Update k8s ConfigMap or Secret without deleting the existing one

Question

You can get YAML from the kubectl create configmap command and pipe it to kubectl replace, like this:

kubectl create configmap foo --from-file foo.properties -o yaml --dry-run | kubectl replace -f -

For future reference, kubectl replace is now a very handy way to achieve this

kubectl replace -f some_spec.yaml Let you update a complete configMap (or other objects)

See doc and examples directly here

Copy/pasted from the help:

# Replace a pod using the data in pod.json.
kubectl replace -f ./pod.json

# Replace a pod based on the JSON passed into stdin.
cat pod.json | kubectl replace -f -

# Update a single-container pod's image version (tag) to v4
kubectl get pod mypod -o yaml | sed 's/\(image: myimage\):.*$/\1:v4/' | kubectl replace -f -

# Force replace, delete and then re-create the resource
kubectl replace --force -f ./pod.json

For small changes in configMap, use edit

kubectl edit configmap <cfg-name>

This will open configMap in vi editor. Make the changes and save it.

kubectl replace fails if a configmap does not already exist:

$ kubectl create configmap foo --from-file foo.properties -o yaml --dry-run=client | kubectl replace -f -

Error from server (NotFound): error when replacing "STDIN": configmaps "falco-config" not found

Best solution is to use kubectl apply which would create configmap if not present else update configmap if it is present:

$ kubectl create configmap foo --from-file foo.properties -o yaml --dry-run=client | kubectl apply -f -

configmap/falco-config configured

Take a copy of the existing configmap:

kubectl get configmap foo -o yaml > foo.yaml

And then do the modifications and use apply command, this should work.

kubectl apply -f foo.yaml

Note: Incase if you see any of the following issue, then include latest "resourceVersion" from the existing config map and try again.

" Operation cannot be fulfilled on configmaps "foo": the object has been modified; please apply your changes to the latest version and try again"