19. Integration with Kubernetes¶
19.1. Topology and CPU Manager¶
Robin Cloud Native Platform integrates with the Kubernetes Topology Manager and CPU Manager to support Non-Uniform Memory Access (NUMA) aware CPU allocation, Single Root I/O Virtualization (SR-IOV) devices, dedicated CPU allocation and FPGA devices for deployments using YAML files and/or Helm charts. This integration enables users to run workloads, such as telecommunication applications, that are latency-sensitive in native Kubernetes environments.
Moreover in environments where Robin Bundles cannot be used due to a preference for homegrown standardized Helm charts, operators, or YAMLs, the integration of the Topology and CPU Manager enables users to utilize the advanced networking and compute features supported by Bundles in a native Kubernetes environment. To support this, Robin provides special annotations for adding multiple interfaces and devices in Helm charts.
The following are advantages of the integration:
Multiple interface support for Pods
Dedicated CPUs for Guaranteed Pods
Helm charts that work in native Kubernetes environment work with Robin
No hardcoding of resources is required in Helm charts per environment (CPU IDs or SR-IOV resource names)
Easy to use annotations for specifying device and interface requests
NUMA-aware memory allocation is not currently supported by the Topology Manager.
19.1.1. Role of Topology Manager¶
The Topology Manager communicates with the CPU Manager and Device Managers to determine the layout of the physical infrastructure of the nodes within a cluster in order to place a Pod on an appropriate NUMA node based on the configured policies. For more information, see Topology Manager.
19.2. CNI plugins¶
Robin supports three CNI plugins, namely Open vSwitch (OVS), Calico and SR-IOV, in order to help orchestrate container networking for applications deployed on Robin. Each of these is regarded as a driver for an IP-Pool without which an application cannot be created. Each has its own advantages and might be the preferred network specification based on the workload. Detailed below are some notes on each driver and the benefits they bring.
Selecting a driver is mandatory for IP-Pool creation.
Robin enhances Kubernetes networking with Calico CNI plugin driven network address assignments and enables a fully distributed network architecture scaling smoothly for any size of deployment (in terms of number of PODs).
Moreover this driver enables policy based networking wherein which ingress/egress policies for Pods can be set up. In addition Robin integrates with Calico Typha in order to scale Kubernetes clusters beyond 50 nodes in size by minimizing the
calico-node, present on every node given the daemonset nature of the Calico CNI plugin,
pod’s impact on the Kubernetes API server datastore. This in turn improves the performance of the cluster.
19.2.2. Open vSwitch¶
Robin provides flat networking support with Open vSwitch (OVS) network driver based CNI IP address allocations to Robin application workloads thereby allowing users to access applications from outside the Robin cluster via a Kubernetes NodePort. This driver is clearly the preferred choice if applications need to be accessed by external services. Robin also provides dual stack networking support with OVS allowing users to assign both Ipv4 and Ipv6 addresses to their application workloads. This flexibility can be an advantage depending on application requirements.
SR-IOV is a specification that allows a PCIe device to appear as multiple separate physical PCIe devices. It works by introducing the idea of physical functions (PFs) and virtual functions (VFs). Physical functions (PFs) are full-featured PCIe functions, where as virtual functions (VFs) are “lightweight” functions that lack configuration resources. In order to function correctly, SR-IOV requires support at BIOS level as well as in the operating system instance or hypervisor that is running on the hardware. Robin allows a user to assign one or more virtual functions from physical functions to PODs created through Robin bundles. In order to achieve this Robin leverages the following CNI’s: Multus, Bond CNI and Intel CNI for SR-IOV.
Robin discovers SR-IOV NICs alongside their Virtual Functions as part of the discovery process (more details available here) and accounts for them similarly to any other compute resource. As a result, Robin supports NUMA awareness for applications not only in terms of memory and CPU but also with regard to VF’s from SR-IOV NICs that are within the NUMA boundary.
Some additional features that complement SR-IOV support include:
Robin has the ability to tag VLAN traffic for networks based on the VFs present
Robin has the ability to bind a DPDK driver to a VF associated with a POD. The user can specify this kernel driver whilst creating an IP-Pool. Note that the kernel driver module has to be pre-loaded on the node for full functionality.
Robin has the ability to bond virtual functions, which are attached to POD, from different physical functions.