Advanced Gateway features configuration

Modifying the zowe.yaml file to configure advanced Gateway features of the API Mediation Layer.

Note: Restart Zowe to apply changes to the parameter.

Follow the procedures in the following sections to customize Gateway parameters according to your preferences:

• Runtime configuration
• SAF as an Authentication provider
• Enable JWT token refresh endpoint
• Enabling PassTicket support
• Gateway retry policy
• Gateway client certificate authentication
• Gateway timeouts
• CORS handling
• Encoded slashes
• Add a custom HTTP Auth header to store Zowe JWT token
• Add custom HTTP Auth headers to store user ID and PassTicket
• Connection limits
• Routed instance header
• Distributed load balancer cache
• Personal Access Token
• API Mediation Layer as a standalone component
• SAF resource checking
• AT-TLS
• Unique cookiename for multiple zowe instances

Runtime configuration

Use the following procedure to customize properties for your runtime configuration.

1. Open the file zowe.yaml.

2. Configure the following properties:

   • apiml.service.hostname
     This property is used to set the API Gateway hostname. The value can be set by defining the ZWE_haInstance_hostname property in the zowe.yaml file.

   • apiml.service.port
     This property is used to set the API Gateway port. The value can be set by defining the ZWE_configs_port property in the zowe.yaml file.

   • apiml.service.discoveryServiceUrls
     This property specifies the Discovery Service URL used by the service to register to Eureka. The value can be set by defining the ZWE_DISCOVERY_SERVICES_LIST property in the zowe.yaml file.

   • components.gateway.apiml.security.ssl.verifySslCertificatesOfServices
     This parameter makes it possible to prevent server certificate validation.

     Important! Ensure that this parameter is set to true in production environments. Setting this parameter to false in production environments significantly degrades the overall security of the system.

   • components.gateway.apiml.security.auth.zosmf.ServiceId
     This parameter specifies the z/OSMF service id used as authentication provider. The service id is defined in the static definition of z/OSMF. The default value is zosmf.

   • ZWE_configs_debug
     This property can be used to unconditionally add active debug profiles. For more information, see the Spring documentation.

   • ZWE_configs_sslDebug
     This property can be used to enable the SSL debugging. This property can also assist with determining what exactly is happening at the SSL layer.

     This property uses the -Djavax.net.debug Java parameter when starting the Gateway component. By setting ZWE_configs_sslDebug to ssl, all the SSL debugging is turned on. The ZWE_configs_sslDebug parameter also accepts other values that enables a different level of tracing. For more information, see the IBM documentation.

     Note: This property can also be enabled for other API ML components.

   • ZWE_configs_server_maxTotalConnections and ZWE_configs_server_maxConnectionsPerRoute
     These two properties are used to set the number of concurrent connections. Further connection requests that put the number of connections over either of these limits are queued until an existing connection completes. The API Gateway is built on top of Apache HTTP components that require these two connection limits for concurrent requests.

3. Restart Zowe.

SAF as an Authentication provider

By default, the API Gateway uses z/OSMF as an authentication provider. It is possible to switch to SAF as the authentication provider instead of z/OSMF. The intended usage of SAF as an authentication provider is for systems without z/OSMF. If SAF is used and the z/OSMF is available on the system, the created tokens are not accepted by z/OSMF. Use the following procedure to switch to SAF.

1. Open the zowe.yaml configuration file.
2. Find or add the property components.gateway.apiml.security.auth.provider and set the value to saf.
3. Restart Zowe.

Authentication requests now utilize SAF as the authentication provider. API ML can run without z/OSMF present on the system.

Enable JWT token refresh endpoint

Enable the /gateway/api/v1/auth/refresh endpoint to exchange a valid JWT token for a new token with a new expiration date. Call the endpoint with a valid JWT token and trusted client certificate. When using the z/OSMF authentication provider, enable API Mediation Layer for passticket generation and configure the z/OSMF APPLID. For more information, see Configure Passtickets

1. Open the file zowe.yaml.

2. Configure the following properties:

   • components.gateway.apiml.security.allowtokenrefresh: true
     Add this property to enable the refresh endpoint.

   • components.gateway.apiml.security.zosmf.applid
     If you use z/OSMF as an authentication provider, provide a valid APPLID. The API ML generates a passticket for the specified APPLID and subsequently uses this passticket to authenticate to z/OSMF. The default value in the installation of z/OSMF is IZUDFLT.

3. Restart Zowe.

Enabling PassTicket support

The following steps outline the procedure for enabling PassTicket Support:

1. Follow the API service documentation that explains how to activate support for PassTickets.
   • The PassTickets for the API service must have the replay protection switched off. The PassTickets are exchanged between Zowe API Gateway and the API Service in a secure mainframe environment.
2. Record the value of the APPLID of the API service.
3. Enable the Zowe started task user ID to generate PassTickets for the API service. For more information, see PassTicket Security Configuration.
4. Enable PassTicket support in the API Gateway for your API service.

Note: PassTickets must be enabled for every user who requires access to the API service.

Gateway retry policy

Use the following procedure to change the Gateway retry policy.

All requests are disabled as the default configuration for retry with one exception: the server retries GET requests that finish with status code 503.

1. Open the zowe.yaml configuration file.
2. Configure the following properties:

• components.gateway.ribbon.retryableStatusCodes
  This property provides a list of status codes, for which the server should retry the request.

  **Example:** `components.gateway.ribbon.retryableStatusCodes: "503, 404"` 

• components.gateway.ribbon.OkToRetryOnAllOperations
  Specifies whether to retry all operations for this service. The default value is false. In this case, only GET requests are retried if they return a response code that is listed in ribbon.retryableStatusCodes. Setting this parameter to true enables retry requests for all methods which return a response code listed in ribbon.retryableStatusCodes.

  **Note:** Enabling retry can impact server resources due to request body buffering.

• components.gateway.ribbon.MaxAutoRetries
  Specifies the number of times a failed request is retried on the same server. This number is multiplied with ribbon.MaxAutoRetriesNextServer. The default value is 0.

• components.gateway.ribbon.MaxAutoRetriesNextServer
  Specifies the number of additional servers that attempt to make the request. This number excludes the first server. The default value is 5.

3. Restart Zowe

Gateway client certificate authentication

Use the following procedure to enable the feature to use a client certificate as the method of authentication for the API Mediation Layer Gateway.

1. Open the zowe.yaml configuration file.

2. Configure the following properties:

   • components.gateway.apiml.security.x509.enabled
     This property is the global feature toggle. Set the value to true to enable client certificate functionality.

   • components.gateway.apiml.security.zosmf.applid
     When z/OSMF is used as an authentication provider, provide a valid APPLID to allow for client certificate authentication. The API ML generates a passticket for the specified APPLID and subsequently uses this passticket to authenticate to z/OSMF. The default value in the installation of z/OSMF is IZUDFLT.

     Note: The following steps are only required if the ZSS hostname or default Zowe user name are altered:

3. Change the following property if user mapping is provided by an external API:

   • components.gateway.apiml.security.x509.externalMapperUrl

     Note: Skip this step if user mapping is not provided by an external API.

   The API Mediation Gateway uses an external API to map a certificate to the owner in SAF. This property informs the Gateway about the location of this API. ZSS is the default API provider in Zowe. You can provide your own API to perform the mapping. In this case, it is necessary to customize this value.

   The following URL is the default value for Zowe and ZSS:

   https://${ZWE_haInstance_hostname}:${GATEWAY_PORT}/zss/api/v1/certificate/x509/map

4. Add the following property if the Zowe runtime userId is altered from the default ZWESVUSR:

   • components.gateway.apiml.security.x509.externalMapperUser

   Note: Skip this step if the Zowe runtime userId is not altered from the default ZWESVUSR.

   To authenticate to the mapping API, a JWT is sent with the request. The token represents the user that is configured with this property. The user authorization is required to use the IRR.RUSERMAP resource within the FACILITY class. The default value is ZWESVUSR. Permissions are set up during installation with the ZWESECUR JCL or workflow.

   If you customized the ZWESECUR JCL or workflow (the customization of zowe runtime user: // SET ZOWEUSER=ZWESVUSR * userid for Zowe started task) and changed the default USERID, create the components.gateway.apiml.security.x509.externalMapperUser property and set the value by adding a new line as in the following example:

   Example:

   components.gateway.apiml.security.x509.externalMapperUser: yournewuserid  

5. Restart Zowe.

Gateway timeouts

Use the following procedure to change the global timeout value for the API Mediation Layer instance.

1. Open the file zowe.yaml.
2. Configure the following properties:

• components.gateway.apiml.gateway.timeoutmillis
  This property defines the global value for http/ws client timeout.

**Note:** Ribbon configures the client that connects to the routed services.

• components.gateway.ribbon.connectTimeout
  Specifies the value in milliseconds which corresponds to the period in which API ML should establish a single, non-managed connection with the service. If omitted, the default value specified in the API ML Gateway service configuration is used.

• components.gateway.ribbon.readTimeout
  Specifies the time in milliseconds of inactivity between two packets in response from this service to API ML. If omitted, the default value specified in the API ML Gateway service configuration is used.

• components.gateway.ribbon.connectionManagerTimeout
  The HttpClient employs a special entity to manage access to HTTP connections called by the HTTP connection manager. The purpose of an HTTP connection manager is to serve as a factory for new HTTP connections, to manage the life cycle of persistent connections, and to synchronize access to persistent connections. Internally, the connections that are managed serve as proxies for real connections. ConnectionManagerTimeout specifies a period during which managed connections with API ML should be established. The value is in milliseconds. If omitted, the default value specified in the API ML Gateway service configuration is used.

3. Restart Zowe.

CORS handling

You can enable the Gateway to terminate CORS requests for itself and also for routed services. By default, Cross-Origin Resource Sharing (CORS) handling is disabled for Gateway routes gateway/api/v1/** and for individual services. After enabling the feature as stated in the following prodecure, API Gateway endpoints start handling CORS requests and individual services can control whether they want the Gateway to handle CORS for them through the Custom Metadata parameters.

When the Gateway handles CORS on behalf of the service, it sanitizes defined headers from the communication (upstream and downstream). Access-Control-Request-Method,Access-Control-Request-Headers,Access-Control-Allow-Origin,Access-Control-Allow-Methods,Access-Control-Allow-Headers,Access-Control-Allow-Credentials,Origin The resulting request to the service is not a CORS request and the service does not need to do anything extra. The list can be overridden by specifying different comma-separated list in the property components.gateway.apiml.service.ignoredHeadersWhenCorsEnabled in zowe.yaml

Additionally, the Gateway handles the preflight requests on behalf of the service when CORS is enabled in Custom Metadata, replying with CORS headers:

• Access-Control-Allow-Methods: GET,HEAD,POST,DELETE,PUT,OPTIONS
• Access-Control-Allow-Headers: origin, x-requested-with
• Access-Control-Allow-Credentials: true
• Access-Control-Allow-Origin: *

Alternatively, list the origins as configured by the service, associated with the value customMetadata.apiml.corsAllowedOrigins in Custom Metadata.

If CORS is enabled for Gateway routes but not in Custom Metadata, the Gateway does not set any of the previously listed CORS headers. As such, the Gateway rejects any CORS requests with an origin header for the Gateway routes.

Use the following procedure to enable CORS handling.

1. Open the file zowe.yaml.
2. Find or add the property components.gateway.apiml.service.corsEnabled and set the value to true.
3. Restart Zowe.

Requests through the Gateway now contain a CORS header.

Encoded slashes

By default, the API Mediation Layer accepts encoded slashes in the URL path of the request. If you are onboarding applications which expose endpoints that expect encoded slashes, it is necessary to keep the default configuration. We recommend that you change the property to false if you do not expect the applications to use the encoded slashes.

Use the following procedure to reject encoded slashes.

1. Open the file zowe.yaml.
2. Find or add the property components.gateway.apiml.service.allowEncodedSlashes and set the value to false.
3. Restart Zowe.

Requests with encoded slashes are now rejected by the API Mediation Layer.

Add a custom HTTP Auth header to store Zowe JWT token

If a southbound service needs to consume the Zowe JWT token from a HTTP request header to participate in the Zowe SSO, you can define a custom HTTP header name as part of the Gateway configuration. The southbound service must use the zoweJwt scheme in order to leverage this functionality. Once the HTTP header name is defined, each request to the southbound service contains the JWT token in the custom header.

Use the following procedure to add the custom HTTP header.

1. Open the file zowe.yaml.
2. Find or add the property components.gateway.apiml.security.auth.jwt.customAuthHeader and set the value which represents the header's name.
3. Restart Zowe.

Requests through the Gateway towards the southbound service now contain the custom HTTP header with the JWT token.

Add custom HTTP Auth headers to store user ID and PassTicket

If a southbound service needs to consume the passticket and the user ID from custom headers to participate in the Zowe SSO, you can define the custom HTTP headers names as part of the Gateway configuration. The southbound service must use the httpBasicPassTicket scheme in order to leverage this functionality. Once the HTTP headers names are defined, each request to the southbound service contains the passticket and the user ID in the custom headers.

Use the following procedure to add the custom HTTP headers.

1. Open the file zowe.yaml.
2. Find or add the property components.gateway.apiml.security.auth.passticket.customAuthHeader and set the value which represents the header's name.
3. Find or add the property components.gateway.apiml.security.auth.passticket.customUserHeader and set the value which represents the header's name.
4. Restart Zowe.

Requests through the Gateway towards the southbound service now contain the custom HTTP headers with the passticket and the user ID.

Connection limits

By default, the API Gateway accepts up to 100 concurrent connections per route, and 1000 total concurrent connections. Any further concurrent requests are queued until the completion of an existing request. The API Gateway is built on top of Apache HTTP components that require these two connection limits for concurrent requests.

Use the following procedure to change the number of concurrent connections.

1. Open the file zowe.yaml.
2. Find or add the property components.gateway.server.maxConnectionsPerRoute and set the value to an appropriate positive integer.
3. Find or add the property components.gateway.server.maxTotalConnections and set the value to an appropriate positive integer.

Routed instance header

The API Gateway can output a special header that contains the value of the instance ID of the API service that the request has been routed to. This is useful for understanding which service instance is being called.

The header name is X-InstanceId, and the sample value is discoverable-client:discoverableclient:10012. This is identical to instanceId property in the registration of the Discovery service.

Use the following procedure to output a special header that contains the value of the instance ID of the API service.

1. Open the file zowe.yaml.
2. Find or add the property with value components.gateway.apiml.routing.instanceIdHeader:true.
3. Restart Zowe.

Distributed load balancer cache

You can choose to distribute the load balancer cache between instances of the API Gateway. To distribute the load balancer cache, it is necessary that the caching service is running. Gateway service instances are reuqired to have the same DN (Distinguished name) on the server certificate.

Use the following procedure to distribute the load balancer cache between instances of the API Gateway.

1. Open the file zowe.yaml.
2. Find or add the property with value components.gateway.apiml.loadBalancer.distribute: true.
3. Restart Zowe.

Replace or remove the Catalog with another service

By default, the API Mediation Layer contains the API Catalog as a service showing available services. As the API Mediation Layer can be successfully run without this component it is possible to replace or remove the service from the Gateway home page and health checks. The following section describes the behavior of the Gateway home page and health checks.

The default option displays the API Catalog.

A value can also be applied to components.gateway.apiml.catalog.serviceId.

Examples:

• none
  Nothing is displayed on the Gateway home page and the Catalog is removed from /application/health

• alternative-catalog
  An alternative to the API Catalog is displayed

• metrics-dashboard
  A possible dashboard that could appear in place of the API Catalog

Notes:

• If the application contains the homePageUrl and statusPageRelativeUrl, then the full set of information is displayed.
• If the application contains the homePageUrl the link is displayed without the UP information.
• If the application contains the statusPageRelativeUrl then UP or DOWN is displayed based on the statusPage without the link.

Use the following procedure to change or replace the Catalog service.

1. Open the file zowe.yaml.

2. Find or add the property components.gateway.apiml.catalog.serviceId. Set the value with the following options:

   • Set the value to none to remove the Catalog service.
   • Set the value to the ID of the service that is onboarded to the API Mediation Layer.

3. Restart Zowe.

Personal Access Token

By default the API Mediation Layer does not provide the ability to use personal access tokens. For more information about about this functionality, see Personal Access Tokens.

Use the following procedure to enable personal access tokens.

1. Open the file zowe.yaml.
2. Find or add the property with the value components.gateway.apiml.security.personalAccessToken.enabled: true.
3. Restart Zowe.

SAF Resource Checking

The API ML can check for the authorization of the user on certain endpoints. Access to a SAF resource is checked with ESM.

Verification of the SAF resource is provided by the following three providers:

• endpoint
  This is the highest priority provider, such as a REST endpoint call (ZSS or similar one). This option is disabled by default. In Zowe, ZSS has the API to check for SAF resource authorization.
• native
  The Native JZOS classes from Java are used to determine SAF resource access. This is the default provider.
• dummy
  This is the lowest priority provider. This is the dummy implementation and is defined in a file.

Note: Verification of the SAF resource uses the first available provider based on the specified priority. The default configuration resolves to the native provider.

You can select a specific provider by specifying the components.gateway.apiml.security.authorization.provider key in the zowe.yaml file. Use the parameter value to strictly define a provider. If verification is disabled, select the endpoint option.

1. Open the file zowe.yaml.
2. Find or add the property components.gateway.apiml.security.authorization.provider and set desired value.
3. Restart Zowe.

Examples:

components.gateway.apiml.security.authorization.endpoint.url: endpoint

Note: To configure the endpoint provider, add the following additional property: components.gateway.apiml.security.authorization.endpoint.enabled: true

components.gateway.apiml.security.authorization.provider: native

components.gateway.apiml.security.authorization.provider: dummy

To use the endpoint provider, customize the URL corresponding to the SAF resource authorization. By default, the ZSS API is configured and used.

1. Open the file zowe.yaml.
2. Find or add the property components.gateway.apiml.security.authorization.endpoint.url and set desired value. The default value for ZSS API is https://${ZWE_haInstance_hostname}:${GATEWAY_PORT}/zss/api/v1/saf-auth
3. Restart Zowe.

For more information about the SAF resource checking providers, see SAF Resource Checking Providers.

AT-TLS

The communication server on z/OS provides a functionality to encrypt HTTP communication for on-platform running jobs. This functionality is refered to as Application Transparent Transport Layer Security (AT-TLS). Starting with Zowe version 1.24, it is possible to leverage AT-TLS within the API Mediation Layer. Each API ML component can run with AT-TLS rules applied. Some components, such as the Discovery service, can be made AT-TLS aware by enabling the AT-TLS profile, whereby TLS information can be utilized. Such information could be a client certificate. To enable the AT-TLS profile and disable the TLS application in API ML, update zowe.yaml with following values under the respective component in the components section:

components.*.spring.profiles.active=attls
components.*.server.ssl.enabled=false
components.*.server.internal.ssl.enabled=false

While API ML can not handle TLS on its own, the Mediation Layer needs information about the server certificate that is defined in the AT-TLS rule. Update the zowe.yaml file for each respective APIML component in the components sections with the path to the SAF Key ring from the AT-TLS rule and specify the alias that is used for Inbound communication:

components.*.certificate.keystore.file=<SAF-key-ring-from-AT-TLS-rule>
components.*.certificate.keystore.type=JCERACFKS
components.*.certificate.keystore.password=<keyring-password>
components.*.certificate.keystore.alias=<certificate-alias-from-AT-TLS-rule>

Note: This procedure does not configure AT-TLS on z/OS, but rather enables API ML to work with AT-TLS in place.

Unique cookie name for multiple zowe instances

By default, in the API Gateway, the cookie name is apimlAuthenticationToken. To prevent overwriting of the default cookie name in the case of multiple Zowe instances, a unique cookie name can be configured for each instance.

Follow this procedure to configure a unique cookie name for the instances:

1. Open the zowe.yaml configuration file.

2. Find or add the property  components.gateway.apiml.security.auth.uniqueCookie, and set it to true. A unique cookie name is generated as apimlAuthenticationToken.cookieIdentifier.

   Example:
   If this parameter is set to true, and the cookieIdentifier is 1, the name of the cookie transforms to apimlAuthenticationToken.1.
   If this property is not set to true, the cookie name remains apimlAuthenticationToken by default.

3. Restart Zowe.