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20. Relocating NXLog

While not officially supported, it is possible to relocate NXLog to a different directory than where it was installed originally. The procedure shown below assumes that NXLog was installed normally, using the system’s package manager. While it is also possible to manually extract the files from the package and perform a manual installation in a custom directory, this is not covered here but the basic principals are the same. This procedure has been tested in GNU/Linux systems and should work in any system that supports run-time search paths.

Both relocation and manual installation can result in a non-functional NXLog agent. Furthermore, subsequent update and removal using the system’s package manager may not work correctly. Follow this procedure at your own risk. This is not recommended for inexperienced users.

Move the NXLog directory structure to the new location. Though not required, it is best to keep the original directory structure. Then proceed to the following sections.

In the examples that follow, NXLog is being relocated from /opt/nxlog to /opt/nxlog_new.

20.1. System V Init File

For systems that manage services with System V, edit the NXLog init file. This file can normally be found at /etc/init.d/nxlog. Modify the init file so that the $BASE variable reflects the new directory. Update the $pidfile, $nxlog, and $conf variables to reference $BASE. Finally, reassign the $nxlog variable to include the configuration file. This must be done after any tests to the binary executable. The init file should look similar to the following.



test -f $nxlog || exit 0

nxlog="$nxlog -c $conf"

On systems that use a hybrid System V and Systemd, reload the init files by executing the following command.

# systemctl daemon-reload

20.2. Systemd Unit File

For systems using Systemd, the /lib/systemd/system/nxlog.service unit file must be edited and the paths updated.

ExecStartPre=/opt/nxlog_new/bin/nxlog -v -c /opt/nxlog_new/etc/nxlog.conf
ExecStart=/opt/nxlog_new/bin/nxlog -f -c /opt/nxlog_new/etc/nxlog.conf
ExecStop=/opt/nxlog_new/bin/nxlog -s -c /opt/nxlog_new/etc/nxlog.conf
ExecReload=/opt/nxlog_new/bin/nxlog -r -c /opt/nxlog_new/etc/nxlog.conf

Reload the modified unit files by executing the following command.

# systemctl daemon-reload

20.3. Edit Configuration File

The configuration file of NXLog itself must be modified to reflect the directory relocation, as well as any changes in the directory structure. For most cases, running sed -i s,/opt/nxlog,/opt/nxlog_new,g /opt/nxlog_new/etc/nxlog.conf will update the configuration file. Alternatively, edit the file manually as shown below.

nxlog.conf [Download file]
define BASE /opt/nxlog_new
define CERTDIR %BASE%/var/lib/nxlog/cert
define CONFDIR %BASE%/var/lib/nxlog
define LOGDIR %BASE%/var/log/nxlog
define LOGFILE "%LOGDIR%/nxlog.log"

SpoolDir %BASE%/var/spool/nxlog

# default values:
PidFile %BASE%/var/run/nxlog/
CacheDir %BASE%/var/spool/nxlog
ModuleDir %BASE%/lib/nxlog/modules
Depending on the architecture and whether system supplied libraries are used, NXLog will store the modules under a different directory such as %BASE%/libexec/nxlog/modules.

20.4. Modify rpath

Depending on the NXLog package used, the run-time search path of the binaries must be changed. This is relevant for the generic versions of NXLog where the libraries are statically linked against the binaries. To check the shared libraries used by the binaries, issue the following command.

# ldd nxlog =>  (0x00007ffc15d36000) => /opt/nxlog/lib/ (0x00007ff7f311e000) => /lib64/ (0x00007ff7f2f14000) => /lib64/ (0x00007ff7f2d0f000) => /opt/nxlog/lib/ (0x00007ff7f2ad9000) => /lib64/ (0x00007ff7f28d0000) => /lib64/ (0x00007ff7f2699000) => /lib64/ (0x00007ff7f247d000) => /lib64/ (0x00007ff7f20bb000)
        /lib64/ (0x00007ff7f336d000) => /lib64/ (0x00007ff7f1eb6000) => /lib64/ (0x00007ff7f1cb3000)

Notice that libpcre and libapr are pointing to the included libraries in /opt/nxlog/lib/. To change the run-time search path of the binaries, a tool such as chrpath or patchelf can be used.

# chrpath -r /opt/nxlog_new/lib nxlog
        nxlog: RPATH=/opt/nxlog/lib:/home/builder/workspace/nxlog3-rpm-generic-amd64/rpmbuild/BUILD/nxlog-deps/opt/nxlog/lib
        nxlog: new RPATH: /opt/nxlog_new/lib

NXLog modules are also linked against statically included libraries. Therefore, if the run-time search path of the binaries required a change, then the rpath of the modules needs updated as well. To change the run-time search path of all the modules (or binaries) in a directory, use a command like this.

# chrpath -r /opt/nxlog_new/lib *

NXLog is now successfully relocated to a new directory.