Logs and Data Protection checks

On Wire.com, we keep logs for a maximum of 72 hours as described in the privacy whitepaper

We recommend you do the same and limit the amount of logs kept on your servers.

How can I see how far in the past access logs are still available on my servers?

Look at the timestamps of your earliest nginz logs:

export NAMESPACE=default # this may be 'default' or 'wire'
kubectl -n "$NAMESPACE" get pods | grep nginz
# choose one of the resulting names, it might be named e.g. nginz-6d75755c5c-h9fwn
kubectl -n "$NAMESPACE" logs <name-from-previous-command> -c nginz | head -10

If the timestamp is more than 3 days in the past, your logs are kept for unnecessary long amount of time and you should configure log rotation.

I used your ansible scripts and prefer to have the default 72 hour maximum log availability configured automatically.

You can use the kubernetes_logging.yml ansible playbook

I am not using ansible and like to SSH into hosts and configure things manually

SSH into one of your kubernetes worker machines.

If you installed as per the instructions on docs.wire.com, then the default logging strategy is json-file with --log-opt max-size=50m --log-opt max-file=5 storing logs in files under /var/lib/docker/containers/<container-id>/<container-id>.log. You can check this with these commands:

docker info --format '{{.LoggingDriver}}'
ps aux | grep log-opt

(Options configured in /etc/systemd/system/docker.service.d/docker-options.conf)

The default will thus keep your logs around until reaching 250 MB per pod, which is far longer than three days. Since docker logs don’t allow a time-based log rotation, we can instead make use of logrotate to rotate logs for us.

Create the file /etc/logrotate.d/podlogs with the following contents:

  rotate 2
  maxage 1

Repeat the same for all the other kubernetes worker machines, the file needs to exist on all of them.

There should already be a cron job for logrotate for other parts of the system, so this should be sufficent, you can stop here.

You can check for the cron job with:

ls /etc/cron.daily/logrotate

And you can manually run a log rotation using:

/usr/sbin/logrotate -v /etc/logrotate.conf

If you want to clear out old logs entirely now, you can force log rotation three times (again, on all kubernetes machines):

/usr/sbin/logrotate -v -f /etc/logrotate.conf
/usr/sbin/logrotate -v -f /etc/logrotate.conf
/usr/sbin/logrotate -v -f /etc/logrotate.conf