aws-update-linux-instance

#!/bin/bash

# This is an updated version of the aws-update-linux-instance
# script that supports SUSE.

PRE_UPDATE_SCRIPT_URL=''
POST_UPDATE_SCRIPT_URL=''

INCLUDE_PACKAGES=''
EXCLUDE_PACKAGES=''

function usage() {
    cat <<- EOF

    Usage: $0 [OPTION]...
    Update the instance's distribution packages and Amazon software

    [-h|--help]
        Print this help message.

    [-d|--debug]
        Show additional debugging info.

    [--pre-update-script <SCRIPT_URL>]
        A script to run before the package manager is invoked for
        updates. By default, when no script is provided, nothing is done
        before system updates.

    [--post-update-script <SCRIPT_URL>]
        A script to run after the package manager is invoked for
        updates. By default, when no script is provided, nothing is done
        before system updates.

    [-i|--include-packages <PACKAGE[,PACKAGE]...>]
        A list of packages that will be updated. When provided, the
        system will atempt to update only these packages and their
        dependencies, but no other updates will be performed. By
        default, when no include packages are explicitly specified, the
        program will update all available packages.

    [-x|--exclude-packages <PACKAGE[,PACKAGE]...>]
       A list of packages that will be held back from updates. If
       provided, these packages will stay at their current versions,
       independent of any other options specified. By default, when no
       exclude packages are specified, no packages will be held back.

EOF

    exit $1
}

function unhold_deb_packages() {
    for package in $EXCLUDE_PACKAGES; do
        apt-mark unhold $package
    done
}

function die() {
    if [ "$(get_dist)" == "debian" ]; then
        unhold_deb_packages
    fi

    echo "$@" >&2
    exit 1
}

function get_contents() {
    if [ -x "$(which curl)" ]; then
        curl -s -f "$1"
    elif [ -x "$(which wget)" ]; then
        wget "$1" -O -
    else
        die "No download utility (curl, wget)"
    fi
}

function sanitize_inputs() {
    value="$(echo $@ | sed 's/,/ /g' | xargs | xargs)"

    if [ ! -z "$value" ] &&
        [ "$value" != "none" ] &&
        [ "$value" != "all" ]; then
        echo "$value"
    fi
}

function get_cli_options() {
    while [ $# -gt 0 ]; do
        arg_required="true"

        case $1 in
            -h|--help)
                usage 0
                ;;
            -i|--include-packages)
                INCLUDE_PACKAGES="$(sanitize_inputs $2)"
                ;;
            -x|--exclude-packages)
                EXCLUDE_PACKAGES="$(sanitize_inputs $2)"
                ;;
            --pre-update-script)
                PRE_UPDATE_SCRIPT_URL="$(sanitize_inputs $2)"
                ;;
            --post-update-script)
                POST_UPDATE_SCRIPT_URL="$(sanitize_inputs $2)"
                ;;
            -d|--debug)
                arg_required="false"
                set -x
                ;;
            *)
                echo "Unknown option: $1" >&2
                usage 1
                ;;
        esac

        if [ "$arg_required" == "true" ]; then
            [ -z "$2" ] && die "$1 requires a value"

            shift
        fi

        shift

    done
}

function echo_options() {
    echo \"\$PRE_UPDATE_SCRIPT_URL\" == \"$PRE_UPDATE_SCRIPT_URL\"
    echo \"\$POST_UPDATE_SCRIPT_URL\" == \"$POST_UPDATE_SCRIPT_URL\"
    echo \"\$INCLUDE_PACKAGES\" == \"$INCLUDE_PACKAGES\"
    echo \"\$EXCLUDE_PACKAGES\" == \"$EXCLUDE_PACKAGES\"
}

function exec_cmd() {
    echo "Invoking $@..."
    eval "$@"

    if [ $? -ne 0 ]; then
        die ""
    fi
}

function is_debuntu() {
    grep -E -i -c 'Debian|Ubuntu' /etc/issue 2>&1 &>/dev/null
    [ $? -eq 0 ] && echo "true" || echo "false"
}

function is_redhat() {
    if [ -f "/etc/system-release" ] ||
        [ -f "/etc/redhat-release" ]; then
        echo "true"
    else
        echo "false"
    fi
}

function is_suse() {
    if [ -f "/etc/os-release" ] ||
        [ -f "/etc/SuSE-release" ]; then
        echo "true"
    else
        echo "false"
    fi
}

function get_dist() {
    if [ "$(is_debuntu)" == "true" ]; then
        echo "debian"
    elif [ "$(is_redhat)" == "true" ]; then
        echo "redhat"
    elif [ "$(is_suse)" == "true" ]; then
        echo "suse"
    else
        die "Unknown distribution"
    fi
}

function run_hook_script() {
    script_url="$1"
    tmp_file="$(mktemp)"

    echo "Downloading hook script from $script_url"

    get_contents "$script_url" > "$tmp_file"
    chmod +x "$tmp_file"

    exec_cmd "$tmp_file"
}

function update_cli() {
    if [ -x "$(which pip 2>/dev/null)" ]; then
        exec_cmd "pip install --upgrade awscli"
    else
        exec_cmd "easy_install --upgrade awscli"
    fi
}

function apt_get_update() {
    exec_cmd "apt-get clean"
    exec_cmd "apt-get update"

    for package in $EXCLUDE_PACKAGES; do
        exec_cmd "apt-mark hold $package"
    done

    if [ -z "$INCLUDE_PACKAGES" ]; then
        exec_cmd "apt-get -y dist-upgrade"
    else
        for package in $INCLUDE_PACKAGES; do
            exec_cmd "apt-get -y install --only-upgrade $package"
        done
    fi

    unhold_deb_packages
}

function yum_upgrade() {
    exec_cmd 'yum clean all'

    yum_cmd='yum -y upgrade'

    for package in $EXCLUDE_PACKAGES; do
        yum_cmd="$yum_cmd -x $package"
    done

    if [ ! -z "$INCLUDE_PACKAGES" ]; then
        yum_cmd="$yum_cmd $INCLUDE_PACKAGES"
    fi

    exec_cmd "$yum_cmd"
}

function zypper_upgrade() {
    exec_cmd 'zypper refresh'

    zypper_cmd='zypper update -y'

    for package in $EXCLUDE_PACKAGES; do
        yum_cmd="zypper al $package"
    done

    exec_cmd "$zypper_cmd"
    
    for package in $EXCLUDE_PACKAGES; do
        yum_cmd="zypper rl $package"
    done
}

function remove_excludes_from_includes() {
    if [ -z "$EXCLUDE_PACKAGES" ] || [ -z "$INCLUDE_PACKAGES" ]; then
        return
    fi

    declare -A includes
    declare -A excludes

    for package in $EXCLUDE_PACKAGES; do
        excludes[$package]="true"
    done

    for package in $INCLUDE_PACKAGES; do
        if [ "${excludes[$package]}" != "true" ]; then
            includes[$package]="true"
        fi
    done

    INCLUDE_PACKAGES="${!includes[@]}"
}

function update_packages() {
    remove_excludes_from_includes

    if [ "$(get_dist)" == "debian" ]; then
        apt_get_update
    elif [ "$(get_dist)" == "redhat" ]; then
        yum_upgrade
    elif [ "$(get_dist)" == "suse" ]; then
        zypper_upgrade
    fi
}

function main() {
    get_cli_options "$@"
    echo_options

    if [ ! -z "$PRE_UPDATE_SCRIPT_URL" ]; then
        run_hook_script "$PRE_UPDATE_SCRIPT_URL"
    fi

    update_cli
    update_packages

    if [ ! -z "$POST_UPDATE_SCRIPT_URL" ]; then
        run_hook_script "$POST_UPDATE_SCRIPT_URL"
    fi

    exit 0
}

main "$@"