Kubectl update configMap

Now you can. Just throw: kubectl edit configmap <name of the configmap> on your command line. Then you can edit your configuration.

kubectl edit configmap -n <namespace> <configMapName> -o yaml

This opens up a vim editor with the configmap in yaml format. Now simply edit it and save it.

Another option is actually you can use this command:

kubectl create configmap some-config \
  --from-file=some-key=some-config.yaml \
  -n some-namespace \
  -o yaml \
  --dry-run | kubectl apply -f -

Refer to Github issue: Support updating config map and secret with --from-file

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