KNELServerBuild/DEVELOPMENT-GUIDELINES.md

TSYS FetchApply Development Guidelines

Overview

This document contains development standards and best practices for the TSYS FetchApply infrastructure provisioning system.

Package Management Best Practices

Combine apt-get Install Commands

Rule: Always combine multiple package installations into a single apt-get install command for performance.

Rationale: Single command execution is significantly faster than multiple separate commands due to:

• Reduced package cache processing
• Single dependency resolution
• Fewer network connections
• Optimized package download ordering

✅ Correct Implementation

# Install all packages in one command
apt-get install -y package1 package2 package3 package4

# Real example from 2FA script
apt-get install -y libpam-google-authenticator qrencode

❌ Incorrect Implementation

# Don't use separate commands for each package
apt-get install -y package1
apt-get install -y package2
apt-get install -y package3

Complex Package Installation Pattern

function install_security_packages() {
    print_info "Installing security packages..."
    
    # Update package cache once
    apt-get update
    
    # Install all packages in single command
    apt-get install -y \
        auditd \
        fail2ban \
        libpam-google-authenticator \
        lynis \
        rkhunter \
        aide \
        chkrootkit \
        clamav \
        clamav-daemon
    
    print_success "Security packages installed successfully"
}

Script Development Standards

Error Handling

• Always use set -euo pipefail at script start
• Implement proper error trapping
• Use framework error handling functions
• Return appropriate exit codes

Function Structure

function function_name() {
    print_info "Description of what function does..."
    
    # Local variables
    local var1="value"
    local var2="value"
    
    # Function logic
    if [[ condition ]]; then
        print_success "Success message"
        return 0
    else
        print_error "Error message"
        return 1
    fi
}

Framework Integration

• Source framework includes at script start
• Use framework logging and pretty print functions
• Follow existing patterns for consistency
• Include proper PROJECT_ROOT path resolution

# Standard framework sourcing pattern
PROJECT_ROOT="$(dirname "$(realpath "${BASH_SOURCE[0]}")")/../.."
source "$PROJECT_ROOT/Framework-Includes/PrettyPrint.sh"
source "$PROJECT_ROOT/Framework-Includes/Logging.sh"
source "$PROJECT_ROOT/Framework-Includes/ErrorHandling.sh"

Code Quality Standards

ShellCheck Compliance

• All scripts must pass shellcheck validation
• Address shellcheck warnings appropriately
• Use proper quoting for variables
• Handle edge cases and error conditions

Variable Naming

• Use UPPERCASE for global constants
• Use lowercase for local variables
• Use descriptive names
• Quote all variable expansions

# Global constants
declare -g BACKUP_DIR="/root/backup"
declare -g CONFIG_FILE="/etc/ssh/sshd_config"

# Local variables
local user_name="localuser"
local temp_file="/tmp/config.tmp"

# Proper quoting
if [[ -f "$CONFIG_FILE" ]]; then
    cp "$CONFIG_FILE" "$BACKUP_DIR/"
fi

Function Documentation

• Include purpose description
• Document parameters if any
• Document return values
• Include usage examples for complex functions

# Configure SSH hardening settings
# Parameters: none
# Returns: 0 on success, 1 on failure
# Usage: configure_ssh_hardening
function configure_ssh_hardening() {
    print_info "Configuring SSH hardening..."
    # Implementation
}

Testing Requirements

Test Coverage

• Every new module must include corresponding tests
• Test both success and failure scenarios
• Validate configurations after changes
• Include integration tests for complex workflows

Test Categories

1. Unit Tests: Individual function validation
2. Integration Tests: Module interaction testing
3. Security Tests: Security configuration validation
4. Validation Tests: System requirement checking

Test Implementation Pattern

function test_function_name() {
    echo "🔍 Testing specific functionality..."
    
    local failed=0
    
    # Test implementation
    if [[ condition ]]; then
        echo "✅ Test passed"
    else
        echo "❌ Test failed"
        ((failed++))
    fi
    
    return $failed
}

Security Standards

Configuration Backup

• Always backup configurations before modification
• Use timestamped backup directories
• Provide restore instructions
• Test backup/restore procedures

Service Management

• Test configurations before restarting services
• Provide rollback procedures
• Validate service status after changes
• Include service dependency handling

User Safety

• Use nullok for gradual 2FA rollout
• Provide clear setup instructions
• Include emergency access procedures
• Test all access methods before enforcement

Documentation Standards

Script Headers

#!/bin/bash

# TSYS Module Name - Brief Description
# Longer description of what this script does
# Author: TSYS Development Team
# Version: 1.0
# Last Updated: YYYY-MM-DD

set -euo pipefail

Inline Documentation

• Comment complex logic
• Explain non-obvious decisions
• Document external dependencies
• Include troubleshooting notes

User Documentation

• Create comprehensive guides for complex features
• Include step-by-step procedures
• Provide troubleshooting sections
• Include examples and use cases

Performance Optimization

Package Management

• Single apt-get commands (as noted above)
• Cache package lists appropriately
• Use specific package versions when stability required
• Clean up package cache when appropriate

Network Operations

• Use connection timeouts for external requests
• Implement retry logic with backoff
• Cache downloaded resources when possible
• Validate download integrity

File Operations

• Use efficient file processing tools
• Minimize file system operations
• Use appropriate file permissions
• Clean up temporary files

Version Control Practices

Commit Messages

• Use descriptive commit messages
• Include scope of changes
• Reference related issues/requirements
• Follow established commit message format

Branch Management

• Test changes in feature branches
• Use pull requests for review
• Maintain clean commit history
• Tag releases appropriately

Code Review Requirements

• All changes require review
• Security changes require security team review
• Test coverage must be maintained
• Documentation must be updated

Deployment Practices

Pre-Deployment

• Run full test suite
• Validate in test environment
• Review security implications
• Update documentation

Deployment Process

• Use configuration validation
• Implement gradual rollout when possible
• Monitor for issues during deployment
• Have rollback procedures ready

Post-Deployment

• Validate deployment success
• Monitor system performance
• Update operational documentation
• Gather feedback for improvements

Example Implementation

Complete Module Template

#!/bin/bash

# TSYS Security Module - Template
# Template for creating new security modules
# Author: TSYS Development Team

set -euo pipefail

# Source framework functions
PROJECT_ROOT="$(dirname "$(realpath "${BASH_SOURCE[0]}")")/../.."
source "$PROJECT_ROOT/Framework-Includes/PrettyPrint.sh"
source "$PROJECT_ROOT/Framework-Includes/Logging.sh"
source "$PROJECT_ROOT/Framework-Includes/ErrorHandling.sh"

# Module configuration
BACKUP_DIR="/root/backup/module-$(date +%Y%m%d-%H%M%S)"
CONFIG_FILE="/etc/example.conf"

# Create backup directory
mkdir -p "$BACKUP_DIR"

print_header "TSYS Module Template"

function backup_configs() {
    print_info "Creating configuration backup..."
    
    if [[ -f "$CONFIG_FILE" ]]; then
        cp "$CONFIG_FILE" "$BACKUP_DIR/"
        print_success "Configuration backed up"
    fi
}

function install_packages() {
    print_info "Installing required packages..."
    
    # Update package cache
    apt-get update
    
    # Install all packages in single command
    apt-get install -y package1 package2 package3
    
    print_success "Packages installed successfully"
}

function configure_module() {
    print_info "Configuring module..."
    
    # Configuration logic here
    
    print_success "Module configured successfully"
}

function validate_configuration() {
    print_info "Validating configuration..."
    
    local failed=0
    
    # Validation logic here
    
    if [[ $failed -eq 0 ]]; then
        print_success "Configuration validation passed"
        return 0
    else
        print_error "Configuration validation failed"
        return 1
    fi
}

function main() {
    # Check if running as root
    if [[ $EUID -ne 0 ]]; then
        print_error "This script must be run as root"
        exit 1
    fi
    
    # Execute module steps
    backup_configs
    install_packages
    configure_module
    validate_configuration
    
    print_success "Module setup completed successfully!"
}

# Run main function
main "$@"

Continuous Improvement

Regular Reviews

• Review guidelines quarterly
• Update based on lessons learned
• Incorporate new best practices
• Gather team feedback

Tool Updates

• Keep development tools current
• Adopt new security practices
• Update testing frameworks
• Improve automation

Knowledge Sharing

• Document lessons learned
• Share best practices
• Provide training materials
• Maintain knowledge base

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Last Updated: July 14, 2025
Version: 1.0
Author: TSYS Development Team

Note: These guidelines are living documents and should be updated as the project evolves and new best practices are identified.