User Interface not working anymore

[stm]

Hello there,

we have a serious problem and I am at a loss.

The user interface on the "master" shows the following error:

Another MWG UI is already attached to this cluster
 Please log on to that one.

Overall Status "STATUS_ERROR":generic error
Node "421112C9-xxxx-xxxx-xxxx-xxxxxxxxxxxx" reports STATUS_ERROR_GUI_ATTACH:
could not attach tomcat to node 62586C84-xxxx-xxxx-xxxx-xxxxxxxxxxxx because there is already a tomcat attached at node 421112C9-xxxx-xxxx-xxxxxxxxxxxxxxxxx
...

The User Interface on a non-master Shows this error:
Resource not found: /Konfigurator/request

After a reboot of all WEB-Gateways the error persits.

In the /var/log/mwg-ui/catalina.out I can see this:

SEVERE: The web application [/Konfigurator] appears to have started a TimerThread named [Timer-0] via the java.util.Timer API but has failed to stop it. To prevent a memory leak, the timer (and hence the associated thread) has been forcibly canceled.

Any help would be gladly appreciated.

Regards, stm

[aloksard]

Hi,

Hope you are doing well.

Resource not found: /Konfigurator/request  , This happens when UI is not able to create the tmp dir in /usr/share/mwg-ui/temp which is symlink . This symlink targets to /var/tmp/mwg-ui .

Observations:- 

1. /var/tmp/mwg-ui and /var/tmp need to have the write access so that UI can create a temporary directories for its use

2.I was able to reproduce this issue by restricting permissions on var/tmp/ and var/tmp/mwg-ui folder to dr--r--r-- (Read Only).

3.Later by allowing write permissions on /var/tmp/ and /var/tmp/mwg-ui . I was able to access the UI again

Request you to check below  once and see if that helps:-

1. Please check the permissions on /var/tmp/mwg-ui directory and also on /var/tmp.

2. If it is read only . Please allow the write permssions and try to access the UI

Regards

Alok Sarda

[stm · Accepted solution]

Thanks, that solved the "Resource not found: /Konfigurator/request" problem.

To get the GUI working again, we had to restart the host with the corresponding UUID, that was blocking the GUI. So my statment, that the error persists after a reboot was not entirely correct. There were a couple more hosts in our cluster (I did not know of), one of wich was blocking the GUI.

Regards, stm

[marcus69]

Thanks a lot Alok,

Your explanation helped a lot to to solve my problem that was similar to this.

For some reason the folder /var/tmp/mwg-ui was completely missing after a reboot of the appliance for some reason. The symbolic link was present in /usr/share/mwg-ui, but target was not accessible for the above reason.

So i've manually created /var/tmp/mwg-ui, für user tomcat:tomcat and assigned Permission 755 to to the folder, as seen on another working MWG of us.

After that i've restarted the mwg-ui service and the GUI was acessible again.

Best Regards,

   Marcus

[aloksard]

Hi Marcus,

Glad that issue is resolved and I was of some help.

systemd has a clean tempfiles service which is triggered daily. With the current configuration of ALL MLOS3 machines, it will clean up everything below /var/tmp which is was not accessed for 30 days.


This is resolved in versions  8.1; 8.0.3; 7.8.2.6

a) the UI has a working directory. This is /usr/share/mwg-ui
b) in this working directory there is a temporary directory (named "temp"), which the UI uses for temporary files. this temporary directory is a symlink to /var/tmp/mwg-ui
c) the UI runs as user tomcat which is in usergroup tomcat

so, you should have:

a) ls /usr/share/mwg-ui/temp -la
lrwxrwxrwx 1 tomcat tomcat 15 Oct 10 09:18 /usr/share/mwg-ui/temp -> /var/tmp/mwg-ui

b) ls /var/tmp/ -la
drwxr-xr-x  3 tomcat tomcat 4096 Oct 25 06:36 mwg-ui



Resource not found: /Konfigurator/request  , This happens when UI is not able to create the tmp dir in /usr/share/mwg-ui/temp which is symlink . This symlink targets to /var/tmp/mwg-ui .

Regards

Alok Sarda

[marcus69]

Hi Alok,

thanks very much for the heads up.

So it seems that the missing directory was kicked out by systemd, as our customer still has Version 7.8.2.3.0 (Build 26967) in use, where i had this issue.

I will recommend him to update to the current Main Release as soon as possible.

Best Regards,

    Marcus

[aloksard]

Hi Marcus,

Also below is for your information and workarounds for this issue:-

1) mkdir /var/tmp/mwg-ui

chown tomcat:tomcat /var/tmp/mwg-ui

chmod 755 /var/tmp/mwg-ui

service mwg-ui restart

 

2) Another workaround will be  you  can put the an mwg-ui.conf file which unforunately I am not able to attach here due to extension not supported, but I advise you to open a cas with support team if you want that   into  /usr/lib/tmpfiles.d/


then please reboot (first line in the conf file will ensure the directory is created on boot if it was already deleted, second line will exclude this directory from deletion when the cleanup is run)



file to put under /usr/lib/tmpfiles.d/
after copying one may want to ensure access rights:
chown root:root /usr/lib/tmpfiles.d/mwg-ui.conf
chmod 644 /usr/lib/tmpfiles.d/mwg-ui.conf

 

Regards

Alok Sarda

[marcus69]

Hi Alok,

well, i already did what you posted on Solution 1), as described in my first posting on this Thread.

- Problem solved

As MWG Versions 8.0.3 and 7.8.2.6 are not released yet this Problem may reappear until Solution 2) is established:

- create file mwg-ui.conf under /usr/lib/tmpfiles.d/
ensure access rights:
- chown root:root /usr/lib/tmpfiles.d/mwg-ui.conf
- chmod 644 /usr/lib/tmpfiles.d/mwg-ui.conf

According to the manpage of tmpfiles.d, mwg-ui-conf should contain the following lines:

Best Regards,

              Marcus