Is there a way to share a configMap in kubernetes between namespaces?

Kubernetes 1.13 and earlier

They cannot be shared, because they cannot be accessed from a pods outside of its namespace. Names of resources need to be unique within a namespace, but not across namespaces.

Workaround it is to copy it over.

Copy secrets between namespaces

kubectl get secret <secret-name> --namespace=<source-namespace> --export -o yaml \
  | kubectl apply --namespace=<destination-namespace> -f -

Copy configmaps between namespaces

kubectl get configmap <configmap-name>  --namespace=<source-namespace> --export -o yaml \
  | kubectl apply --namespace=<destination-namespace> -f -

Kubernetes 1.14+

The --export flag was deprecated in 1.14 Instead following command can be used:

kubectl get secret <secret-name> --namespace=<source-namespace>  -o yaml \
  | sed 's/namespace: <from-namespace>/namespace: <to-namespace>/' \
  | kubectl create -f -

If someone still see a need for the flag, there’s an export script written by @zoidbergwill.