View source for Fixing problems with Cpanel::JSON::XS module

[https://integrics.com/enswitch/guides/ Enswitch 4.1 and newer versions] require [https://metacpan.org/pod/Crypt::JWT Crypt::JWT], which depends on [https://metacpan.org/pod/CryptX CryptX].

In some systems, there are some known issues related with Perl's [https://metacpan.org/pod/Cpanel::JSON::XS Cpanel::JSON::XS] module, which is not required by Enswitch, but could have been installed either as an operating system package or from CPAN.

Those known issues and the ways to deal with them are detailed bellow.

=== Message ''Can't locate Cpanel/JSON/XS.pm in @INC'' appears in the system log files ===

==== Symptom ====

The operating system log files like ''/var/log/syslog'' or ''/var/log/messages'' show lines saying something like this:

  localhost systemd[1]: Started Kamailio server.
  localhost /sbin/kamailio[32260]: ERROR: app_perl [kamailioxs.xs:1041]: XS_Kamailio__Message_log(): perl error: Can't locate Cpanel/JSON/XS.pm in @INC (you may need to install the Cpanel::JSON::XS module) (@INC contains: /opt/enswitch/current/perllib /etc/perl /usr/local/lib/x86_64-linux-gnu/perl/5.26.1 /usr/local/share/perl/5.26.1 /usr/lib/x86_64-linux-gnu/perl5/5.26 /usr/share/perl5 /usr/lib/x86_64-linux-gnu/perl/5.26 /usr/share/perl/5.26 /usr/local/lib/site_perl) at /usr/local/lib/x86_64-linux-gnu/perl/5.26.1/CryptX.pm line 14.

==== Cause ====

The installed module [https://metacpan.org/pod/CryptX CryptX] tries to load the [https://metacpan.org/pod/Cpanel::JSON::XS Cpanel::JSON::XS] module but can not find it.

This happens when a version <= 0.072 of [https://metacpan.org/pod/CryptX CryptX] is used.

==== What to do? ====

* Do nothing. This is because those log lines are harmless.
* Install [https://metacpan.org/pod/Cpanel::JSON::XS Cpanel::JSON::XS] with the operating system package manager tools or directly from CPAN, for example with any of these commands:
** For Debian or Ubuntu based systems: ''apt-get install libcpanel-json-xs-perl''.
** For CentOS based systems: ''yum install perl-Cpanel-JSON-XS''.
** Directly from CPAN: ''cpanm Cpanel::JSON::XS''.
* If [https://metacpan.org/pod/Cpanel::JSON::XS Cpanel::JSON::XS] was installed, restart ''Kamailio''. After this, the system log should not add lines with the mentioned messages.

=== Segmentation faults for the Apache web server are reported in the system log files ===

==== Symptoms ====

* The operating system log files like ''/var/log/syslog'' or ''/var/log/messages'' show lines saying something like this:

  localhost kernel: [10306754.605002] apache2[4013806]: segfault at 8 ip 00007fb92a1ebf47 sp 00007fff905b0cb8 error 4 in XS.so[7fb92a1eb000+f000]
  localhost kernel: [10306754.605011] Code: 1f 40 00 f3 0f 1e fa 48 63 15 dd 30 01 00 48 8b 87 78 0b 00 00 48 83 6f 78 04 48 8b 04 d0 48 8b 70 30 48 c7 40 30 00 00 00 00 <8b> 56 08 83 fa 01 76 11 83 ea 01 89 56 08 c3 66 2e 0f 1f 84 00 00

* The Apache error log shows lines like this one:

  [:error] [pid 4014780] Undefined subroutine &Enswitch::Utilities::file_delete called at /usr/local/lib/site_perl/Enswitch/Utilities.pm line 790.

* The web browser or any other HTTP client sometimes receives the expected response, but other times receives an error message, like a 500 status code indicating a failure in the server side. This happens for the same input parameters and is not reproducible at will.

* This has been observed in Ubuntu versions 20.04 and 21.04, but could also happen in other versions or with other distributions.

==== Cause ====

[https://metacpan.org/pod/CryptX CryptX] will use [https://metacpan.org/pod/Cpanel::JSON::XS Cpanel::JSON::XS] if both of these happen:

* [https://metacpan.org/pod/Cpanel::JSON::XS Cpanel::JSON::XS] is installed.
* The installed version of [https://metacpan.org/pod/CryptX CryptX] is <= 0.072.

If [https://metacpan.org/pod/CryptX CryptX] is using [https://metacpan.org/pod/Cpanel::JSON::XS Cpanel::JSON::XS] as the preferred implementation of JSON::XS, a bug that seems to affect the ''XS.so'' file provided by [https://metacpan.org/pod/Cpanel::JSON::XS Cpanel::JSON::XS] will cause the mentioned segmentation faults.

That ''XS.so'' file is a shared library that comes from compiled C code.

There is an issue report [https://github.com/rurban/Cpanel-JSON-XS/issues/179 in the official sources repository of the Cpanel::JSON::XS] that offers more details.

==== What to do? ====

Apply all of the following:

* Remove the [https://metacpan.org/pod/Cpanel::JSON::XS Cpanel::JSON::XS] module. Depending on the way used to install it, any of these commands could be used:
** For Debian or Ubuntu based systems: ''apt-get purbe libcpanel-json-xs-perl''.
** For CentOS based systems: ''yum remove perl-Cpanel-JSON-XS''.
** Directly from CPAN: ''cpanm --uninstall Cpanel::JSON::XS''.

* Restart the Apache web server process.

=== What if ''Cpanel/JSON/XS.pm'' is still needed? ===

If for some reason a customer installation requires [https://metacpan.org/pod/Cpanel::JSON::XS Cpanel::JSON::XS] for other purposes not related with [https://enswitch.com Enswitch], more tests will be needed to check the following:

* If the processes of the Apache web server are adversely affected, like detailed before, by merely having the ''XS.so'' file of [https://metacpan.org/pod/Cpanel::JSON::XS Cpanel::JSON::XS] in the filesystem.
* If having [https://metacpan.org/pod/CryptX CryptX] > 0.072 is enough to avoid the mentioned segmentation faults, even if [https://metacpan.org/pod/Cpanel::JSON::XS Cpanel::JSON::XS] is installed with its ''XS.so'' file.