4. Component Level Architecture

4.1. Introduction

This chapter describes in detail the Kubernetes Reference Architecture in terms of the functional capabilities and how they relate to the Reference Model requirements, i.e. how the infrastructure profiles are determined, documented and delivered.

The specifications defined in this chapter will be detailed with unique identifiers, which will follow the pattern: ra2.<section>.<index>, e.g. ra2.ch.001 for the first requirement in the Kubernetes Node section. These specifications will then be used as requirements input for the Kubernetes Reference Implementation and any vendor or community implementations.

Figure 4-1 below shows the architectural components that are described in the subsequent sections of this chapter.

Figure 4-1: Kubernetes Reference Architecture

4.2. Kubernetes Node

This section describes the configuration that will be applied to the physical or virtual machine and an installed Operating System. In order for a Kubernetes Node to be conformant with the Reference Architecture it must be implemented as per the following specifications:

Ref	Specification	Details		Requirement Trace	Reference Implementation Trace
ra2.ch.001	Huge pages	When hosting workloads matching the High Performance profile, it must be possible to enable Huge pages (2048KiB and 1048576KiB) within the Kubernetes Node OS, exposing schedu lable resources hugepages-2Mi and hugepages-1Gi.		infra.com.cfg.004	RI2 4.3.1
ra2.ch.002	SR-IOV capable NICs	When hosting workloads matching the High Performance profile, the physical machines on which the Kubernetes Nodes run must be equipped with NICs that are SR-IOV capable.		e.cap.013	RI2 3.3
ra2.ch.003	SR-IOV Virtual Functions Functions	When hosting workloads matching the High Performance profile, SR-IOV virtual functions (VFs) must be configured within the Kubernetes Node OS, as the SR-IOV Device Plugin does not manage the creation of these VFs.		e.cap.013	RI2 4.3.1
ra2.ch.004	CPU Simultaneo us Multi-Threa ding (SMT)	SMT must be enabled in the BIOS on the physical machine on which the Kubernetes Node runs.		infra.hw.cpu.cfg.004	RI2 3.3
ra2.ch.005	CPU Allocation Ratio - VMs	For Kubernetes nodes running as Virtual Machines, the CPU allocation ratio between vCPU and physical CPU core must be 1:1.
ra2.ch.006	CPU Allocation Ratio - Pods	To ensure the CPU allocation ratio between vCPU and physical CPU core is 1:1, the sum of CPU requests and limits by containers in Pod specifications must remain less than the allocatable quantity of CPU resources (i.e. requests.cpu < allocatable.cpu and limits.cpu < allocatable.cpu).		infra.com.cfg.001	RI2 3.3
ra2.ch.007	IPv6DualStack	To support IPv4/IPv6 dual stack networking, the Kubernetes Node OS must support and be allocated routable IPv4 and IPv6 addresses.
ra2.ch.008	Physical CPU Quantity	The physical machines on which the Kubernetes Nodes run must be equipped with at least 2 physical sockets, each with at least 20 CPU cores.		infra.hw.cpu.cfg.001 infra.hw.cpu.cfg.002	RI2 3.3
ra2.ch.009	Physical Storage	The physical machines on which the Kubernetes Nodes run should be equipped with Sold State Drives (SSDs).		infra.hw.stg.ssd.cfg.0 02	RI2 3.3
ra2.ch.010	Local Filesystem Storage Quantity	The Kubernetes Nodes must be equipped with local filesystem capacity of at least 320GB for unpacking and executing containers. Note, extra should be provisioned to cater for any overhead required by the Operating System and any required OS processes such as the container runtime, Kubernetes agents, etc.		e.cap.003	RI2 3.3
ra2.ch.011	Virtual Node CPU Quantity	If using VMs, the Kubernetes Nodes must be equipped with at least 16 vCPUs. Note, extra should be provisioned to cater for any overhead required by the Operating System and any required OS processes such as the container runtime, Kubernetes agents, etc.		e.cap.001
ra2.ch.012	Kubernetes Node RAM Quantity	The Kubernetes Nodes must be equipped with at least 32GB of RAM. Note, extra should be provisioned to cater for any overhead required by the Operating System and any required OS processes such as the container runtime, Kubernetes agents, etc.		e.cap.002	RI2 3.3
ra2.ch.013	Physical NIC Quantity	The physical machines on which the Kubernetes Nodes run must be equipped with at least four (4) Network Interface Card (NIC) ports.		infra.hw.nic.cfg.001	RI2 3.3
ra2.ch.014	Physical NIC Speed - Basic Profile	The speed of NIC ports housed in the physical machines on which the Kubernetes Nodes run for workloads matching the Basic Profile must be at least 10Gbps.		infra.hw.nic.cfg.002	RI2 3.3
ra2.ch.015	Physical NIC Speed - High Performance Profile	The speed of NIC ports housed in the physical machines on which the Kubernetes Nodes run for workloads matching the High Performance profile must be at least 25Gbps.		infra.hw.nic.cfg.002	RI2 3.3
ra2.ch.016	Physical PCIe slots	The physical machines on which the Kubernetes Nodes run must be equipped with at least eight (8) Gen3.0 PCIe slots, each with at least eight (8) lanes.
ra2.ch.017	Immutable infrastructure	Whether physical or virtual machines are used, the Kubernetes Node must not be changed after it is instantiated. New changes to the Kubernetes Node must be implemented as new Node instances. This covers any changes from BIOS through Operating System to running processes and all associated configurations.		req.gen.cnt.02	RI2 4.3.1
ra2.ch.018	NFD	Node Feature Discovery must be used to ad vertise the detailed software and hardware capabilities of each node in the Kubernetes Cluster.		tbd	RI2 4.3.1

Table 4-1: Node Specifications

4.3. Node Operating System

In order for a Host OS to be compliant with this Reference Architecture it must meet the following requirements:

Ref	Specification	Details		Requirement Trace	Reference Implementation Trace
ra2.os.001	Linux Distribution	A deb/rpm compatible distribution of Linux (this must be used for the master nodes, and can be used for worker nodes).		tbd	tbd
ra2.os.002	Linux Kernel Version	A version of the Linux kernel that is compatible with kubeadm - this has been chosen as the baseline because kubeadm is focussed on installing and managing the lifecycle of Kubernetes and nothing else, hence it is easily integrated into higher-level and more complete tooling for the full lifecycle management of the infrastructure, cluster add-ons, etc.		tbd	tbd
ra2.os.003	Windows Server	Windows Server (this can be used for worker nodes, but be aware of the limitations).		tbd	tbd
ra2.os.004	Disposable OS	In order to support req.gen.cnt.03 (immutable infrastructure), the Host OS must be disposable, meaning the configuration of the Host OS (and associated infrastructure such as VM or bare metal server) must be consistent - e.g. the system software and configuration of that software must be identical apart from those areas of configuration that must be different such as IP addresses and hostnames.		tbd	tbd
ra2.os.005	Automated Deployment	This approach to configuration management supports req.lcm.gen.01 (automated deployments)		tbd	tbd

Table 4-2: Operating System Requirements

Table 4-3 lists the kernel versions that comply with this Reference Architecture specification.

OS Family	Kernel Version(s)	Notes
Linux	3.10+
Windows	1809 (10.0.17763)	For worker nodes only

Table 4-3: Operating System Versions

4.4. Kubernetes

In order for the Kubernetes components to be conformant with the Reference Architecture they must be implemented as per the following specifications:

Ref	Specification	Details	Requirement Trace	Reference Implementation Trace
ra2.k8s.001	Kubernetes Conformance	The Kubernetes distribution, product, or installer used in the implementation must be listed in the Kubernetes Distributions and Platforms document and marked (X) as conformant for the Kubernetes version defined in Required versions of most important components.	req.gen.cnt. 03	RI2 4.3.1
ra2.k8s.002	Highly available etcd	An implementation must consist of either three, five or seven nodes running the etcd service (can be colocated on the master nodes, or can run on separate nodes, but not on worker nodes).	req.gen.rsl. 02, req.gen. avl.01	RI2 4.3.1
ra2.k8s.003	Highly available control plane	An implementation must consist of at least one master node per availability zone or fault domain to ensure the high availability and resilience of the Kubernetes control plane services.
ra2.k8s.012	Control plane services	A master node must run at least the following Kubernetes control plane services: kube-apiserver, kube-scheduler and kube-controller-manager.	req.gen.rsl. 02, req.gen.avl. 01	RI2 4.3.1
ra2.k8s.004	Highly available worker nodes	An implementation must consist of at least one worker node per availability zone or fault domain to ensure the high availability and resilience of workloads managed by Kubernetes	req.gen.rsl. 01, req.gen. avl.01, req. kcm.gen.02, req.inf.com. 02
ra2.k8s.005	Kubernetes API Version	In alignment with the Kubernetes version support policy, an implementation must use a Kubernetes version as per the subcomponent versions table in Required versions of most important components.
ra2.k8s.006	NUMA Support	When hosting workloads matching the High Performance profile, the TopologyManager and CPUManager feature gates must be enabled and configured on the kubelet (note, TopologyManager is enabled by default in Kubernetes v1.18 and later, with CPUManager enabled by default in Kubernetes v1.10 and later). --feature-gates="..., TopologyManager=true,CPUManager=true" --topology-manager-policy=single-numa-node --cpu-manager-policy=static	e.cap.007, infra.com.cfg .002, infra.hw.cpu. cfg.003
ra2.k8s.007	DevicePlugins Feature Gate	When hosting workloads matching the High Performance profile, the DevicePlugins feature gate must be enabled (note, this is enabled by default in Kubernetes v1.10 or later). --feature-gates="...,DevicePlugins=true,..."	Various, e.g. e.cap.013	RI2 4.3.1
ra2.k8s.008	System Resource Reservations	To avoid resource starvation issues on nodes, the implementation of the architecture must reserve compute resources for system daemons and Kubernetes system daemons such as kubelet, container runtime, etc. Use the following kubelet flags: --reserved-cpus=[a-z], using two of a-z to reserve 2 SMT threads.	i.cap.014
ra2.k8s.009	CPU Pinning	When hosting workloads matching the High Performance profile, in order to support CPU Pinning, the kubelet must be started with the --cpu-manager-policy=static option. (Note, only containers in Guaranteed pods - where CPU resource requests and limits are identical - and configured with positive-integer CPU requests will take advantage of this. All other Pods will run on CPUs in the remaining shared pool.)	infra.com.cfg .003
ra2.k8s.010	IPv6DualStack	To support IPv6 and IPv4, the IPv6DualStack feature gate must be enabled on various components (requires Kubernetes v1.16 or later). kube-apiserver: --feature-gates="IPv6DualStack=true". kube-controller-manager: --feature-gates="IPv6DualStack=true" --cluster-cidr=<IPv4 CIDR>,<IPv6 CIDR> --service-cluster-ip-range=<IPv4 CIDR>, <IPv6 CIDR> --node-cidr-mask-size-ipv4 ¦ --node-cidr-mask-size-ipv6 defaults to /24 for IPv4 and /64 for IPv6. kubelet: --feature-gates="IPv6DualStack=true". kube-proxy: --cluster-cidr=<IPv4 CIDR>, <IPv6 CIDR> --feature-gates="IPv6DualStack=true"	req.inf.ntw. 04
ra2.k8s.011	Anuket profile labels	To clearly identify which worker nodes are compliant with the different profiles defined by Anuket the worker nodes must be labelled according to the following pattern: an anuket.io/profile/basic label must be set to true on the worker node if it can fulfil the requirements of the basic profile and an anuket.io/profile/network-intensive label must be set to true on the worker node if it can fulfil the requirements of the High Performance profile. The requirements for both profiles can be found in Reference Model Requirements
ra2.k8s.012	Kubernetes APIs	Kubernetes Alpha API are recommended only for testing, therefore all Alpha APIs must be disabled.
ra2.k8s.013	Kubernetes APIs	Backward compatibility of all supported GA APIs of Kubernetes must be supported.
ra2.k8s.014	Security Groups	Kubernetes must support NetworkPolicy feature.
ra2.k8s.015	Publishing Services (ServiceTypes)	Kubernetes must support LoadBalancer Publishing Service (ServiceTypes).
ra2.k8s.016	Publishing Services (ServiceTypes)	Kubernetes must support Ingress.
ra2.k8s.017	Publishing Services (ServiceTypes)	Kubernetes should support NodePort Publishing Service (ServiceTypes).	req.inf.ntw. 17
ra2.k8s.018	Publishing Services (ServiceTypes)	Kubernetes should support ExternalName Publishing Service (ServiceTypes).
ra2.k8s.019	Kubernetes APIs	Kubernetes Beta APIs must be supported only when a stable GA of the same version doesn’t exist.	req.int.api. 04

Table 4-4: Kubernetes Specifications

4.5. Container runtimes

Ref	Specification	Details	Requirement Trace	Reference Implementation Trace
ra2.crt.001	Conformance with OCI 1.0 runtime spec	The container runtime must be implemented as per the OCI 1.0 (Open Container Initiative 1.0) specification.	req.gen.ost. 01	RI2 4.3.1
ra2.crt.002	Kubernetes Container Runtime Interface (CRI)	The Kubernetes container runtime must be implemented as per the Kubernetes Container Runtime Interface (CRI)	req.gen.ost. 01	RI2 4.3.1

Table 4-5: Container Runtime Specifications

4.6. Networking solutions

In order for the networking solution(s) to be conformant with the Reference Architecture they must be implemented as per the following specifications:

Ref	Specification	Details	Requirement Trace	Reference Implementation Trace
ra2.ntw.001	Centralised network administration	The networking solution deployed within the implementation must be administered through the Kubernetes API using native Kubernetes API resources and objects, or Custom Resources.	req.inf.ntw. 03	RI2 4.3.1
ra2.ntw.002	Default Pod Network - CNI	The networking solution deployed within the implementation must use a CNI-conformant Network Plugin for the Default Pod Network, as the alternative (kubenet) does not support cross-node networking or Network Policies.	req.gen.ost. 01 req.inf.ntw. 08	RI2 4.3.1
ra2.ntw.003	Multiple connection points	The networking solution deployed within the implementation must support the capability to connect at least FIVE connection points to each Pod, which are additional to the default connection point managed by the default Pod network CNI plugin.	e.cap.004	RI2 4.3.1
ra2.ntw.004	Multiple connection points presentation	The networking solution deployed within the implementation must ensure that all additional non-default connection points are requested by Pods using standard Kubernetes resource scheduling mechanisms such as annotations or container resource requests and limits.	req.inf.ntw. 03	RI2 4.3.1
ra2.ntw.005	Multiplexer / meta-plugin	The networking solution deployed within the implementation may use a multiplexer/meta-plugin.	req.inf.ntw. 06, req.inf.ntw. 07	RI2 4.3.1
ra2.ntw.006	Multiplexer / meta-plugin CNI Conformance	If used, the selected multiplexer/meta-plugin must integrate with the Kubernetes control plane via CNI.	req.gen.ost. 01	RI2 4.3.1
ra2.ntw.007	Multiplexer / meta-plugin CNI Plugins	If used, the selected multiplexer/meta-plugin must support the use of multiple CNI-conformant Network Plugins.	req.gen.ost. 01, req.inf.ntw. 06	RI2 4.3.1
ra2.ntw.008	SR-IOV Device Plugin for High Performance	When hosting workloads that match the High Performance profile and require SR-IOV acceleration, a Device Plugin for SR-IOV must be used to configure the SR-IOV devices and advertise them to the kubelet.	e.cap.013	RI2 4.3.1
ra2.ntw.009	Multiple connection points with multiplexer / meta-plugin	When a multiplexer/meta-plugin is used, the additional non-default connection points must be managed by a CNI-conformant Network Plugin.	req.gen.ost. 01	RI2 4.3.1
ra2.ntw.010	User plane networking	When hosting workloads matching the High Performance profile, CNI network plugins that support the use of DPDK, VPP, and/or SR-IOV must be deployed as part of the networking solution.	infra.net.acc .cfg.001	RI2 4.3.1
ra2.ntw.011	NATless connectivity	When hosting workloads that require source and destination IP addresses to be preserved in the traffic headers, a NATless CNI plugin that exposes the pod IP directly to the external networks (e.g. Calico, MACVLAN or IPVLAN CNI plugins) must be used.	req.inf.ntw. 14
ra2.ntw.012	Device Plugins	When hosting workloads matching the High Performance profile that require the use of FPGA, SR-IOV or other Acceleration Hardware, a Device Plugin for that FPGA or Acceleration Hardware must be used.	e.cap.016 e.cap.013	RI2 4.3.1
ra2.ntw.013	Dual stack CNI	The networking solution deployed within the implementation must use a CNI-conformant Network Plugin that is able to support dual-stack IPv4/IPv6 networking.	req.inf.ntw. 04
ra2.ntw.014	Security Groups	The networking solution deployed within the implementation must support network policies.	infra.net.cfg .004
ra2.ntw.015	IPAM plugin for multiplexer	When a multiplexer/meta-plugin is used, a CNI-conformant IPAM Network Plugin must be installed to allocate IP addresses for secondary network interfaces across all nodes of the cluster.	req.inf.ntw. 10

Table 4-6: Networking Solution Specifications

4.7. Storage components

In order for the storage solutions to be conformant with the Reference Architecture they must be implemented as per the following specifications:

Ref	Specification	Details	Requirement Trace	Reference Implementation Trace
ra2.stg.001	Ephemeral Storage	An implementation must support ephemeral storage, for the unpacked container images to be stored and executed from, as a directory in the filesystem on the worker node on which the container is running. See the Container runtimes section above for more information on how this meets the requirement for ephemeral storage for containers.
ra2.stg.002	Kubernetes Volumes	An implementation may attach additional storage to containers using Kubernetes Volumes.
ra2.stg.003	Kubernetes Volumes	An implementation may use Volume Plugins (see ra2.stg.005 below) to allow the use of a storage protocol (e.g., iSCSI, NFS) or management API (e.g., Cinder, EBS) for the attaching and mounting of storage into a Pod.
ra2.stg.004	Persistent Volumes	An implementation may support Kubernetes Persistent Volumes (PV) to provide persistent storage for Pods. Persistent Volumes exist independent of the lifecycle of containers and/or pods.	req.inf.stg. 01
ra2.stg.005	Storage Volume Types	An implementation must support the following Volume types: emptyDir, ConfigMap, Secret and PersistentVolumeClaim. Other Volume plugins may be supported to allow for the use of a range of backend storage systems.
ra2.stg.006	Container Storage Interface (CSI)	An implementation may support the Container Storage Interface (CSI), an Out-of-tree plugin. In order to support CSI, the feature gates CSIDriverRegistry and CSINodeInfo must be enabled. The implementation must use a CSI driver (a full list of CSI drivers can be found here). An implementation may support ephemeral storage through a CSI-compatible volume plugin in which case the CSIInlineVolume feature gate must be enabled. An implementation may support Persistent Volumes through a CSI-compatible volume plugin in which case the CSIPersistentVolume feature gate must be enabled.
ra2.stg.007		An implementation should use Kubernetes Storage Classes to support automation and the separation of concerns between providers of a service and consumers of the service.

Table 4-7: Storage Solution Specifications

A note on object storage:

• This Reference Architecture does not include any specifications for object storage, as this is neither a native Kubernetes object, nor something that is required by CSI drivers. Object storage is an application-level requirement that would ordinarily be provided by a highly scalable service offering rather than being something an individual Kubernetes cluster could offer.

Todo: specifications/commentary to support req.inf.stg.04 (SDS) and req.inf.stg.05 (high performance and horizontally scalable storage). Also req.sec.gen.06 (storage resource isolation), req.sec.gen.10 (CIS - if applicable) and req.sec.zon.03 (data encryption at rest).

4.8. Service meshes

Application service meshes are not in scope for the architecture. The service mesh is a dedicated infrastructure layer for handling service-to-service communication, and it is recommended to secure service-to-service communications within a cluster and to reduce the attack surface. The benefits of the service mesh framework are described in Use Transport Layer Security and Service Mesh. In addition to securing communications, the use of a service mesh extends Kubernetes capabilities regarding observability and reliability.

Network service mesh specifications are handled in section 4.5 Networking solutions.

4.9. Kubernetes Application package manager

In order for the application package managers to be conformant with the Reference Architecture they must be implemented as per the following specifications:

Ref	Specification	Details	Requirement Trace	Reference Implementation Trace
ra2.pkg.001	API-based package management	A package manager must use the Kubernetes APIs to manage application artifacts. Cluster-side components such as Tiller are not supported.	req.int.api. 02
ra2.pkg.002	Helm version 3	All workloads must be packaged using Helm (version 3) charts.

Helm version 3 has been chosen as the Application packaging mechanism to ensure compliance with the ONAP ASD NF descriptor specification and ETSI SOL0001 rel. 4 MCIOP specification.

Table 4-8: Kubernetes Application Package Manager Specifications

4.10. Kubernetes workloads

In order for the Kubernetes workloads to be conformant with the Reference Architecture they must be implemented as per the following specifications:

Ref	Specification	Details	Requirement Trace	Reference Implementation Trace
ra2.app.001	Root Parameter Group (OCI Spec)	Specifies the container’s root filesystem.	TBD	N/A
ra2.app.002	Mounts Parameter Group (OCI Spec)	Specifies additional mounts beyond root.	TBD	N/A
ra2.app.003	Process Parameter Group (OCI Spec)	Specifies the container process.	TBD	N/A
ra2.app.004	Hostname Parameter Group (OCI Spec)	Specifies the container’s hostname as seen by processes running inside the container.	TBD	N/A
ra2.app.005	User Parameter Group (OCI Spec)	User for the process is a platform-specific structure that allows specific control over which user the process runs as.	TBD	N/A
ra2.app.006	Consumption of additional, non-default connection points	Any additional non-default connection points must be requested through the use of workload annotations or resource requests and limits within the container spec passed to the Kubernetes API Server.	req.int.api.01	N/A
ra2.app.007	Host Volumes	Workloads should not use hostPath volumes, as Pods with identical configuration (such as those created from a PodTemplate) may behave differently on different nodes due to different files on the nodes.	req.kcm.gen.02	N/A
ra2.app.008	Infrastructure dependency	Workloads must not rely on the availability of the master nodes for the successful execution of their functionality (i.e. loss of the master nodes may affect non-functional behaviours such as healing and scaling, but components that are already running will continue to do so without issue).	TBD	N/A
ra2.app.009	Device plugins	Workload descriptors must use the resources advertised by the device plugins to indicate their need for an FPGA, SR-IOV or other acceleration device.	TBD	N/A
ra2.app.010	Node Feature Discovery (NFD)	Workload descriptors must use the labels advertised by Node Feature Discovery to indicate which node software of hardware features they need.	TBD	N/A
ra2.app.011	Published helm chart	Helm charts of the CNF must be published into a helm registry and must not be used from local copies.	CNCF CNF Testsuite	N/A
ra2.app.012	Valid Helm chart	Helm charts of the CNF must be valid and should pass the helm lint validation.	CNCF CNF Testsuite	N/A
ra2.app.013	Rolling update	Rolling update of the CNF must be possible using Kubernetes deployments.	CNCF CNF Testsuite	N/A
ra2.app.014	Rolling downgrade	Rolling downgrade of the CNF must be possible using Kubernetes deployments.	CNCF CNF Testsuite	N/A
ra2.app.015	CNI compatibility	The CNF must use CNI compatible networking plugins.	CNCF CNF Testsuite	N/A
ra2.app.016	Kubernetes API stability	The CNF must not use any Kubernetes alpha API-s.	CNCF CNF Testsuite	N/A
ra2.app.017	CNF resiliency (node drain)	CNF must not loose data, must continue to run and its readiness probe outcome must be Success even in case of a node drain and rescheduling occurs.	CNCF CNF Testsuite	N/A
ra2.app.018	CNF resiliency (network latency)	CNF must not loose data, must continue to run and its readiness probe outcome must be Success even in case of network latency up to 2000 ms occurs.	CNCF CNF Testsuite	N/A
ra2.app.019	CNF resiliency (pod delete)	CNF must not loose data, must continue to run and its readiness probe outcome must be Success even in case of pod delete occurs.	CNCF CNF Testsuite	N/A
ra2.app.020	CNF resiliency (pod memory hog)	CNF must not loose data, must continue to run and its readiness probe outcome must be Success even in case of pod memory hog occurs.	CNCF CNF Testsuite	N/A
ra2.app.021	CNF resiliency (pod I/O stress)	CNF must not loose data, must continue to run and its readiness probe outcome must be Success even in case of pod I/O stress occurs.	CNCF CNF Testsuite	N/A
ra2.app.022	CNF resiliency (pod network corruption)	CNF must not loose data, must continue to run and its readiness probe outcome must be Success even in case of pod network corruption occurs.	CNCF CNF Testsuite	N/A
ra2.app.023	CNF resiliency (pod network duplication)	CNF must not loose data, must continue to run and its readiness probe outcome must be Success even in case of pod network duplication occurs.	CNCF CNF Testsuite	N/A
ra2.app.024	CNF resiliency (pod DNS error)	CNF must not loose data, must continue to run and its readiness probe outcome must be Success even in case of pod DNS error occurs.		N/A
ra2.app.025	CNF local storage	CNF must not use local storage.	CNCF CNF Testsuite	N/A
ra2.app.026	Liveness probe	All Pods of the CNF must have livenessProbe defined.	CNCF CNF Testsuite	N/A
ra2.app.027	Readiness probe	All Pods of the CNF must have readinessProbe defined.	CNCF CNF Testsuite	N/A
ra2.app.028	No access to container daemon sockets	The CNF must not have any of the container daemon sockets (e.g.: /var/run/docker.sock, /var/run/containerd.sock or /var/run/crio.sock) mounted.		N/A
ra2.app.029	No automatic service account mapping	Non specified service accounts must not be automatically mapped. To prevent this the automountServiceAccountToken: false flag must be set in all Pods of the CNF.	CNCF CNF Testsuite	N/A
ra2.app.030	No host network access	Host network must not be attached to any of the Pods of the CNF. hostNetwork attribute of the Pod specifications must be False or should not be specified.	CNCF CNF Testsuite	N/A
ra2.app.031	Host process namespace separation	Pods of the CNF must not share the host process ID namespace or the host IPC namespace. Pod manifests must not have the hostPID or the hostIPC attribute set to true.	CNCF CNF Testsuite	N/A
ra2.app.032	Resource limits	All containers and namespaces of the CNF must have defined resource limits for at least CPU and memory resources.	CNCF CNF Testsuite	N/A
ra2.app.033	Read only filesystem	All containers of the CNF must have a read only filesystem. The readOnlyRootFilesystem attribute of the Pods in the their securityContext should be set to true.	CNCF CNF Testsuite	N/A
ra2.app.034	Container image tags	All referred container images in the Pod manifests must be referred by a version tag pointing to a concrete version of the image. latest tag must not be used.		N/A
ra2.app.035	No hardcoded IP addresses	The CNF must not have any hardcoded IP addresses in its Pod specifications.	CNCF CNF Testsuite	N/A
ra2.app.036	No node ports	Service declarations of the CNF must not contain nodePort definition.	Kubernetes documentation	N/A
ra2.app.037	Immutable config maps	ConfigMaps used by the CNF must be immutable.	Kubernetes documentation	N/A
ra2.app.038	Horizontal scaling	Increasing and decreasing of the CNF capacity should be implemented using horizontal scaling. If horizontal scaling is supported, automatic scaling must be possible using Kubernetes Horizontal Pod Autoscale (HPA) feature.	TBD	N/A
ra2.app.039	CNF image size	The different container images of the CNF should not be bigger than 5GB.	CNCF CNF Testsuite	N/A
ra2.app.040	CNF startup time	Startup time of the Pods of a CNF should not be more than 60s where startup time is the time between starting the Pod until the readiness probe outcome is Success.	CNCF CNF Testsuite	N/A
ra2.app.041	No privileged mode	None of the Pods of the CNF should run in privileged mode.	CNCF CNF Testsuite	N/A
ra2.app.042	No root user	None of the Pods of the CNF should run as a root user.	CNCF CNF Testsuite	N/A
ra2.app.043	No privilege escalation	None of the containers of the CNF should allow privilege escalation.	CNCF CNF Testsuite	N/A
ra2.app.044	Non-root user	All Pods of the CNF should be able to execute with a non-root user having a non-root group. Both runAsUser and runAsGroup attributes should be set to a greater value than 999.	CNCF CNF Testsuite	N/A
ra2.app.045	Labels	Pods of the CNF should define at least the following labels: app.kubernetes.io/name, app.kubernetes.io/version and app.kubernetes.io/part-of	Kubernetes documentation	N/A

Table 4-9: Kubernetes Workload Specifications

4.11. Additional required components

This chapter should list any additional components needed to provide the services defined in Chapter 3.2 (e.g., Prometheus)