接下来，就让我们看看forever能不能实现目标。
一、forever介绍
forever是一个简单的命令式nodejs的守护进程，能够启动，停止，重启App应用。forever完全基于命令行操作，在forever进程之下，创建node的子进程，通过monitor监控node子进程的运行情况，一旦文件更新，或者进程挂掉，forever会自动重启node服务器，确保应用正常运行。
二、forever安装
全局安装forever
复制代码代码如下:
~ D:/workspace/javascript>npm install -g forever
D:/toolkit/nodejs/forever -> D:/toolkit/nodejs/node_modules/forever/bin/forever
D:/toolkit/nodejs/foreverd -> D:/toolkit/nodejs/node_modules/forever/bin/foreverd
查看forever帮助
复制代码代码如下:
~ D:/workspace/javascript>forever -h
help: usage: forever [action] [options] SCRIPT [script-options]
help:
help: Monitors the script specified in the current process or as a daemon
help:
help: actions:
help: start Start SCRIPT as a daemon
help: stop Stop the daemon SCRIPT
help: stopall Stop all running forever scripts
help: restart Restart the daemon SCRIPT
help: restartall Restart all running forever scripts
help: list List all running forever scripts
help: config Lists all forever user configuration
help: set <key> <val> Sets the specified forever config <key>
help: clear <key> Clears the specified forever config <key>
help: logs Lists log files for all forever processes
help: logs <script|index> Tails the logs for <script|index>
help: columns add <col> Adds the specified column to the output in `forever list`
help: columns rm <col> Removed the specified column from the output in `forever list`
help: columns set <cols> Set all columns for the output in `forever list`
help: cleanlogs [CAREFUL] Deletes all historical forever log files
help:
help: options:
help: -m MAX Only run the specified script MAX times
help: -l LOGFILE Logs the forever output to LOGFILE
help: -o OUTFILE Logs stdout from child script to OUTFILE
help: -e ERRFILE Logs stderr from child script to ERRFILE
help: -p PATH Base path for all forever related files (pid files, etc.)
help: -c COMMAND COMMAND to execute (defaults to node)
help: -a, --append Append logs
help: -f, --fifo Stream logs to stdout
help: -n, --number Number of log lines to print
help: --pidFile The pid file
help: --sourceDir The source directory for which SCRIPT is relative to
help: --minUptime Minimum uptime (millis) for a script to not be considered "spinning"
help: --spinSleepTime Time to wait (millis) between launches of a spinning script.
help: --colors --no-colors will disable output coloring
help: --plain alias of --no-colors
help: -d, --debug Forces forever to log debug output
help: -v, --verbose Turns on the verbose messages from Forever
help: -s, --silent Run the child script silencing stdout and stderr
help: -w, --watch Watch for file changes
help: --watchDirectory Top-level directory to watch from
help: --watchIgnore To ignore pattern when watch is enabled (multiple option is allowed)
help: -h, --help You're staring at it
help:
help: [Long Running Process]
help: The forever process will continue to run outputting log messages to the console.
help: ex. forever -o out.log -e err.log my-script.js
help:
help: [Daemon]
help: The forever process will run as a daemon which will make the target process start
help: in the background. This is extremely useful for remote starting simple node.js scripts
help: without using nohup. It is recommended to run start with -o -l, & -e.
help: ex. forever start -l forever.log -o out.log -e err.log my-daemon.js
help: forever stop my-daemon.js
help:
我们看到forever支持的命令和配置项确实不少，应该是偏命令行的管理工具。
三、forever命令行的中文解释
子命令actions：
复制代码代码如下:
start:启动守护进程
stop:停止守护进程
stopall:停止所有的forever进程
restart:重启守护进程
restartall:重启所有的foever进程
list:列表显示forever进程
config:列出所有的用户配置项
set <key> <val>: 设置用户配置项
clear <key>: 清楚用户配置项
logs: 列出所有forever进程的日志
logs <script|index>: 显示最新的日志
columns add <col>: 自定义指标到forever list
columns rm <col>: 删除forever list的指标
columns set<cols>: 设置所有的指标到forever list
cleanlogs: 删除所有的forever历史日志
配置参数options：
复制代码代码如下:
-m MAX: 运行指定脚本的次数
-l LOGFILE: 输出日志到LOGFILE
-o OUTFILE: 输出控制台信息到OUTFILE
-e ERRFILE: 输出控制台错误在ERRFILE
-p PATH: 根目录
-c COMMAND: 执行命令，默认是node
-a, append: 合并日志
-f, fifo: 流式日志输出
-n, number: 日志打印行数
pidFile: pid文件
sourceDir: 源代码目录
minUptime: 最小spinn更新时间(ms)
spinSleepTime: 两次spin间隔时间
colors: 控制台输出着色
plain: no-colors的别名，控制台输出无色
-d, debug: debug模式
-v, verbose: 打印详细输出
-s, silent: 不打印日志和错误信息
-w, watch: 监控文件改变
watchDirectory: 监控顶级目录
watchIgnore: 通过模式匹配忽略监控
-h, help: 命令行帮助信息
四、forever服务器管理
创建一个web项目(express3+ejs)，使用forever管理服务器。
安装express3
复制代码代码如下:
~ D:/workspace/javascript>express -e nodejs-forever
~ D:/workspace/javascript>cd nodejs-forever && npm install
通过forever启动应用
复制代码代码如下:
~ D:/workspace/javascript/nodejs-forever>forever start app.js
warn: --minUptime not set. Defaulting to: 1000ms
warn: --spinSleepTime not set. Your script will exit if it does not stay up for at least 1000ms
info: Forever processing file: app.js
打开浏览器: http://localhost:3000，可以看到web界面
在win下面查看forever状态
复制代码代码如下:
~ D:/workspace/javascript/nodejs-forever>forever list
info: No forever processes running
~ D:/workspace/javascript/nodejs-forever>forever stop app.js
error: Forever cannot find process with index: app.js
我们发现forever的程序，工作不对了！！程序明明是运行状态，通过list确看不到。接下来，切换成Linux Ubuntu继续测试。
五、forever在Ubuntu进行服务器管理
Linux的系统环境
Linux: Ubuntu 12.04.2 64bit Server
Node: v0.11.2
Npm: 1.2.21
初始化项目：安装命令不解释了
复制代码代码如下:
~ cd /home/conan/nodejs
~ express -e nodejs-forever
~ cd nodejs-forever && npm install
~ sudo npm install forever -g
启动forever
复制代码代码如下:~ forever start app.js
warn: --minUptime not set. Defaulting to: 1000ms
warn: --spinSleepTime not set. Your script will exit if it does not stay up for at least 1000ms
info: Forever processing file: app.js
查看node服务器状态
复制代码代码如下:~ forever list
info: Forever processes running
data: uid command script forever pid logfile uptime
data: [0] L2tY /usr/local/bin/node app.js 18276 18279 /home/conan/.forever/L2tY.log 0:0:0:37.792
# 系统进程
~ ps -aux|grep node
Warning: bad ps syntax, perhaps a bogus '-'? See http://procps.sf.net/faq.html
conan 18296 0.5 1.1 597696 23776 ? Ssl 15:48 0:00 /usr/local/bin/node /usr/local/lib/node_modules/forever/bin/monitor app.js
conan 18299 0.4 0.8 630340 18392 ? Sl 15:48 0:00 /usr/local/bin/node /home/conan/nodejs/nodejs-forever/app.js
# 端口占用
~ netstat -nltp|grep node
tcp 0 0 0.0.0.0:3000 0.0.0.0:* LISTEN 18299/node
停止服务器
复制代码代码如下:~ forever stop app.js
info: Forever stopped process:
data: uid command script forever pid logfile uptime
[0] L2tY /usr/local/bin/node app.js 18276 18279 /home/conan/.forever/L2tY.log 0:0:0:45.621
我们看到在Linux Ubuntu环境中是正常的。
六、模拟服务器宕机
两种测试方案：
1. 用Linux命令，直接杀死node进程
2. 在应用中，模拟异常退出
1). 用Linux命令，直接杀死node进程
复制代码代码如下:
# 查看node进程，PID=18299
~ ps -aux|grep node
conan 18296 0.0 1.1 597696 23776 ? Ssl 15:48 0:00 /usr/local/bin/node /usr/local/lib/node_modules/forever/bin/monitor app.js
conan 18299 0.0 0.8 630340 18392 ? Sl 15:48 0:00 /usr/local/bin/node /home/conan/nodejs/nodejs-forever/app.js
conan 18315 0.0 0.0 13584 956 pts/5 R+ 15:52 0:00 grep --color=auto node
# 杀死PID=19299
~ kill -9 18299
# 再看node进程，node自动重启，新的PID=18324
~ ps -aux|grep node
conan 18296 0.0 1.1 597696 23916 ? Ssl 15:48 0:00 /usr/local/bin/node /usr/local/lib/node_modules/forever/bin/monitor app.js
conan 18316 2.6 0.8 630340 18412 ? Sl 15:52 0:00 /usr/local/bin/node /home/conan/nodejs/nodejs-forever/app.js
conan 18324 0.0 0.0 13584 956 pts/5 R+ 15:52 0:00 grep --color=auto node
我们看到看杀死node进程，forever会帮助我们，重启node。
杀死forever的monitor
复制代码代码如下:
~ kill -9 18296
~ ps -aux|grep node
conan 18316 0.0 0.9 630340 18644 ? Sl 15:52 0:00 /usr/local/bin/node /home/conan/nodejs/nodejs-forever/app.js
conan 18333 0.0 0.0 13584 952 pts/5 S+ 15:57 0:00 grep --color=auto node
# 再杀死node进程
~ kill -9 18316
~ ps -aux|grep node
conan 18336 0.0 0.0 13584 956 pts/5 S+ 15:58 0:00 grep --color=auto node
我们尝试杀死了forever的monitor，monitor程序没有自动重启，然后再杀死node进程后，node也不会自动重启了。
2). 在应用中，模拟异常退出
修改文件：app.js
复制代码代码如下:
~ vi app.js
//..
http.createServer(app).listen(app.get('port'), function(){
console.log(new Date());
console.log('Express server listening on port ' + app.get('port'));
});
setTimeout(function(){
console.log(new Date());
throw new Error('App is error from inner!');
},10*1000);
通过node命令启动
复制代码代码如下:~ node app.js
Thu Sep 26 2013 16:08:44 GMT+0800 (CST)
Express server listening on port 3000
Thu Sep 26 2013 16:08:54 GMT+0800 (CST)
/home/conan/nodejs/nodejs-forever/app.js:41
throw new Error('App is error from inner!');
^
Error: App is error from inner!
at null._onTimeout (/home/conan/nodejs/nodejs-forever/app.js:41:9)
at Timer.listOnTimeout [as ontimeout] (timers.js:110:15)
10秒后，由于内部错误， node进程挂掉了。
通过forever命令启动
复制代码代码如下:
~ mkdir logs
~ chmod 777 -R logs
~ forever -p . -l ./logs/access.log -e ./logs/error.log start app.js
# 检查错误日志
~ cat logs/access.log ls
Thu Sep 26 2013 16:15:02 GMT+0800 (CST)
Express server listening on port 3000
Thu Sep 26 2013 16:15:12 GMT+0800 (CST)
/home/conan/nodejs/nodejs-forever/app.js:41
throw new Error('App is error from inner!');
^
Error: App is error from inner!
at null._onTimeout (/home/conan/nodejs/nodejs-forever/app.js:41:9)
at Timer.listOnTimeout [as ontimeout] (timers.js:110:15)
error: Forever detected script exited with code: 8
error: Forever restarting script for 1 time
Thu Sep 26 2013 16:15:13 GMT+0800 (CST)
Express server listening on port 3000
Thu Sep 26 2013 16:15:23 GMT+0800 (CST)
/home/conan/nodejs/nodejs-forever/app.js:41
throw new Error('App is error from inner!');
^
Error: App is error from inner!
at null._onTimeout (/home/conan/nodejs/nodejs-forever/app.js:41:9)
at Timer.listOnTimeout [as ontimeout] (timers.js:110:15)
error: Forever detected script exited with code: 8
error: Forever restarting script for 2 time
Thu Sep 26 2013 16:15:23 GMT+0800 (CST)
Express server listening on port 3000
Thu Sep 26 2013 16:15:33 GMT+0800 (CST)
/home/conan/nodejs/nodejs-forever/app.js:41
throw new Error('App is error from inner!');
^
Error: App is error from inner!
at null._onTimeout (/home/conan/nodejs/nodejs-forever/app.js:41:9)
at Timer.listOnTimeout [as ontimeout] (timers.js:110:15)
error: Forever detected script exited with code: 8
error: Forever restarting script for 3 time
Thu Sep 26 2013 16:15:33 GMT+0800 (CST)
Express server listening on port 3000
Thu Sep 26 2013 16:15:43 GMT+0800 (CST)
/home/conan/nodejs/nodejs-forever/app.js:41
throw new Error('App is error from inner!');
^
Error: App is error from inner!
at null._onTimeout (/home/conan/nodejs/nodejs-forever/app.js:41:9)
at Timer.listOnTimeout [as ontimeout] (timers.js:110:15)
error: Forever detected script exited with code: 8
error: Forever restarting script for 4 time
我们发现每10秒种，node内部挂掉，然后再被forever重启！！
通过list我们手动刷新几次也可以看到pid是变的。
复制代码代码如下:
~ forever list
info: Forever processes running
data: uid command script forever pid logfile uptime
data: [0] SmtT /usr/local/bin/node app.js 18444 18579 logs/access.log 0:0:0:7.211
~ forever list
info: Forever processes running
data: uid command script forever pid logfile uptime
data: [0] SmtT /usr/local/bin/node app.js 18444 18579 logs/access.log 0:0:0:8.921
~ forever list
info: Forever processes running
data: uid command script forever pid logfile uptime
data: [0] SmtT /usr/local/bin/node app.js 18444 18604 logs/access.log 0:0:0:0.177
~ forever list
info: Forever processes running
data: uid command script forever pid logfile uptime
data: [0] SmtT /usr/local/bin/node app.js 18444 18604 logs/access.log 0:0:0:2.206
这样forever就帮助我们完成了，几项比较重要服务器管理功能：“启动/停止命令简单”，“支持热部署”，“宕机重启”，“监控界面和日志”。
比起upstart管理，省略了配置脚本的步骤(/etc/init/nodejs-xx.conf)。其他的功能，还要更近一步的使用才知道。
七、开发环境和生产环境的启动配置
开发环境
复制代码代码如下:
~ cd /home/conan/nodejs/nodejs-forever/
~ forever -p . -l ./logs/access.log -e ./logs/error.log -a -w start app.js
生产环境
复制代码代码如下:~ export LOG=/var/log/nodejs/project
~ export PID=/var/log/nodejs/project/forever.pid
~ export APP_PATH=/home/conan/nodejs/nodejs-forever
~ export APP=$APP_PATH/app.js
~ forever -p $APP_PATH -l $LOG/access.log -e $LOG/error.log -o $LOG/out.log -a --pidFile $PID start $APP