SYSTEM Cited by 1 source

k6

k6 is an open-source, Grafana-maintained load- and performance-testing tool. Tests are authored in JavaScript, define one or more scenarios (traffic-shape generators), and encode pass/fail conditions as thresholds on metrics. k6 is used to prove a system meets availability and latency SLOs under representative and adversarial load before it takes production traffic.

Core primitives (as used in the wild)

• Scenarios — named traffic generators. The constant-arrival-rate executor drives a fixed request rate (open model) independent of response latency, using preAllocatedVUs / maxVUs to size the virtual-user pool.
• Thresholds — SLO assertions evaluated over the run. Failing a threshold fails the test. Examples: http_req_failed: ["rate<0.01"] (availability), http_req_duration{status:200}: ["p(95)<500", "p(99)<1000"] (latency percentiles, filtered to 200-status responses).
• summaryTrendStats — which aggregates to report (avg, min, med, max, p90/p95/p99, count).

Seen in

• sources/2026-08-24-cloudflare-the-cloudflare-blog-brought-to-you-by-emdash — Cloudflare used k6 to validate the EmDash-on-Workers blog migration against real traffic patterns (normal ~75 RPS, spikes >5,000 RPS). Three scenarios: Ramp (gradually to 3× prod baseline then cool down), Breakpoint (0→100 RPS over 10 min, stop at breakage), Burst (immediate 7,000 RPS). SLOs encoded as thresholds: <0.01% 5xx, p95 < 500 ms, p99 < 1000 ms. Canonical wiki instance of k6, and of the ramp/breakpoint/burst scenario suite.

Related

• systems/cloudflare-workers — the system under test in the wiki's canonical k6 instance.
• load-test-scenario-suite-ramp-breakpoint-burst — the scenario-design pattern k6 realises.
• concepts/core-web-vitals — complementary browser-side perf measurement (k6 measures server-side latency/availability).
• companies/cloudflare — operator of the canonical instance.