The present process for non-root install of Couchbase Server is as documented in Installing as non-root, non-sudo
General steps (or a variation of this):
1. stop the old version of couchbase
2. unpack the new version to a new directory using rpm2cpio, cpio, reloc.sh
3. copy opt/couchbase/var/lib/couchbase to the previous version to the new version*
4. copy opt/couchbase/etc/couchdb/local.ini from the previous version to the new version
5. change a symlink named "current" to point to the newly installed couchbase dir
6. delete the old installation
7. start up the new couchbase version
In addition to this, Starting / Stopping / Status of the server was also performed by modifying opt/couchbase/etc/couchbase_init.d file.
For upgrading from Couchbase Server 5.5.4 to 6.0.3, scripts were also supplied to perform non-root upgrade. Basically above steps to upgrade.
Issues with Couchbase Server 6.5.0:
This process and scripts supplied will not work with Couchbase Server 6.5.0 since the data storage has changed due to the support for Collections.
Couchbase Server 6.5.0 is certified only on Centos/RHEL Versions 7 and 8 and these do not have opt/couchbase/etc/couchbase_init.d which customers use to start, stop and check the status of the server
Non-root install/upgrade would be implemented as a “first class citizen”. That is, non-root install/upgrade would behave the exact same way as root install/upgrade.
Use systemctl for Start/Stop/Status of Couchbase Server