  Recently, the calculation of tunneling actions, that control the exponential
suppression of the decay of metastable vacua, has been reformulated as an
elementary variational problem in field space. This paper extends this
formalism to include the effect of gravity. Considering tunneling potentials
$V_t(\phi)$ that go from the false vacuum $\phi_+$ to some $\phi_0$ on the
stable basin of the scalar potential $V(\phi)$, the tunneling action is the
minimum of the functional $S_E[V_t]=6
\pi^2m_P^4\int_{\phi_+}^{\phi_0}(D+V_t')^2/(V_t^2D)d\phi $, where $D\equiv
[(V_t')^2+6(V-V_t)V_t/m_P^2]^{1/2}$, $V_t'=dV_t/d\phi$ and $m_P$ is the reduced
Planck mass. This one-line simple result applies equally to AdS, Minkowski or
dS vacua decays and reproduces the Hawking-Moss action in the appropriate
cases. This formalism provides new handles for the theoretical understanding of
different features of vacuum decay in the presence of gravity.
