Upgrading from v2 to v3 on CentOS 7
From Rivendell Wiki
Updating Rivendell 2.x on CentOS 7 to Rivendell 3.x
The process consists of two major steps: 1) updating the repository assignments and code, and (optionally) converting any RLM instances to PyPAD ones.
Updating Repository Assignments and Code
First, check that the system is in fact running CentOS 7 by executing the following command:
You should get back something like this:
CentOS Linux release 7.6.1810 (Core)
Verify that the first number in the version string ('7.6.1810') is a 7. If it is not, or you get a 'No such file or directory' error, then STOP. You are not running CentOS 7, and proceeding may damage or destroy your installation!