k6 step-load rig: staircase scenarios, per-step/per-endpoint tagging, live Prometheus remote-write, Grafana dashboard

This commit is contained in:
Adam Carr
2026-09-20 11:12:03 -07:00
parent 2bc85826f1
commit 97d5cda6f9
5 changed files with 248 additions and 0 deletions

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@@ -0,0 +1,94 @@
apiVersion: v1
kind: ConfigMap
metadata:
name: k6-step-script
namespace: loadtest
data:
step.js: |
// Step-load (staircase) test. Hits a collection of endpoints, stepping
// the request rate up over time, tagging every request with its step and
// endpoint so latency can be sliced either way in Grafana.
//
// Env:
// BASE_URL - target base URL
// ENDPOINTS_JSON - [{"name":"list","method":"GET","path":"/x","weight":2}, ...]
// START_RPS - rate of step 1
// STEP_RPS - rate added each step
// STEP_DURATION - hold time per step, e.g. "2m"
// STEPS - number of steps
import http from 'k6/http';
import { check } from 'k6';
import exec from 'k6/execution';
const BASE = __ENV.BASE_URL;
let endpoints;
try {
endpoints = JSON.parse(__ENV.ENDPOINTS_JSON);
} catch (e) {
throw new Error('ENDPOINTS_JSON is not valid JSON: ' + e.message);
}
// expand weights
const pool = [];
for (const ep of endpoints) {
for (let i = 0; i < (ep.weight || 1); i++) pool.push(ep);
}
const startRps = parseInt(__ENV.START_RPS || '50');
const stepRps = parseInt(__ENV.STEP_RPS || '50');
const stepDurMs = ms(__ENV.STEP_DURATION || '2m');
const steps = parseInt(__ENV.STEPS || '5');
const rampMs = 5000;
// Build stage list and per-step [startMs, endMs, label] windows.
// Each step: 5s quick ramp to the rate, then a hold.
const stages = [];
const windows = [];
let clock = 0;
for (let i = 0; i < steps; i++) {
const rate = startRps + i * stepRps;
stages.push({ duration: ms2str(rampMs), target: rate });
clock += rampMs;
const wStart = clock;
stages.push({ duration: ms2str(stepDurMs), target: rate });
clock += stepDurMs;
windows.push([wStart, clock, `step${i + 1} @ ${rate} rps`]);
}
const totalMs = clock;
const maxRate = startRps + (steps - 1) * stepRps;
const vus = Math.max(10, Math.ceil(maxRate * 2));
function ms(s) {
const m = /^(\d+)(ms|s|m)$/.exec(String(s));
if (!m) throw new Error('bad duration: ' + s);
return +m[1] * ({ ms: 1, s: 1000, m: 60000 })[m[2]];
}
function ms2str(n) { return n + 'ms'; }
export const options = {
discardResponseBodies: true,
scenarios: {
staircase: {
executor: 'ramping-arrival-rate',
startRate: 0,
preAllocatedVUs: vus,
maxVUs: vus,
stages: stages,
},
},
thresholds: { http_req_failed: ['rate<0.05'] },
};
export default function () {
const elapsed = exec.scenario.progress * totalMs;
let step = 'ramp-up';
for (const [s, e, label] of windows) {
if (elapsed >= s && elapsed < e) { step = label; break; }
}
const ep = pool[exec.scenario.iterationInTest % pool.length];
const url = BASE + ep.path;
const params = { tags: { name: ep.name, step: step }, timeout: '15s' };
const res = (ep.method || 'GET') === 'POST'
? http.post(url, ep.body || '', params)
: http.get(url, params);
check(res, { ok: (r) => r.status < 300 });
}

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@@ -0,0 +1,86 @@
apiVersion: v1
kind: ConfigMap
metadata:
name: grafana-dashboard-provider
namespace: monitoring
data:
dashboards.yaml: |
apiVersion: 1
providers:
- name: default
orgId: 1
folder: ""
type: file
disableDeletion: false
updateIntervalSeconds: 30
options:
path: /var/lib/grafana/dashboards
---
apiVersion: v1
kind: ConfigMap
metadata:
name: grafana-dashboards
namespace: monitoring
data:
k6-step-load.json: |
{
"title": "k6 Step Load",
"uid": "k6step",
"timezone": "browser",
"refresh": "5s",
"time": { "from": "now-30m", "to": "now" },
"panels": [
{
"id": 1, "type": "timeseries", "title": "Request rate (the staircase)",
"gridPos": {"x": 0, "y": 0, "w": 24, "h": 8},
"targets": [
{"expr": "sum(rate(k6_http_reqs_total[30s]))", "legendFormat": "total rps"},
{"expr": "sum by (name) (rate(k6_http_reqs_total[30s]))", "legendFormat": "{{name}}"}
],
"fieldConfig": {"defaults": {"unit": "reqps"}, "overrides": []}
},
{
"id": 2, "type": "timeseries", "title": "Latency avg / p50 / p95 / p99",
"gridPos": {"x": 0, "y": 8, "w": 12, "h": 8},
"targets": [
{"expr": "k6_http_req_duration_avg", "legendFormat": "avg"},
{"expr": "k6_http_req_duration_p50", "legendFormat": "p50"},
{"expr": "k6_http_req_duration_p95", "legendFormat": "p95"},
{"expr": "k6_http_req_duration_p99", "legendFormat": "p99"}
],
"fieldConfig": {"defaults": {"unit": "ms"}, "overrides": []}
},
{
"id": 3, "type": "timeseries", "title": "p95 latency per step",
"gridPos": {"x": 12, "y": 8, "w": 12, "h": 8},
"targets": [
{"expr": "k6_http_req_duration_p95", "legendFormat": "{{step}}"}
],
"fieldConfig": {"defaults": {"unit": "ms"}, "overrides": []}
},
{
"id": 4, "type": "timeseries", "title": "p95 latency per endpoint",
"gridPos": {"x": 0, "y": 16, "w": 12, "h": 8},
"targets": [
{"expr": "k6_http_req_duration_p95", "legendFormat": "{{name}}"}
],
"fieldConfig": {"defaults": {"unit": "ms"}, "overrides": []}
},
{
"id": 5, "type": "timeseries", "title": "Error rate",
"gridPos": {"x": 12, "y": 16, "w": 12, "h": 8},
"targets": [
{"expr": "sum(rate(k6_http_req_failed_total[30s])) / sum(rate(k6_http_reqs_total[30s]))", "legendFormat": "error fraction"}
],
"fieldConfig": {"defaults": {"unit": "percentunit", "min": 0, "max": 1}, "overrides": []}
},
{
"id": 6, "type": "timeseries", "title": "Active VUs",
"gridPos": {"x": 0, "y": 24, "w": 24, "h": 6},
"targets": [{"expr": "k6_vus", "legendFormat": "vus"}],
"fieldConfig": {"defaults": {"unit": "short"}, "overrides": []}
}
],
"schemaVersion": 39,
"version": 1
}

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@@ -49,9 +49,15 @@ spec:
limits: {memory: 512Mi}
volumeMounts:
- {name: datasources, mountPath: /etc/grafana/provisioning/datasources}
- {name: dashboard-provider, mountPath: /etc/grafana/provisioning/dashboards}
- {name: dashboards, mountPath: /var/lib/grafana/dashboards}
volumes:
- name: datasources
configMap: {name: grafana-datasources}
- name: dashboard-provider
configMap: {name: grafana-dashboard-provider}
- name: dashboards
configMap: {name: grafana-dashboards}
---
apiVersion: v1
kind: Service

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@@ -84,6 +84,7 @@ spec:
- --config.file=/etc/prometheus/prometheus.yml
- --storage.tsdb.retention.time=15d
- --storage.tsdb.path=/data
- --web.enable-remote-write-receiver
ports:
- containerPort: 9090
resources:

61
scripts/stepload.sh Executable file
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#!/bin/bash
# Run a step-load (staircase) test across a collection of endpoints.
# Usage:
# ./scripts/stepload.sh <base-url> <endpoints-json> [start-rps] [step-rps] [step-duration] [steps]
# Example:
# ./scripts/stepload.sh https://api.example.com \
# '[{"name":"login","method":"POST","path":"/login"},{"name":"list","path":"/items","weight":3}]' \
# 25 25 2m 6
# -> starts at 25 rps, +25 rps every 2 minutes, 6 steps (ending at 150 rps)
set -euo pipefail
BASE=${1:?usage: stepload.sh <base-url> <endpoints-json> [start-rps] [step-rps] [step-duration] [steps]}
EPS=${2:?endpoints-json required - see script header for format}
START=${3:-50}
STEP=${4:-50}
DUR=${5:-2m}
STEPS=${6:-5}
NAME="stepload-$(date +%s)"
PROM_RW="http://prometheus.monitoring.svc:9090/api/v1/write"
kubectl -n loadtest apply -f - <<EOF
apiVersion: batch/v1
kind: Job
metadata:
name: $NAME
spec:
parallelism: 1
ttlSecondsAfterFinished: 1800
template:
spec:
restartPolicy: Never
containers:
- name: k6
image: grafana/k6:1.4.0
command: ["k6", "run", "/scripts/step.js", "-o", "experimental-prometheus-rw"]
env:
- {name: BASE_URL, value: "$BASE"}
- {name: ENDPOINTS_JSON, value: '$EPS'}
- {name: START_RPS, value: "$START"}
- {name: STEP_RPS, value: "$STEP"}
- {name: STEP_DURATION, value: "$DUR"}
- {name: STEPS, value: "$STEPS"}
- {name: K6_PROMETHEUS_RW_SERVER_URL, value: "$PROM_RW"}
- {name: K6_PROMETHEUS_RW_TREND_STATS, value: "avg,p(50),p(95),p(99),min,max"}
resources:
requests: {cpu: 200m, memory: 256Mi}
limits: {memory: 512Mi}
volumeMounts:
- {name: scripts, mountPath: /scripts}
volumes:
- name: scripts
configMap: {name: k6-step-script}
EOF
MAX=$(( START + (STEPS - 1) * STEP ))
echo "Staircase '$NAME': $STEPS steps, $START -> $MAX rps (+$STEP each), $DUR holds"
echo "Total duration: $STEPS x $DUR (plus 5s ramps per step)"
echo ""
echo "Watch live: Grafana -> the 'k6 Step Load' dashboard (or kubectl -n loadtest logs -f job/$NAME)"
echo "Logs: kubectl -n loadtest logs -f job/$NAME"
echo "Stop early: kubectl -n loadtest delete job $NAME"