update-image.sh

#!/bin/bash

# Adapted from...
# https://stackoverflow.com/questions/26423515/how-to-automatically-update-your-docker-containers-if-base-images-are-updated

DATAPATH='./data/docker/updater/data'

UNAME="<DOCKER_HUB_USERNAME>"
UPASS="<DOCKER_HUB_PASSWORD>"

# aquire token
TOKEN=$(curl -s -H "Content-Type: application/json" -X POST -d '{"username": "'${UNAME}'", "password": "'${UPASS}'"}' https://hub.docker.com/v2/users/login/ | jq -r .token)

if [ ! -d "${DATAPATH}" ]; then
        mkdir -p "${DATAPATH}";
fi

IMAGE="tmaslen/tweetgest"
ORIGIMAGE=${IMAGE}
if [[ "$IMAGE" != *\/* ]]; then
        IMAGE=library/${IMAGE}
fi
IMAGE=${IMAGE%%:*}
echo "Checking ${IMAGE}"
PARSED=${IMAGE//\//.}
if [ ! -f "${DATAPATH}/${PARSED}" ]; then
        # File doesn't exist yet, make baseline
        echo "Setting baseline for ${IMAGE}"
        curl -s -H "Authorization: JWT ${TOKEN}" "https://registry.hub.docker.com/v2/repositories/${IMAGE}/tags/" > "${DATAPATH}/${PARSED}"
else
        # File does exist, do a compare
        NEW=$(curl -s -H "Authorization: JWT ${TOKEN}" "https://registry.hub.docker.com/v2/repositories/${IMAGE}/tags/")
        OLD=$(cat "${DATAPATH}/${PARSED}")
        if [[ "${OLD}" == "${NEW}" ]]; then
                echo "Image ${IMAGE} is up to date";
        else
                echo ${NEW} > "${DATAPATH}/${PARSED}"
                echo "Image ${IMAGE} needs to be updated";
                docker pull ${IMAGE}:latest
                #H=`hostname`
                #echo " \"MAIL FROM: root@${H}\"; echo \"RCPT TO: <USER>@<EMAILHOST>.com\"; echo \"DATA\"; echo \"Subject: ${H} - ${IMAGE} needs update\"; echo \"\"; echo -e \"\n${IMAGE} needs update.\n\ndocker pull ${ORIGIMAGE}\" "
                # ssh -i /data/keys/<KEYFILE> <USER>@<REMOTEHOST>.com "{ echo \"MAIL FROM: root@${H}\"; echo \"RCPT TO: <USER>@<EMAILHOST>.com\"; echo \"DATA\"; echo \"Subject: ${H} - ${IMAGE} needs update\"; echo \"\"; echo -e \"\n${IMAGE} needs update.\n\ndocker pull ${ORIGIMAGE}\"; echo \"\"; echo \".\"; echo \"quit\"; sleep 1; } | telnet <SMTPHOST> 25"
        fi

fi