Use the geodesic Lagrangian
where here the overdot on a coordinate means differentiation with respect to the affine parameter. Applying the Euler-Lagrange equation to each coordinate and comparing with the geodesic equation
determines the Christoffel symbols. To display derivatives of the metric coefficients unambiguously, write , , and similarly for . The nonzero symbols, together with those obtained by symmetry in the two lower indices, are
This is the Christoffel symbols of a diagonal spherical spacetime metric.