At SHARE Pittsburgh, the IBM z/OS team outlined its plans for z/OS Container Extensions (zCX) and provided attendees with background on all existing zCX standard features, as well as how they can get started using containers. Dave Jeffries, vice president for development and offering management for IBM z/OS software, says IBM wants to ease clients’ extension and modernization of the native z/OS ecosystem of applications and software through an agile and flexible deployment of Linux on Z applications into z/OS, while delivering IBM Z qualities of service.
zCX is a pre-packaged Docker appliance provided and maintained by IBM. IBM says the tool can be used by z/OS clients to modernize their infrastructure, applications, and/or data to drive hybrid multicloud integration without undermining their current functionality.
zCX enables a z14 or z15 server with the Container Hosting Foundation feature running z/OS 2.4 to host Docker Containers on z/OS. A separately provisioned Linux server is not required, and overall solution operational control is maintained within z/OS with z/OS Qualities of Service.
Capabilities of zCX
zCX is provisioned using z/OSMF workloads for continuous simplification of OS management. The standard Docker interface in zCX supports deployment of any software available as a Docker image for Linux on Z, and communications with native z/OS applications occur using TCP/IP semantics. This enables clients to deploy Linux on Z applications as Docker containers in a z/OS system to directly support z/OS workloads. Customers’ Linux applications can use existing z/OS application data. Application developers can also develop open source programs, and data centers can operate popular open source packages, Linux applications, IBM software, and third-party software together with z/OS applications and data through zCX.
z/OSMF workflows are included to simplify and automate deployment of zCX instances. Once deployed, application developers can use the Docker command user interface and standard Linux skills to run Linux applications on z/OS, without requiring in-depth z/OS skills porting.  This means that to the developer, applications will look like Linux Docker applications, not z/OS applications.
Similarly, for systems administrators, minimal Linux system administration skills are needed due to the accompanying Docker command line interface. “zCX is configured and managed using z/OS operational procedures without needing to install and maintain Linux and Docker,” says Jeffries.
Benefits of zCX
For IBM Z clients, zCX allows them to extend their applications and workloads to use services currently unavailable under z/OS. For non-Linux clients, zCX helps them access and introduce new technology to the z/OS from a large ecosystem of open source and Linux on Z workloads that can now be co-located on the z/OS platform, says Jeffries. “Proximity of Linux software (due to co-location) to z/OS transaction data enables operational control and exploitation of z/OS platform benefits,” he adds. While zCX can be used to deploy any Linux on Z docker images, it is designed for use cases where there is an affinity to z/OS software and workloads.
Although developed on Linux, Jeffries says applications and services will transparently benefit from the z/OS QoS. Workloads in zCX can benefit from high availability and DR planning via features like IBM HyperSwap, storage replication, and IBM GDPS. Applications within zCX also leverage z/OS workload management capabilities for capacity planning and tuning. Users requiring additional scalability and availability can use multiple IBM zCX instances to form a Docker swarm cluster, with multiple copies of containers deployed, including load balancing and high availability. “IBM’s statement of direction indicates intent to also support Kubernetes orchestration in IBM zCX in support of further integration of compatible cloud platforms,” he explains.
zCX Can Expand z/OS Capabilities
Jeffries adds that IBM zCX can also help overcome cross-platform operational challenges by managing and servicing the entire software appliance, including the Linux and underlying Docker components required. This, he says, poses less of a burden on operations and dependency management because there are no requirements on systems operators and application developers to acquire new skills. He says zCX can open the door to new software capabilities on the z/OS platform, while not requiring clients to replace native z/OS software that exploits z/OS services or other Linux on IBM Z environments, effectively expanding the application ecosystem.