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Authenticate Azure-hosted Java applications

  • Artikkeli

This article looks at how the Azure Identity library supports Microsoft Entra token authentication for applications hosted on Azure. This support is made possible through a set of TokenCredential implementations, which are discussed in this article.

This article covers the following subjects:

For troubleshooting authentication issues related to Azure-hosted applications, see Troubleshoot Azure-hosted application authentication.

DefaultAzureCredential

DefaultAzureCredential combines credentials that are commonly used to authenticate when deployed, with credentials that are used to authenticate in a development environment. For more information, see DefaultAzureCredential overview.

Configure DefaultAzureCredential

DefaultAzureCredential supports a set of configurations through setters on the DefaultAzureCredentialBuilder or environment variables.

  • Setting the environment variables AZURE_CLIENT_ID, AZURE_CLIENT_SECRET, and AZURE_TENANT_ID as defined in Environment variables configures DefaultAzureCredential to authenticate as the service principal specified by the values.
  • Setting .managedIdentityClientId(String) on the builder or the environment variable AZURE_CLIENT_ID configures DefaultAzureCredential to authenticate as a user-assigned managed identity, while leaving them empty configures it to authenticate as a system-assigned managed identity.
  • Setting .tenantId(String) on the builder or the environment variable AZURE_TENANT_ID configures DefaultAzureCredential to authenticate to a specific tenant for either the shared token cache or IntelliJ IDEA.
  • Setting the environment variable AZURE_USERNAME configures DefaultAzureCredential to pick the corresponding cached token from the shared token cache.

Authenticate with DefaultAzureCredential

The following example demonstrates authenticating the SecretClient from the azure-security-keyvault-secrets client library using DefaultAzureCredential:

// Azure SDK client builders accept the credential as a parameter.
SecretClient client = new SecretClientBuilder()
  .vaultUrl("https://<KEY_VAULT_NAME>.vault.azure.net")
  .credential(new DefaultAzureCredentialBuilder().build())
  .buildClient();

Authenticate a user-assigned managed identity with DefaultAzureCredential

The following example demonstrates authenticating the SecretClient from the azure-security-keyvault-secrets client library using DefaultAzureCredential deployed to an Azure resource with a user-assigned managed identity configured.

/**
 * DefaultAzureCredential uses the user-assigned managed identity with the specified client ID.
 */
DefaultAzureCredential credential = new DefaultAzureCredentialBuilder()
  .managedIdentityClientId("<CLIENT_ID>")
  .build();

// Azure SDK client builders accept the credential as a parameter.
SecretClient client = new SecretClientBuilder()
  .vaultUrl("https://<KEY_VAULT_NAME>.vault.azure.net")
  .credential(credential)
  .buildClient();

ManagedIdentityCredential

ManagedIdentityCredential authenticates the managed identity (system-assigned or user-assigned) of an Azure resource. So, if the application is running inside an Azure resource that supports managed identity through IDENTITY/MSI, IMDS endpoints, or both, then this credential gets your application authenticated, and offers a secretless authentication experience.

For more information, see What are managed identities for Azure resources?.

Authenticate in Azure with managed identity

The following example demonstrates authenticating the SecretClient from the azure-security-keyvault-secrets client library using the ManagedIdentityCredential in a Virtual Machine, App Service, Functions app, Cloud Shell, Service Fabric, Arc, or AKS environment on Azure, with system-assigned or user-assigned managed identity enabled.

/**
 * Authenticate with a user-assigned managed identity.
 */
ManagedIdentityCredential credential = new ManagedIdentityCredentialBuilder()
  .clientId("<CLIENT_ID>") // required only for user-assigned
  .build();

// Azure SDK client builders accept the credential as a parameter.
SecretClient client = new SecretClientBuilder()
  .vaultUrl("https://<KEY_VAULT_NAME>.vault.azure.net")
  .credential(credential)
  .buildClient();

Environment variables

You can configure DefaultAzureCredential and EnvironmentCredential with environment variables. Each type of authentication requires values for specific variables:

Service principal with secret

Variable name Value
AZURE_CLIENT_ID ID of a Microsoft Entra application.
AZURE_TENANT_ID ID of the application's Microsoft Entra tenant.
AZURE_CLIENT_SECRET One of the application's client secrets.

Service principal with certificate

Variable name Value
AZURE_CLIENT_ID ID of a Microsoft Entra application.
AZURE_TENANT_ID ID of the application's Microsoft Entra tenant.
AZURE_CLIENT_CERTIFICATE_PATH Path to a PEM-encoded certificate file including private key (without password protection).
AZURE_CLIENT_CERTIFICATE_PASSWORD (optional) Password of the certificate file, if any.
AZURE_CLIENT_SEND_CERTIFICATE_CHAIN (optional) Send certificate chain in x5c header to support subject name / issuer-based authentication.

Username and password

Variable name Value
AZURE_CLIENT_ID ID of a Microsoft Entra application.
AZURE_TENANT_ID ID of the application's Microsoft Entra tenant.
AZURE_USERNAME A username (usually an email address).
AZURE_PASSWORD The associated password for the given username.

Configuration is attempted in this order. For example, if values for a client secret and certificate are both present, the client secret is used.

Next steps

This article covered authentication for applications hosted in Azure. This form of authentication is one of multiple ways you can authenticate in the Azure SDK for Java. The following articles describe other ways:

If you run into issues related to Azure-hosted application authentication, see Troubleshoot Azure-hosted application authentication.

After you've mastered authentication, see Configure logging in the Azure SDK for Java for information on the logging functionality provided by the SDK.