What is the best way to implement "launching" separate instances of the service for different users?

Question

Software design

Suppose there is a forum (just for definiteness), now it is set separately for each client, the task is to get away from the need for this installation + I want to keep the ability to synchronize the code with the source. I personally see the following options:
1) Automate the installation.
+: simple; relatively fast implementation
-: a hundred clients - a hundred separate databases, how / by whom is it all to be maintained and updated?
2) Add client_id field to tables and separate data
+: same database, same code, easy to maintain and update
-: harder to implement, harder to synchronize code
Which would you choose and why?

Answer 1

1. We must start with this. Update automatically. According to the database, these are migrations.
2. If you provide hosting and support, it's a good idea to share in basins.