apophis-fastify/docs/observe.md

Observe Mode

Runtime visibility and drift detection without blocking by default.

Observe extends the invariant framework from Invariant-Driven Automated Testing (Malhado Ribeiro, 2021) to production environments: contracts run continuously against live traffic to detect behavioral drift without affecting requests.

What Observe Does

apophis observe validates your runtime observe configuration:

1. Checks that observe mode is allowed in the current environment
2. Validates reporting sink setup (logs, metrics, traces)
3. Confirms non-blocking semantics
4. Reports what would be observed and why it is safe

When to Use It

• Staging: Validate observe config before promoting to production
• Production: Monitor contract drift without affecting requests
• Platform teams: Centralized visibility across services

Safety Boundaries

Observe mode is non-blocking by default:

• Non-blocking by default: Contract violations are logged, not thrown
• No request failures in non-blocking mode: Violations are reported instead of thrown
• Explicit opt-in for blocking: Requires allowBlocking: true in environment policy
• Production gating: Blocking behavior is blocked in production by default

Sink Configuration

Observe mode requires a reporting sink. Configure it in your environment policy:

environments: {
  staging: {
    name: 'staging',
    allowVerify: true,
    allowObserve: true,
    allowQualify: false,
    allowChaos: false,
    allowBlocking: false,
    requireSink: true
  }
}

APOPHIS supports these sink types:

• Logs: Structured logging of contract violations
• Metrics: Counter and histogram metrics for violation rates
• Traces: Distributed tracing integration for violation context

Sampling

Control observation overhead with sampling:

profiles: {
  'staging-observe': {
    name: 'staging-observe',
    mode: 'observe',
    preset: 'platform-observe',
    routes: []
  }
}

The platform-observe preset enables sampling. Configure the rate explicitly:

profiles: {
  'staging-observe': {
    mode: 'observe',
    preset: 'platform-observe',
    routes: [],
    sampling: 1.0  // 100% of requests observed
  }
}

Staging vs Production

Environment	Blocking	Sampling	Sink Required
Staging	No (default)	100%	Yes
Production	No (default)	100%	Yes

Default is 1.0 (100%). Configure lower rates for production explicitly:

profiles: {
  'prod-observe': {
    mode: 'observe',
    preset: 'platform-observe',
    routes: [],
    sampling: 0.1  // 10% of requests observed
  }
}

--check-config Flag

Validate config without activating observe mode:

apophis observe --profile staging-observe --check-config

This is useful in CI to ensure observe config is valid before deployment.

Exit Codes

Code	Meaning
0	Observe config is valid and safe
2	Safety violation or invalid config

Config Example

// apophis.config.js
export default {
  mode: 'observe',
  profile: 'staging-observe',
  profiles: {
    'staging-observe': {
      name: 'staging-observe',
      mode: 'observe',
      preset: 'platform-observe',
      routes: []
    }
  },
  presets: {
    'platform-observe': {
      name: 'platform-observe',
      depth: 'standard',
      timeout: 10000,
      parallel: true,
      chaos: false,
      observe: true
    }
  },
  environments: {
    staging: {
      name: 'staging',
      allowVerify: true,
      allowObserve: true,
      allowQualify: false,
      allowChaos: false,
      allowBlocking: false,
      requireSink: true
    },
    production: {
      name: 'production',
      allowVerify: true,
      allowObserve: true,
      allowQualify: false,
      allowChaos: false,
      allowBlocking: false,
      requireSink: true
    }
  }
};

Sink Endpoint Configuration

Configure the reporting sink endpoint in your observe config:

observe: {
  sink: {
    endpoint: 'http://collector.internal:4318'
  }
}

Monorepo Validation

For monorepos, use apophis doctor --workspace to validate observe configuration across all workspace packages. observe itself does not support --workspace; use doctor to check config in each package.

Mode Mismatch

Profiles configured for verify mode will be rejected by apophis observe. Only profiles with mode: 'observe' are valid.