I have two GKE clusters: c1, c2,
I use gcloud config set container/cluster c1 to set the default cluster to c1, after that I run kubectl run, seems the new pods still created in c2.
how can i switch to c2? and what is the purpose of gcloud config set container/cluster cluster_name?
The gcloud container cluster commands are for administrating your clusters from a GCP perspective, e.g. adding another node-pool for a GKE kubernetes cluster using the node-pools create command.
Controlling which cluster is used for kubectl is done via .kube/config file which has a so called current-context. There is the kubectx/kubens project that provides some nice helpers to allow switching between clusters (and namespaces) more easily.