Watch Envoy's config files and use the required mv command to trigger a reload

inotify_watcher.sh

#!/bin/bash

# Install the inotify tools in Dockerfile:
# RUN apt-get update && apt-get install -y inotify-tools

# Then establish the watch in the Docker entrypoint.sh:
# ./inotify_watcher.sh &

inotifywait --monitor "/etc/envoy/k8s/" --event create --event modify --event moved_to |
    while read path action file; do
        # echo "File '$file', path '$path' -> '$action'"
        if [[ "$file" = "..data" ]]; then
            cp /etc/envoy/k8s/clusters.yaml /tmp/clusters.yaml || true
            cp /etc/envoy/k8s/listeners.yaml /tmp/listeners.yaml || true

            mv /tmp/clusters.yaml /etc/envoy/clusters.yaml || true
            mv /tmp/listeners.yaml /etc/envoy/listeners.yaml || true
        fi
    done

# Warning:
# This does not work reliably, if listeners refer to clusters that don't exist yet the change is refused
# This script does not ensure that the clusters are loaded before the listeners