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Attaching Sidecar

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

Show the Usage of Sidecar#

kubectl vela show sidecar
# Properties
+---------+-----------------------------------------+-----------------------+----------+---------+
| NAME | DESCRIPTION | TYPE | REQUIRED | DEFAULT |
+---------+-----------------------------------------+-----------------------+----------+---------+
| name | Specify the name of sidecar container | string | true | |
| cmd | Specify the commands run in the sidecar | []string | false | |
| image | Specify the image of sidecar container | string | true | |
| volumes | Specify the shared volume path | [[]volumes](#volumes) | false | |
+---------+-----------------------------------------+-----------------------+----------+---------+
## volumes
+-----------+-------------+--------+----------+---------+
| NAME | DESCRIPTION | TYPE | REQUIRED | DEFAULT |
+-----------+-------------+--------+----------+---------+
| name | | string | true | |
| path | | string | true | |
+-----------+-------------+--------+----------+---------+

Deploy the Application#

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.

kubectl apply -f app.yaml

On runtime cluster, check the name of running pod.

kubectl get pod
NAME READY STATUS RESTARTS AGE
log-gen-worker-76945f458b-k7n9k 2/2 Running 0 90s

And check the logging output of sidecar.

kubectl logs -f log-gen-worker-76945f458b-k7n9k 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
Last updated on by kubevela-bot