This section outlines the CNF requirements and how CNF can be onboarded and instantiated via TCA.

HELM Charts

Helm is the default package manager in Kubernetes, and it is widely leveraged by CNF vendors to simplify container packaging. With Helm charts, dependencies between CNFs are handled in the formats agreed upon by the upstream community; allowing Telco operators to consume CNF packages in a declarative and easy to operate manner. With proper version management, Helm charts also simplify workload updates and inventory control.

Production CNF Helm charts must be stored centrally and accessible by the Tanzu Standard for Telco Kubernetes clusters. To reduce the number of management endpoints, the Helm repository must work seamlessly with container images. A container registry must be capable of supporting both container image and Helm charts.

CSAR Design

Network Function (NF) Helm charts are uploaded as a catalog offering wrapped around the CSAR descriptor file. The descriptor file includes the structure and composition of the NF and supporting artifacts such as Helm charts version, provider, and set of pre-instantiation jobs. Network Functions have sets of prerequisite configurations on the underlying Kubernetes cluster. Those requirements are also defined in the Network Function CSAR. The summary of features supported by the CSAR extension is:

  • NUMA Alignment of vCPUs and Virtual Functions

  • Latency Sensitivity

  • Custom Operating system package installations

  • Full GRUB configuration

The following table outlines those extensions in detail:

Component

Type

Description

node_components

Kernel_type

Type of Linux Kernel and version.

Based on the Kernel version and type, TCA downloads and installs from VMware Photon Linux repo during Kubernetes node customization.

kernel_args

Kernel boot parameters: Required for CPU isolation and so on. Parameters are free-form text strings. The syntaxes are as follows:

  • Key: the name of the parameter

  • Value: the value corresponding to the key

Note: The Value field is optional for those Kernel parameters that do not require a value.

custom_packages

Custom packages include lxcfs, tuned, and pci-utils. TCA downloads and installs from VMware Photon Linux repo during node customization.

network

deviceType

Types of network device.

resourceName

Resource name refers to the label in the Network Attachment Definition (NAD).

count

Number of adapters required

caas_components

CaaS components define the CaaS CNI, CSI, and HELM components for the Kubernetes cluster
CSAR files can be updated to reflect changes in CNF requirements or deployment model. CNF developers can update the CSAR package directly within the TCA designer or leverage an external CICD process to maintain and build newer versions of the CSAR package.

Design Decision

Design Justification

Design Implication

Deploy all containers using the TCA Manager interface.

Direct access to the Kubernetes cluster is not supported.

Some containers may not be available with a CSAR package to be deployed through TCA.

Define all CNF infrastructure requirements using the TOSCA CSAR extension.

When infrastructure requirements are bundled into the CSAR package, TCA provides placement assistance to locate a Kubernetes cluster that meets CNF requirements.

If TCA cannot place the CNF workload due to the lack of resources, TCA leverages the node Operator to update an existing cluster with the required hardware and software based on the CSAR file definition.

CNF developers must work closely with CNF vendors to ensure that the infrastructure requirements are captured correctly in the CSAR file.

Store the TOSCA-compliant CSAR files in a GIT repository.

  • GIT repository is ideal for centralized change control.

  • CSAR package versioning, traceability, and peer review are built into GIT when a proper git-flow is implemented and followed.

Git and Git-flow is outside the scope of this reference architecture guide.

Develop a unit test framework to validate each commit into the GIT repository.

A well-defined unit test framework catches potential syntax issues associated with each commit.

Unit test framework is outside the scope of this reference architecture guide.

Leverage existing CI workflow to maintain the builds and releases of CSAR Packages.

Modern CI pipeline fully integrates with GIT and unit test framework.

CI pipeline is outside the scope of this reference architecture guide.
Note:

VMware Offers a certification program for CNF and VNF vendors to create certified and validated CSARs packages.