scripts/template-update.sh

#!/bin/sh

### update script for <ab-container> utility scripts
# version x.y.z
# script by Asif Bacchus
# usage of this script is subject to the license terms found at:
# https://git.asifbacchus.app/ab-docker/scripts/LICENSE


### pre-requisites

# check if wget is installed
if ! command -v wget > /dev/null 2>&1; then
    printf "\nSorry, this script requires that 'wget' is installed in order to automatically update files.\nExiting.\n\n"
    exit 1
fi

# is user root or in the docker group?
if [ ! "$( id -u )" -eq 0 ]; then
    if ! id -Gn | grep docker > /dev/null; then
        consoleError '1' "You must either be root or in the 'docker' group to run this script since you must be able to run 'docker exec' commands against the container!"
    fi
fi

# zero counters
updatesAvailable=0
downloadFailed=0
downloadSuccess=0
updateFailed=0
updateSuccess=0

# reference constants
containerName=''
server='https://git.asifbacchus.app/ab-docker/scripts/raw/branch/master/'
checksumFilename='checksums.sha256'

# files to update
localScriptName='update.sh'
repoScriptName="${containerName}-update.sh"
updateFiles=""

printf "\n*** Updating %s container service scripts ***\n\n" "$containerName"


### download latest checksums
printf "Getting latest checksums from ab-git server... "
if ! wget --quiet --tries=3 --timeout=10 -N "${server}${checksumFilename}"; then
    printf "[ERROR]\n"
    printf "Unable to download checksums from ab-git server. Try again later.\n\n"
    exit 1
else
    printf "[OK]\n"
fi


### check for updates to this script
printf "Checking for updates to this script... "
repoScriptChecksum=$( grep "$repoScriptName" "$checksumFilename" | grep -o '^\S*' )
localScriptChecksum=$( sha256sum "$localScriptName" | grep -o '^\S*' )
if [ "$localScriptChecksum" = "$repoScriptChecksum" ]; then
    printf "[NONE]\n"
else
    # download updated script
    if ! wget --quiet --tries=3 --timeout=10 -O $localScriptName "${server}${repoScriptName}"; then
        printf "[ERROR]\n"
        printf "Unable to download script update. Try again later.\n\n"
        exit 1
    else
        # verify download
        localScriptChecksum=$( sha256sum "$localScriptName" | grep -o '^\S*' )
        if ! [ "$localScriptChecksum" = "$repoScriptChecksum" ]; then
            printf "[ERROR]\n"
            printf "Unable to verify checksum of updated script. Try again later.\n\n"
        else
        printf "[UPDATED]\n\n"
        printf "*** This script has been updated. Please re-run it to load the updated version of this file. ***\n\n"
        exit 0
        fi
    fi
fi


### update files
set -- dummy $updateFiles
shift
for file; do
    updateTarget="$file"
    printf "\nChecking '%s' for updates... " "$updateTarget"
    repoFile=$( grep "$updateTarget" "$checksumFilename" | grep -o '^\S*' )
    if [ -f "$file" ]; then
        localFile=$( sha256sum "$updateTarget" | grep -o '^\S*' )
    else
        localFile=0
    fi

    if ! [ "$localFile" = "$repoFile" ]; then
        printf "[AVAILABLE]\n"
        updatesAvailable=$((updatesAvailable+1))
        # download update
        printf "Downloading updated '%s'... " "$updateTarget"
        # specify a name here instead of using the server name so that wget
        # overwrites the file
        if ! wget --quiet --tries=3 --timeout=10 -O "$updateTarget" "${server}${updateTarget}"; then
            printf "[ERROR]\n"
            downloadFailed=$((downloadFailed+1))
        else
            printf "[OK]\n"
            downloadSuccess=$((downloadSuccess+1))
            # verify download
            printf "Verifying '%s'... " "$updateTarget"
            localFile=$( sha256sum "$updateTarget" | grep -o '^\S*' )
            if ! [ "$localFile" = "$repoFile" ]; then
                printf "[INVALID]\n"
                updateFailed=$((updateFailed+1))
            else
                printf "[OK]\n"
                updateSuccess=$((updateSuccess+1))
            fi
        fi
    else
        printf "[NONE]\n"
    fi
done


### display results
printf "\nResults:\n"
printf "\tUpdates: %s available\n" "$updatesAvailable"
printf "\tDownloads: %s successful, %s failed\n" "$downloadSuccess" "$downloadFailed"
printf "\tUpdates: %s applied, %s failed\n" "$updateSuccess" "$updateFailed"

exit 0