Fluentd is necessary software for operating Kubernetes clusters. Variables in the Fluentd’s configs are useful because they reduce redundant writing and also it will come in handy to switch environments between development and production. For example, I configure the fluentd which is running on our Kubernetes cluster …

One day, I realized that the fluentd on our Kubernetes cluster was logging a lot of "invalid date" errors like this. 1#0 dump an error event: error_class=ArgumentError error="invalid date" …

When I was setting up HAProxy running on our Kubernetes cluster, I defined the log format as JSON and I got a lot of BADREQ logs with status code 400 as follows. 1{ 2 "conn": { 3 "act": 7, 4 "fe": 7, 5 "be": 0, 6 "srv": 0 7 }, 8 "queue": { 9 "backend": 0, 10 …