rely on depsSha256 instead of a hack

Author: manveru

nix/mantis.nix

@@ -14,6 +14,7 @@
 , substituteAll
 , writeBashBinChecked
 , mantis-extvm-pb
+, depsSha256
 }:
 
 let
@@ -66,10 +67,20 @@ in sbt.mkDerivation rec {
   # This sha represents the change dependencies of mantis.
   # Update this sha whenever you change the dependencies using the
   # update-nix.sh script
-  depsSha256 = "sha256-csNBHVOC2bNSOjLjWleiVeS5ts3qFS7V8DxBv2nVDqE=";
+  inherit depsSha256;
 
   # this is the command used to to create the fixed-output-derivation
-  depsWarmupCommand = "PROTOC_CACHE=.nix/protoc-cache; HOME=$TMPDIR; PATH=${PATH}:$PATH; sbt clean; sbt compile --debug";
+  depsWarmupCommand = ''
+    export PROTOC_CACHE=.nix/protoc-cache
+    export HOME="$TMPDIR"
+    export PATH="${PATH}:$PATH"
+
+    mkdir -p src/main/protobuf/extvm
+    cp ${mantis-extvm-pb}/msg.proto src/main/protobuf/extvm/msg.proto
+
+    sbt clean
+    sbt compile --debug
+  '';
 
   installPhase = ''
     sbt stage

nix/overlay.nix

@@ -3,24 +3,18 @@ rev: final: prev: {
 
   mantis = final.callPackage ./mantis.nix {
     src = ../.;
+    depsSha256 = "sha256-csNBHVOC2bNSOjLjWleiVeS5ts3qFS7V8DxBv2nVDqE=";
   };
 
-  mantis-hash = { ref, rev }:
-    (final.callPackage ./mantis.nix {
-      src = builtins.fetchGit {
-        url = "https://github.com/input-output-hk/mantis";
-        inherit rev ref;
-      };
-    }).overrideAttrs (_: {
-      outputHash = "sha256-0000000000000000000000000000000000000000000=";
-      outputHashMode = "recursive";
-    });
+  mantis-hash = final.mantis.override {
+    depsSha256 = "sha256-0000000000000000000000000000000000000000000=";
+  };
 
   # Last change to this was in 2018, so to avoid submodules we just clone
   # ourselves instead.
   mantis-extvm-pb = builtins.fetchGit {
     url = "https://github.com/input-output-hk/mantis-extvm-pb";
-    rev =  "53eb31f3c59f7200994915b834e626bd292df7ed";
+    rev = "53eb31f3c59f7200994915b834e626bd292df7ed";
   };
 
   writeBashChecked = final.writers.makeScriptWriter {

update-nix.sh

@@ -21,46 +21,39 @@ fi
 
 echo "Determining new sha for sbt build, this can take several minutes to do a 'sbt compile'"
 
-branch="$(git rev-parse --abbrev-ref HEAD)"
-revision="$(git rev-parse HEAD)"
+current_sha=$(nix eval --raw '.#mantis.deps.outputHash')
 
 output="$(
 nix build \
   --impure \
-  --expr "
-    (builtins.getFlake (toString ./.)).legacyPackages.x86_64-linux.mantis-hash {
-      ref = \"${branch}\";
-      rev = \"${revision}\";
-    }
-  " 2>&1 || true
+  --expr "(builtins.getFlake (toString ./.)).legacyPackages.x86_64-linux.mantis-hash" \
+  2>&1 || true
 )"
 
-NEW_SHA=$(
-echo "$output" \
-  | awk '/^\s+got: / { print $2 }'
-)
+new_sha="$(echo "$output" | awk '/^\s*got: / { print $2 }')"
+current_sha=$(nix eval --raw '.#mantis.deps.outputHash')
 
-if [ -z "$NEW_SHA" ]; then
+if [ -z "$new_sha" ]; then
   echo "$output"
   echo "calculating hash failed!"
   exit 1
 fi
 
-echo "Calculated sha: $NEW_SHA"
+echo "Calculated sha: $new_sha"
 
 update_sha() {
-  echo "Updating sha in ./nix/mantis.nix"
-  sed -r -i -e "s|depsSha256 = \"[^\"]+\";|depsSha256 = \"${NEW_SHA}\";|" ./nix/mantis.nix
-  echo "./nix/mantis.nix has been updated"
+  echo "Updating sha in ./nix/overlay.nix"
+  sed -i "s|depsSha256 = \"$current_sha\";|depsSha256 = \"$new_sha\";|" nix/overlay.nix
+  echo "./nix/overlay.nix has been updated"
 }
 
 if [ $# == 1 ] || [ "${1:-}" == "--check" ]; then
-  current_sha=$(grep depsSha256 ./nix/mantis.nix | sed 's/\s*depsSha256\s*=\s*//g' | sed -e 's/"//g' -e 's/;//g' | xargs nix-hash --to-base32 --type sha256 )
-  if [ "$current_sha" == "$NEW_SHA" ]; then
-    echo "./nix/mantis.nix is up-to-date"
+  current_sha=$(nix eval --raw '.#mantis.deps.outputHash')
+  if [ "$current_sha" == "$new_sha" ]; then
+    echo "./nix/overlay.nix is up-to-date"
     exit 0
   else
-    echo "wanted: $NEW_SHA"
+    echo "wanted: $new_sha"
     echo "   got: $current_sha"
     update_sha
     exit 1