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    Merge pull request #40634 from Crassirostris/use-docker-log-rotation · b18bad15
    Kubernetes Submit Queue authored
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    Use docker log rotation mechanism instead of logrotate
    
    This is a solution for https://github.com/kubernetes/kubernetes/issues/38495.
    
    Instead of rotating logs using logrotate tool, which is configured quite rigidly, this PR makes docker responsible for the rotation and makes it possible to configure docker logging parameters. It solves the following problems:
    
    * Logging agent will stop loosing lines upon rotation
    * Container's logs size will be more strictly constrained. Instead of checking the size hourly, size will be checked upon write, preventing https://github.com/kubernetes/kubernetes/issues/27754
    
    It's still far from ideal, for example setting logging options per pod, as suggested in https://github.com/kubernetes/kubernetes/issues/15478 would be much more flexible, but latter approach requires deep changes, including changes in API, which may be in vain because of CRI and long-term vision for logging.
    
    Changes include:
    
    * Change in salt. It's possible to configure docker log parameters, using variables in pillar. They're exported from env variables on `gce`, but for different cloud provider they have to be exported first.
    * Change in `configure-helper.sh` scripts for those os on `gce` that don't use salt + default values exposed via env variables
    
    This change may be problematic for kubelet logs functionality with CRI enabled, that will be tackled in the follow-up PR, if confirmed.
    
    CC @piosz @Random-Liu @yujuhong @dashpole @dchen1107 @vishh @kubernetes/sig-node-pr-reviews
    
    ```release-note
    On GCI by default logrotate is disabled for application containers in favor of rotation mechanism provided by docker logging driver.
    ```
    b18bad15
common.sh 39.7 KB