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

Question

We are using one namespace for the develop environment and one for the staging environment. Inside each one of this namespaces we have several configMaps and secrets but there are a lot of share variables between the two environments so we will like to have a common file for those.

Is there a way to have a base configMap into the default namespace and refer to it using something like:

- envFrom:     - configMapRef:         name: default.base-config-map 

If this is not possible, is there no other way other than duplicate the variables through namespaces?

Answer 1

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.