spring boot在linux部署到/etc/init.d/app.jar 实现原理揭秘

从spring boot的文档知道，spring boot打包一个可以在systemV，直接执行的jar文件。操作也很简单，只需要在pom.xml中加入

<plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> <configuration> <executable>true</executable> </configuration> </plugin>

通过配置后， 进行打包，生成的jar文件就可以放到 /etc/init.d/ 里面（ln -s 的软引用也可以）。这样配置之后java应用， 就可以和mysql等等的服务一样使用/etc/init.d/app.jar {start|stop|status|restart|force-reload}  进行操作了。

我们来探究一下，它是如何实现的

通过查阅资料systemV目录 /etc/init.d/ 中的文件得知， /etc/init.d/中全部是shell脚本，但是我们的app.jar是一个jar文件，对jar文件的认识它的真实格式是zip压缩文件， 这个jar有什么魔力呢？把app.jar，拖入到jd-gui.exe ， 看看它到底长什么样，结果报错说文件是无效的，这明明就是个jar文件， 为什么会这样， 难道是jd-gui.exe的bug ？尝试使用360压缩打开这个app.jar， 成功打开， 看到里面有一些spring boot引导启动的class和自己写的class以及第三方库的class文件，但是它到底怎么实现的原理还没找到

最后我们把jar文件拖入 winhex （一个文件二进制查看器）

我们可以看到，这个文件开头是 #!/bin/bash ，那么它是一个bash脚本文件，继续往下看

看到pk 这是zip格式的开头，到这里明白了， 这个jar文件是一个 bash shell和 jar文件的合体文件， spring boot 打包时候把 /etc/init.d/用到脚本加在了文件前面，这个实现方法确实巧妙。

来看看这个脚本的真容

#!/bin/bash # # . ____ _ __ _ _ # /\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \ # ( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \ # \\/ ___)| |_)| | | | | || (_| | ) ) ) ) # ' |____| .__|_| |_|_| |_\__, | / / / / # =========|_|==============|___/=/_/_/_/ # :: Spring Boot Startup Script :: # ### BEGIN INIT INFO # Provides: xxxx # Required-Start: $remote_fs $syslog $network # Required-Stop: $remote_fs $syslog $network # Default-Start: 2 3 4 5 # Default-Stop: 0 1 6 # Short-Description: xxxx # Description: log collect system # chkconfig: 2345 99 01 ### END INIT INFO [[ -n "$DEBUG" ]] && set -x # Initialize variables that cannot be provided by a .conf file WORKING_DIR="$(pwd)" # shellcheck disable=SC2153 [[ -n "$JARFILE" ]] && jarfile="$JARFILE" [[ -n "$APP_NAME" ]] && identity="$APP_NAME" # Follow symlinks to find the real jar and detect init.d script cd "$(dirname "$0")" || exit 1 [[ -z "$jarfile" ]] && jarfile=$(pwd)/$(basename "$0") while [[ -L "$jarfile" ]]; do if [[ "$jarfile" =~ init\.d ]]; then init_script=$(basename "$jarfile") else configfile="${jarfile%.*}.conf" # shellcheck source=/dev/null [[ -r ${configfile} ]] && source "${configfile}" fi jarfile=$(readlink "$jarfile") cd "$(dirname "$jarfile")" || exit 1 jarfile=$(pwd)/$(basename "$jarfile") done jarfolder="$( (cd "$(dirname "$jarfile")" && pwd -P) )" cd "$WORKING_DIR" || exit 1 # Inline script specified in build properties # Source any config file configfile="$(basename "${jarfile%.*}.conf")" # Initialize CONF_FOLDER location defaulting to jarfolder [[ -z "$CONF_FOLDER" ]] && CONF_FOLDER="${jarfolder}" # shellcheck source=/dev/null [[ -r "${CONF_FOLDER}/${configfile}" ]] && source "${CONF_FOLDER}/${configfile}" # ANSI Colors echoRed() { echo $'\e[0;31m'"$1"$'\e[0m'; } echoGreen() { echo $'\e[0;32m'"$1"$'\e[0m'; } echoYellow() { echo $'\e[0;33m'"$1"$'\e[0m'; } # Initialize PID/LOG locations if they weren't provided by the config file [[ -z "$PID_FOLDER" ]] && PID_FOLDER="/var/run" [[ -z "$LOG_FOLDER" ]] && LOG_FOLDER="/var/log" ! [[ "$PID_FOLDER" == /* ]] && PID_FOLDER="$(dirname "$jarfile")"/"$PID_FOLDER" ! [[ "$LOG_FOLDER" == /* ]] && LOG_FOLDER="$(dirname "$jarfile")"/"$LOG_FOLDER" ! [[ -x "$PID_FOLDER" ]] && echoYellow "PID_FOLDER $PID_FOLDER does not exist. Falling back to /tmp" && PID_FOLDER="/tmp" ! [[ -x "$LOG_FOLDER" ]] && echoYellow "LOG_FOLDER $LOG_FOLDER does not exist. Falling back to /tmp" && LOG_FOLDER="/tmp" # Set up defaults [[ -z "$MODE" ]] && MODE="auto" # modes are "auto", "service" or "run" [[ -z "$USE_START_STOP_DAEMON" ]] && USE_START_STOP_DAEMON="true" # Create an identity for log/pid files if [[ -z "$identity" ]]; then if [[ -n "$init_script" ]]; then identity="${init_script}" else identity=$(basename "${jarfile%.*}")_${jarfolder//\//} fi fi # Initialize log file name if not provided by the config file [[ -z "$LOG_FILENAME" ]] && LOG_FILENAME="${identity}.log" # Initialize stop wait time if not provided by the config file [[ -z "$STOP_WAIT_TIME" ]] && STOP_WAIT_TIME="60" # Utility functions checkPermissions() { touch "$pid_file" &> /dev/null || { echoRed "Operation not permitted (cannot access pid file)"; return 4; } touch "$log_file" &> /dev/null || { echoRed "Operation not permitted (cannot access log file)"; return 4; } } isRunning() { ps -p "$1" &> /dev/null } await_file() { end=$(date +%s) let "end+=10" while [[ ! -s "$1" ]] do now=$(date +%s) if [[ $now -ge $end ]]; then break fi sleep 1 done } # Determine the script mode action="run" if [[ "$MODE" == "auto" && -n "$init_script" ]] || [[ "$MODE" == "service" ]]; then action="$1" shift fi # Build the pid and log filenames PID_FOLDER="$PID_FOLDER/${identity}" pid_file="$PID_FOLDER/${identity}.pid" log_file="$LOG_FOLDER/$LOG_FILENAME" # Determine the user to run as if we are root # shellcheck disable=SC2012 [[ $(id -u) == "0" ]] && run_user=$(ls -ld "$jarfile" | awk '{print $3}') # Run as user specified in RUN_AS_USER if [[ -n "$RUN_AS_USER" ]]; then if ! [[ "$action" =~ ^(status|run)$ ]]; then id -u "$RUN_AS_USER" || { echoRed "Cannot run as '$RUN_AS_USER': no such user" exit 2 } [[ $(id -u) == 0 ]] || { echoRed "Cannot run as '$RUN_AS_USER': current user is not root" exit 4 } fi run_user="$RUN_AS_USER" fi # Issue a warning if the application will run as root [[ $(id -u ${run_user}) == "0" ]] && { echoYellow "Application is running as root (UID 0). This is considered insecure."; } # Find Java if [[ -n "$JAVA_HOME" ]] && [[ -x "$JAVA_HOME/bin/java" ]]; then javaexe="$JAVA_HOME/bin/java" elif type -p java > /dev/null 2>&1; then javaexe=$(type -p java) elif [[ -x "/usr/bin/java" ]]; then javaexe="/usr/bin/java" else echo "Unable to find Java" exit 1 fi arguments=(-Dsun.misc.URLClassPath.disableJarChecking=true $JAVA_OPTS -jar "$jarfile" $RUN_ARGS "$@") # Action functions start() { if [[ -f "$pid_file" ]]; then pid=$(cat "$pid_file") isRunning "$pid" && { echoYellow "Already running [$pid]"; return 0; } fi do_start "$@" } do_start() { working_dir=$(dirname "$jarfile") pushd "$working_dir" > /dev/null if [[ ! -e "$PID_FOLDER" ]]; then mkdir -p "$PID_FOLDER" &> /dev/null if [[ -n "$run_user" ]]; then chown "$run_user" "$PID_FOLDER" fi fi if [[ ! -e "$log_file" ]]; then touch "$log_file" &> /dev/null if [[ -n "$run_user" ]]; then chown "$run_user" "$log_file" fi fi if [[ -n "$run_user" ]]; then checkPermissions || return $? if [ $USE_START_STOP_DAEMON = true ] && type start-stop-daemon > /dev/null 2>&1; then start-stop-daemon --start --quiet \ --chuid "$run_user" \ --name "$identity" \ --make-pidfile --pidfile "$pid_file" \ --background --no-close \ --startas "$javaexe" \ --chdir "$working_dir" \ -- "${arguments[@]}" \ >> "$log_file" 2>&1 await_file "$pid_file" else su -s /bin/sh -c "$javaexe $(printf "\"%s\" " "${arguments[@]}") >> \"$log_file\" 2>&1 & echo \$!" "$run_user" > "$pid_file" fi pid=$(cat "$pid_file") else checkPermissions || return $? "$javaexe" "${arguments[@]}" >> "$log_file" 2>&1 & pid=$! disown $pid echo "$pid" > "$pid_file" fi [[ -z $pid ]] && { echoRed "Failed to start"; return 1; } echoGreen "Started [$pid]" } stop() { working_dir=$(dirname "$jarfile") pushd "$working_dir" > /dev/null [[ -f $pid_file ]] || { echoYellow "Not running (pidfile not found)"; return 0; } pid=$(cat "$pid_file") isRunning "$pid" || { echoYellow "Not running (process ${pid}). Removing stale pid file."; rm -f "$pid_file"; return 0; } do_stop "$pid" "$pid_file" } do_stop() { kill "$1" &> /dev/null || { echoRed "Unable to kill process $1"; return 1; } for i in $(seq 1 $STOP_WAIT_TIME); do isRunning "$1" || { echoGreen "Stopped [$1]"; rm -f "$2"; return 0; } [[ $i -eq STOP_WAIT_TIME/2 ]] && kill "$1" &> /dev/null sleep 1 done echoRed "Unable to kill process $1"; return 1; } force_stop() { [[ -f $pid_file ]] || { echoYellow "Not running (pidfile not found)"; return 0; } pid=$(cat "$pid_file") isRunning "$pid" || { echoYellow "Not running (process ${pid}). Removing stale pid file."; rm -f "$pid_file"; return 0; } do_force_stop "$pid" "$pid_file" } do_force_stop() { kill -9 "$1" &> /dev/null || { echoRed "Unable to kill process $1"; return 1; } for i in $(seq 1 $STOP_WAIT_TIME); do isRunning "$1" || { echoGreen "Stopped [$1]"; rm -f "$2"; return 0; } [[ $i -eq STOP_WAIT_TIME/2 ]] && kill -9 "$1" &> /dev/null sleep 1 done echoRed "Unable to kill process $1"; return 1; } restart() { stop && start } force_reload() { working_dir=$(dirname "$jarfile") pushd "$working_dir" > /dev/null [[ -f $pid_file ]] || { echoRed "Not running (pidfile not found)"; return 7; } pid=$(cat "$pid_file") rm -f "$pid_file" isRunning "$pid" || { echoRed "Not running (process ${pid} not found)"; return 7; } do_stop "$pid" "$pid_file" do_start } status() { working_dir=$(dirname "$jarfile") pushd "$working_dir" > /dev/null [[ -f "$pid_file" ]] || { echoRed "Not running"; return 3; } pid=$(cat "$pid_file") isRunning "$pid" || { echoRed "Not running (process ${pid} not found)"; return 1; } echoGreen "Running [$pid]" return 0 } run() { pushd "$(dirname "$jarfile")" > /dev/null "$javaexe" "${arguments[@]}" result=$? popd > /dev/null return "$result" } # Call the appropriate action function case "$action" in start) start "$@"; exit $?;; stop) stop "$@"; exit $?;; force-stop) force_stop "$@"; exit $?;; restart) restart "$@"; exit $?;; force-reload) force_reload "$@"; exit $?;; status) status "$@"; exit $?;; run) run "$@"; exit $?;; *) echo "Usage: $0 {start|stop|force-stop|restart|force-reload|status|run}"; exit 1; esac exit 0