how do I pipe in file content as args to kubectl? - bash

Question

I wish to run k6 in a container with some simple javascript load from local file system,
It seems the below had some syntax error
$ cat simple.js
import http from 'k6/http';
import { sleep } from 'k6';
export const options = {
vus: 10,
duration: '30s',
};
export default function () {
http.get('http://100.96.1.79:8080');
sleep(1);
}
$kubectl run k6 --image=grafana/k6 -- run - <simple.js
//OR
$kubectl run k6 --image=grafana/k6 run - <simple.js
in the k6 pod log, I got
│ time="2023-02-16T12:12:05Z" level=error msg="could not initialize '-': could not load JS test 'file:///-': no exported functions in s │
I guess this means the simple.js is not really passed to k6 this way?
thank you!

Answer 1

I think you can't pipe (host) files into Kubernetes containers this way.
One way that it should work is to:
Create a ConfigMap to represent your file
Apply a Pod config that mounts the ConfigMap file
NAMESPACE="..." # Or default
kubectl create configmap simple \
--from-file=${PWD}/simple.js \
--namespace=${NAMESPACE}
kubectl get configmap/simple \
--output=yaml \
--namespace=${NAMESPACE}
Yields:
apiVersion: v1
kind: ConfigMap
metadata:
name: simple
data:
simple.js: |
import http from 'k6/http';
import { sleep } from 'k6';
export default function () {
http.get('http://test.k6.io');
sleep(1);
}
NOTE You could just create e.g. configmap.yaml with the above YAML content and apply it.
Then with pod.yaml:
apiVersion: v1
kind: Pod
metadata:
name: simple
spec:
containers:
- name: simple
image: docker.io/grafana/k6
args:
- run
- /m/simple.js
volumeMounts:
- name: simple
mountPath: /m
volumes:
- name: simple
configMap:
name: simple
Apply it:
kubectl apply \
--filename=${PWD}/pod.yaml \
--namespace=${NAMESPACE}
Then, finally:
kubectl logs pod/simple \
--namespace=${NAMESPACE}
Yields:
/\ |‾‾| /‾‾/ /‾‾/
/\ / \ | |/ / / /
/ \/ \ | ( / ‾‾\
/ \ | |\ \ | (‾) |
/ __________ \ |__| \__\ \_____/ .io
execution: local
script: /m/simple.js
output: -
scenarios: (100.00%) 1 scenario, 1 max VUs, 10m30s max duration (incl. graceful stop):
* default: 1 iterations for each of 1 VUs (maxDuration: 10m0s, gracefulStop: 30s)
running (00m01.0s), 1/1 VUs, 0 complete and 0 interrupted iterations
default [ 0% ] 1 VUs 00m01.0s/10m0s 0/1 iters, 1 per VU
running (00m01.4s), 0/1 VUs, 1 complete and 0 interrupted iterations
default ✓ [ 100% ] 1 VUs 00m01.4s/10m0s 1/1 iters, 1 per VU
data_received..................: 17 kB 12 kB/s
data_sent......................: 542 B 378 B/s
http_req_blocked...............: avg=128.38ms min=81.34ms med=128.38ms max=175.42ms p(90)=166.01ms p(95)=170.72ms
http_req_connecting............: avg=83.12ms min=79.98ms med=83.12ms max=86.27ms p(90)=85.64ms p(95)=85.95ms
http_req_duration..............: avg=88.61ms min=81.28ms med=88.61ms max=95.94ms p(90)=94.47ms p(95)=95.2ms
{ expected_response:true }...: avg=88.61ms min=81.28ms med=88.61ms max=95.94ms p(90)=94.47ms p(95)=95.2ms
http_req_failed................: 0.00% ✓ 0 ✗ 2
http_req_receiving.............: avg=102.59µs min=67.99µs med=102.59µs max=137.19µs p(90)=130.27µs p(95)=133.73µs
http_req_sending...............: avg=67.76µs min=40.46µs med=67.76µs max=95.05µs p(90)=89.6µs p(95)=92.32µs
http_req_tls_handshaking.......: avg=44.54ms min=0s med=44.54ms max=89.08ms p(90)=80.17ms p(95)=84.62ms
http_req_waiting...............: avg=88.44ms min=81.05ms med=88.44ms max=95.83ms p(90)=94.35ms p(95)=95.09ms
http_reqs......................: 2 1.394078/s
iteration_duration.............: avg=1.43s min=1.43s med=1.43s max=1.43s p(90)=1.43s p(95)=1.43s
iterations.....................: 1 0.697039/s
vus............................: 1 min=1 max=1
vus_max........................: 1 min=1 max=1
Tidy:
kubectl delete \
--filename=${PWD}/pod.yaml \
--namespace=${NAMESPACE}
kubectl delete configmap/simple \
--namespace=${NAMESPACE}
kubectl delete namespace/${NAMESPACE}