Backup rake task doesn't support database SSL
The GitLab application, as a side-effect of using ActiveRecord and associated gems, supports SSL communication with the database-- even using client keys. Such a setup (for PostgreSQL) might look like this:
#...
production:
adapter: postgresql
encoding: unicode
pool: 10
host: gitlab-db
database: gitlab
username: git
password: "my_password"
sslmode: 'verify-full'
sslrootcert: '/path/to/ca/cert.crt'
sslcert: '/path/to/client/cert.crt'
sslkey: '/path/to/client/key.pem'
#...However, as can be seen by this function, the GitLab backup tasks only supports a specific user, host, port, and password for the database-- no SSL. This makes taking backups of SSL-protected databases very inconvenient, and probably should be supported by GitLab.