Pack constraints are a set of rules defined at the pack level to validate the packs for a Profile or a Cluster before it gets created or updated. Packs must be validated before the cluster is submitted to ensure a successful deployment.

A Spectro Pack currently supports various configurations through a configuration file called values.yaml. The values defined in the config file are applied while deploying the Kubernetes cluster. The values defined in the pack are default values and can be overridden in the Cluster Profile or during the Cluster deployment.

Since the default pack values can be overridden, users may inadvertently set incorrect values leading to cluster deployment failure. These failures can occur at any point during the cluster deployment process. If the system is capable of detecting invalid pack values before the cluster is submitted for deployment, then deployment failures can be overcome to some extent.

Pack value constraints are additional information provided through a template file called schema.yaml in the pack. They define the schema format of the pack values. The pack constraints framework auto-checks for any schema constraints defined in the pack and validates the pack values. This checking occurs while creating or updating Cluster Profiles and Clusters.

Every schema constraint consists of a key name and the schema template. The key name must be the complete path of the parameter which is defined in the config file.

Required

Defines whether the pack value is optional or required.

registry.hostname:
 schema: '{{ required }}'

Readonly

The pack value is not editable if marked as readonly.

registry.hostname:
 schema: '{{ readonly }}'

Format

Defines the pack value format: the value is valid only when the value format matches the format defined in the pack.

Format Syntax

A format template consists of one or more format types along with the optional regex and number range values.

registry.hostname:
  schema: '{{ required | format "${FORMAT_TYPE:/REGEX/ OR [NUMBER RANGE] OR [LIST_OPTIONS]}" }}'

Format Types

registry.hostname:
  schema: '{{ format "${string}" }}'
registry.hostname:
  schema: '{{ format "${string:/^([a-z0-9].*)$/}" }}'

Examples

Schema constraints can be combined to support multiple validations using a single template.

registry.addresses.$[]:
 schema: '{{ required | format "${ipv4} - ${ipv4}" | hints "ip pool range"}}'

Spectro Cloud provides the flexibility to choose any pack of any version in the profile. Clusters are deployed based on the packs selected in the profile. While this works for most of the cases, it is sometimes required to select a minimum or maximum pack version, or to have dependencies between the packs to ensure the Kubernetes cluster is deployed successfully as desired.

Pack dependency constraints are the rules defined in the pack metadata file pack.json. They are used to define the minimum and maximum supported versions, and also to specify which pack is required or not supported. The pack constraints framework auto-checks for any schema constraints defined in the pack and validates the pack values. This checking occurs while creating or updating Cluster Profiles and Clusters.

Pack dependency constraints must be defined in the pack.json file. The sample pack metadata shown below defines the dependencies under constraints key.

{
  "addonType": "system app",
  "cloudTypes": [
    "all"
  ],
  "displayName": "Test Pack",
  "kubeManifests": [],
  "layer": "addon",
  "name": "pack-constraints-test",
  "version": "1.0.0",
  "constraints": {
    "dependencies": [
      {
        "packName": "vault",
        "minVersion": "0.6.0",
        "maxVersion": "",
        "type": "optional"
      },
      {
        "packName": "csi-vsphere-volume",
        "minVersion": "1.0.0",
        "maxVersion": "",
        "type": "notSupported"
      },
      {
        "packName": "kubernetes",
        "minVersion": "1.17.0",
        "maxVersion": "1.18.6",
        "type": "required"
      }
    ]
  }
}

A successful Kubernetes Cluster deployment is possible only when the cluster has sufficient hardware requirements. We consider the CPU, Memory, and Disk size as the hardware requirements. The minimum resource requests can be varied depending on the workload to be deployed in the cluster. Spectro Cloud users are allowed to select the desired instance type, and the disk size while configuring the machine pool in the Cluster deployment procedure. If the user selects the instance type which does not satisfy the minimum CPU or Memory or Disk size requirements, then there is a high probability that the cluster deployment may not succeed due to insufficient CPU or Memory or Disk size.

Pack Resource Constraints are a set of rules defined in the pack metadata pack.json to specify the minimum CPU, Memory, and Disk size requirements. The pack constraints framework auto-checks the resource constraints and validates the user-selected instance type specifications before the cluster is submitted for deployment. The total input resource capacity is evaluated against the machine pool size with the actual hardware specifications of a selected instance type.

Pack resource constraints must be defined in the pack.json file. The sample pack metadata is shown below to define the resources under constraints key.

{
  "addonType": "system app",
  "cloudTypes": [
    "all"
  ],
  "displayName": "Test Pack",
  "kubeManifests": [],
  "layer": "addon",
  "name": "pack-constraints-test",
  "version": "1.0.0",
  "constraints": {
    "resources": [
      {
        "type": "cpu",
        "minLimit": 2000,
        "components": [
          {
            "resourceRequestParamRef": "requests.cpu",
            "replicaCountParamRef": "replicas",
            "scheduleType": "all"
          }
        ]
      },
      {
        "type": "memory",
        "minLimit": 2048,
        "components": [
          {
            "resourceRequestParamRef": "requests.memory",
            "replicaCountParamRef": "replicas",
            "scheduleType": "worker"
          }
        ]
      },
      {
        "type": "diskSize",
        "minLimit": 10
      }
    ]
  }
}

Pack Presets are the predefined values in a file called presets.yaml in the pack. It contains an array of the presets for the pack, and is visible in the pack parameters of the Cluster profile and the Cluster. Users can select any preset from the available pack presets, and the predefined values of a selected preset are applied automatically by the Spectro Cloud UI. Presets make pack configuration much easier as multiple pack values are updated at a time and the user does not need to understand all the configuration parameters which get changed depending on various factors.

This presets.yaml shows two presets

• privatePackRegistry
• publicPackRegistry

with a different set of pre-defined values.

presets:
- name: "privatePackRegistry"
  displayName: "Private Registry"
  group: "registry"
  remove: ["registry.ingress.host"]
  add: |
    registry:
      private: true
      type: "PACK"
      host:
       ip: "127.0.0.1"
       port: 5000
- name: "publicPackRegistry"
  displayName: "Public Registry"
  group: "registry"
  remove: ["registry.ingress.host"]
  add: |
    registry:
      private: false
      type: "PACK"
      host:
       ip: "13.233.2.255"
       port: 80

Pack macros are the variables defined in the Cluster profile or in Cluster pack values, and these variables are resolved only at the cluster deployment time.

user:
 name: "{{ .spectro.system.[VARIABLE_NAME] }}"

Users are allowed to use the sprig template functions to modify the resolved variable value.

Examples

user:
 name: "{{ .spectro.system.user.name | upper }}"

upper - sprig template function which converts resolved user name to upper case

k8s:
 version: "{{ .spectro.pack.kubernetes.version | default \"1.19.0\"}}"