Advanced Gateway features configuration

As a system programmer who wants to configure advanced Gateway features of the API Mediation Layer, you can customize Gateway parameters by modifying either of the following files:

• <Zowe install directory>/components/api-mediation/bin/start-gateway.sh
• <Zowe instance directory>/instance.env

The parameters begin with the -D prefix, similar to all the other parameters in the file.

Note: Restart Zowe to apply changes to the parameter.

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

• Prefer IP Address for API Layer services
• SAF as an Authentication provider
• Gateway retry policy
• Gateway timeouts
• Cors handling
• Encoded slashes
• Connection limits
• API Mediation Layer as a standalone component

Prefer IP Address for API Layer services

API Mediation Layer services use the hostname when communicating with each other. This behavior can be changed so that the IP address is used instead.

Follow these steps:

1. Open the <Zowe instance directory>/instance.env configuration file.
2. Find the property APIML_PREFER_IP_ADDRESS and set the value to true.
3. Restart Zowe&trade.

Note: Changing the value of this property might introduce problems with certificates. Ensure that the IP Address is present on the certificate SAN name.

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.

Follow these steps:

1. Open the <Zowe instance directory>/instance.env configuration file.
2. Find the property APIML_SECURITY_AUTH_PROVIDER and set the value to saf.
3. Restart Zowe&trade.

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

Gateway retry policy

To change the Gateway retry policy, edit properties in the <Zowe install directory>/components/api-mediation/bin/start.sh file:

All requests are disabled as the default configuration for retry with one exception: the server retries GET requests that finish with status code 503. To change this default configuration, include the following parameters:

• ribbon.retryableStatusCodes

  Provides a list of status codes, for which the server should retry the request.

  Example: -Dribbon.retryableStatusCodes="503, 404"

• 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.

• 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.

• 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.

Gateway timeouts

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

Follow these steps:

1. Open the file <Zowe instance directory>/instance.env.
2. Find the property APIML_GATEWAY_TIMEOUT_MILLIS and set the value to the desired value.
3. Restart Zowe&trade.

If you require finer control, you can edit the <Zowe install directory>/components/api-mediation/bin/start.sh, and modify the following properties:

• apiml.gateway.timeoutMillis

  This property defines the global value for http/ws client timeout.

Add the following properties to the file for API Gateway:

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

• 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.

• 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.

• 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.

CORS handling

By default, Cross-Origin Resource Sharing (CORS) is disabled in the API Gateway for the Gateway routes api/v1/gateway/**. To enable CORS at the service level, it is necessary to enable CORS in the Gateway. Use the following procedure to enable CORS.

Follow these steps:

1. Open the file <Zowe instance directory>/instance.env.
2. Find the property APIML_CORS_ENABLED and set the value to true.
3. Restart Zowe&trade.

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.

Follow these steps:

1. Open the file <Zowe instance directory>/instance.env.
2. Find the property APIML_ALLOW_ENCODED_SLASHES and set the value to false.
3. Restart Zowe&trade.

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

Connection limits

By default, the API Gateway accepts up to 100 conncurrent 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. For more information, see Apache documentation.

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

Follow these steps:

1. Open the file <Zowe instance directory>/instance.env.
2. Find the property APIML_MAX_CONNECTIONS_PER_ROUTE and set the value to an appropriate positive integer.
3. Find the property APIML_MAX_TOTAL_CONNECTIONS and set the value to an appropriate positive integer.

API Mediation Layer as a standalone component

By default, the Gateway, Zowe System Services, and Virtual Desktop start when Zowe runs. To limit consumed resources when the Virtual Desktop or Zowe System Services are not required, it is possible to specify which components start in the context of Zowe. No change is required during the installation process to support this setup.

Once Zowe is installed, use the following procedure to limit which components start.

Follow these steps:

1. Open the file <Zowe instance directory>/instance.env.
2. Find the property LAUNCH_COMPONENT_GROUPS and set GATEWAY
3. Restart Zowe&trade.

To learn more about the related section of the environment file, see Creating and configuring the Zowe instance directory.