  We perform a thermal unflavored leptogenesis analysis on minimal left-right
symmetric models with discrete left-right symmetry identified as generalized
parity or charge conjugation. When left-right symmetry is unbroken in the
lepton Yukawa sector, the neutrino Dirac coupling matrix is completely
determined by neutrino masses and mixing angles, allowing CP violation needed
to generate leptogenesis totally resides in the low-energy sector. With two
lepton asymmetry generation ways, both type I and mixed type I$+$II neutrino
mass generation mechanisms are considered. After solving the Boltzmann
equations numerically, we find that the low-energy CP phases in the lepton
mixing matrix can successfully produce the observed baryon asymmetry, and in
some cases, the Dirac CP phase can be the only source of CP violation. Finally,
we discuss the interplay among low-energy CP phase measurements, leptogenesis,
and neutrinoless double beta decay. We show that the viable models for
successful leptogenesis can be probed in next-generation neutrinoless
double-beta decay experiments.
