsConfig);
            // Initialize a request to call the DescribeRegions operation. 
            AlibabaCloud.SDK.Ecs20140526.Models.DescribeRegionsRequest describeInstancesRequest = new AlibabaCloud.SDK.Ecs20140526.Models.DescribeRegionsRequest();
            // Initialize the runtime configurations. 
            AlibabaCloud.TeaUtil.Models.RuntimeOptions runtime = new AlibabaCloud.TeaUtil.Models.RuntimeOptions();
            // Call the GetInstance operation and obtain a response. 
            AlibabaCloud.SDK.Ecs20140526.Models.DescribeRegionsResponse response = escClient.DescribeRegionsWithOptions(describeInstancesRequest, runtime);
            Console.WriteLine(response.Body.ToMap());
        }
    }
}

Method 6: Use the RAM role of an OIDC IdP

To ensure the security of cloud resources and enable untrusted applications to securely obtain required STS tokens, you can use the RAM Roles for Service Accounts (RRSA) feature to grant minimum necessary permissions to an application. ACK creates and mounts corresponding OpenID Connect (OIDC) token files for different application pods, and passes relevant configuration information to environment variables. The Credentials tool obtains the configuration information from the environment variables and calls the AssumeRoleWithOIDC operation of STS to obtain the STS token for attached roles.

The following environment variables are injected into the pod:

ALIBABA_CLOUD_ROLE_ARN: the ARN of the RAM role.

ALIBABA_CLOUD_OIDC_PROVIDER_ARN: the ARN of the OIDC identity provider (IdP).

ALIBABA_CLOUD_OIDC_TOKEN_FILE: the path of the OIDC token file.

using Aliyun.Credentials.Models;

namespace credentials_demo
{
    class Program
    {
        static void Main(string[] args)
        {
            Config config = new Config()
            {
                Type = "oidc_role_arn",
                // Specify the ARN of the RAM role to be assumed. You can configure the ARN as the ALIBABA_CLOUD_ROLE_ARN environment variable.
                RoleArn = "<RoleArn>",
                // Specify the ARN of the OIDC IdP. You can configure the ARN of the OIDC IdP as the ALIBABA_CLOUD_OIDC_PROVIDER_ARN environment variable.
                OIDCProviderArn = "<OidcProviderArn>",
                // Specify the path of the OIDC token file. You can configure the path of the OIDC token file as the ALIBABA_CLOUD_OIDC_TOKEN_FILE environment variable.
                OIDCTokenFilePath = "<OidcTokenFilePath>",
                // Specify the role session name. You can configure the role session name as the ALIBABA_CLOUD_ROLE_SESSION_NAME environment variable.
                RoleSessionName = "<RoleSessionName>",
                // Optional. Specify limited permissions for the RAM role. Example: {"Statement": [{"Action": ["*"],"Effect": "Allow","Resource": ["*"]}],"Version":"1"}.
                Policy = "<Policy>",
                RoleSessionExpiration = 3600
            };
            var ecsCredential = new Aliyun.Credentials.Client(config);
        }
    }
}

Example

The following sample code shows how to call the DescribeRegions operation of ECS. Before you call this operation, you must install ECS SDK for .NET.

using System;
using Aliyun.Credentials.Models;
using Tea;
using Tea.Utils;

namespace credentials_demo
{
    public class Sample
    {
        static void Main(string[] args)
        {
            // Use the RAM role of an OIDC IdP to initialize a Credentials client. 
            Aliyun.Credentials.Models.Config credentialsConfig = new Aliyun.Credentials.Models.Config()
            {
                // The credential type. 
                Type = "oidc_role_arn",
                // Specify the ARN of the RAM role to be assumed. You can configure the ARN as the ALIBABA_CLOUD_ROLE_ARN environment variable.
                RoleArn = "<RoleArn>",
                // Specify the ARN of the OIDC IdP. You can configure the ARN of the OIDC IdP as the ALIBABA_CLOUD_OIDC_PROVIDER_ARN environment variable.
                OIDCProviderArn = "<OidcProviderArn>",
                // Specify the path of the OIDC token file. You can configure the path of the OIDC token file as the ALIBABA_CLOUD_OIDC_TOKEN_FILE environment variable.
                OIDCTokenFilePath = "<OidcTokenFilePath>",
                // Specify the role session name. You can configure the role session name as the ALIBABA_CLOUD_ROLE_SESSION_NAME environment variable.
                RoleSessionName = "<RoleSessionName>",
                // Optional. Specify limited permissions for the RAM role. Example: {"Statement": [{"Action": ["*"],"Effect": "Allow","Resource": ["*"]}],"Version":"1"}.
                Policy = "<Policy>",
                RoleSessionExpiration = 3600
            };
            Aliyun.Credentials.Client credentialClient = new Aliyun.Credentials.Client(credentialsConfig);

            AlibabaCloud.OpenApiClient.Models.Config ecsConfig = new AlibabaCloud.OpenApiClient.Models.Config();
            // Specify the endpoint of ECS. 
            ecsConfig.Endpoint = "ecs.cn-beijing.aliyuncs.com";
            // Specify the credential. 
            ecsConfig.Credential = credentialClient;
            // Initialize an ECS SDK client. 
            AlibabaCloud.SDK.Ecs20140526.Client escClient = new AlibabaCloud.SDK.Ecs20140526.Client(ecsConfig);
            // Initialize a request to call the DescribeRegions operation. 
            AlibabaCloud.SDK.Ecs20140526.Models.DescribeRegionsRequest describeInstancesRequest = new AlibabaCloud.SDK.Ecs20140526.Models.DescribeRegionsRequest();
            // Initialize the runtime configurations. 
            AlibabaCloud.TeaUtil.Models.RuntimeOptions runtime = new AlibabaCloud.TeaUtil.Models.RuntimeOptions();
            // Call the GetInstance operation and obtain a response. 
            AlibabaCloud.SDK.Ecs20140526.Models.DescribeRegionsResponse response = escClient.DescribeRegionsWithOptions(describeInstancesRequest, runtime);
            Console.WriteLine(response.Body.ToMap());
        }
    }
}

Method 7: Use a credential URI

This method lets you encapsulate an STS token in your application and provide a custom URI to external resources. Other services can obtain the STS token only through the URI. This minimizes the risk of AccessKey exposure. The Credentials tool lets you obtain the STS token by calling the service URI to initialize the Credentials client.

using Aliyun.Credentials.Models;

namespace credentials_demo
{
    class Program
    {
        static void Main(string[] args)
        {
            Config config = new Config()
            {
                Type = "credentials_uri",
              	// Specify the URI of the credential in the http://local_or_remote_uri/ format. You can obtain the value from the ALIBABA_CLOUD_CREDENTIALS_URI environment variable.
                CredentialsURI = "<CredentialsURI>"     
            };
        }
    }
}

Example

The following sample code shows how to call the DescribeRegions operation of ECS. Before you call this operation, you must install ECS SDK for .NET.

using System;
using Aliyun.Credentials.Models;
using Tea;
using Tea.Utils;

namespace credentials_demo
{
    public class Sample
    {
        static void Main(string[] args)
        {
            // Use a URI to initialize a Credentials client. 
            Aliyun.Credentials.Models.Config credentialsConfig = new Aliyun.Credentials.Models.Config()
            {
                // The credential type. 
                Type = "credentials_uri",
              	// Specify the URI of the credential in the http://local_or_remote_uri/ format. You can obtain the value from the ALIBABA_CLOUD_CREDENTIALS_URI environment variable.
                CredentialsURI = "<CredentialsURI>" 
            };
            Aliyun.Credentials.Client credentialClient = new Aliyun.Credentials.Client(credentialsConfig);

            AlibabaCloud.OpenApiClient.Models.Config ecsConfig = new AlibabaCloud.OpenApiClient.Models.Config();
            // Specify the endpoint of ECS. 
            ecsConfig.Endpoint = "ecs.cn-beijing.aliyuncs.com";
            // Specify the credential. 
            ecsConfig.Credential = credentialClient;
            // Initialize an ECS SDK client. 
            AlibabaCloud.SDK.Ecs20140526.Client escClient = new AlibabaCloud.SDK.Ecs20140526.Client(ecsConfig);
            // Initialize a request to call the DescribeRegions operation. 
            AlibabaCloud.SDK.Ecs20140526.Models.DescribeRegionsRequest describeInstancesRequest = new AlibabaCloud.SDK.Ecs20140526.Models.DescribeRegionsRequest();
            // Initialize the runtime configurations. 
            AlibabaCloud.TeaUtil.Models.RuntimeOptions runtime = new AlibabaCloud.TeaUtil.Models.RuntimeOptions();
            // Call the GetInstance operation and obtain a response. 
            AlibabaCloud.SDK.Ecs20140526.Models.DescribeRegionsResponse response = escClient.DescribeRegionsWithOptions(describeInstancesRequest, runtime);
            Console.WriteLine(response.Body.ToMap());
        }
    }
}

Method 8: Use a bearer token

Only Cloud Call Center allows you to use a bearer token to initialize a Credentials client.

using Aliyun.Credentials.Models;

namespace credentials_demo
{
    class Program
    {
        static void Main(string[] args)
        {
            Config config = new Config()
            {
                Type = "bearer",     
              	// Specify the bearer token.
                BearerToken = "<BearerToken>"      
            };
            var bearerCredential = new Aliyun.Credentials.Client(config);

            string bearerToken = bearerCredential.GetBearerToken();
            string credentialType = bearerCredential.GetType();
        }
    }
}

Example

The following sample code shows how to call the GetInstance operation of Cloud Call Center. Before you call this operation, you must install Cloud Call Center SDK for .NET.

using System;
using Aliyun.Credentials.Models;
using Tea;
using Tea.Utils;

namespace credentials_demo
{
    public class Sample
    {
        static void Main(string[] args)
        {
            // Use a bearer token to initialize a Credentials client. 
            Aliyun.Credentials.Models.Config credentialsConfig = new Aliyun.Credentials.Models.Config()
            {
                // The credential type. 
                Type = "bearer",
                // Specify the bearer token.
                BearerToken = "<BearerToken>"
            };
            Aliyun.Credentials.Client credentialClient = new Aliyun.Credentials.Client(credentialsConfig);

            AlibabaCloud.OpenApiClient.Models.Config cccConfig = new AlibabaCloud.OpenApiClient.Models.Config()
            {
                // Specify the endpoint of ECS. 
                Endpoint = "ccc.cn-shanghai.aliyuncs.com",
                // Specify the credential. 
                Credential = credentialClient
            };

            # Use the Credentials client to initialize the Cloud Call Center SDK client. 
            AlibabaCloud.SDK.CCC20200701.Client cccClient = new AlibabaCloud.SDK.CCC20200701.Client(cccConfig);
            // Initialize a request to call the GetInstance operation. 
            AlibabaCloud.SDK.CCC20200701.Models.GetInstanceRequest getInstanceRequest = new AlibabaCloud.SDK.CCC20200701.Models.GetInstanceRequest
            {
                InstanceId = "ccc-test",
            };
            // Initialize the runtime configurations. 
            AlibabaCloud.TeaUtil.Models.RuntimeOptions runtime = new AlibabaCloud.TeaUtil.Models.RuntimeOptions();
            // Call the GetInstance operation and obtain a response. 
            AlibabaCloud.SDK.CCC20200701.Models.GetInstanceResponse response = cccClient.GetInstanceWithOptions(getInstanceRequest, runtime);
            Console.WriteLine(response.Body.ToMap());
        }
    }
}

Default credential provider chain

If you want to use different types of credentials in the development and production environments of your application, you generally need to obtain the environment information from the code and write code branches to obtain different credentials for the development and production environments. The default credential provider chain of Alibaba Cloud Credentials for .NET allows you to use the same code to obtain credentials for different environments based on configurations independent of the application. If you use new Client(config) to initialize a Credentials client without specifying an initialization method, the Credentials tool obtains the credential information in the order described in this section.

1. Obtain the credential information from environment variables

If no credential information is found in the system attributes, the Credentials continues to check the environment variables.

If both the ALIBABA_CLOUD_ACCESS_KEY_ID and ALIBABA_CLOUD_ACCESS_KEY_SECRET environment variables are specified, they are used as the default credential.
If ALIBABA_CLOUD_ACCESS_KEY_ID, ALIBABA_CLOUD_ACCESS_KEY_SECRET, and ALIBABA_CLOUD_SECURITY_TOKEN are specified, the STS token is used as the default credential.

2. Obtain the credential information by using the RAM role of an OIDC IdP

If no credentials with a higher priority are found, the Credentials tool checks the following environment variables that are related to the RAM role of the OIDC IdP:

ALIBABA_CLOUD_ROLE_ARN: the ARN of the RAM role.
ALIBABA_CLOUD_OIDC_PROVIDER_ARN: the ARN of the OIDC IdP.
ALIBABA_CLOUD_OIDC_TOKEN_FILE: the file path of the OIDC token.

If the preceding three environment variables are specified and valid, the Credentials tool uses the environment variables to call the AssumeRoleWithOIDC operation of STS to obtain an STS token as the default credential.

3. Obtain the credential information from the config.json configuration file

If no credentials with a higher priority are found, the Credentials tool attempts to load the config.json file. Default file path:

Linux/macOS: ~/.aliyun/config.json
Windows: C:\Users\USER_NAME\.aliyun\config.json

Do not change the preceding default paths. If you want to use this method to configure an access credential, manually create a config.json file in the corresponding path. Example:

{
	"current": "<PROFILE_NAME>",
	"profiles": [
		{
			"name": "<PROFILE_NAME>",
			"mode": "AK",
			"access_key_id": "<ALIBABA_CLOUD_ACCESS_KEY_ID>",
			"access_key_secret": "<ALIBABA_CLOUD_ACCESS_KEY_SECRET>"
		},
		{
			"name": "<PROFILE_NAME1>",
			"mode": "StsToken",
			"access_key_id": "<ALIBABA_CLOUD_ACCESS_KEY_ID>",
			"access_key_secret": "<ALIBABA_CLOUD_ACCESS_KEY_SECRET>",
			"sts_token": "<SECURITY_TOKEN>"
		},
		{
			"name":"<PROFILE_NAME2>",
			"mode":"RamRoleArn",
			"access_key_id":"<ALIBABA_CLOUD_ACCESS_KEY_ID>",
			"access_key_secret":"<ALIBABA_CLOUD_ACCESS_KEY_SECRET>",
			"ram_role_arn":"<ROLE_ARN>",
			"ram_session_name":"<ROLE_SESSION_NAME>",
			"expired_seconds":3600
		},
		{
			"name":"<PROFILE_NAME3>",
			"mode":"EcsRamRole",
			"ram_role_name":"<RAM_ROLE_ARN>"
		},
		{
			"name":"<PROFILE_NAME4>",
			"mode":"OIDC",
			"oidc_provider_arn":"<OIDC_PROVIDER_ARN>",
			"oidc_token_file":"<OIDC_TOKEN_FILE>",
			"ram_role_arn":"<ROLE_ARN>",
			"ram_session_name":"<ROLE_SESSION_NAME>",
			"expired_seconds":3600
		},
		{
			"name":"<PROFILE_NAME5>",
			"mode":"ChainableRamRoleArn",
			"source_profile":"<PROFILE_NAME>",
			"ram_role_arn":"<ROLE_ARN>",
			"ram_session_name":"<ROLE_SESSION_NAME>",
			"expired_seconds":3600
		}
	]
}

In the config.json file, you can use mode to specify a type of credential:

AK: uses the AccessKey pair of a RAM user to obtain the credential information.
StsToken: uses the STS token as the credential information.
RamRoleArn: uses the ARN of a RAM role to obtain the credential information.
EcsRamRole: uses the RAM role attached to an ECS instance to obtain the credential information.
OIDC: uses the ARN of an OIDC IdP and the OIDC token file to obtain the credential information.
ChainableRamRoleArn: utilizes a role chaining mechanism. It allows you to assume a new RAM role and acquire a new, temporary credential by referencing another credential profile, which is specified by the source_profile parameter.

After you complete the configurations, the Credentials tool selects the credential specified by the current parameter in the configuration file and initialize the client. You can also specify the ALIBABA_CLOUD_PROFILE environment variable to specify the credential information. For example, you can set the ALIBABA_CLOUD_PROFILE environment variable to client1.

4. Obtain the credential information by using the RAM role of an ECS instance

If no credentials with a higher priority are found, the Credentials tool attempts to use the RAM role assigned to the ECS instance to obtain a credential. By default, the Credentials tool accesses the metadata server of ECS in security hardening mode (IMDSv2) to obtain the STS token of the RAM role used by the ECS instance and uses the STS token as the default credential. The Credentials tool automatically accesses the metadata server of ECS to obtain the name of the RAM role (RoleName) and then obtains the credential. Two requests are sent in this process. If you want to send only one request, add the ALIBABA_CLOUD_ECS_METADATA environment variable to specify the name of the RAM role. If an exception occurs in the security hardening mode (IMDSv2), the Credentials tool obtains the access credential in normal mode (IMDSv1). You can also configure the ALIBABA_CLOUD_IMDSV1_DISABLE environment variable to specify an exception handling logic. Valid values:

false: The Credentials tool continues to obtain the access credential in normal mode (IMDSv1).
true: The exception is thrown and the Credentials tool continues to obtain the access credential in security hardening mode.

The configurations for the metadata server determine whether the server supports the security hardening mode (IMDSv2).

In addition, you can specify ALIBABA_CLOUD_ECS_METADATA_DISABLED=true to disable access from the Credentials tool to the metadata server of ECS.

Note

For more information about ECS instance metadata, see Obtain instance metadata.
For more information about how to attach a RAM role to an ECS instance, see the "Create an instance RAM role and attach the instance RAM role to an ECS instance" section of the Instance RAM roles topic. For more information about how to attach a RAM role to an elastic container instance, see the "Assign the instance RAM role to an elastic container instance" section of the Use an instance RAM role by calling API operations topic.

5. Obtain the credential information based on a URI

If no valid credential is obtained using the preceding methods, the Credentials tool checks the ALIBABA_CLOUD_CREDENTIALS_URI environment variable. If this environment variable exists and specifies a valid URI, the Credentials tool initiates an HTTP requests to obtain an STS token as the default credential.

Automatic update mechanism of session credentials

Session credentials include ARNs of RAM roles (RamRoleArn), RAM roles of ECS instances, RAM roles of OIDC IdPs (OIDCRoleArn), and credential URIs. The Credentials tool provides a built-in automatic update mechanism for session credentials. After a credential is obtained from the first call, the Credentials tool stores the credential in the cache. In subsequent calls, the credential is read from the cache as long as the credential is not expired. Otherwise, the Credentials tool makes a call to obtain the credential again, and updates the credential in the cache.

Note

For RAM roles of ECS instances, the Credentials tool updates the credential 15 minutes before the cache time-to-live (TTL) ends.

In the following example, the Credentials client is created in single-instance mode and is used to initialize the cloud service client. Then, an API operation is called during different time periods to check whether internal cache is used and whether the credential is refreshed after the cache expires.

using System;
using System.Threading.Tasks;
using Aliyun.Credentials.Models;
using AlibabaCloud.SDK.Ecs20140526;
using AlibabaCloud.OpenApiClient.Models;
using AlibabaCloud.TeaUtil.Models;

namespace Example
{
    /// <summary>
    /// The Credentials class is used to manage Alibaba Cloud credential instances in static singleton mode. 
    /// </summary>
    public static class Credential
    {
        private static readonly Lazy<Aliyun.Credentials.Client> _instance = new(() =>
        {
            try
            {
                var config = new Aliyun.Credentials.Models.Config
                {
                    Type = "ram_role_arn",
                    AccessKeyId = Environment.GetEnvironmentVariable("ALIBABA_CLOUD_ACCESS_KEY_ID"),
                    AccessKeySecret = Environment.GetEnvironmentVariable("ALIBABA_CLOUD_ACCESS_KEY_SECRET"),
                    RoleArn = Environment.GetEnvironmentVariable("ALIBABA_CLOUD_ROLE_ARN"),
                    RoleSessionName = "RamRoleArnTest",
                    RoleSessionExpiration = 3600
                };

                return new Aliyun.Credentials.Client(config);
            }
            catch (Exception ex)
            {
                throw new InvalidOperationException("Credential initialization failed: " + ex.Message, ex);
            }
        });

        public static Aliyun.Credentials.Client Instance => _instance.Value;
    }

    /// <summary>
    /// The EcsClient class is used to manage ECS clients in static singleton mode. 
    /// You must use the Initialize parameter to configure the endpoint and credential. 
    /// </summary>
    public static class EcsClient
    {
        private static string _endpoint=string.Empty; // Explicit initialization. Do not set the value to null.
        private static Aliyun.Credentials.Client _credential=null!; // Explicit initialization. Do not set the value to null.

        private static readonly Lazy<AlibabaCloud.SDK.Ecs20140526.Client> _instance = new(() =>
        {
            if (string.IsNullOrEmpty(_endpoint))
            {
                throw new InvalidOperationException("Endpoint must be set before initializing the ECS client.");
            }

            if (_credential == null)
            {
                throw new InvalidOperationException("Credential must be set before initializing the ECS client.");
            }

            try
            {
                var ecsConfig = new AlibabaCloud.OpenApiClient.Models.Config
                {
                    Endpoint = _endpoint,
                    Credential = _credential
                };

                return new AlibabaCloud.SDK.Ecs20140526.Client(ecsConfig);
            }
            catch (Exception ex)
            {
                throw new InvalidOperationException("ECS client initialization failed: " + ex.Message, ex);
            }
        });

        public static void Initialize(string endpoint, Aliyun.Credentials.Client credential)
        {
            if (string.IsNullOrEmpty(endpoint))
            {
                throw new ArgumentException("Endpoint cannot be null or empty.", nameof(endpoint));
            }

            if (credential == null)
            {
                throw new ArgumentNullException(nameof(credential), "Credential cannot be null.");
            }

            _endpoint = endpoint;
            _credential = credential;
        }

        public static AlibabaCloud.SDK.Ecs20140526.Client Instance => _instance.Value;
    }

    public class Program
    {
        public static async Task Main(string[] args)
        {
            // Initialize the EcsClient instance.
            EcsClient.Initialize("ecs.cn-hangzhou.aliyuncs.com", Credential.Instance);

            Action task = () =>
            {
                try
                {
                    var credential = Credential.Instance.GetCredential();
                    Console.WriteLine(DateTime.Now);
                    Console.WriteLine($"AK ID: {credential.AccessKeyId}, AK Secret: {credential.AccessKeySecret}, STS Token: {credential.SecurityToken}");

                    var ecsClient = EcsClient.Instance;
                    var request = new AlibabaCloud.SDK.Ecs20140526.Models.DescribeRegionsRequest();
                    var runtime = new AlibabaCloud.TeaUtil.Models.RuntimeOptions();

                    var response = ecsClient.DescribeRegionsWithOptions(request, runtime);
                    Console.WriteLine($"Invoke result: {response.StatusCode}");
                }
                catch (Exception ex)
                {
                    Console.WriteLine($"ECS client execution failed: {ex.Message}");
                }
            };

            // Immediately run the task for one time.
            task();

            // Start multiple asynchronous tasks at the same time.
            var tasks = new[]
            {
                ScheduleTaskAsync(task, 600),
                ScheduleTaskAsync(task, 4200),
                ScheduleTaskAsync(task, 4300)
            };

            await Task.WhenAll(tasks);

            Console.WriteLine("All tasks completed.");
        }

        private static async Task ScheduleTaskAsync(Action task, int delaySeconds)
        {
            await Task.Delay(TimeSpan.FromSeconds(delaySeconds));
            task();
        }
    }
}

Log analysis:

In the first call, the system obtains the credential based on the configurations because the credential is not cached. After the system obtains the credential, the credential is stored in the cache.
The second call uses the same credential as the first call, which indicates that the credential is obtained from the cache.
In the third call, the credential has expired because the third call is 4,200 seconds later than the first call while the credential TTL (RoleSessionExpiration) is set to 3,600 seconds. The SDK obtains the credential again based on the automatic update mechanism and stored the credential in the cache.
The fourth call uses the same credential as the third call, which indicates that the credential is updated after cache expiration.

References

For more information about RAM, see Terms.
For more information about how to create an AccessKey pair, see Create an AccessKey pair.
For more information about how to create a RAM user, an AccessKey pair, a RAM role, and a policy and grant permissions to a RAM user, see RAM SDK overview.
For more information about how to assume a role using a program, see STS SDK overview.
For more information about RAM and STS-related API operations, see API Reference.
Best practices for using an access credential to call API operations
Solutions to AccessKey pair leaks