Removing the last admin account is now forbidden. This should prevent most
cases where users could lock themselves out of the administrative
interface.
This change does allow a non-root network user to be the last admin
account. In practice this does not prevent the root user from gaining
access to maxadmin. Access can be gained by removing the users file and
restarting MaxScale or by editing the users file by hand.
Added a utility function for checking if an admin user has been
created. Removed unused promote and demote commands which can be replaced
with a call to remove and add.
The users can now be dumped and loaded as JSON objects. This allows easier
parsing and handling of users while still retaining the possibility to
manually edit the output. Added tests for dumping and loading the JSON
form users.
Also fixed a deadlock in Users::remove() where the same lock was acquired
twice and a faulty test case where failed authentication was expected to
work.
The type of the user being created is defined at creation time. This
allows the creation of basic users.
Although the users can be created internally, they cannot yet be created
via maxadmin or the REST API.
The Users class now performs locking when a method is called. This will
prevent concurrent access to the internal map of users.
Added missing const versions of SpinLockGuard.
Made the USERS an opaque object to reduce the amount of exposed
interfaces. Moved the storage of users into a C++ class and exposed that
class via the users interface functions.
Removed unused code and cleaned up the documentation in the header. Added
helper functions for printing the stored users.
