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# Testing

This document describes the test infrastructure for validating Dynamo's fault tolerance mechanisms. The testing framework supports request cancellation, migration, etcd HA, and hardware fault injection scenarios.

## Overview

Dynamo's fault tolerance test suite is located in `tests/fault_tolerance/` and includes:

| Test Category | Location | Purpose |
|---------------|----------|---------|
| Cancellation | `cancellation/` | Request cancellation during in-flight operations |
| Migration | `migration/` | Request migration when workers fail |
| etcd HA | `etcd_ha/` | etcd failover and recovery |
| Hardware | `hardware/` | GPU and network fault injection |
| Deployment | `deploy/` | End-to-end deployment testing |

## Test Directory Structure

```
tests/fault_tolerance/
├── cancellation/
│   ├── test_vllm.py
│   ├── test_trtllm.py
│   ├── test_sglang.py
│   └── utils.py
├── migration/
│   ├── test_vllm.py
│   ├── test_trtllm.py
│   ├── test_sglang.py
│   └── utils.py
├── etcd_ha/
│   ├── test_vllm.py
│   ├── test_trtllm.py
│   ├── test_sglang.py
│   └── utils.py
├── hardware/
│   └── fault_injection_service/
│       ├── api_service/
│       └── agents/
├── deploy/
│   ├── test_deployment.py
│   ├── scenarios.py
│   ├── base_checker.py
│   └── ...
└── client.py
```

## Request Cancellation Tests

Test that in-flight requests can be properly canceled.

### Running Cancellation Tests

```bash
# Run all cancellation tests
pytest tests/fault_tolerance/cancellation/ -v

# Run for specific backend
pytest tests/fault_tolerance/cancellation/test_vllm.py -v
```

### Cancellation Test Utilities

The `cancellation/utils.py` module provides:

#### CancellableRequest

Thread-safe request cancellation via TCP socket manipulation:

```python
from tests.fault_tolerance.cancellation.utils import CancellableRequest

request = CancellableRequest()

# Send request in separate thread
thread = Thread(target=send_request, args=(request,))
thread.start()

# Cancel after some time
time.sleep(1)
request.cancel()  # Closes underlying socket
```

#### send_completion_request / send_chat_completion_request

Send cancellable completion requests:

```python
from tests.fault_tolerance.cancellation.utils import (
    send_completion_request,
    send_chat_completion_request
)

# Non-streaming
response = send_completion_request(
    base_url="http://localhost:8000",
    model="Qwen/Qwen3-0.6B",
    prompt="Hello, world!",
    max_tokens=100
)

# Streaming with cancellation
responses = send_chat_completion_request(
    base_url="http://localhost:8000",
    model="Qwen/Qwen3-0.6B",
    messages=[{"role": "user", "content": "Hello!"}],
    stream=True,
    cancellable_request=request
)
```

#### poll_for_pattern

Wait for specific patterns in logs:

```python
from tests.fault_tolerance.cancellation.utils import poll_for_pattern

# Wait for cancellation confirmation
found = poll_for_pattern(
    log_file="/var/log/dynamo/worker.log",
    pattern="Request cancelled",
    timeout=30,
    interval=0.5
)
```

## Migration Tests

Test that requests migrate to healthy workers when failures occur.

### Running Migration Tests

```bash
# Run all migration tests
pytest tests/fault_tolerance/migration/ -v

# Run for specific backend
pytest tests/fault_tolerance/migration/test_vllm.py -v
```

### Migration Test Utilities

The `migration/utils.py` module provides:

- Frontend wrapper with configurable request planes
- Long-running request spawning for migration scenarios
- Health check disabling for controlled testing

### Example Migration Test

```python
def test_migration_on_worker_failure():
    # Start deployment with 2 workers
    deployment = start_deployment(workers=2)

    # Send long-running request
    request_thread = spawn_long_request(max_tokens=1000)

    # Kill one worker mid-generation
    kill_worker(deployment.workers[0])

    # Verify request completes on remaining worker
    response = request_thread.join()
    assert response.status_code == 200
    assert len(response.tokens) > 0
```

## etcd HA Tests

Test system behavior during etcd failures and recovery.

### Running etcd HA Tests

```bash
pytest tests/fault_tolerance/etcd_ha/ -v
```

### Test Scenarios

- **Leader failover**: etcd leader node fails, cluster elects new leader
- **Network partition**: etcd node becomes unreachable
- **Recovery**: System recovers after etcd becomes available

## Hardware Fault Injection

The fault injection service enables testing under simulated hardware failures.

<Warning>
**Test harness only — never deploy in production.** The fault injection service ships with a `ClusterRole` (`fault-injection-api`) granting `patch` on nodes/pods/services, `create`/`delete` on `NetworkPolicy`, and full control on chaos-mesh CRDs (`NetworkChaos`, `PodChaos`, `StressChaos`, `IoChaos`). It also deploys a privileged kernel-mode `DaemonSet` capable of synthesizing GPU XID errors. Any caller reachable to the API can cause arbitrary pod kills, network partitions, IO faults, and GPU XID errors across the cluster. Deploy only into dedicated test clusters that you are willing to disrupt, never expose the API externally, and tear down with `kubectl delete -f deploy/` after each test run. See [`tests/fault_tolerance/hardware/fault_injection_service/README.md`](../../tests/fault_tolerance/hardware/fault_injection_service/README.md) for the full security posture.
</Warning>

### Fault Injection Service

Located at `tests/fault_tolerance/hardware/fault_injection_service/`, this FastAPI service orchestrates fault injection:

```bash
# Start the fault injection service
cd tests/fault_tolerance/hardware/fault_injection_service
python -m api_service.main
```

### Supported Fault Types

#### GPU Faults

| Fault Type | Description |
|------------|-------------|
| `XID_ERROR` | Simulate GPU XID error (various codes) |
| `THROTTLE` | GPU thermal throttling |
| `MEMORY_PRESSURE` | GPU memory exhaustion |
| `OVERHEAT` | GPU overheating condition |
| `COMPUTE_OVERLOAD` | GPU compute saturation |

#### Network Faults

| Fault Type | Description |
|------------|-------------|
| `FRONTEND_WORKER` | Partition between frontend and workers |
| `WORKER_NATS` | Partition between workers and NATS |
| `WORKER_WORKER` | Partition between workers |
| `CUSTOM` | Custom network partition |

### Fault Injection API

#### Inject GPU Fault

```bash
curl -X POST http://localhost:8080/api/v1/faults/gpu/inject \
  -H "Content-Type: application/json" \
  -d '{
    "target_pod": "vllm-worker-0",
    "fault_type": "XID_ERROR",
    "severity": "HIGH"
  }'
```

#### Inject Specific XID Error

```bash
# Inject XID 79 (GPU memory page fault)
curl -X POST http://localhost:8080/api/v1/faults/gpu/inject/xid-79 \
  -H "Content-Type: application/json" \
  -d '{"target_pod": "vllm-worker-0"}'
```

Supported XID codes: 43, 48, 74, 79, 94, 95, 119, 120

#### Inject Network Partition

```bash
curl -X POST http://localhost:8080/api/v1/faults/network/inject \
  -H "Content-Type: application/json" \
  -d '{
    "partition_type": "FRONTEND_WORKER",
    "duration_seconds": 30
  }'
```

#### Recover from Fault

```bash
curl -X POST http://localhost:8080/api/v1/faults/{fault_id}/recover
```

#### List Active Faults

```bash
curl http://localhost:8080/api/v1/faults
```

### GPU Fault Injector Agent

The GPU fault injector runs as a DaemonSet on worker nodes:

```yaml
apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: gpu-fault-injector
spec:
  selector:
    matchLabels:
      app: gpu-fault-injector
  template:
    spec:
      containers:
      - name: agent
        image: dynamo/gpu-fault-injector:latest
        securityContext:
          privileged: true
        volumeMounts:
        - name: dev
          mountPath: /dev
```

The agent injects fake XID messages via `/dev/kmsg` to trigger NVSentinel detection.

## Deployment Testing Framework

The `deploy/` directory contains an end-to-end testing framework.

### Test Phases

Tests run through three phases:

| Phase | Description |
|-------|-------------|
| `STANDARD` | Baseline performance under normal conditions |
| `OVERFLOW` | System behavior during fault/overload |
| `RECOVERY` | System recovery after fault resolution |

### Scenario Configuration

Define test scenarios in `scenarios.py`:

```python
from tests.fault_tolerance.deploy.scenarios import Scenario, Load, Failure

scenario = Scenario(
    name="worker_failure_migration",
    backend="vllm",
    load=Load(
        clients=10,
        requests_per_client=100,
        max_tokens=256
    ),
    failure=Failure(
        type="pod_kill",
        target="vllm-worker-0",
        trigger_after_requests=50
    )
)
```

### Running Deployment Tests

```bash
# Run all deployment tests
pytest tests/fault_tolerance/deploy/test_deployment.py -v

# Run specific scenario
pytest tests/fault_tolerance/deploy/test_deployment.py::test_worker_failure -v
```

### Validation Checkers

The framework includes pluggable validators:

```python
from tests.fault_tolerance.deploy.base_checker import BaseChecker, ValidationContext

class MigrationChecker(BaseChecker):
    def check(self, context: ValidationContext) -> bool:
        # Verify migrations occurred
        migrations = context.metrics.get("migrations_total", 0)
        return migrations > 0
```

### Results Parsing

Parse test results for analysis:

```python
from tests.fault_tolerance.deploy.parse_results import process_overflow_recovery_test

results = process_overflow_recovery_test(log_dir="/path/to/logs")
print(f"Success rate: {results['success_rate']}")
print(f"P99 latency: {results['p99_latency_ms']}ms")
```

## Client Utilities

The `client.py` module provides shared client functionality:

### Multi-Threaded Load Generation

```python
from tests.fault_tolerance.client import client

# Generate load with multiple clients
results = client(
    base_url="http://localhost:8000",
    num_clients=10,
    requests_per_client=100,
    model="Qwen/Qwen3-0.6B",
    max_tokens=256,
    log_dir="/tmp/test_logs"
)
```

### Request Options

| Parameter | Description |
|-----------|-------------|
| `base_url` | Frontend URL |
| `num_clients` | Number of concurrent clients |
| `requests_per_client` | Requests per client |
| `model` | Model name |
| `max_tokens` | Max tokens per request |
| `log_dir` | Directory for client logs |
| `endpoint` | `completions` or `chat/completions` |

## Running the Full Test Suite

### Prerequisites

1. Kubernetes cluster with GPU nodes
2. Dynamo deployment
3. etcd cluster (for HA tests)
4. Fault injection service (for hardware tests)

### Environment Setup

```bash
export KUBECONFIG=/path/to/kubeconfig
export DYNAMO_NAMESPACE=dynamo-test
export FRONTEND_URL=http://localhost:8000
```

### Run All Tests

```bash
# Install test dependencies
pip install pytest pytest-asyncio

# Run all fault tolerance tests
pytest tests/fault_tolerance/ -v --tb=short

# Run with specific markers
pytest tests/fault_tolerance/ -v -m "not slow"
```

### Test Markers

| Marker | Description |
|--------|-------------|
| `slow` | Long-running tests (> 5 minutes) |
| `gpu` | Requires GPU resources |
| `k8s` | Requires Kubernetes cluster |
| `etcd_ha` | Requires multi-node etcd |

## Best Practices

### 1. Isolate Test Environments

Run fault tolerance tests in dedicated namespaces:

```bash
kubectl create namespace dynamo-fault-test
```

### 2. Clean Up After Tests

Ensure fault injection is recovered:

```bash
# List and recover all active faults
curl http://localhost:8080/api/v1/faults | jq -r '.[].id' | \
  xargs -I {} curl -X POST http://localhost:8080/api/v1/faults/{}/recover
```

### 3. Collect Logs

Preserve logs for debugging:

```bash
pytest tests/fault_tolerance/ -v \
  --log-dir=/tmp/fault_test_logs \
  --capture=no
```

### 4. Monitor During Tests

Watch system state during tests:

```bash
# Terminal 1: Watch pods
watch kubectl get pods -n dynamo-test

# Terminal 2: Watch metrics
watch 'curl -s localhost:8000/metrics | grep -E "(migration|rejection)"'
```

## Related Documentation

- [Request Migration](/dynamo/dev/user-guides/fault-tolerance/request-migration) - Migration implementation details
- [Request Cancellation](/dynamo/dev/user-guides/fault-tolerance/request-cancellation) - Cancellation implementation
- [Health Checks](/dynamo/dev/user-guides/observability-local/health-checks) - Health monitoring
- [Metrics](/dynamo/dev/user-guides/observability-local/metrics) - Available metrics for monitoring