  The flux of positrons and electrons ($e^+ + e^-$) has been measured by the
$Fermi$ Large Area Telescope (LAT) in the energy range between 7 GeV and 2 TeV.
We discuss a number of interpretations of Pass 8 $Fermi$-LAT $e^+ + e^-$
spectrum, combining electron and positron emission from supernova remnants
(SNRs) and pulsar wind nebulae (PWNe), or produced by the collision of cosmic
rays with the interstellar medium. We find that the $Fermi$-LAT spectrum is
compatible with the sum of electrons from a smooth SNR population, positrons
from cataloged PWNe, and a secondary component. If we include in our analysis
constraints from AMS-02 positron spectrum, we obtain a slightly worse fit to
the $e^+ + e^-$ $Fermi$-LAT spectrum, depending on the propagation model. As an
additional scenario, we replace the smooth SNR component within 0.7 kpc with
the { individual sources} found in Green's catalog of Galactic SNRs. We find
that separate consideration of far and near sources helps to reproduce the $e^+
+ e^-$ $Fermi$-LAT spectrum. However, we show that the fit degrades when the
radio constraints on the positron emission from Vela SNR (which is the main
contributor at high energies) are taken into account. We find that a break in
the power-law injection spectrum at about 100 GeV can also reproduce the
measured $e^+ + e^-$ spectrum} and, among the cosmic-ray propagation models
that we consider, no reasonable break of the power-law dependence of the
diffusion coefficient can modify the electron flux enough to reproduce the
observed shape.
