Cron作业无法正确启动Node.js

Question

This is a bit of a weird one and I have no clue what to do. I have a small node express api which is hosted on my Raspberry Pi which is running raspbian.

The js file is started in a cron job:

@reboot sudo /usr/bin/node /var/www/html/api/server.js &

And the API itself works fine, I can access it and it returns my requests without a problem.

But the API is also supposed to write to a log file when someone makes a request:

fs.appendFile("./ServerLog.log", "[" + dateTime + "]" + " [" + status + "] " + message + "\n", null, () => {
});

This does not work. But when I kill the process which was started through the cronjob and start it manually it creates a log.

I tried launching node with bash, ie:

@reboot sudo bash -c "sudo  /usr/bin/node /var/www/html/api/server.js &"

But that did not change anything. I also changed the output to just write "TEST" but that did not work either. I do have a shebang at the beginning of my js file : #!/usr/bin/env node

These are the lines which are printed to the syslog:

Nov 18 20:20:05 raspberrypi cron[331]: (CRON) INFO (pidfile fd = 3)
Nov 18 20:20:05 raspberrypi cron[331]: (CRON) INFO (Running @reboot jobs)

And in auth.log:

Nov 18 20:20:05 raspberrypi systemd-logind[309]: New seat seat0.
Nov 18 20:20:05 raspberrypi CRON[343]: pam_unix(cron:session): session opened for user root by (uid=0)
Nov 18 20:20:05 raspberrypi CRON[343]: pam_unix(cron:session): session closed for user root
Nov 18 20:20:05 raspberrypi sudo:     root : TTY=unknown ; PWD=/root ; USER=root ; COMMAND=/usr/bin/node /var/www/html/api/server.js
Nov 18 20:20:05 raspberrypi sudo: pam_unix(sudo:session): session opened for user root by (uid=0)

Answer 1

You get a different environment in cron started jobs than you have in an interactive shell. Typically the PATH is by far not as elaborate as in an interactive shell. Easiest to fix this is to explicitly set the full path.

#!/usr/bin/env node actually uses the environment to find the executable called 'node'. Simplest is to replace it with an explicit path to node eg #!/usr/local/bin/node or wherever it is installed on your system. To find where it is installed: use which node in an interactive shell.

sudo is a command that lets you run a command as another user, it'll not help you as such to set PATH values in cron like you have in an interactive shell.

Answer 2

the issue is with the PATH.

for me I was using serveStatic and providing the path to the static folder like ./public . This was resolving to the wrong path. By providing complete URL i was able to resolve the issue.

You may solve the same issue with other solutions also, the point is that your code is not resolving to the write file because of PATH.