postgresql read-only user

There seem to be different ways of creating a read-only user in postgresql, depending on the version, and depending on whether you want the user to have access to future tables and so on. 

https://stackoverflow.com/questions/760210/how-do-you-create-a-read-only-user-in-postgresql

And when creating a user like that, we have to connect to the database first, using

\connect dbname
to prevent errors

https://dba.stackexchange.com/questions/173635/postgres-permission-denied-for-schema