Requests

The flow: of a scenario is a list of steps, each a single-key mapping: request, think_time, js, or group.

flow:
  - request:
      name: create order          # metric tag (defaults to the URL string)
      protocol: http              # inferred from URL scheme when omitted
      method: POST                # default GET (POST when a body is present)
      url: /orders                # absolute, or relative to defaults.http.base_url
      params: { source: loadtest }    # query string parameters
      headers:
        X-Idempotency-Key: "${js: crypto.uuidv4()}"
      body: ...                   # see below
      timeout: 10s                # per-request override
      follow_redirects: false     # per-request override
      tags: { endpoint: orders }  # extra metric tags
      extract: [ ... ]            # see Extraction
      assert: [ ... ]             # failures mark the request failed
      checks: [ ... ]             # recorded only
  - think_time: { type: uniform, min: 1s, max: 3s }
  - js: "session.counterAdd('orders_created', 1)"
  - group:
      name: checkout              # nested samples get group="::checkout"
      steps: [ ... ]

Bodies

body: 'raw string with ${interpolation}'
# or structured (exactly one key):
body: { json: { sku: "W-1", qty: 2, note: "${vars.note}" } }   # sets Content-Type
body: { file: ./payload.bin }                                  # loaded at start
body: { form: { user: alice, pass: "${secrets.pw}" } }         # urlencoded
body:
  multipart:
    - { name: meta, value: '{"kind":"avatar"}', content_type: application/json }
    - { name: file, file: ./avatar.png, filename: avatar.png }

JSON bodies interpolate every string leaf; a leaf that is only ${expr} keeps its JSON type when the value parses as JSON ("${count}" → 7, not "7").

Protocol-specific blocks

Non-HTTP requests use the same step with an extra options block — see the protocol chapters:

- request: { url: wss://x/ws, ws: { send: ["hi"], receive_count: 1 } }
- request: { url: grpc://x:50051, grpc: { service: pkg.Svc, method: M, reflection: true, message: {...} } }
- request: { url: /graphql, protocol: graphql, graphql: { query: "...", variables: {...} } }
- request: { url: tcp://x:7000, socket: { send_text: "PING\n", read_bytes: 64 } }

Cookies

With defaults.http.cookies: true (the default) every VU has its own cookie jar: Set-Cookie responses are stored (RFC 6265 domain/path/secure/expiry matching) and sent automatically. Manual control is available from JS: session.cookieSet(url, name, value), session.cookieGet(url, name), session.cookiesClear().