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API Management authentication policies

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This article provides a reference for API Management policies used for authentication with API backends.

More information about policies:

Authentication policies

Authenticate with Basic

Use the authentication-basic policy to authenticate with a backend service using Basic authentication. This policy effectively sets the HTTP Authorization header to the value corresponding to the credentials provided in the policy.

Note

Set the policy's elements and child elements in the order provided in the policy statement. Learn more about how to set or edit API Management policies.

Policy statement

<authentication-basic username="username" password="password" />

Example

<authentication-basic username="testuser" password="testpassword" />

Elements

Name Description Required
authentication-basic Root element. Yes

Attributes

Name Description Required Default
username Specifies the username of the Basic credential. Yes N/A
password Specifies the password of the Basic credential. Yes N/A

Usage

This policy can be used in the following policy sections and scopes.

  • Policy sections: inbound

  • Policy scopes: all scopes

Authenticate with client certificate

Use the authentication-certificate policy to authenticate with a backend service using a client certificate. The certificate needs to be installed into API Management first and is identified by its thumbprint or certificate ID (resource name).

Caution

If the certificate references a certificate stored in Azure Key Vault, identify it using the certificate ID. When a key vault certificate is rotated, its thumbprint in API Management will change, and the policy will not resolve the new certificate if it is identified by thumbprint.

Note

Set the policy's elements and child elements in the order provided in the policy statement. Learn more about how to set or edit API Management policies.

Policy statement

<authentication-certificate thumbprint="thumbprint" certificate-id="resource name"/>

Examples

In this example, the client certificate is identified by the certificate ID:

<authentication-certificate certificate-id="544fe9ddf3b8f30fb490d90f" />

In this example, the client certificate is identified by its thumbprint:

<authentication-certificate thumbprint="CA06F56B258B7A0D4F2B05470939478651151984" />

In this example, the client certificate is set in the policy rather than retrieved from the built-in certificate store:

<authentication-certificate body="@(context.Variables.GetValueOrDefault<byte[]>("byteCertificate"))" password="optional-certificate-password" />

Elements

Name Description Required
authentication-certificate Root element. Yes

Attributes

Name Description Required Default
thumbprint The thumbprint for the client certificate. Either thumbprint or certificate-id must be present. N/A
certificate-id The certificate resource name. Either thumbprint or certificate-id must be present. N/A
body Client certificate as a byte array. No N/A
password Password for the client certificate. Used if certificate specified in body is password protected. N/A

Usage

This policy can be used in the following policy sections and scopes.

  • Policy sections: inbound

  • Policy scopes: all scopes

Authenticate with managed identity

Use the authentication-managed-identity policy to authenticate with a backend service using the managed identity. This policy essentially uses the managed identity to obtain an access token from Azure Active Directory for accessing the specified resource. After successfully obtaining the token, the policy will set the value of the token in the Authorization header using the Bearer scheme.

Both system-assigned identity and any of the multiple user-assigned identities can be used to request a token. If client-id is not provided, system-assigned identity is assumed. If the client-id variable is provided, token is requested for that user-assigned identity from Azure Active Directory.

Note

Set the policy's elements and child elements in the order provided in the policy statement. Learn more about how to set or edit API Management policies.

Policy statement

<authentication-managed-identity resource="resource" client-id="clientid of user-assigned identity" output-token-variable-name="token-variable" ignore-error="true|false"/>

Example

Use managed identity to authenticate with a backend service

<authentication-managed-identity resource="https://graph.microsoft.com"/> 

<authentication-managed-identity resource="https://management.azure.com/"/> <!--Azure Resource Manager-->

<authentication-managed-identity resource="https://vault.azure.net"/> <!--Azure Key Vault-->

<authentication-managed-identity resource="https://servicebus.azure.net/"/> <!--Azure Service Bus-->

<authentication-managed-identity resource="https://storage.azure.com/"/> <!--Azure Blob Storage-->

<authentication-managed-identity resource="https://database.windows.net/"/> <!--Azure SQL-->

<authentication-managed-identity resource="AD_application_id"/> <!--Application (client) ID of your own Azure AD Application-->

Use managed identity and set header manually

<authentication-managed-identity resource="AD_application_id"
   output-token-variable-name="msi-access-token" ignore-error="false" /> <!--Application (client) ID of your own Azure AD Application-->
<set-header name="Authorization" exists-action="override">
   <value>@("Bearer " + (string)context.Variables["msi-access-token"])</value>
</set-header>

Use managed identity in send-request policy

<send-request mode="new" timeout="20" ignore-error="false">
    <set-url>https://example.com/</set-url>
    <set-method>GET</set-method>
    <authentication-managed-identity resource="ResourceID"/>
</send-request>

Elements

Name Description Required
authentication-managed-identity Root element. Yes

Attributes

Name Description Required Default
resource String. The App ID of the target web API (secured resource) in Azure Active Directory. Yes N/A
client-id String. The App ID of the user-assigned identity in Azure Active Directory. No system-assigned identity
output-token-variable-name String. Name of the context variable that will receive token value as an object type string. No N/A
ignore-error Boolean. If set to true, the policy pipeline will continue to execute even if an access token is not obtained. No false

Usage

This policy can be used in the following policy sections and scopes.

  • Policy sections: inbound

  • Policy scopes: all scopes

Next steps

For more information about working with policies, see: