How to save content of a configmap to a file with kubectl and jsonpath?

There’s an open issue at the Kubernetes GitHub repo with a list of things that needs to be fixed in regards to kubectl (and JSONpath), one of them are issue 16707 jsonpath template output should be json.

Edit:

How about this:

kubectl get cm my-configmap -o jsonpath='{.data.my\.file\.json}'

I just realized i had answered another question related (kind of) to this one. The above command should output what you had in mind!

If you have the ability to use jq, then you can use the following approach to e.g. "list" all config maps by selector, and extract the files:

readarray -d $'\0' -t a < <(kubectl get cm -l grafana=dashboards -o json | jq -cj '.items[] | . as $cm | .data | to_entries[] | [ ($cm.metadata.name + "-" + .key), .value ][]+"\u0000"') ; count=0; while [ $count -lt ${#a[@]} ]; do echo "${a[$((count + 1))]}" > ${a[$count]}; count=$(( $count + 2)); done

This uses kubectl (using -l for a label selector) to get all configmaps. Next it pipes them through jq, creating key value pairs with a null byte termination (the key also contains the name of the configmap, this way I ensured that duplicate file names are not an issue). Then it reads this into a bash array, iterating over the array in steps of 2. Creating files with the content.

This also works file config map values that contain newlines.