github-release - A simple github release asset downloader

github-release.sh

#!/bin/bash
#
# github-release v1.0.0
# A simple github release asset downloader
# Author: MineBartekSA
# Gist: https://gist.github.com/MineBartekSA/5234f09c1048f9ba007d0a26a8fd654e
#

function help() {
    echo "Usage: $0 <repository> [options]"
    echo "Options:"
    echo "    -t, --tag <release tag> - Set the release tag"
    echo "    -f, --filter <filter>   - Add a asset filter"
    echo "    -o, --output <name>     - Set the output name"
    echo "    -a, --auth <secret>     - Authenticate using OAuth2 key/secret or personal access token"
    echo "    -d, --dry               - Will only print asset url(s)"
    echo "    -s, --silent            - Disable output"
    echo "    -v, --version           - See app version"
    echo "    -h, --help              - See this message"
    echo
    echo "Example:"
    echo "    $0 example/repo -v v1.1.3 -f linux -f gnu -f .tar"
}

if [ $# -lt 1 ]
then
    exec 1>&2
    help
    exit 2
fi

case $1 in
-v | --version)
    echo "github-release v1.0.0"
    exit 0
    ;;
-h | --help)
    help
    exit 0
    ;;
esac

curl --version >> /dev/null
if [ $? -ne 0 ]
then
    echo -e "\e[91mcURL not found!\e[0m" >&2
    echo "Please check if you have installed cURL on your system" >&2
    exit 1
fi

jq --version >> /dev/null
if [ $? -ne 0 ]
then
    echo -e "\e[91mjq not found!\e[0m" >&2
    echo "Please check if you have installed jq on your system" >&2
    exit 1
fi

repo=$1
tag="latest"
output=""
curl_add=""
dry=0
silent=0
to_filter=()

declare -i count=2
while [ $count -le $# ]
do
    case ${!count} in
    -t | --tag)
        count+=1
        tag=${!count}
        ;;
    -f | --filter)
        count+=1
        to_filter+=(${!count})
        ;;
    -o | --output)
        count+=1
        output=${!count}
        ;;
    -a | --auth)
        count+=1
        curl_add+="-u ${!count}"
        ;;
    -d | --dry)
        dry=1
        ;;
    -d | --silent)
        silent=1
        ;;
    esac
    count+=1
done

filter=".assets[] | "

for f in ${to_filter[*]}
do
    filter+="select(.name | contains(\"$f\")) | "
done

filter+=".browser_download_url"

[ "$tag" != "latest" ] && tag="tags/$tag"
data=$(curl -sSL --fail-with-body $curl_add "https://api.github.com/repos/$repo/releases/$tag")
if [ $? -ne 0 ]
then
    echo "Failed to fetch release information" >&2
    echo $data | jq . >&2
    exit 3
fi

read -r -d '' -a urls <<< $(echo $data | jq  -r "$filter")
if [ $dry -eq 1 ]
then
    IFS=$'\n'
    echo "${urls[*]}"
    exit 0
fi

if [ ${#urls[@]} -eq 0 ]
then
    [ $silent -eq 0 ] && echo "Nothing to download"
    exit 0
fi

[ $silent -eq 0 ] && echo "Downloading"
if [ "$output" == "" ]
then
    for url in ${urls[@]}
    do
        filename=${url##*/}
        [ $silent -eq 0 ] && echo -e "\e[1m$filename\e[0m: $url"
        curl -sSL --fail-with-body $url -o $filename
    done 
    exit 0
fi

function extension {
    ext=${1##*.}
    if [ "$ext" == "gz" ]
    then
        isTar=${1##*.tar.}
        [ "$isTar" == "gz" ] && ext="tar.gz"
    fi
    printf $ext
}

if [ ${#urls[@]} -eq 1 ]
then
    url=${urls[0]}
    ext=$(extension ${url##*/})
    out=$output.$ext
    [ $silent -eq 0 ] && echo -e "\e[1m$out\e[0m: $url"
    curl -sSL $url -o $out
    exit 0
fi

for index in ${!urls[@]}
do
    url=${urls[$index]}
    ext=$(extension ${url##*/})
    out=$output-$[$index + 1].$ext
    [ $silent -eq 0 ] && echo -e "\e[1m$out\e[0m: $url"
    curl -sSL --fail-with-body $url -o $out
done