upgrade_containers.sh

#!/bin/bash

API="https://registry.hub.docker.com/v2/repositories"
HASH_DIR="/home/david/k8s/scripts/hash"
# image tag namespace { space deliminated list of labels }
IMAGES="wordpress latest friends app=george
beamdog/nwserver latest games app=nwn
itzg/minecraft-server latest games app=minecraft instance=mc-persistent"
do_sleep=false

while read image tag namespace labels; do
  newhash=$(wget -qO- $API/$image/tags/$tag | jq -r '.images[]|select(.architecture == "amd64")|.digest')
  oldhash=$(cat $HASH_DIR/$image/$tag.dat 2>&1)
  if [[ $newhash != $oldhash ]]; then
    $do_sleep && {
      echo "Waiting 5 minutes between restarting different pods..."
      sleep 300
    }
    selector=
    for label in $labels; do
      selector="$selector --selector=$label"
    done
    pod=$(kubectl -n $namespace get pods $selector -o json | jq -r '.items | .[].metadata.name' | head -n1)
    echo Restarting $namespace/$pod
    kubectl -n $namespace delete pod $pod
    mkdir -p $HASH_DIR/$image
    echo $newhash > $HASH_DIR/$image/$tag.dat
    do_sleep=true
  fi
done <<< "$IMAGES"