Gunicorn3's service unit file throws errors from a shell command defined in a python script

Question

I have a flask app that is now served by gunicorn3 + ngingx, the flask app uses a python script that uses an internal command to perform a few actions and throws the result on to the html page.

Everything works fine, except that it seems gunicorn3 calls the flask app, it throws an error(perl based i think because of the internal command). I suspect a permission issue, but i'm not sure.

root@dev-elk-app01:/etc/init.d# service nexus status
● nexus.service - Gunicorn instance For Serving the flask App
   Loaded: loaded (/etc/systemd/system/nexus.service; disabled; vendor preset: enabled)
   Active: active (running) since Fri 2021-12-24 10:23:42 UTC; 29s ago
 Main PID: 2427 (gunicorn3)
    Tasks: 2 (limit: 4915)
   CGroup: /system.slice/nexus.service
           ├─2427 /usr/bin/python3 /usr/bin/gunicorn3 --log-syslog nexus:app
           └─2451 /usr/bin/python3 /usr/bin/gunicorn3 --log-syslog nexus:app

Dec 24 10:23:42 dev-elk-app01 systemd[1]: Started Gunicorn instance For Serving the Nexus App.
Dec 24 10:23:42 dev-elk-app01 gunicorn3[2427]: [2021-12-24 10:23:42 +0000] [2427] [INFO] Starting gunicorn 19.7.1
Dec 24 10:23:42 dev-elk-app01 gunicorn3[2427]: [2021-12-24 10:23:42 +0000] [2427] [INFO] Listening at: http://127.0.0.1:8000 (2427)
Dec 24 10:23:42 dev-elk-app01 gunicorn3[2427]: [2021-12-24 10:23:42 +0000] [2427] [INFO] Using worker: sync
Dec 24 10:23:42 dev-elk-app01 gunicorn3[2427]: [2021-12-24 10:23:42 +0000] [2451] [INFO] Booting worker with pid: 2451
Dec 24 10:24:06 dev-elk-app01 gunicorn3[2427]: Can't locate object method "ReadHistory" via package "Term::ReadLine::Stub" at /usr/local/share/perl/5.26.1/Shell
lines 1-15/15 (END)

To test the outcome, i stopped the service and used just the gunicorn to host the app and that worked, no errors this time.

root@dev-elk-app01:/var/www/html/flask_nexus# /usr/bin/gunicorn3 --log-syslog nexus:app
[2021-12-24 10:37:18 +0000] [2592] [INFO] Starting gunicorn 19.7.1
[2021-12-24 10:37:18 +0000] [2592] [INFO] Listening at: http://127.0.0.1:8000 (2592)
[2021-12-24 10:37:18 +0000] [2592] [INFO] Using worker: sync
[2021-12-24 10:37:18 +0000] [2595] [INFO] Booting worker with pid: 2595

Answer 1

Update: i have fixed the problem,i had enabled verbose in all the scripts and it seemed gunicorn3 had trouble with huge data that it was receiving from our internal perl script. as seen below with the BLOB data.

Dec 24 18:53:33 dev-elk-app01 gunicorn3[26598]: [1B blob data]
Dec 24 18:53:33 dev-elk-app01 gunicorn3[26598]: Can't locate object method "ReadHistory" via package "Term::ReadLine::Stub" at /usr/local/share/perl/5.26.1/Shel
Dec 24 18:53:34 dev-elk-app01 gunicorn3[26598]: Can't locate object method "ReadHistory" via package "Term::ReadLine::Stub" at /usr/local/share/perl/5.26.1/Shel
Dec 24 18:53:35 dev-elk-app01 gunicorn3[26598]: Can't locate object method "ReadHistory" via package "Term::ReadLine::Stub" at /usr/local/share/perl/5.26.1/Shel
Dec 24 18:53:36 dev-elk-app01 gunicorn3[26598]: Can't locate object method "ReadHistory" via package "Term::ReadLine::Stub" at /usr/local/share/perl/5.26.1/Shel

since the same script worked when we invoked from shell, i used TERM=linux in the systemd unitfile under the [service] tag, in an attempt to emulate the linux terminal and it worked. NO more errors,the file fetch now happens successfully.