The high-luminosity upgrade of the LHC (HL-LHC) is expected to reach an instantaneous luminosity of roughly a factor five of the current value. The resulting requirements for background monitoring and luminosity measurement create the need for new high-precision instrumentation at CMS, using radiation-hard detector technologies. This contribution presents the strategy for bunch-by-bunch online luminosity measurements based on various detector technologies. A main component of the system is the Tracker Endcap Pixel Detector with dedicated triggers for the online measurement of the luminosity and the beam-induced background using the pixel cluster counting method as implemented in FPGAs. The potential of exploiting the outer tracker, the forward hadron calorimeter, and muon trigger objects is discussed, as well as the concept of a standalone luminosity and beam-induced background monitor using silicon-pad sensors.