fix(fluentd): Fix missing container startup logs

felixbuenemann commented 7 years ago

This changes the tail mode for container logs to include the beginning of the file instead of simply tailing it.

This is required, because there is a delay of some seconds between container startup and fluentd picking up the log file and starting to tail it.

The source is already using a pos_file /var/log/containers.log.pos that is persisted on the host filesystem, so even if fluentd crashes or is restarted during upgrades logs are not duplicated.

I have tested this on my clusted using quay.io/felixbuenemann/fluentd:git-7fb4691 and it fixes issues were log messages generated at container startup are missing.

Fixes #76.

deis-admin commented 7 years ago

Thanks for the contribution! Please ensure your commits follow our style guide. This code will be tested once a Deis maintainer reviews it.

deis-bot commented 7 years ago

@jchauncey is a potential reviewer of this pull request based on my analysis of git blame information. Thanks @felixbuenemann!

felixbuenemann commented 7 years ago

I have done the following steps to test this change:

Update daemon set with new image and kill all existing fluentd pods to switch to the new version
Scale an app where startup messages where previously missing to 0 and back to 1
Check startup messages appears in the logs
KIll the fluentd pod on the host of the above mentioned app
Verify no log messages are duplicated after fluentd has started and picked up the existing log

mboersma commented 7 years ago

Jenkins, add to whitelist.

deis / fluentd

fix(fluentd): Fix missing container startup logs #77