Add logging to ci build script

ci/build-dependencies

@@ -4,24 +4,36 @@ CACHE_CLOSURE_FILE=/tmp/build-inputs.closure
 
 main() {
   cache_restore
-  cache_store "$(nix-build -A inputDerivation --no-link)"
+  cache_store "$(build_dependencies)"
 }
 
 cache_restore() {
+  echo '===> restoring from cache'
   cache restore "nix-$SEMAPHORE_GIT_BRANCH,nix-master,nix-store"
 
   if [[ -f $CACHE_CLOSURE_FILE ]]; then
+    echo "===> importing cached closure into the nix store"
     nix-store --import < $CACHE_CLOSURE_FILE
+  else
+    echo "===> cache did not contain a file called $CACHE_CLOSURE_FILE"
   fi
 }
 
+build_dependencies() {
+  echo '===> building dependencies'
+  nix-build -A inputDerivation --no-link
+}
+
 cache_store() {
   local deps_store_path=$1
 
   local cache_key
   cache_key="nix-$SEMAPHORE_GIT_BRANCH-$(output_hash "$deps_store_path")"
 
-  if ! cache has_key "$cache_key"; then
+  if cache has_key "$cache_key"; then
+    echo "===> cache already contains key $cache_key, nothing to do"
+  else
+    echo "===> caching store closure"
     nix-store --export "$(nix-store -qR "$deps_store_path")" > $CACHE_CLOSURE_FILE
     cache store "$cache_key" $CACHE_CLOSURE_FILE
   fi