OP5 Monitor - Nachos.log errors "PermissionError, ConfigGenerationException", "ConfigBackupException"

If you are seeing any of these errors in your Nachos.log file, then Nachos may be having an issue accessing your configuration files. You may see lines like the following:

(...) 2019-11-04 09:35:11.700 81166 ERROR nachos.engine.export.config_export [-] PermissionError(13, 'Permission denied'): nachos.common.exceptions.ConfigGenerationException: PermissionError(13, 'Permission denied')#033[00m
(...) 2019-11-04 09:35:11.705 81166 CRITICAL nachos.engine.export.config_export [-] Rollback failed: PermissionError(13, 'Permission denied'): nachos.common.exceptions.ConfigBackupException: PermissionError(13, 'Permission denied')#033[00m

You can run the following command to list all files that Nacoma knows about, and their permissions:

# cd /opt/monitor/ && mysql -D nacoma -e "select file_name from file_tbl order by id" -sr | xargs -n 1 ls -alh

Note that these files should all be owned by monitor:apache and should be readable and writable. Nachos also needs to be able to traverse to the directory, so you also need to check that permissions allow for monitor to see the directory. For example, if the /opt/monitor directory is restricted for the monitor user, you may have issues like shown below.

Example: incorrect folder permissions on /opt/monitor (other users cannot read/execute, the expected permission is 755):

drwx------   9 root    root   96 Jul  4 15:24 monitor

Listing of underlying folder fails, despite correct permissions there:

# asmonitor ls -alh /opt/monitor/etc/
ls: cannot access /opt/monitor/etc/: Permission denied

This can be corrected with the command:

chmod 0755 /opt/monitor

To ensure correct ownership of files under /opt/monitor/etc use the command:

chown -R monitor:apache /etc/monitor/etc