ec2-init.openrc

#!/sbin/openrc-run

# Author:  Artem Butusov <art.sormy@gmail.com>
# License: MIT
# Version: 1.0.4
# https://github.com/sormy/ec2-init

# shellcheck shell=sh
# shellcheck disable=SC2129

EC2_META_DATA_URL="http://169.254.169.254/latest/meta-data"
EC2_USER_DATA_URL="http://169.254.169.254/latest/user-data"

EC2_INIT_MODULES="${EC2_INIT_MODULES:-hostname ssh exec}"

EC2_INIT_LOCK="${EC2_INIT_LOCK:-/var/lib/ec2-init.lock}"
EC2_INIT_LOG="${EC2_INIT_LOG:-/var/log/ec2-init.log}"
EC2_INIT_USER_DATA="${EC2_INIT_USER_DATA:-/var/lib/ec2-init.user-data}"

CURL="${CURL:-curl --silent --max-time 1 --retry-delay 1 --retry 10 --retry-all-errors --fail}"

depend() {
    before hostname
    need net.eth0
}

start() {
    einfo "Running EC2 initialization ..."
    echo "Running EC2 initialization" > "$EC2_INIT_LOG"

    timestamp=$(date -u +"%Y-%m-%dT%H:%M:%SZ")
    echo "Start time: $timestamp" >> "$EC2_INIT_LOG"

    instance_id=$($CURL "$EC2_META_DATA_URL/instance-id")

    if [ "$instance_id" = "" ]; then
        eerror "Unable to obtain EC2 metadata"
        echo "Unable to obtain EC2 metadata" >> "$EC2_INIT_LOG"
        return 1
    fi

    echo "Discovered EC2 instance ID: $instance_id" >> "$EC2_INIT_LOG"

    if [ -f "$EC2_INIT_LOCK" ] && [ "$(cat "$EC2_INIT_LOCK")" = "$instance_id" ]; then
        einfo "EC2 initialization is already completed"
        echo "EC2 initialization is already completed" > "$EC2_INIT_LOG"
        return 0
    fi

    eindent
    echo "$EC2_INIT_MODULES" | grep -q '\bhostname\b' && init_hostname
    echo "$EC2_INIT_MODULES" | grep -q '\bssh\b' && init_ssh
    echo "$EC2_INIT_MODULES" | grep -q '\bexec\b' && init_exec "$instance_id"
    eoutdent

    echo "$instance_id" > "$EC2_INIT_LOCK"
    chmod o-rwx "$EC2_INIT_LOCK"

    chmod o-rwx "$EC2_INIT_LOG"

    timestamp=$(date -u +"%Y-%m-%dT%H:%M:%SZ")
    echo "End time: $timestamp" >> "$EC2_INIT_LOG"

    einfo "EC2 initialization is completed"
    echo "EC2 initialization is completed" >> "$EC2_INIT_LOG"
}

init_hostname() {
    ebegin "Setting up hostname"
    echo "Setting up hostname" >> "$EC2_INIT_LOG"

    hostname=$($CURL "$EC2_META_DATA_URL/local-hostname")
    echo "Discovered hostname: $hostname" >> "$EC2_INIT_LOG"

    echo "hostname=$hostname" > /etc/conf.d/hostname

    eend $?
}

init_ssh() {
    ebegin "Setting up SSH"
    echo "Setting up SSH" >> "$EC2_INIT_LOG"

    ssh_user_name="${SSH_USER_NAME:-$(whoami)}"
    ssh_user_home="${SSH_USER_HOME:-$(user_home "$ssh_user_name")}"

    ssh_conf_home="$ssh_user_home/.ssh"

    echo "Loading SSH authorized keys to $ssh_conf_home" >> "$EC2_INIT_LOG"

    [ -e "$ssh_conf_home" ] && rm -rf "$ssh_conf_home"
    mkdir -p "$ssh_conf_home"
    chown "$ssh_user_name:$ssh_user_name" "$ssh_conf_home"
    chmod 750 "$ssh_conf_home"

    $CURL "$EC2_META_DATA_URL/public-keys" \
        | cut -d = -f 1 \
        | xargs printf "$EC2_META_DATA_URL/public-keys/%s/openssh-key\n" \
        | xargs $CURL \
        > "$ssh_conf_home/authorized_keys"

    result=$?

    chown "$ssh_user_name:$ssh_user_name" "$ssh_conf_home/authorized_keys"
    chmod 640 "$ssh_conf_home/authorized_keys"

    eend $result
}

init_exec() {
    instance_id="$1"

    ebegin "Executing user script"
    echo "Executing user script" >> "$EC2_INIT_LOG"

    $CURL "$EC2_USER_DATA_URL" > "$EC2_INIT_USER_DATA"
    chmod o-rwx "$EC2_INIT_USER_DATA"

    if [ "$(stat --printf="%s" "$EC2_INIT_USER_DATA")" = 0 ]; then
        echo "User script is empty, nothing to execute" >> "$EC2_INIT_LOG"
    elif [ "$(sed -n '/^#!/p;q' "$EC2_INIT_USER_DATA")" != "" ]; then
        echo "User script output:" >> "$EC2_INIT_LOG"
        echo "---" >> "$EC2_INIT_LOG"
        sh "$EC2_INIT_USER_DATA" >> "$EC2_INIT_LOG" 2>&1
        result=$?
        echo "---" >> "$EC2_INIT_LOG"
    else
        result=1
        echo "User script has missing shebang" >> "$EC2_INIT_LOG"
    fi

    eend $result
}

user_home() {
    grep "^$1:" /etc/passwd | cut -d : -f 6
}