Plasmas are believed to be possibly the most abundant form of visible matter in the Universe. Investigation in this paper is given to a variable-coefficient derivative nonlinear Schrödinger equation describing the nonlinear Alfvén waves in an inhomogeneous plasma. With respect to the left polarized Alfvén wave, the odd-fold Darboux transformation, breather, rogue-wave and semirational solutions are constructed on the periodic background. Conditions for the antidark/gray/black soliton solutions or periodic solutions are obtained. Period of the Akhmediev breather is independent of the dispersion coefficient. When such an equation has a constant dispersion, with the increasing value of the dispersion coefficient, quasi-period of the Kuznetsov-Ma breather decreases, quasi-periods of the spatio-temporal breathers along the 𝝃 and 𝝉 axes both decrease and range of the rogue wave along the 𝝉 axis decreases, where 𝝃 and 𝝉 are the stretched time and space variables, respectively. When such an equation has a 𝝉-dependent linear dispersion, with the increasing value of |𝝉|, quasi-period of the Kuznetsov-Ma breather decreases and quasi-periods of the spatio-temporal breathers along the 𝝃 and 𝝉 axes both decrease. When such an equation has a constant loss/gain, linearly periodic background is exhibited. When such an equation has a 𝝉-dependent linear loss/gain, parabolic-periodic background is shown.