Upgrade from 3.9.2 to 4.2.0 on CentOS 7 -- Python?

[Jared]

Hi all,

I'm looking to upgrade to 4.2.0 to get off legacy Python 2.  I'm running CentOS 7.8 and I'm looking for guidance on how to deal with Python.  I'm assuming upgrading WeeWX alone won't work since "python" currently maps to Python 2.7.  I'm worried that if I install Python 3 it still won't work unless I do some symlink acrobatics.  I'm not very proficient in Linux, and Python version weirdness is not easy to untangle.

I'd rather upgrade WeeWx first and then move to CentOS 8 down the line, but if it's significantly easier to start fresh and jump to CentOS 8 now, I can bring my customizations over to a fresh install.  It would be time-consuming, but should not be challenging.

Advice?

[mwall]

On Thursday, November 5, 2020 at 8:42:11 AM UTC-5, Jared wrote:

Hi all,

I'm looking to upgrade to 4.2.0 to get off legacy Python 2.  I'm running CentOS 7.8 and I'm looking for guidance on how to deal with Python.  I'm assuming upgrading WeeWX alone won't work since "python" currently maps to Python 2.7.  I'm worried that if I install Python 3 it still won't work unless I do some symlink acrobatics.  I'm not very proficient in Linux, and Python version weirdness is not easy to untangle.

how did you install weewx on the centos7 system?  did you use the rpm/yum or did you do a setup.py install?

if you did the rpm/yum install, then you can do this:

1) install python3 and the weewx python3 pre-requisites

2) change /etc/default/weewx to use python3 instead of python

beware that (1) can be a hassle on centos7.  you will probably want to update python using pip, not rpm/yum.  so that means you might want to install your own python3, not a system-wide python3.  ymmv.  it is not difficult, but there are a lot of rabbit holes that dead end in places that you do not want to be.

if you did a setup.py install, then you can do (1) then reinstall weewx using 'python3 install' instead of 'python install'.  be sure to make a snapshot of the /home/weewx directory first (in particular, make a copy of your database, skins, and user directory)

 

I'd rather upgrade WeeWx first and then move to CentOS 8 down the line, but if it's significantly easier to start fresh and jump to CentOS 8 now, I can bring my customizations over to a fresh install.  It would be time-consuming, but should not be challenging.

if your intent is to move to centos8, then you might want take the leap.  just install centos8, install weewx, then copy your db/skins/user stuff from the old weewx installation.  this assumes that you have a new, separate computer on which to install centos8.

i would avoid upgrading centos7 to centos8 - that process can leave turds that make a mess (or at least cause confusion) later on.

m

 

[p q]

Do a trial run on a spare system. If you don't have spare hardware use a VM. 

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[Jared]

Okay, that makes sense, thanks.  I realized that I do have a spare laptop that I can use long term for this (hopefully the battery is okay).  I didn't want to switch to a VM and then have to switch again back to the laptop, but I agree, it would be better to start fresh on CentOS 8, and now I can make the switch only a single time.

I had installed WeeWx on CentOS 7 using the rpm.  Is setup.py the preferred method these days?  The docs say this makes it easier to modify and doesn't require root, but I'm primarily interested in ease of upgrades long term.