# System Overview

Complete architecture of the Provisioning Infrastructure Automation Platform.

## Architecture Layers

Provisioning uses a 5-layer modular architecture:

```text
┌─────────────────────────────────────────────────────────────┐
│ User Interface Layer                                        │
│ • CLI (provisioning command)  • Web Control Center (UI)     │
│ • REST API  • MCP Server (AI) • Batch Scheduler             │
└──────────────────────────┬──────────────────────────────────┘
                           ↓
┌─────────────────────────────────────────────────────────────┐
│ Core Engine Layer (provisioning/core/)                      │
│ • 211-line CLI dispatcher (84% code reduction)              │
│ • 476+ configuration accessors (hierarchical)               │
│ • Provider abstraction (multi-cloud support)                │
│ • Workspace management system                               │
│ • Infrastructure validation (54+ Nushell libraries)         │
│ • Secrets management (SOPS + Age integration)               │
└──────────────────────────┬──────────────────────────────────┘
                           ↓
┌─────────────────────────────────────────────────────────────┐
│ Orchestration Layer (provisioning/platform/)                │
│ • Hybrid Orchestrator (Rust + Nushell)                      │
│ • Workflow execution with checkpoints                       │
│ • Dependency resolver & task scheduler                      │
│ • File-based persistence                                    │
│ • REST API endpoints (83+)                                  │
│ • State management (SurrealDB)                              │
└──────────────────────────┬──────────────────────────────────┘
                           ↓
┌─────────────────────────────────────────────────────────────┐
│ Extension Layer (provisioning/extensions/)                  │
│ • Cloud Providers (UpCloud, AWS, Hetzner, Local)            │
│ • Task Services (50+ services in 18 categories)             │
│ • Clusters (9 pre-built cluster templates)                  │
│ • Batch Workflows (automation templates)                    │
│ • Nushell Plugins (10-50x performance gains)                │
└──────────────────────────┬──────────────────────────────────┘
                           ↓
┌─────────────────────────────────────────────────────────────┐
│ Infrastructure Layer                                        │
│ • Cloud Resources (servers, networks, storage)              │
│ • Running Services (Kubernetes, databases, etc.)            │
│ • State Persistence (SurrealDB, file storage)               │
│ • Monitoring & Logging (Prometheus, Loki)                   │
└─────────────────────────────────────────────────────────────┘
```

## Core System Components

### 1. CLI Layer (`provisioning/core/cli/`)

**Entry Point**: `provisioning/core/cli/provisioning`

- **Bash wrapper** (210 lines) - Minimal bootstrap
- Routes commands to Nushell dispatcher
- Loads environment and validates workspace
- Handles error reporting

**Key Features**:
- Single entry point
- Pluggable architecture
- Support for 111+ commands
- 80+ shortcuts for productivity

### 2. Core Engine (`provisioning/core/nulib/`)

**Structure**: 54 Nushell libraries organized by function

**Main Components**:

#### **Configuration Management** (`lib_provisioning/config/`)
- **Hierarchical loading**: 5-layer precedence system
- **476+ accessors**: Type-safe configuration access
- **Variable interpolation**: Template expansion
- **TOML merging**: Environment-specific overrides
- **Validation**: Schema enforcement

#### **Provider Abstraction** (`lib_provisioning/providers/`)
- **Multi-cloud support**: UpCloud, AWS, Hetzner, Local
- **Unified interface**: Single API for all providers
- **Dynamic loading**: Load providers on-demand
- **Credential management**: Encrypted credential handling
- **State tracking**: Provider-specific state persistence

#### **Workspace Management** (`lib_provisioning/workspace/`)
- **Workspace registry**: Track all workspaces
- **Switching**: Atomic workspace transitions
- **Isolation**: Independent state per workspace
- **Configuration loading**: Workspace-specific overrides
- **Extensions**: Inherit from platform extensions

#### **Infrastructure Validation** (`lib_provisioning/infra_validator/`)
- **Schema validation**: Nickel contract checking
- **Constraint enforcement**: Business rule validation
- **Dependency analysis**: Infrastructure dependency graph
- **Type checking**: Static type validation
- **Error reporting**: Detailed error messages with suggestions

#### **Secrets Management** (`lib_provisioning/secrets/`)
- **SOPS integration**: Mozilla SOPS for encryption
- **Age encryption**: Modern symmetric encryption
- **KMS backends**: Cosmian, AWS KMS, local
- **Credential injection**: Runtime variable substitution
- **Audit logging**: Track secret access

#### **Command Utilities** (`lib_provisioning/cmd/`)
- **SSH operations**: Remote command execution
- **Batch operations**: Parallel command execution
- **Error handling**: Structured error reporting
- **Logging**: Comprehensive operation logging
- **Retry logic**: Automatic retry with backoff

### 3. Orchestration Engine (`provisioning/platform/`)

**Technology**: Rust + Nushell hybrid

**12 Microservices** (Rust crates):

| Service | Purpose | Key Features |
| --- | --- | --- |
| orchestrator | Workflow execution | Scheduler, file persistence, REST API |
| control-center | API gateway + auth | RBAC, Cedar policies, audit logging |
| control-center-ui | Web dashboard | Infrastructure view, config management |
| mcp-server | AI integration | Model Context Protocol, auto-completion |
| vault-service | Secrets storage | Encryption, KMS, credential injection |
| extension-registry | OCI registry | Extension distribution, versioning |
| ai-service | LLM features | Prompt optimization, context awareness |
| detector | Anomaly detection | Health monitoring, pattern recognition |
| rag | Knowledge retrieval | Document embedding, semantic search |
| provisioning-daemon | Background service | Event monitoring, task scheduling |
| platform-config | Config management | Schema validation, environment handling |
| service-clients | API clients | SDK for platform services, cloud APIs |

**Detailed Services**:

#### **Orchestrator** (`crates/orchestrator/`)
- **High-performance scheduler**: Rust core
- **File-based persistence**: Durable queue
- **Workflow execution**: Dependency-aware scheduling
- **Checkpoint recovery**: Resume from failures
- **Parallel execution**: Multi-task handling
- **State management**: Track job status
- **REST API**: 9 core endpoints
- **Port**: 9090 (health check endpoint)

#### **Control Center** (`crates/control-center/`)
- **Authorization engine**: Cedar policy enforcement
- **RBAC system**: Role-based access control
- **Audit logging**: Complete audit trail
- **API gateway**: REST API for all operations
- **System configuration**: Central configuration management
- **Health monitoring**: Real-time system status

#### **Control Center UI** (`crates/control-center-ui/`)
- **Web dashboard**: Real-time infrastructure view
- **Workflow visualization**: Batch job monitoring
- **Configuration management**: Web-based configuration
- **Resource explorer**: Browse infrastructure
- **Audit viewer**: Security audit trail

#### **MCP Server** (`crates/mcp-server/`)
- **AI integration**: Model Context Protocol support
- **Natural language**: Parse infrastructure requests
- **Auto-completion**: Intelligent configuration suggestions
- **7 settings tools**: Configuration management via LLM
- **Context-aware**: Understand workspace context

#### **Vault Service** (`crates/vault-service/`)
- **Secrets backend**: Encrypted credential storage
- **KMS integration**: Key Management System support
- **SOPS + Age**: SOPS encryption backend
- **Credential injection**: Secure credential delivery
- **Audit logging**: Secret access tracking

#### **Extension Registry** (`crates/extension-registry/`)
- **OCI distribution**: Container image distribution
- **Extension packaging**: Provider/taskserv distribution
- **Version management**: Semantic versioning
- **Registry API**: Content addressable storage

#### **AI Service** (`crates/ai-service/`)
- **LLM integration**: Large Language Model support
- **Prompt optimization**: Infrastructure request parsing
- **Context awareness**: Workspace context enrichment
- **Response generation**: Configuration suggestions

#### **Detector** (`crates/detector/`)
- **Anomaly detection**: System health monitoring
- **Pattern recognition**: Infrastructure issue identification
- **Alert generation**: Alerting system integration
- **Real-time monitoring**: Continuous surveillance

#### **Platform Config** (`crates/platform-config/`)
- **Configuration management**: Centralized config loading
- **Schema validation**: Configuration validation
- **Environment handling**: Multi-environment support
- **Default settings**: System-wide defaults

#### **Provisioning Daemon** (`crates/provisioning-daemon/`)
- **Background service**: Continuous operation
- **Event monitoring**: System event handling
- **Task scheduling**: Background job execution
- **State synchronization**: Infrastructure state sync

#### **RAG Service** (`crates/rag/`)
- **Retrieval Augmented Generation**: Knowledge base integration
- **Document embedding**: Semantic search
- **Context retrieval**: Intelligent response context
- **Knowledge synthesis**: Answer generation

#### **Service Clients** (`crates/service-clients/`)
- **API clients**: Client SDK for platform services
- **Cloud providers**: Multi-cloud provider SDKs
- **Request handling**: HTTP/RPC client utilities
- **Connection pooling**: Efficient resource management

### 4. Extensions (`provisioning/extensions/`)

**Modular infrastructure components**:

#### **Providers** (5 cloud providers)
- **UpCloud** - Primary European cloud
- **AWS** - Amazon Web Services
- **Hetzner** - Baremetal & cloud servers
- **Local** - Development environment
- **Demo** - Testing & mocking

Each provider includes:
- Nickel schemas for configuration
- API client implementation
- Server creation/deletion logic
- Network management
- State tracking

#### **Task Services** (50+ services in 18 categories)

| Category | Services | Purpose |
| --- | ---------| - --- |
| Container Runtime | containerd, crio, podman, crun, youki, runc | Container execution |
| Kubernetes | kubernetes, etcd, coredns, cilium, flannel, calico | Orchestration |
| Storage | rook-ceph, local-storage, mayastor, external-nfs | Data persistence |
| Databases | postgres, redis, mysql, mongodb | Data management |
| Networking | ip-aliases, proxy, resolv, kms | Network services |
| Security | webhook, kms, oras, radicle | Security services |
| Observability | prometheus, grafana, loki, jaeger | Monitoring & logging |
| Development | gitea, coder, desktop, buildkit | Developer tools |
| Hypervisor | kvm, qemu, libvirt | Virtualization |

#### **Clusters** (9 pre-built templates)
- **web** - Web service cluster (nginx + postgres)
- **oci-reg** - Container registry
- **git** - Git hosting (Gitea)
- **buildkit** - Build infrastructure
- **k8s-ha** - HA Kubernetes (3 control planes)
- **postgresql** - HA PostgreSQL cluster
- **cicd-argocd** - GitOps CI/CD
- **cicd-tekton** - Tekton pipelines

### 5. Infrastructure Layer

**What Provisioning Manages**:

- **Cloud Resources**: VMs, networks, storage
- **Services**: Kubernetes, databases, monitoring
- **Applications**: Web services, APIs, tools
- **State**: Configuration, data, logs
- **Monitoring**: Metrics, traces, logs

## Configuration System

**Hierarchical 5-Layer System**:

```text
Precedence (High → Low):

1. Runtime Arguments   (CLI flags: --provider upcloud)
   ↓
2. Environment Variables (PROVISIONING_PROVIDER=aws)
   ↓
3. Workspace Config    (~workspace/config/provisioning.yaml)
   ↓
4. Environment Defaults (workspace/config/prod-defaults.toml)
   ↓
5. System Defaults     (~/.config/provisioning/ + platform defaults)
```

**Configuration Languages**:

| Format | Purpose | Validation | Editability |
| --- | --------| - --- | ------------ |
| **Nickel** | Infrastructure source | ✅ Type-safe, contracts | Direct |
| **TOML** | Settings, defaults | Schema validation | Direct |
| **YAML** | User config, metadata | Schema validation | Direct |
| **JSON** | Exported configs | Schema validation | Generated |

**Key Features**:
- Lazy evaluation
- Recursive merging
- Variable interpolation
- Constraint checking
- Automatic validation

## State Management

**SurrealDB Graph Database**:

Stores complex infrastructure relationships:

```text
Nodes:
- Servers (compute)
- Networks (connectivity)
- Storage (persistence)
- Services (software)
- Workflows (automation)

Edges:
- Server → Network (connected)
- Server → Storage (mounted)
- Service → Server (running on)
- Workflow → Dependency (depends on)
```

**File-Based Persistence**:

For orchestrator queue and checkpoints:

```text
~/.provisioning/
├── state/              # Infrastructure state
├── checkpoints/        # Workflow checkpoints
├── queue/              # Orchestrator queue
└── logs/               # Operational logs
```

## Security Architecture

**4-Layer Security Model**:

| Layer | Components | Features |
| --- | ----------| - --- |
| **Authentication** | JWT, sessions, MFA | 2FA, TOTP, WebAuthn |
| **Authorization** | Cedar policies, RBAC | Fine-grained permissions |
| **Encryption** | AES-256-GCM, TLS | At-rest & in-transit |
| **Audit** | Logging, compliance | 7-year retention |

**Security Services**:
- JWT token validation
- Argon2id password hashing
- Multi-factor authentication
- Cedar policy enforcement
- Encrypted credential storage
- KMS integration (5 backends)
- Audit logging (5 export formats)
- Compliance checking (SOC2, GDPR, HIPAA)

## Performance Characteristics

**Modular CLI** (84% code reduction):
- Main CLI: 211 lines (vs. 1,329 before)
- Command discovery: O(1) dispatcher
- Lazy loading: Commands loaded on-demand
- Caching: Configuration cached after first load

**Orchestrator Performance**:
- Dependency resolution: O(n log n) topological sort
- Parallel execution: Configurable task limit
- Checkpoint recovery: Resume from failure point
- Memory efficient: File-based queue

**Provider Operations**:
- Batch creation: Parallel server provisioning
- Bulk operations: Multi-resource transactions
- State tracking: Efficient state queries
- Rollback: Atomic operation reversal

**Nushell Plugins** (10-50x speedup):
- Compiled Rust extensions
- Direct native code execution
- Zero-copy data passing
- Async I/O support

## Deployment Modes

**Three Operational Modes**:

| Mode | Interaction | Configuration | Rollback | Use Case |
| --- | ------------| - --- | ---------| - --- |
| **Interactive TUI** | Ratatui UI | Manual input | Automatic | Development |
| **Headless CLI** | Command-line | Script-driven | Manual | Automation |
| **Unattended CI/CD** | Non-interactive | Configuration file | Automatic | CI/CD pipelines |

## Technology Stack

| Component | Technology | Why |
| --- | ----------| - --- |
| **IaC Language** | Nickel | Type-safe, lazy evaluation, contracts |
| **Scripting** | Nushell 0.109+ | Structured data pipelines |
| **Performance** | Rust | Zero-cost abstractions, memory safety |
| **State** | SurrealDB | Graph database for relationships |
| **Encryption** | SOPS + Age | Industry-standard encryption |
| **Security** | Cedar + JWT | Policy enforcement + tokens |
| **Orchestration** | Custom | Specialized for infrastructure workflows |

## File Organization

```text
provisioning/
├── core/                       # CLI engine (Nushell)
│   ├── cli/provisioning       # Main entry point
│   ├── nulib/                 # 54 core libraries
│   ├── plugins/               # Nushell plugins (Rust)
│   └── scripts/               # Utility scripts
│
├── platform/                   # Microservices (Rust)
│   ├── crates/                # 12 microservices
│   │   ├── orchestrator/      # Workflow scheduler
│   │   ├── control-center/    # API gateway + auth
│   │   ├── control-center-ui/ # Web dashboard
│   │   ├── mcp-server/        # AI integration
│   │   ├── vault-service/     # Secrets backend
│   │   ├── extension-registry/ # OCI registry
│   │   ├── ai-service/        # LLM features
│   │   ├── detector/          # Anomaly detection
│   │   ├── rag/               # Knowledge retrieval
│   │   ├── provisioning-daemon/ # Background service
│   │   ├── platform-config/   # Config management
│   │   └── service-clients/   # API clients
│   └── Cargo.toml             # Rust workspace
│
├── extensions/                # Extensible components
│   ├── providers/             # Cloud providers (5)
│   ├── taskservs/             # Task services (50+)
│   ├── clusters/              # Cluster templates (9)
│   └── workflows/             # Automation templates
│
├── schemas/                   # Nickel schemas
│   ├── main.ncl              # Entry point
│   ├── config/               # Configuration schemas
│   ├── infrastructure/       # Infrastructure schemas
│   ├── operations/           # Operational schemas
│   └── [other schemas]       # Additional schemas
│
├── config/                    # System configuration
│   └── config.defaults.toml  # Default settings
│
├── bootstrap/                 # Installation
│   ├── install.sh            # Bash bootstrap
│   └── install.nu            # Nushell installer
│
├── docs/                      # Product documentation
│   └── src/                  # mdBook source
│
└── README.md                  # Project overview
```

## Component Interaction

**Typical Workflow**:

```text
User Input
   ↓
CLI Dispatcher (provisioning/core/cli/provisioning)
   ↓
Nushell Handler (provisioning/core/nulib/commands/)
   ↓
Configuration Loading (lib_provisioning/config/)
   ↓
Provider Selection (lib_provisioning/providers/)
   ↓
Validation (lib_provisioning/infra_validator/)
   ↓
Orchestrator Queue (provisioning/platform/orchestrator/)
   ↓
Task Execution (provider + task service)
   ↓
State Update (SurrealDB / file storage)
   ↓
Audit Logging (security system)
   ↓
User Feedback
```

## Scalability

Provisioning scales from:

- **Solo**: 2 CPU cores, 4GB RAM (single instance)
- **MultiUser**: 4-8 CPU cores, 8GB RAM (small team)
- **CICD**: 8+ CPU cores, 16GB RAM (enterprise)
- **Enterprise**: Multi-node Kubernetes (unlimited)

**Bottlenecks & Solutions**:

| Component | Bottleneck | Solution |
| --- | ----------| - --- |
| **Orchestrator** | Task queue | Partition by workspace |
| **State** | SurrealDB | Horizontal scaling |
| **Providers** | API rate limits | Exponential backoff |
| **Storage** | Disk I/O | SSD + caching |

## Integration Points

Provisioning integrates with:

- **Kubernetes API** - Cluster management
- **Cloud Provider APIs** - Resource provisioning
- **SOPS + Age** - Secrets encryption
- **Prometheus** - Metrics collection
- **Cedar** - Policy enforcement
- **SurrealDB** - State persistence
- **MCP** - AI integration
- **KMS** - Key management (Cosmian, AWS, local)

## Reliability Features

**Fault Tolerance**:
- Checkpoint recovery - Resume from failure
- Automatic rollback - Revert failed operations
- Retry logic - Exponential backoff
- Health checks - Continuous monitoring
- Backup & restore - Data protection

**High Availability**:
- Multi-node orchestrator
- Database replication
- Service redundancy
- Load balancing
- Failover automation

## Related Documentation

- [Design Principles](design-principles.md)
- [Component Architecture](component-architecture.md)
- [Integration Patterns](integration-patterns.md)