Publish Web Content to S3

I host a little website at https://apps.frickjack.com by publishing static web files to an S3 bucket behind a cloudfront CDN. One way to improve the performance of an S3 web site is to configure each file's (s3 object) content encoding (gzip'ing the file if required), content type, and cache control at upload time (S3 natively specifies an Etag).

Here's a little script that makes that easy (also at https://github.com/frickjack/misc-stuff/blob/master/AWS/bin/s3web.sh), but rather than copy the script - you can install it like this:

git clone https://github.com/frickjack/misc-stuff.git
alias little="bash $(pwd)/Code/misc-stuff/AWS/little.sh"

little help s3web
little s3web publish localFolder s3Path [--dryrun]

Given a local source folder with html and other web content, then little s3web publish localFolder s3://destiation does the following:

• html files are gzipped, and annotated with headers content-encoding gzip, mime-type, cache for one hour
• css, js, svg, map, json, md files are gzipped, and annotated with content-encoding, mime-type, and cache for 1000 hours
• png, jpg, wepb files are not gzipped, and annotated with mime-type and cache for 1000 hours

This caching policy assumes that html files may periodically change to reference new assets (javascript, css, etc), but the referenced assets are immutable. For example, https://apps.frickjack.com loads javascript and CSS assets from a versioned subpath, and every update to https://apps.frickjack.com publishes a new folder of assets.

#
# helpers for publishing web content to S3
#

source "${LITTLE_HOME}/lib/bash/utils.sh"

# lib ------------------------

#
# Determine mime type for a particular file name
#
# @param path
# @return echo mime type
#
s3webPath2ContentType() {
    local path="$1"
    shift
    case "$path" in
        *.html)
            echo "text/html; charset=utf-8"
            ;;
        *.json)
            echo "application/json; charset=utf-8"
            ;;
        *.js)
            echo "application/javascript; charset=utf-8"
            ;;
        *.mjs)
            echo "application/javascript; charset=utf-8"
            ;;
        *.css)
            echo "text/css; charset=utf-8"
            ;;
        *.svg)
            echo "image/svg+xml; charset=utf-8"
            ;;
        *.png)
            echo "image/png"
            ;;
        *.jpg)
            echo "image/jpeg"
            ;;
        *.webp)
            echo "image/webp"
            ;;
        *.txt)
            echo "text/plain; charset=utf-8"
            ;;
        *.md)
            echo "text/markdown; charset=utf-8"
            ;;
        *)
            echo "text/plain; charset=utf-8"
            ;;
    esac
}

#
# Get the npm package name from the `package.json`
# in the current directory
#
s3webPublish() {
    local srcFolder
    local destPrefix
    local dryRun=off

    if [[ $# -lt 2 ]]; then
        gen3_log_err "s3web publish takes 2 arguments"
        little help s3web
        return 1
    fi
    srcFolder="$1"
    shift
    destPrefix="$1"
    shift
    if [[ $# -gt 0 && "$1" =~ ^-*dryrun ]]; then
        shift
        dryRun=on
    fi
    if [[ ! -d "$srcFolder" ]]; then
        gen3_log_err "invalid source folder: $srcFolder"
        return 1
    fi
    if ! [[ "$destPrefix" =~ ^s3://.+ ]]; then
        gen3_log_err "destination prefix should start with s3:// : $destPrefix"
        return 1
    fi
    local filePath
    local ctype
    local encoding
    local cacheControl
    local errCount=0
    local gzTemp
    local commandList
    (
        commandList=()
        cd "$srcFolder"
        gzTemp="$(mktemp "$XDG_RUNTIME_DIR/gzTemp_XXXXXX")"
        find . -type f -print | while read -r filePath; do
            ctype="$(s3webPath2ContentType "$filePath")"
            encoding="gzip"
            cacheControl="max-age=3600000, public"
            destPath="${destPrefix%/}/${filePath#./}"
            if [[ "$ctype" =~ ^image/ && ! "$ctype" =~ ^image/svg ]]; then
                encoding=""
            fi
            if [[ "$ctype" =~ ^text/html || "$ctype" =~ ^application/json ]]; then
                cacheControl="max-age=3600, public"
            fi

            if [[ "$encoding" == "gzip" ]]; then
                gzip -c "$filePath" > "$gzTemp"
                commandList=(aws s3 cp "$gzTemp" "$destPath" --content-type "$ctype" --content-encoding "$encoding" --cache-control "$cacheControl")
            else
                commandList=(aws s3 cp "$filePath" "$destPath" --content-type "$ctype" --cache-control "$cacheControl")
            fi
            gen3_log_info "dryrun=$dryRun - ${commandList[@]}"
            if [[ "$dryRun" == "off" ]]; then
                "${commandList[@]}" 1>&2
            fi
            errCount=$((errCount + $?))
            if [[ -f "$gzTemp" ]]; then
                /bin/rm "$gzTemp"
            fi
        done
        [[ $errCount == 0 ]]
    )
}

# main ---------------------

# GEN3_SOURCE_ONLY indicates this file is being "source"'d
if [[ -z "${GEN3_SOURCE_ONLY}" ]]; then
    command="$1"
    shift

    case "$command" in
        "content-type")
            s3webPath2ContentType "$@"
            ;;
        "publish")
            s3webPublish "$@"
            ;;
        *)
            little help s3web
            ;;
    esac
fi