Make two Debian systems as identical as possible

[drkirkby]

I have my companies website

https://www.kickbymicrowave.co.uk/

hosted in the UK on a VPS with Debian 9. The hosting has been generally quite reliable - so far this year, I have had only two outages of one minute each, based on monitoring results from a remote monitoring service. So an uptime of 99.998% so far this year. HOWEVER, last year there was a 14-hour outage, and I want to reduce the chances of another long outage by having a copy of the website on another server, so I can point the DNS servers at a new IP address in the event of problems.

How can I get the two installations as similar as possible? But that I mean each has exactly the same packages installed. I don't know how to list them. Anything related to Apache would be particularly important, such as any Apache plugins I might have installed on the first system.

[Bulkley]

You probably want rsync.

[Deb-fan]

^ Him ... what I was going to post but didn't prior. You're asking what could be a complicated question and think should be asking a search engine and doing your research. Rather than asking strangers on a nix forum. Not that there's anything wrong with soliciting pointers/tips I guess. My post is clearly another vote for rsync, think it's amazing and hats off to the people who develop such tools.

Only 2 cents on this deal.

Edit: Nah screw that, think this is spam, you got in a link to your website here and are touting this VPS host and their amazing 99.998% uptime. Ah whatever ...

[arzgi]

I'd suggest

Code: Select all

# dpkg --get-selections

[Bloom]

I use this to copy an installed system to another with different hardware. The target system must have the same Linux, minimally installed.

Code: Select all

rsync -avxHAXS --numeric-ids --info=progress2 --stats \
  --exclude={"/dev/*","/proc/*","/sys/*","/tmp/*","/run/*","/mnt/*","/media/*","/lost+found","/etc/udev/rules.d/*","/lib/modprobe.d/*"} \
  --exclude='/home/*/.local/share/Trash' \
  --exclude='/var/run/*' \
  --exclude='/var/lock/*' \
  --exclude='/lib/modules/*/volatile/.mounted' \
  --exclude='/var/cache/*' \
  --exclude='/home/*/.mozilla/firefox/*/Cache' \
  --exclude='/home/*/.cache' \
  --exclude='/home/*/.thumbnails' \
  --exclude=.cache --exclude Cache --exclude cache \
   "$1" "$2"

(Formatted for legibility). If it's for a server, you can exclude /home entirely.

[zarathustra-f90]

Maybe this post (http://forums.debian.net/viewtopic.php?f=10&t=148967) can give you a guide, it is about finding the installed packages by a user. That way you could install them in your new OS. Donno if this is exactly what you were looking for but I'm also interested in this idea, so if i find something more I'll come back with another answer

[sunrat]

Maybe this post (http://forums.debian.net/viewtopic.php?f=10&t=148967) can give you a guide,

That thread has little relation to this topic.