Docker: Install `dnsutils` in Debian Stretch
This update should fix the following Cabal warning:
> Warning: 'nslookup' tool missing - can't locate mirrors
.
@@ -74,6 +74,7 @@ RUN apt-get update \
lcov \
valgrind \
ed \
+ dnsutils \
&& rm -rf /var/lib/apt/lists/*
RUN cabal update && cabal install hspec QuickCheck
