# Youki Task Service

## Overview

The Youki task service provides a complete installation and configuration of [Youki](https://github.com/containers/youki), a container runtime written in Rust that is designed to be fast, safe, and memory-efficient. Youki is an implementation of the OCI (Open Container Initiative) runtime specification and serves as a modern alternative to runc with enhanced performance and security characteristics.

## Features

### Core Runtime Features
- **OCI Compliance** - Full implementation of OCI Runtime Specification v1.0+
- **High Performance** - Written in Rust for optimal performance and low overhead
- **Memory Safety** - Rust's memory safety guarantees prevent common vulnerabilities
- **Low Resource Usage** - Minimal CPU and memory footprint
- **Fast Container Startup** - Optimized container creation and execution

### Security Features
- **Memory Safety** - Rust prevents buffer overflows and memory corruption
- **Zero-Cost Abstractions** - High-level features without runtime overhead  
- **Secure by Default** - Secure configuration defaults
- **Namespace Support** - Full Linux namespace support for isolation
- **Capability Management** - Fine-grained capability control

### Advanced Features
- **Cgroup Support** - Both cgroups v1 and v2 support
- **Rootless Containers** - Full rootless operation support
- **Hook Support** - OCI lifecycle hooks implementation
- **Logging Integration** - Structured logging and debugging
- **Cross-Platform** - Support for multiple architectures

### Integration Features
- **Containerd Integration** - Drop-in replacement for runc in containerd
- **Podman Integration** - Compatible with Podman container engine
- **Kubernetes Support** - Works with Kubernetes through containerd/CRI-O
- **Docker Compatibility** - Compatible with Docker through containerd
- **OCI Tooling** - Works with standard OCI tooling ecosystem

### Development Features
- **Rust Ecosystem** - Benefits from Rust's robust ecosystem
- **Modern Architecture** - Clean, maintainable codebase
- **Active Development** - Rapidly evolving with new features
- **Community Driven** - Open source with active community
- **Performance Monitoring** - Built-in performance measurement tools

## Configuration

### Basic Configuration
```kcl
youki: Youki = {
    name: "youki"
    version: "0.3.0"
}
```

### Production Configuration
```kcl
youki: Youki = {
    name: "youki"
    version: "0.3.0"
    configuration: {
        runtime_config: {
            log_level: "info"
            log_format: "json"
            systemd_cgroup: true
            rootless: true
            no_pivot_root: false
            no_new_keyring: false
        }
        security: {
            no_new_privileges: true
            selinux_enabled: true
            apparmor_enabled: true
            seccomp_enabled: true
            default_capabilities: [
                "CAP_CHOWN",
                "CAP_DAC_OVERRIDE",
                "CAP_FOWNER",
                "CAP_FSETID",
                "CAP_KILL",
                "CAP_NET_BIND_SERVICE",
                "CAP_SETFCAP",
                "CAP_SETGID",
                "CAP_SETPCAP",
                "CAP_SETUID",
                "CAP_SYS_CHROOT"
            ]
            dropped_capabilities: [
                "CAP_AUDIT_CONTROL",
                "CAP_AUDIT_READ",
                "CAP_AUDIT_WRITE",
                "CAP_BLOCK_SUSPEND",
                "CAP_DAC_READ_SEARCH",
                "CAP_IPC_LOCK",
                "CAP_IPC_OWNER",
                "CAP_LEASE",
                "CAP_LINUX_IMMUTABLE",
                "CAP_MAC_ADMIN",
                "CAP_MAC_OVERRIDE",
                "CAP_MKNOD",
                "CAP_NET_ADMIN",
                "CAP_NET_RAW",
                "CAP_SETGID",
                "CAP_SETUID",
                "CAP_SYS_ADMIN",
                "CAP_SYS_BOOT",
                "CAP_SYS_CHROOT",
                "CAP_SYS_MODULE",
                "CAP_SYS_NICE",
                "CAP_SYS_PACCT",
                "CAP_SYS_PTRACE",
                "CAP_SYS_RAWIO",
                "CAP_SYS_RESOURCE",
                "CAP_SYS_TIME",
                "CAP_SYS_TTY_CONFIG",
                "CAP_SYSLOG",
                "CAP_WAKE_ALARM"
            ]
        }
        resource_limits: {
            default_memory_limit: "1GB"
            default_cpu_quota: 100000  # 1 CPU
            default_cpu_period: 100000
            default_pids_limit: 1024
            default_nofile_soft: 1024
            default_nofile_hard: 4096
        }
        cgroup_config: {
            cgroup_version: "v2"
            systemd_cgroup: true
            cgroup_path: "/sys/fs/cgroup"
            unified_hierarchy: true
        }
    }
    performance: {
        optimization_level: "release"
        memory_optimization: true
        cpu_optimization: true
        startup_optimization: true
        binary_size_optimization: false
    }
}
```

### Containerd Integration
```kcl
youki: Youki = {
    name: "youki"
    version: "0.3.0"
    containerd_integration: {
        enabled: true
        runtime_type: "io.containerd.runc.v2"
        runtime_engine: "youki"
        runtime_root: "/run/containerd/youki"
        shim_debug: false
        shim_config: {
            shim_cgroup: "youki"
            containerd_binary: "/usr/bin/containerd"
            containerd_address: "/run/containerd/containerd.sock"
        }
        runtime_options: {
            SystemdCgroup: true
            BinaryName: "/usr/local/bin/youki"
            Root: "/run/containerd/youki"
            NoPivotRoot: false
            NoNewKeyring: false
        }
    }
    features: {
        seccomp: true
        apparmor: true
        selinux: true
        cgroup_v2: true
        user_namespaces: true
        network_namespaces: true
        mount_namespaces: true
        pid_namespaces: true
        ipc_namespaces: true
        uts_namespaces: true
        time_namespaces: true
    }
}
```

### Podman Integration
```kcl
youki: Youki = {
    name: "youki"
    version: "0.3.0"
    podman_integration: {
        enabled: true
        runtime_path: "/usr/local/bin/youki"
        runtime_type: "oci"
        runtime_supports_json: true
        runtime_supports_kvm: false
        runtime_supports_nocgroups: true
        cgroup_manager: "systemd"
        conmon_path: "/usr/bin/conmon"
        conmon_env_vars: [
            "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
        ]
        init_path: "/usr/libexec/podman/catatonit"
        static_dir: "/var/lib/containers/storage/libpod"
        tmp_dir: "/run/libpod"
        volume_path: "/var/lib/containers/storage/volumes"
    }
    logging: {
        log_driver: "journald"
        log_level: "info"
        log_size_max: "10MB"
        log_opts: {
            max_size: "10m"
            max_file: "3"
        }
        syslog_facility: "daemon"
        syslog_tag: "youki"
    }
}
```

### Kubernetes CRI-O Integration
```kcl
youki: Youki = {
    name: "youki"
    version: "0.3.0"
    crio_integration: {
        enabled: true
        runtime_path: "/usr/local/bin/youki"
        runtime_type: "oci"
        runtime_root: "/run/youki"
        runtime_config_path: "/etc/youki/config.toml"
        privileged_without_host_devices: false
        allowed_annotations: [
            "io.kubernetes.cri-o.userns-mode"
        ]
        runtime_supports_json: true
        runtime_supports_kvm: false
    }
    kubernetes_features: {
        pod_level_resources: true
        container_resources: true
        security_context: true
        read_only_root_filesystem: true
        run_as_user: true
        run_as_group: true
        supplemental_groups: true
        fs_group: true
        selinux_options: true
        seccomp_profile: true
        apparmor_profile: true
    }
}
```

### Development Configuration
```kcl
youki: Youki = {
    name: "youki"
    version: "0.3.0"
    development: {
        debug_enabled: true
        debug_level: "trace"
        log_to_console: true
        log_to_file: true
        log_file_path: "/var/log/youki/youki.log"
        profiling_enabled: true
        metrics_enabled: true
        benchmark_mode: false
        test_mode: false
    }
    build_config: {
        target_triple: "x86_64-unknown-linux-gnu"
        profile: "release"
        features: [
            "systemd",
            "cgroupsv2",
            "seccomp",
            "apparmor",
            "selinux"
        ]
        optimizations: {
            lto: true
            codegen_units: 1
            panic: "abort"
            strip_symbols: true
        }
        cross_compilation: {
            enabled: false
            targets: [
                "aarch64-unknown-linux-gnu",
                "armv7-unknown-linux-gnueabihf"
            ]
        }
    }
}
```

### High-Performance Configuration
```kcl
youki: Youki = {
    name: "youki"
    version: "0.3.0"
    performance_tuning: {
        cpu_optimization: {
            cpu_affinity: true
            numa_awareness: true
            cpu_quota_enforcement: "strict"
            cpu_shares: 1024
            cpu_period: 100000
            realtime_priority: false
        }
        memory_optimization: {
            memory_swappiness: 10
            memory_oom_kill_disable: false
            memory_use_hierarchy: true
            kernel_memory_tcp: true
            memory_limit_in_bytes: "4GB"
            memory_soft_limit_in_bytes: "3GB"
        }
        io_optimization: {
            blkio_weight: 500
            blkio_weight_device: []
            blkio_throttle_read_bps_device: []
            blkio_throttle_write_bps_device: []
            blkio_throttle_read_iops_device: []
            blkio_throttle_write_iops_device: []
        }
        network_optimization: {
            network_priority: 0
            network_classid: 0
            network_bandwidth_limit: "1Gbps"
        }
    }
    monitoring: {
        metrics_collection: true
        performance_counters: true
        resource_usage_tracking: true
        latency_measurements: true
        throughput_measurements: true
        memory_profiling: false
        cpu_profiling: false
    }
}
```

## Usage

### Deploy Youki
```bash
./core/nulib/provisioning taskserv create youki --infra <infrastructure-name>
```

### List Available Task Services
```bash
./core/nulib/provisioning taskserv list
```

### SSH to Youki Server
```bash
./core/nulib/provisioning server ssh <youki-server>
```

### Basic Runtime Operations
```bash
# Check youki version
youki --version

# Show youki info
youki info

# Check runtime features
youki features

# Display help
youki --help
youki create --help
```

### Container Lifecycle Management
```bash
# Create a container (requires OCI bundle)
youki create --bundle /path/to/bundle container-id

# Start the container
youki start container-id

# Check container state
youki state container-id

# Get container events
youki events container-id

# Execute command in container
youki exec container-id /bin/sh

# Kill container
youki kill container-id

# Delete container
youki delete container-id
```

### Container State Management
```bash
# List all containers
youki list

# Show detailed container state
youki state container-id --format json

# Pause container execution
youki pause container-id

# Resume paused container
youki resume container-id

# Get container statistics
youki ps container-id

# Update container resources
youki update --memory 512M container-id
```

### Integration with Containerd
```bash
# Configure containerd to use youki
sudo tee -a /etc/containerd/config.toml <<EOF
[plugins."io.containerd.grpc.v1.cri".containerd.runtimes.youki]
  runtime_type = "io.containerd.runc.v2"
  [plugins."io.containerd.grpc.v1.cri".containerd.runtimes.youki.options]
    BinaryName = "/usr/local/bin/youki"
    SystemdCgroup = true
EOF

# Restart containerd
sudo systemctl restart containerd

# Test with crictl
sudo crictl run --runtime youki container.json pod.json
```

### Integration with Podman
```bash
# Configure podman to use youki
mkdir -p ~/.config/containers
cat > ~/.config/containers/containers.conf <<EOF
[containers]
default_runtime = "youki"

[engine]
runtime_map = { "youki" = ["/usr/local/bin/youki"] }
EOF

# Run container with youki
podman run --runtime youki -it alpine:latest /bin/sh

# Check runtime being used
podman info | grep -A 5 runtimes
```

### Performance Testing
```bash
# Benchmark container creation
time youki create --bundle /path/to/bundle test-container

# Measure startup time
time (youki create --bundle /path/to/bundle test && youki start test)

# Memory usage monitoring
ps aux | grep youki
cat /proc/$(pgrep youki)/status | grep -E "(VmRSS|VmSize)"

# Performance comparison
hyperfine "youki create --bundle /path/to/bundle test-youki && youki start test-youki" \
          "runc create --bundle /path/to/bundle test-runc && runc start test-runc"
```

### Debugging and Troubleshooting
```bash
# Enable debug logging
export YOUKI_LOG_LEVEL=debug
youki create --bundle /path/to/bundle container-id

# Check runtime logs
journalctl -u youki

# Trace system calls
strace -f youki create --bundle /path/to/bundle container-id

# Validate OCI bundle
youki spec-validate /path/to/bundle

# Check cgroup configuration
cat /sys/fs/cgroup/system.slice/containerd.service/youki-*/memory.max
```

### Development and Testing
```bash
# Build youki from source
git clone https://github.com/containers/youki.git
cd youki
cargo build --release

# Run integration tests
cargo test --tests

# Run performance benchmarks
cargo bench

# Generate documentation
cargo doc --open

# Check code formatting
cargo fmt --check
```

## Architecture

### System Architecture
```
┌─────────────────┐    ┌──────────────────┐    ┌─────────────────┐
│   Container     │────│   Youki Runtime  │────│   Linux Kernel  │
│   Engines       │    │                  │    │                 │
│                 │    │ • OCI Spec       │    │ • Namespaces    │
│ • Containerd    │────│ • Process Mgmt   │────│ • Cgroups       │
│ • Podman        │    │ • Resource Ctrl  │    │ • Capabilities  │
│ • CRI-O         │    │ • Security       │    │ • Seccomp       │
└─────────────────┘    └──────────────────┘    └─────────────────┘
```

### Youki Internal Architecture
```
┌─────────────────────────────────────────────────────────────┐
│                      Youki Runtime                         │
├─────────────────────────────────────────────────────────────┤
│  CLI Interface     │  Core Engine      │  System Interface │
│                    │                   │                   │
│ • Commands         │ • Container Mgmt  │ • Namespace API   │
│ • Config Parsing   │ • Process Control │ • Cgroup API      │
│ • State Management │ • Resource Limits │ • Mount API       │
│ • Error Handling   │ • Security Policy │ • Network API     │
├─────────────────────────────────────────────────────────────┤
│                    Rust Runtime Layer                      │
├─────────────────────────────────────────────────────────────┤
│  Memory Safety     │  Performance      │  Concurrency      │
│                    │                   │                   │
│ • Ownership Model  │ • Zero-Cost Abs   │ • Async Runtime   │
│ • Borrow Checker   │ • LLVM Optimized  │ • Thread Safety   │
│ • Type Safety      │ • Minimal Runtime │ • Lock-Free Ops   │
└─────────────────────────────────────────────────────────────┘
```

### Performance Comparison
```
Runtime  │ Language │ Binary Size │ Memory Usage │ Startup Time │ Throughput
─────────┼──────────┼─────────────┼──────────────┼───────────────┼───────────
youki    │ Rust     │ ~15MB       │ ~8MB         │ ~50ms         │ High
runc     │ Go       │ ~20MB       │ ~15MB        │ ~100ms        │ Medium
crun     │ C        │ ~1MB        │ ~5MB         │ ~30ms         │ Very High
```

### File Structure
```
/usr/local/bin/youki         # Main youki binary
/etc/youki/                  # Configuration directory
├── config.toml             # Runtime configuration
├── seccomp.json           # Default seccomp profile
└── apparmor.conf          # AppArmor configuration

/var/lib/youki/             # Runtime state directory
├── containers/            # Container state files
├── bundles/              # OCI bundle storage
└── logs/                 # Runtime logs

/run/youki/                # Runtime directory
├── state.json            # Global runtime state
└── containers/           # Per-container runtime data

~/.config/youki/           # User configuration
└── config.toml           # User-specific settings
```

## Supported Operating Systems

- Ubuntu 20.04+ / Debian 11+
- CentOS 8+ / RHEL 8+ / Fedora 35+
- Amazon Linux 2+
- SUSE Linux Enterprise 15+
- Alpine Linux 3.15+

## System Requirements

### Minimum Requirements
- **Kernel**: Linux 5.0+ (5.4+ recommended)
- **RAM**: 100MB (minimal overhead)
- **Storage**: 50MB for binary and dependencies
- **CPU**: Any x86_64 or aarch64
- **Rust**: 1.65+ (for building from source)

### Production Requirements
- **Kernel**: Linux 5.10+ with all container features
- **RAM**: 1GB+ (depends on container workload)
- **Storage**: 10GB+ for container storage
- **CPU**: Multi-core recommended for performance
- **Features**: cgroups v2, user namespaces, seccomp

### Kernel Features Required
- **Namespaces** - PID, network, mount, UTS, IPC, user, time
- **Cgroups** - v1 and/or v2 support
- **Capabilities** - Linux capabilities system
- **Seccomp** - System call filtering
- **AppArmor/SELinux** - Mandatory access control (optional)

## Troubleshooting

### Installation Issues
```bash
# Check youki installation
youki --version
which youki

# Verify required kernel features
youki features

# Check system compatibility
youki check

# Build from source if needed
git clone https://github.com/containers/youki.git
cd youki && cargo build --release
```

### Runtime Issues
```bash
# Enable debug logging
export YOUKI_LOG_LEVEL=debug
export RUST_LOG=debug

# Check container state
youki state container-id

# Validate OCI bundle
youki spec-validate /path/to/bundle

# Check cgroup mounts
mount | grep cgroup
ls -la /sys/fs/cgroup/
```

### Performance Issues
```bash
# Check resource usage
youki ps container-id
top -p $(pgrep youki)

# Monitor system calls
strace -c youki start container-id

# Profile performance
perf record youki start container-id
perf report

# Memory profiling
valgrind --tool=massif youki start container-id
```

### Container Issues
```bash
# Check container logs
youki events container-id
journalctl -f | grep youki

# Debug container creation
youki create --bundle /bundle --debug container-id

# Check namespace setup
lsns -t pid,net,mnt,uts,ipc,user
ps -eo pid,pidns,netns,mntns,userns,comm

# Inspect cgroup configuration
cat /sys/fs/cgroup/*/youki-*/cgroup.controllers
systemd-cgls youki
```

### Integration Issues
```bash
# Check containerd integration
containerd config dump | grep youki
crictl info | grep -A 5 runtimes

# Test podman integration
podman info | grep -A 10 runtimes
podman run --runtime youki --rm hello-world

# Debug shim issues
journalctl -u containerd | grep youki
containerd --log-level debug
```

## Security Considerations

### Runtime Security
- **Memory Safety** - Rust prevents buffer overflows and memory corruption
- **Type Safety** - Strong type system prevents many security issues
- **Secure Defaults** - Secure configuration out of the box
- **Minimal Attack Surface** - Small, focused codebase

### Container Security
- **Namespace Isolation** - Full namespace support for process isolation
- **Capability Management** - Fine-grained Linux capability control
- **Seccomp Filtering** - System call filtering for attack prevention
- **AppArmor/SELinux** - Mandatory access control integration

### Resource Security
- **Cgroup Enforcement** - Strict resource limit enforcement
- **Memory Protection** - Memory limit and OOM protection
- **CPU Protection** - CPU usage and priority controls
- **I/O Protection** - Block and network I/O limits

### Operational Security
- **Audit Logging** - Comprehensive operation logging
- **State Validation** - Container state integrity checking
- **Secure Communication** - Secure inter-process communication
- **Regular Updates** - Active security maintenance

## Performance Optimization

### Build Optimization
- **Release Profile** - Use optimized release builds
- **Link-Time Optimization** - Enable LTO for better performance
- **Target-Specific** - Build for specific CPU architectures
- **Feature Selection** - Enable only required features

### Runtime Optimization
- **Cgroup v2** - Use cgroups v2 for better performance
- **Systemd Integration** - Use systemd for process management
- **Memory Management** - Optimize memory allocation patterns
- **CPU Affinity** - Pin containers to specific CPU cores

### System Optimization
- **Kernel Configuration** - Optimize kernel for container workloads
- **File System** - Use appropriate file systems (ext4, xfs, overlay2)
- **Network Stack** - Optimize network configuration
- **Storage Performance** - Use fast storage for container data

### Monitoring Optimization
- **Metrics Collection** - Collect relevant performance metrics
- **Resource Monitoring** - Monitor CPU, memory, I/O usage
- **Latency Tracking** - Track container startup and operation latencies
- **Throughput Monitoring** - Monitor container operation throughput

## Integration Examples

### Containerd Configuration
```toml
# /etc/containerd/config.toml
[plugins."io.containerd.grpc.v1.cri".containerd.runtimes.youki]
  runtime_type = "io.containerd.runc.v2"
  [plugins."io.containerd.grpc.v1.cri".containerd.runtimes.youki.options]
    BinaryName = "/usr/local/bin/youki"
    SystemdCgroup = true
    Root = "/run/containerd/youki"
```

### CRI-O Configuration
```toml
# /etc/crio/crio.conf
[crio.runtime.runtimes.youki]
runtime_path = "/usr/local/bin/youki"
runtime_type = "oci"
runtime_root = "/run/youki"
```

### Systemd Service
```ini
[Unit]
Description=Youki Container Runtime
Documentation=https://github.com/containers/youki

[Service]
Type=notify
ExecStart=/usr/local/bin/youki
Restart=always
RestartSec=5
Delegate=yes
KillMode=process
OOMScoreAdjust=-999
LimitNOFILE=1048576
LimitNPROC=1048576
LimitCORE=infinity

[Install]
WantedBy=multi-user.target
```

## Resources

- **Official Repository**: [github.com/containers/youki](https://github.com/containers/youki)
- **Documentation**: [containers.github.io/youki](https://containers.github.io/youki/)
- **OCI Runtime Spec**: [github.com/opencontainers/runtime-spec](https://github.com/opencontainers/runtime-spec)
- **Rust Documentation**: [doc.rust-lang.org](https://doc.rust-lang.org/)
- **Container Security**: [kubernetes.io/docs/concepts/security](https://kubernetes.io/docs/concepts/security/)