z/OS Provisioning Toolkit images

A z/OS PT image is a binary object that contains the configuration, application code, and environment variables to rapidly provision a preconfigured environment that is tailored to a specific user's requirements. An image can also name a template that z/OS PT uses to provision the middleware that is specified in the template. z/OS PT provides a set of sample CICS® and z/OS Connect EE images to help you get started.

Overview of z/OS PT images

A z/OS PT image is a set of files and configuration information that is built from a zosptfile, which contains syntax statements about what to include in an image, and what the image needs to run in a container. After an image is built, you can use z/OS PT to run it and provision a container with the image contents. If you run the same image multiple times, you provision identical containers. A z/OS PT image extends the configuration of an environment that is defined by a template that you load into z/OSMF. By providing configuration in images, you have more flexibility to tailor the environment to a user's needs, and can reduce the number of templates that need to be loaded in z/OSMF.

The template contains a base set of configuration that can be overridden in the images. The environment variables that you can set in an image vary by subsystem. For CICS, you can choose which environment variables you want to allow an image to override. See Modifying the set of CICS configuration properties that can be overridden.

Why use a z/OS PT image?

z/OS PT enables users to build images to configure a middleware instance that is provisioned from a z/OSMF template. Some of the benefits of using z/OS PT images are as follows:
  • Images enable a single z/OSMF template to be used to provision systems with different configurations.
  • An image can contain zFS artifacts that are deployed to the file system and used by the provisioned subsystem.
  • Images are reusable and can be run multiple times.
  • Images are easy to build and do not require reapproval of the template.
  • An application developer can build images upon an image that is supplied by the system programmer.
The following diagram shows that the CICS system programmer provides the base image for any developer who needs a CICS TS V5.5 container. A developer can choose to have a Java™ Liberty environment or a JSON web services environment. By basing an image upon the cics_55 image, all three use cases can use the same CICS TS V5.5 template in z/OSMF. Each image only needs to provide a few environment variables to customize the CICS region to meet a developer's needs. The application developer runs the cics_55_json image, which uses the base image that the system programmer supplied, and the cics_55 template in z/OSMF to provision a CICS container that provisions an Axis2 JVM server for JSON web services.
Figure 1. Images that are built from a base image
This diagram shows that you can build images upon other images, as described in the surrounding text.

Using a simple from statement in the zosptfile, you can build dependencies between images until you have a stack of images. A base image has from scratch as the first line. It has no dependencies and must contain the name of a template in z/OSMF. You can choose how granular to make your images. The following example shows three images in a stack, where the base image, cics_55, can be run to provision a simple CICS region. The next image, cics_55_liberty, contains configuration such that when it is run, it provisions a CICS region with a Liberty server. The first image, my_java_app, built by an application developer, builds a Java application. If an application developer runs the image, a CICS region is provisioned with Liberty and with the Java application running inside.

Figure 2. A stack of z/OS PT images
This diagram shows that you can build a stack of images, as described in the surrounding text.

z/OS PT sample images

z/OS PT provides sample images in the zospt/images directory, which are built from the corresponding sample zosptfile from the zospt/samples directory. For more information about the sample images that are provided with z/OS PT, see Sample images and the source artifacts that are used to build them.