The high-luminosity upgrade of the LHC (HL-LHC) brings unprecedented requirements for real-time and precision bunch-by-bunch luminosity measurement and beam-induced background monitoring. A key component of the CMS Beam Radiation Instrumentation and Luminosity (BRIL) system is a stand-alone luminometer, the Fast Beam Condition Monitor (FBCM), which is fully independent of the CMS central timing and control distribution, as well as data acquisition services and able to operate at all times with a triggerless readout. In addition, BRIL exploits measurements from the front-end of various CMS subsystems for luminometry. A brief overview of the BRIL Phase-2 strategy, the instrumentation and approaches to achieve 1\% offline precision for luminosity measurements is given.