Logging integration doesn't work if Docker Root is not default /var/lib/docker

Issue

As of the time of this writing, Rancher Logging is broken when the Docker root is configured to something other than /var/lib/docker.

This issue is tracked in GitHub issue #21112.

Pre-requisites

• Rancher 2.x managed/imported cluster with logging enabled.
• Docker root configured to something other than /var/lib/docker on the nodes (confirmed with docker info | grep Root).

Workaround

These steps will assume you have the Docker data root set to /other-docker-root. Change /other-docker-root to whatever your custom path is:

1. Rancher UI -> Cluster -> System Project -> Workloads -> cattle-logging Namespace

2. Find workload rancher-logging-fluentd-linux

3. Edit YAML

4. Edit volume dockerroot

5. Change "Path on the Node" from /var/lib/docker to /other-docker-root

6. Add volume (with the following details):

Volume Name: dockerrootcustom
Type: bind-mount
Path on the Node: /other-docker-root
Mount Point: /other-docker-root

1. Click Save

At this point logging should be working with your non-default Docker root directory. You should be able to verify this on your logging target. Keep in mind it may take a few minutes for logs to show up there as fluentd is configured to clear its buffer every 60 seconds by default.