You could watch the properties files for modifications and recreate the ConfigMap whenever they change.

To do so, there are different tools for macOS and Linux.

Linux

On Linux, you can watch files for changes with inotifywait. You could do something along the following lines:

Create the file monitor.sh:

#!/bin/bash

FILE=$1
inotifywait -m -e modify "$FILE" |
  while read; do
    kubectl create configmap "$(basename $FILE)" --from-file="$FILE" --dry-run -o yaml | kubectl apply -f -
  done

Then execute it for each properties file:

./monitor.sh /path/app.properties

This will generate an updated ConfigMap YAML manifest with kubectl create and apply it with kubectl apply every time the /path/app.properties file is modified.

You can install inotifywait with:

sudo apt-get install inotify-tools

macOS

On macOS, you can use fswatch to watch for file modifications.

Create the file monitor.sh:

#!/bin/bash

FILE=$1
fswatch "$FILE" |
  while read; do
    kubectl create configmap "$(basename $FILE)" --from-file="$FILE" --dry-run -o yaml | kubectl apply -f -
  done

Then execute it for each properties file:

./monitor.sh /path/app.properties

This will generate an updated ConfigMap YAML manifest with kubectl create and apply it with kubectl apply every time the /path/app.properties file is modified.

You can install fswatch with:

brew install fswatch

Note

fswatch might also be available on Linux (sudo apt-get install fswatch), in which case you can use the monitor.sh script for macOS on Linux too. However, you might need to use fswatch -o (with the -o option) to ensure only a single output line.