Krateo Core Provider

The core-provider is the first component of Krateo Composable Operations (KCO) and is vital to the Krateo PlatformOps product.

Summary

• Architecture
• Overview
  • Authentication
  • RBAC Generation
  • Multi-Version Support
  • Composition Definition
• Examples
  • How to Install
  • Apply the CompositionDefinition Manifest
  • Upgrade Chart Version
    • Update the Fireworksapp Chart in the CompositionDefinition
    • Automatic Deletion of Unused composition-dynamic-controller Deployments
    • Multi-Version Management
  • Authentication
    • OCI Registry
    • Helm Repository
• Configuration
  • Security Features
  • Best Practices

Architecture

Here's the updated Overview section with more details about authentication and RBAC generation:

Overview

The core-provider is a Kubernetes operator that downloads and manages Helm charts. It checks for the existence of values.schema.json and uses it to generate a Custom Resource Definition (CRD) in Kubernetes, accurately representing the possible values that can be expressed for the installation of the chart.

Kubernetes is designed to validate resource inputs before applying them to the cluster, and the core-provider provides input validation to ensure that incorrect inputs are not accepted.

Authentication

The core-provider also handles authentication to private OCI registries and Helm repositories. Users can provide their credentials through Kubernetes secrets, and the core-provider will use them to download the necessary chart resources.

RBAC Generation

When the CompositionDefinition manifest is applied to the cluster, the core-provider not only generates the CRDs but also deploys an instance of the composition-dynamic-controller. This controller is instructed to manage resources of the type defined by the CRD, and the deployment applies the most restrictive RBAC policy possible to ensure that the composition-dynamic-controller instance can only manage the resources contained within the chart. Upon deleting the CR, the composition-dynamic-controller instance is undeployed, and the RBAC policy is removed.

Multi-Version Support

The core provider supports managing multiple versions of the same chart, including different values for each version. This feature addresses the common requirement of maintaining multiple versions of a composition.

Composition Definition

A Composition is a Helm Chart archive (.tgz) with a JSON Schema for the values.yaml file. The JSON Schema file must be named values.schema.json.

Here are some online tools to generate and validate JSON Schemas:

• https://jsonformatter.org/yaml-to-jsonschema
• https://codebeautify.org/yaml-to-json-schema-generator
• https://www.jsonschemavalidator.net/
• https://json-schema.hyperjump.io/

Examples

How to Install

$ helm repo add krateo https://charts.krateo.io
$ helm repo update krateo
$ helm install krateo-core-provider krateo/core-provider

Apply the CompositionDefinition Manifest

apiVersion: core.krateo.io/v1alpha1
kind: CompositionDefinition
metadata:
  annotations:
     "krateo.io/connector-verbose": "true"
     "krateo.io/paused": "false"
     "krateo.io/release-name": "my-composition-release"
  name: postgresql
  namespace: krateo-system
spec:
  chart:
    url: oci://registry-1.docker.io/bitnamicharts/postgresql
    version: "12.8.3"

When the CompositionDefinition manifest is applied to the cluster, the core-provider generates the CRDs from the schema defined in the values.schema.json file included in the chart. It then deploys an instance of the composition-dynamic-controller, instructing it to manage resources of the type defined by the CRD. The deployment applies the most restrictive RBAC policy possible, ensuring that the composition-dynamic-controller instance can only manage the resources contained within the chart.

Upon deleting the CR, the composition-dynamic-controller instance is undeployed, and the RBAC policy is removed.

Upgrade Chart Version

CompositionDefinition fireworksapp source Manifest

apiVersion: core.krateo.io/v1alpha1
kind: CompositionDefinition
metadata:
  annotations:
    krateo.io/connector-verbose: "true"
  name: fireworksapp-1-1-5
  namespace: fireworksapp-system
spec:
  chart:
    repo: fireworks-app
    url: https://charts.krateo.io
    version: 1.1.5

Update the Fireworksapp Chart in the CompositionDefinition

The requirement for this step is that the values.schem.json cointained in the chart should not change between versions of the chart. If your values.schem.json go to section Multi version Management.

1. To update them chart version of existing CompositionDefinition called fireworksapp-1-1-5 in the fireworksapp-system namespace to change the spec.chart.version to 1.1.6:

kubectl patch compositiondefinition fireworksapp-1-1-5 -n fireworksapp-system --type=merge -p '{"spec":{"chart":{"version":"1.1.6"}}}'

2. Wait for the fireworksapp-1-1-5 CompositionDefinition to be in the Ready=True condition in the fireworksapp-system namespace:

kubectl wait compositiondefinition fireworksapp-1-1-5 --for condition=Ready=True --namespace fireworksapp-system

3. Inspect the CustomResourceDefinition fireworksapps.composition.krateo.io to see the added version:

kubectl get crd fireworksapps.composition.krateo.io -o yaml

4. Check if the fireworksapps-v1-1-6-controller deployment to be ready in the fireworksapp-system namespace:

kubectl wait deployment fireworksapps-v1-1-6-controller --namespace fireworksapp-system --for condition=Available=True

5. Check that the previously installed chart have the expected version:

helm list -n fireworksapp-system

This procedure update the existing fireworksapp installations to use the new version 1.1.6 of the chart, since the values.schema.json does not change between the two versions.

Automatic Deletion of Unused composition-dynamic-controller Deployments

Notice that the previously deployed instances (pods) of composition-dynamic-controller that were configured to manage resources of version 1.1.5 no longer exist in the cluster.

This is due to the automatic cleanup mechanism that removes older and unused deployments along with their associated RBAC resources from the cluster:

kubectl get po -n fireworksapp-system

This automatic cleanup helps maintain cluster cleaniness by removing outdated controller instances when they are no longer needed.

Multi-Version Management

The core provider now supports managing multiple versions of the same composition.

To perform a version upgrade or rollback:

1. Pause the current version: Add the "krateo.io/paused": "true" annotation to the CompositionDefinition for the current version.

2. Install the new version: Create a new CompositionDefinition for the new version without the krateo.io/paused annotation or set it to "false". Include the "krateo.io/release-name": "my-composition-release" annotation, using the same name as the release for the previous version. This ensures that the upgrade is performed correctly.

Note: If omitted, the CDC will use the composition's metadata.name as the release name.

This process allows for seamless upgrades and rollbacks between different versions of the same composition, maintaining consistency in release names and ensuring proper management of multiple versions.

Authentication

OCI Registry

Create the Kubernetes secret:

kubectl create secret generic docker-hub --from-literal=token=your_token -n krateo-system

Apply the Manifest:

Check the Manifest

apiVersion: core.krateo.io/v1alpha1
kind: CompositionDefinition
metadata:
  annotations:
     "krateo.io/connector-verbose": "true"
  name: fireworks-private
  namespace: krateo-system
spec:
  chart:
    url: oci://registry-1.docker.io/yourusername/fireworks-app
    version: "0.1.0"
    credentials:
      username: yourusername
      passwordRef:
        key: token
        name: docker-hub
        namespace: krateo-system

Helm Repository

kubectl create secret generic helm-repo --from-literal=token=your_token -n krateo-system

Apply the Manifest:

Check the Manifest

apiVersion: core.krateo.io/v1alpha1
kind: CompositionDefinition
metadata:
  annotations:
     "krateo.io/connector-verbose": "true"
  name: fireworks-private
  namespace: krateo-system
spec:
  chart:
    repo: fireworks-app
    url: https://theurltoyourhelmrepo
    version: 0.3.0
    credentials:
      username: yourusername
      passwordRef:
        key: token
        name: helm-repo
        namespace: krateo-system

Configuration

To view the CRD configuration, visit this link.

Security Features

• Generates CRDs based on the chart's schema, preventing invalid configurations
• Deploys composition-dynamic-controller with minimal necessary permissions
• Removes RBAC policies upon deletion of the CR
• Implements mutating webhook and conversion webhook for enhanced security and flexibility

Best Practices

1. Always include a values.schema.json file in your Helm charts
2. Use the krateo.io/paused annotation to manage composition lifecycle
3. Utilize the krateo.io/release-name annotation for consistent naming across versions
4. Leverage the multi-version support for smooth upgrades and rollbacks

By implementing these improvements and best practices, the Krateo Core Provider offers enhanced flexibility, security, and version management capabilities for Kubernetes-based applications.