10. Manifest Generation and Template Management

Date

2025-03-09

Status

Accepted

Decision Makers

Stakeholders

Context

The project requires a robust and flexible approach to generating OpenShift installation manifests and managing configuration templates. This includes handling various platform types (bare metal, vSphere, none), supporting disconnected installations, and managing complex network configurations.

Considered Options

  1. Manual manifest creation and management
  2. Pure YAML with includes
  3. Helm charts
  4. Custom Go templates
  5. Ansible templating system

Decision

We have implemented a comprehensive manifest generation and templating system using Ansible:

  1. Centralized Manifest Generation
    • Single playbook (create-manifests.yml) for all manifest generation
    • Templated configuration files
    • Support for site-specific configurations
  2. Template Organization
    • Modular template structure
    • Platform-specific configurations
    • Network configuration templates
    • Security and authentication templates
  3. Configuration Management
    • Site-specific configuration support
    • Environment-based customization
    • Secure credential handling
    • Multi-platform compatibility
  4. Template Categories
    • Base Configuration (install-config.yml.j2)
    • Agent Configuration (agent-config.yml.j2)
    • Cluster Deployment (clusterdeployment.yml.j2)
    • Image Management (clusterimageset.yml.j2, imagedigestmirrorset.yml.j2)
    • Security (pull-secret.yml.j2)
    • Update Services (updateservice.yml.j2)

Rationale

Consequences

Positive

  1. Consistent manifest generation
  2. Reduced manual errors
  3. Platform-specific customization
  4. Secure credential handling
  5. Support for disconnected environments
  6. Easy template maintenance

Negative

  1. Requires Ansible knowledge
  2. Template complexity can increase
  3. Need to manage template versioning
  4. Additional abstraction layer

Implementation Details

Manifest Generation Process

Template Structure

playbooks/templates/
├── agent-config.yml.j2
├── agentclusterinstall.yml.j2
├── clusterdeployment.yml.j2
├── clusterimageset.yml.j2
├── imagedigestmirrorset.yml.j2
├── install-config.yml.j2
├── pull-secret.yml.j2
└── updateservice.yml.j2

Configuration Categories

  1. Base Installation
    • Cluster metadata
    • Network configuration
    • Platform settings
  2. Agent Configuration
    • Node specifications
    • Network settings
    • Resource requirements
  3. Deployment Settings
    • Cluster deployment parameters
    • Image configuration
    • Security settings
  4. Platform-Specific
    • Bare metal configurations
    • vSphere settings
    • Network architecture

Test Cases

Code References

External References