Attaching Sidecar

The sidecar trait allows you to attach a sidecar container to the component.

Note: sidecar trait is hidden by default in VelaUX, you can use it in CLI.

How to use

In this Application, component log-gen-worker and sidecar share the data volume that saves the logs. The sidebar will re-output the log to stdout.

# app.yaml

apiVersion: core.oam.dev/v1beta1

kind: Application

metadata:

name: vela-app-with-sidecar

spec:

components:

- name: log-gen-worker

type: worker

properties:

image: busybox

cmd:

- /bin/sh

- -c

- >

i=0;

while true;

do

echo "$i: $(date)" >> /var/log/date.log;

i=$((i+1));

sleep 1;

done

volumes:

- name: varlog

mountPath: /var/log

type: emptyDir

traits:

- type: sidecar

properties:

name: count-log

image: busybox

cmd: [ /bin/sh, -c, 'tail -n+1 -f /var/log/date.log']

volumes:

- name: varlog

path: /var/log

Deploy this Application.

vela up -f app.yaml

Use vela ls to check the application state:

$ vela ls

APP COMPONENT TYPE TRAITS PHASE HEALTHY STATUS CREATED-TIME

vela-app-with-sidecar log-gen-worker worker sidecar running healthy 2021-08-29 22:07:07 +0800 CST

And check the logging output of sidecar.

vela logs vela-app-with-sidecar -c count-log

0: Fri Apr 16 11:08:45 UTC 2021

1: Fri Apr 16 11:08:46 UTC 2021

2: Fri Apr 16 11:08:47 UTC 2021

3: Fri Apr 16 11:08:48 UTC 2021

4: Fri Apr 16 11:08:49 UTC 2021

5: Fri Apr 16 11:08:50 UTC 2021

6: Fri Apr 16 11:08:51 UTC 2021

7: Fri Apr 16 11:08:52 UTC 2021

8: Fri Apr 16 11:08:53 UTC 2021

9: Fri Apr 16 11:08:54 UTC 2021