A Cluster Profile is made up of preconfigured layers, each of which is called a pack. In other words, Packs are the building block of a cluster profile to create layers such as operating systems, Kubernetes, network, storage, and add-ons. Packs can be broadly categorized into two types:
- Core packs - These packs model the core layers to provision a Kubernetes cluster. These packs include the operating system, Kubernetes, the container network interface (CNI), and the container storage interface (CSI) specifications. Spectro Cloud builds and maintains these core packs for updates.
- Add-On packs - These packs model the infrastructure integrations and applications that exist on top of the core packs. Examples of applications are system, authentication, security, monitoring, logging, ingress, load balancer, service mesh, or helm charts.
Both the core and add-on packs described above are configurable, and you can define new add-on custom packs from scratch as well. The use case for defining new add-on packs is to have desired consistent governance across your profile deployments.
Palette provides a rich collection of out-of-the-box packs for various integrations and also offers extensibility through custom-built packs. To configure an existing pack (core or add-on) or to define a new add-on custom pack from scratch, it is essential to understand the pack structure.
Each pack is a collection of files such as manifests, helm charts, Ansible roles, configuration files, and more. Ansible roles, if provided, are used to customize cluster VM images, whereas Kubernetes manifests and Helm charts are applied to the Kubernetes clusters after deployment. The following is a typical pack structure:
| Pack Name | Requirement | Description |
|---|---|---|
pack.json | mandatory | Pack metadata. |
values.yaml | mandatory | Pack configuration, parameters exposed from the underlying charts, and templated parameters from Ansible roles. |
charts/ | mandatory | Mandatory for Helm chart-based packs. Contains the Helm charts to be deployed for the pack. |
manifests/ | mandatory | Mandatory for Manifest-based packs. Contains the manifest files to be deployed for the pack. |
ansible-roles | optional | Ansible roles used to install the pack. |
logo.png | optional | Contains the pack logo. |
README.md | optional | The pack description. |
Let's look at the examples below to better understand pack structure.
The example shows the structure of a Helm chart-based pack, istio-1.6.2, which is made up of two charts: istio-controlplane and istio-operator. Each chart has its values.yaml file. In this example, we have a pack-level values.yaml file and individual chart-level values.yaml files.
.├── charts/│ ├── istio-controlplane.tgz│ ├── istio-controlplane│ │ ├── Chart.yaml│ │ ├── templates/│ │ └── values.yaml│ ├── istio-operator.tgz│ └── istio-operator│ ├── Chart.yaml│ ├── templates/│ └── values.yaml├── logo.png├── pack.json└── values.yaml
The pack registry is a server-side application to store and serve packs to its clients. Packs from a pack registry are retrieved and presented as options during the creation of a cluster profile. Palette supports the configuration of multiple registries.
The default pack registry is Spectro Cloud's public pack registry. It consists of several packs that make it easy for a user to quickly create a cluster profile and launch a Kubernetes cluster with their choice of integrations. Palette maintains all packs in this pack registry and takes care of upgrading packs in the pack registry whenever required.
Users can set up a custom pack registry using a Docker image provided by Spectro Cloud to upload and maintain custom packs. Spectro Cloud provides a CLI tool to interact with and manage pack content in the pack registry. Custom registries offer a mechanism of extending the capabilities of a platform by defining additional integrations.
The Spectro Cloud Command Line Interface (CLI) is a tool to interact with a Spectro Cloud pack registry. You can use the CLI to upload and download packs. The CLI must authenticate with the pack registry before executing any CLI commands. Review the Spectro Cloud CLI reference page for usage instructions.