  Nearby type Ia supernovae (SNe Ia), such as SN 2017cbv, are useful events to
address the question of what the elusive progenitor systems of the explosions
are. Hosseinzadeh et al. (2017) suggested that the early blue excess of the
lightcurve of SN 2017cbv could be due to the supernova ejecta interacting with
a non-degenerate companion star. Some SN Ia progenitor models suggest the
existence of circumstellar (CS) environments in which strong outflows create
low density cavities of different radii. Matter deposited at the edges of the
cavities, should be at distances at which photoionisation due to early
ultraviolet (UV) radiation of SNe Ia causes detectable changes to the
observable Na I D and Ca II H&K absorption lines. To study possible narrow
absorption lines from such material, we obtained a time-series of
high-resolution spectra of SN 2017cbv at phases between $-14.8$ and $+83$ days
with respect to $B$-band maximum, covering the time at which photoionisation is
predicted to occur. Both narrow Na I D and Ca II H&K are detected in all
spectra, with no measurable changes between the epochs. We use photoionisation
models to rule out the presence of Na I and Ca II gas clouds along the
line-of-sight of SN 2017cbv between $\sim8\times10^{16}$--$2\times10^{19}$~cm
and $\sim10^{15}$--$10^{17}$~cm, respectively. Assuming typical abundances, the
mass of a homogenous spherical CS gas shell with radius $R$ must be limited to
$M^{\rm CSM}_{\rm HI}<3\times10^{-4}\times(R/10^{17}[{\rm cm}])^2$ M$_{\odot}$.
The bounds point to progenitor models that deposit little gas in their CS
environment.
