Helmet

A framework for building Kubernetes installers with Helm

Helmet provides a reusable, batteries-included framework for creating intelligent Kubernetes installers that understand dependency relationships, manage configuration, and orchestrate complex deployments.

Overview

Helmet is designed to be imported as a Go library to build custom installers for Kubernetes-based product suites. It handles the complexity of dependency resolution, configuration management, and deployment orchestration, allowing you to focus on defining your products and their relationships.

Key Capabilities

• Automatic Dependency Resolution: Declares dependencies via Helm chart annotations and automatically determines installation order
• Configuration Management: YAML-based configuration with Kubernetes ConfigMap persistence
• Template Engine: Go templates for dynamic Helm values with cluster introspection
• Integration System: Pluggable integrations for external services (Git providers, registries, etc.)
• Hook Scripts: Execute custom logic before and after chart installations
• CLI Generation: Automatically generates a complete CLI with config, deploy, and integration commands
• MCP Support: Built-in Model Context Protocol server for AI assistant integration
• Monitoring: Resource readiness checks and Helm test execution

Quick Start

package main

import (
    _ "embed"
    "os"
    "github.com/redhat-appstudio/helmet/api"
    "github.com/redhat-appstudio/helmet/framework"
)

//go:embed installer.tar
var installerTarball []byte

func main() {
    // Create application context with metadata
    appCtx := &api.AppContext{
        Name:    "myapp",
        Version: "1.0.0",
    }

    // Create and run the installer from embedded tarball
    app, _ := framework.NewAppFromTarball(
        appCtx,
        installerTarball,
        os.Getwd(),
        framework.WithInstallerTarball(installerTarball),
    )

    app.Run()
}

This generates a complete CLI with commands for configuration, deployment, topology inspection, and more.

Architecture

Helmet uses a convention-based approach where your installer assets are organized in a predictable structure:

installer/
├── config.yaml         # Configuration schema
├── values.yaml.tpl     # Go template for Helm values
├── charts/             # Helm charts directory
│   ├── database/
│   ├── api-server/
│   └── frontend/
└── instructions.md     # MCP server instructions (optional)

Charts declare dependencies and metadata via annotations:

# charts/api-server/Chart.yaml
annotations:
  helmet.redhat-appstudio.github.com/product-name: "api"
  helmet.redhat-appstudio.github.com/depends-on: "database"
  helmet.redhat-appstudio.github.com/weight: "100"

The framework resolves dependencies, builds an installation topology, and orchestrates deployment in the correct order.

Features

Dependency Resolution

Automatically resolves and orders chart installations based on:

• Declared dependencies (depends-on annotation)
• Weight-based prioritization (weight annotation)
• Product associations (product-name annotation)
• Integration requirements (integrations-required CEL expressions)

See Topology Documentation for details.

Configuration System

Product-based configuration with dynamic updates:

myapp:
  settings:
    crc: false
  products:
    - name: test-product-name
      enabled: true
      namespace: test-product-namespace
      properties:
        manageSubscription: true

Configuration is stored as Kubernetes ConfigMaps and can be updated programmatically.

Template Engine

Render Helm values dynamically based on configuration and cluster state:

{{- $db := .Installer.Products.Database -}}
{{- if $db.Enabled }}
database:
  replicas: {{ $db.Properties.replicas | default 1 }}
  host: db.{{ .OpenShift.Ingress.Domain }}
{{- end }}

Generated CLI

The framework automatically generates a complete CLI:

myapp config --create                    # Create configuration
myapp integration github --token=<token> # Configure integrations
myapp topology                           # View installation order
myapp deploy                            # Deploy all products
myapp mcp                               # Start MCP server

Extensibility

Extend the framework with custom integrations, commands, and MCP tools:

app := framework.NewApp("myapp", filesystem,
    framework.WithInstallerTarball(InstallerTarball),
    framework.WithIntegrations(customIntegrations...),
    framework.WithMCPToolsBuilder(customMCPTools),
)

// Add custom commands
rootCmd := app.Command()
rootCmd.AddCommand(myCustomCommand)

app.Run()

Installation

As a Library

Import Helmet into your Go project:

go get github.com/redhat-appstudio/helmet/framework

Documentation

• Dependency Topology - Chart dependency resolution and installation ordering
• MCP Server - AI assistant integration via Model Context Protocol
• Contributing Guide - Development guidelines and best practices

Examples

Complete Example Application

See example/helmet-ex/ for a comprehensive example demonstrating all framework features.

Basic Installer

package main

import (
    _ "embed"
    "os"
    "github.com/redhat-appstudio/helmet/api"
    "github.com/redhat-appstudio/helmet/framework"
)

//go:embed installer.tar
var installerTarball []byte

func main() {
    appCtx := &api.AppContext{Name: "myinstaller"}
    cwd, _ := os.Getwd()

    app, _ := framework.NewAppFromTarball(
        appCtx,
        installerTarball,
        cwd,
        framework.WithInstallerTarball(installerTarball),
    )
    app.Run()
}

With Custom Integrations

import (
    _ "embed"
    "os"
    "github.com/redhat-appstudio/helmet/api"
    "github.com/redhat-appstudio/helmet/framework"
)

//go:embed installer.tar
var installerTarball []byte

type CustomIntegration struct{}

func (i *CustomIntegration) Name() string { return "custom" }
func (i *CustomIntegration) Init(ctx context.Context, logger logr.Logger, k8s *kubernetes.Clientset) (api.Integration, error) {
    // Implementation
    return &CustomIntegrationImpl{}, nil
}
func (i *CustomIntegration) Command(logger logr.Logger) (*cobra.Command, error) {
    // CLI command definition
    return &cobra.Command{Use: "custom"}, nil
}

func main() {
    appCtx := &api.AppContext{Name: "myinstaller"}
    cwd, _ := os.Getwd()

    // Combine standard integrations with custom ones
    integrations := append(
        framework.StandardIntegrations(),
        &CustomIntegration{},
    )

    app, _ := framework.NewAppFromTarball(
        appCtx,
        installerTarball,
        cwd,
        framework.WithInstallerTarball(installerTarball),
        framework.WithIntegrations(integrations...),
    )
    app.Run()
}

With Custom MCP Tools

import (
    _ "embed"
    "os"
    "github.com/redhat-appstudio/helmet/api"
    "github.com/redhat-appstudio/helmet/framework"
    "github.com/redhat-appstudio/helmet/framework/mcpserver"
)

//go:embed installer.tar
var installerTarball []byte

func customTools(ctx api.AppContext, s *mcpserver.Server) error {
    s.AddTool(mcpserver.Tool{
        Name:        "myapp_status",
        Description: "Get deployment status",
        Handler: func(args map[string]interface{}) (interface{}, error) {
            // Implementation
            return map[string]string{"status": "healthy"}, nil
        },
    })
    return nil
}

func main() {
    appCtx := &api.AppContext{Name: "myinstaller"}
    cwd, _ := os.Getwd()

    app, _ := framework.NewAppFromTarball(
        appCtx,
        installerTarball,
        cwd,
        framework.WithInstallerTarball(installerTarball),
        framework.WithMCPToolsBuilder(customTools),
    )
    app.Run()
}

Design Principles

• Convention over Configuration: Predictable structure with sensible defaults
• Interface-Driven: Extensibility through well-defined interfaces
• API Stability: Functional options pattern for backward compatibility
• Kubernetes-Native: First-class support for namespaces, RBAC, and cluster introspection
• Helm-Centric: Leverages Helm's ecosystem and tooling

Contributing

Contributions are welcome! Please see CONTRIBUTING.md for:

• Development environment setup
• Code style guidelines
• Testing requirements
• Pull request process

When contributing, please consider:

• API stability and backward compatibility
• Documentation for framework consumers
• Test coverage for new features
• Impact on existing consumers

Resources

• Project Homepage
• Documentation
• Issue Tracker
• Releases

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Note: This is a framework for building installers. For specific product installers built with Helmet, please refer to their respective repositories.