Chapter 2. Technology overview We offer a solution for running Red Hat OpenShift Container Platform 4.12 on Red Hat OpenStack Platform 16. Our solution deploys Red Hat OpenShift Container Platform 4.12 to physical servers that run Red Hat OpenStack Platform 16.2. We use Red Hat OpenStack Platform director to perform the initial OpenStack installation and Day 2 operations. 2.1. Relationship between OpenShift and OpenStack The relationship between OpenStack and OpenShift is complementary. OpenStack exposes resources through an application programming interface (API) and OpenShift requests them. OpenStack provides OpenShift with compute, storage, and networking infrastructure, plus additional resources, such as self-service load balancers and encryption. OpenShift runs its containerized applications on the infrastructure provisioned by OpenStack. The products are tightly integrated. OpenShift can consume OpenStack resources on demand and without user intervention. 2.1.1. Red Hat Enterprise Linux CoreOS (RHCOS) Beginning with OpenShift 4, OpenShift nodes now run on Red Hat Enterprise Linux (RHEL) CoreOS (RHCOS). RHEL CoreOS combines the ease of over-the-air updates from Container Linux (formerly known as CoreOS) with the Red Hat Enterprise Linux kernel to deliver a more secure, easily managed container host. In an installer-provisioned infrastructure based deployment, RHCOS is the supported operating system for all the OpenShift Container Platform nodes and is used by default for workers and controllers. It is also an OpenShift requirement that the controller nodes run RHCOS. Currently, RHCOS is only used with OpenShift, it is not provided for use as an independent operating system. For more information see Red Hat Enterprise Linux (RHEL) CoreOS . 2.2. Solution overview Although there are many available options for placing OpenShift on OpenStack, we provide one validated solution to ensure clarity, simplicity, and supportability. The Red Hat Tested Solution represents the components and integrations of this solution, which has been tested by QE and is a starting point for all enterprise deployments. Figure 2.1. Diagram of the Red Hat solution We made these key choices to complete the installation and setup shown in the Diagram of the Red Hat solution : Installation OpenStack is installed using director. OpenStack is installed using external TLS encryption. OpenShift is installed using installer-provisioned infrastructure (IPI). OpenShift is installed from the director host using a non-privileged OpenStack tenant. Storage OpenStack deploys Fileshare-as-a-Service (manila) usable with RWX container workloads. OpenStack deploys the Block Storage service (cinder) usable with RWO container workloads. OpenStack uses local storage for Compute (nova) ephemeral storage. OpenStack uses Red Hat Ceph Storage (RHCS) for Image (glance), Block Storage (cinder), Object (swift), and optionally Compute (nova). OpenStack uses RHCS with Ganesha for Fileshare-as-a-Service (manila). OpenShift uses a Container Storage Interface (CSI) driver to provide access to manila. OpenShift uses Object storage for the internal registry. Compute OpenShift control-plane and worker VMs are deployed using nova availability zones to provide high availability. Networking OpenStack uses Open Virtual Network (OVN) for its SDN. OpenShift networking is managed by OVN-Kubernetes. OpenStack deploys Load-Balancing-as-a-Service (Octavia) for OpenShift load balancing. OpenShift uses the Amphora driver for Octavia to provide load balancing.

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