Load

A preview environment with one person clicking through it does not resemble production. Load replays your real traffic shape against the branch: the same endpoint mix, the same relative rates, at whatever fraction of production you ask for.

load:
  enabled: true
  source: datadog
  scale: 0.05
  duration: 5m
  safe_routes: ["GET /*", "POST /api/search"]
  unsafe_routes: ["POST /api/payments/*", "DELETE /*"]
  thresholds:
    p95_increase: 0.25
    error_rate: 0.01

Where the shape comes from

Source	What it reads
`datadog`	Endpoint mix and rates from APM
`newrelic`	The same, from New Relic
`otel`	An OpenTelemetry collector
`access_log`	A log file, when you have no APM
`none`	No shape; only what the manifest states

The shape is the point. Uniform traffic across every endpoint exercises nothing real: production is ninety percent reads on three routes, and a change that makes the fourth-busiest endpoint slow is invisible under a flat mix.

Arrivals are Poisson, not evenly spaced, because real traffic arrives in clumps and evenly spaced requests hide the queueing behaviour that matters.

Safe and unsafe routes

unsafe_routes are never called. Payments, deletes, anything that emails a person. Everything they touch is still sandboxed, so this is a second layer rather than the only one, but a load run that charges a thousand sandbox cards is a mess to read even when no money moves.

safe_routes is the allowlist when you would rather state what may be called than what may not.

Thresholds

AF-LOD-011 Load exceeded 2 thresholds the manifest sets.

Thresholds are deltas against the same run on the base branch, not absolute numbers. Absolute numbers fail on a slow CI runner and tell you nothing about the change. p95_increase: 0.25 means a quarter slower than base is a failure.

Aborting

AF-LOD-002 The load run was aborted after the error rate exceeded 50% for 30s.

A branch that is failing every request has already answered the question, and continuing wastes several minutes to produce a number nobody needs.

Targets

AF-LOD-001 The load target https://staging.example.com is not an environment
this engine created.

Load runs against environments Antifailure made, and refuses anything else. This is a load generator with a production traffic shape pointed at it; the one thing it must never do is point at production.

Related: insights, scheduling.