Accessing VM (Virtual Machine) via Horizon is a common practice, but you cannot copy text from the instance console. Sometimes, you may need to collect information from the instance console. For example, if the VM failed to boot up, you would need to collect boot info, then check what stopped it.

Nova can provide the console log for VMs, which is under the /var/lib/nova/instances/ <VM uuid> / folder. 

root@test:~# tailf -n 20  /var/lib/nova/instances/11be31d6-0df2-4992-a033-23a99cee65b5/console.log 
[  OK  ] Started Hold until boot process finishes up.
[  OK  ] Started Terminate Plymouth Boot Screen.
         Starting Set console scheme...
[  OK  ] Started Serial Getty on ttyS0.
[  OK  ] Started Getty on tty1.
[  OK  ] Reached target Login Prompts.
[  OK  ] Reached target Multi-User System.
         Starting Execute cloud user/final scripts...
[  OK  ] Reached target Graphical Interface.
         Starting Update UTMP about System Runlevel Changes...
[  OK  ] Started Set console scheme.
[  OK  ] Started Update UTMP about System Runlevel Changes.
[   61.023082] cloud-init[1142]: Cloud-init v. 0.7.9 running 'modules:final' at Thu, 19 Sep 2019 23:12:02 +0000. Up 60.87 seconds.
[   61.072752] cloud-init[1142]: Cloud-init v. 0.7.9 finished at Thu, 19 Sep 2019 23:12:03 +0000. Datasource DataSourceOpenStack [net,ver=2].  Up 61.01 seconds
[  OK  ] Started Execute cloud user/final scripts.
[  OK  ] Reached target Cloud-init target.

Ubuntu 16.04.2 LTS vm-ubuntu ttyS0

vm-ubuntu login: