Inspecting a container

Whenever our application behaves abnormally, we will definitely want to know what happened, using all means, such as checking logs, resource usage, processes watchdog, or even getting into the running host directly to dig problems out. In Kubernetes, we have kubectl get and kubectl describe that can query deployment states, which will help us determine if an application has crashed or works as desired.

Further, if we want to know what is going on from the outputs of an application, we also have kubectl logs that redirects a container's stdout to our Terminal. For CPU and memory usage stats, there's also a top-like command we can employ, kubectl top. kubectl top node, which gives an overview of the resource usages of nodes, and kubectl top pod <POD_NAME> which displays per-pod usage:

# kubectl top node
NAME        CPU(cores)   CPU%      MEMORY(bytes)  MEMORY%   
node-1      42m          4%        273Mi           12%       
node-2      152m         15%       1283Mi...