[CentOS] Upgrade path from CentOS 7 to future versions

[Alice Wonder]

On 05/10/2016 12:19 AM, Johnny Hughes wrote:
> On 05/10/2016 02:08 AM, Venkateswara Rao Dokku wrote:
>> Hi,
>>
>> I would like to know whether the valid upgrade path will be present from
>> CentOS 7 to future versions like we get for Ubuntu or some other operating
>> systems.
>>
>> Right now, I am sure that we do not have proper update path in CentOS to
>> move from one version to another.
>>
>
> If you mean upgrade to all CentOS-7 point releases, yes (from source
> code for RHEL-7.0 to RHEL-7.1, to RHEL-7.2).  If you mean from CentOS-7
> to CentOS-8, there is no way to know.  There is no RHEL-8 to look at.
>
> Red Hat has source code for preupgrade-assistant and
> redhat-upgrade-tool.  That is created for inplace upgrades from one
> major version to another.  Currently those tools are community and
> maintained and they are several updates behind because currently no one
> in the community has stepped up to maintain them.
>
> But, CentOS-7 has an EOL of June 30, 2024 .. so there is security
> updates for 8 more years.
>
>

I tend to keep all server content in /srv and all user content in /home

Upgrading from one major version to another then is pretty simple - but 
not on the same machine.

I do a fresh install of the new version in a new vm, make sure all the 
services are in place, and all the user and group ids match.

I can then rsync the old /home and /srv to the new system.

Yes there are server migration files that need to be migrated but what I 
like about this approach is I can keep serving from the old server until 
this is done and tested in the new server, and then it is just a simple 
DNS change and the new server is used.

Migrating configuration files to me means starting with the defaults in 
the new version and modifying them to match the needs of the service, 
not replacing them with the old files.

I have tried updating between major versions in Fedora before and there 
were always too many glitches, it really is better to clean install and 
migrate the data. In my opinion. Especially if you skip a release like I 
tend to do.