Version: v1.2

Attaching Sidecar

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

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.

  1. # app.yaml
  3. apiVersion: core.oam.dev/v1beta1
  5. kind: Application
  7. metadata:
  9.   name: vela-app-with-sidecar
  11. spec:
  13.   components:
  15.     - name: log-gen-worker
  17.       type: worker
  19.       properties:
  21.         image: busybox
  23.         cmd:
  25.           - /bin/sh
  27.           - -c
  29.           - >
  31.             i=0;
  33.             while true;
  35.             do
  37.               echo "$i: $(date)" >> /var/log/date.log;
  39.               i=$((i+1));
  41.               sleep 1;
  43.             done
  45.         volumes:
  47.           - name: varlog
  49.             mountPath: /var/log
  51.             type: emptyDir
  53.       traits:
  55.         - type: sidecar
  57.           properties:
  59.             name: count-log
  61.             image: busybox
  63.             cmd: [ /bin/sh, -c, 'tail -n+1 -f /var/log/date.log']
  65.             volumes:
  67.               - name: varlog
  69.                 path: /var/log

Deploy this Application.

  1. vela up -f app.yaml

Use vela ls to check the application state:

  1. $ vela ls
  3. APP                     COMPONENT       TYPE        TRAITS  PHASE   HEALTHY STATUS  CREATED-TIME                 
  5. 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.

  1. vela logs vela-app-with-sidecar -c count-log
  1. 0: Fri Apr 16 11:08:45 UTC 2021
  3. 1: Fri Apr 16 11:08:46 UTC 2021
  5. 2: Fri Apr 16 11:08:47 UTC 2021
  7. 3: Fri Apr 16 11:08:48 UTC 2021
  9. 4: Fri Apr 16 11:08:49 UTC 2021
  11. 5: Fri Apr 16 11:08:50 UTC 2021
  13. 6: Fri Apr 16 11:08:51 UTC 2021
  15. 7: Fri Apr 16 11:08:52 UTC 2021
  17. 8: Fri Apr 16 11:08:53 UTC 2021
  19. 9: Fri Apr 16 11:08:54 UTC 2021

Specification

  1. vela show sidecar
  1. # Properties
  3. +---------+-----------------------------------------+-----------------------+----------+---------+
  5. |  NAME   |               DESCRIPTION               |         TYPE          | REQUIRED | DEFAULT |
  7. +---------+-----------------------------------------+-----------------------+----------+---------+
  9. | name    | Specify the name of sidecar container   | string                | true     |         |
  11. | cmd     | Specify the commands run in the sidecar | []string              | false    |         |
  13. | image   | Specify the image of sidecar container  | string                | true     |         |
  15. | volumes | Specify the shared volume path          | [[]volumes](#volumes) | false    |         |
  17. +---------+-----------------------------------------+-----------------------+----------+---------+
  25. ## volumes
  27. +-----------+-------------+--------+----------+---------+
  29. |   NAME    | DESCRIPTION |  TYPE  | REQUIRED | DEFAULT |
  31. +-----------+-------------+--------+----------+---------+
  33. | name      |             | string | true     |         |
  35. | path      |             | string | true     |         |
  37. +-----------+-------------+--------+----------+---------+