Move dependency dir out of project directory (#12)

This means that sbt can be used anywhere in the source tree and will
always be able to find its dependencies.

README.md

@@ -219,7 +219,7 @@ If you're not ready to migrate, the previous version is kept in a branch called
 
 ### Changed behaviour
 - `postConfigure` will now run after extracting the dependencies (was running before). The whole configure phase is used to extract the dependencies.
-- The dependencies are no longer stored in a `.nix` directory, but rather in the default locations provided by sbt in `--no-share` mode.
+- The dependencies are no longer stored in a `.nix` directory, but rather in a temporary global directory mirroring the structure used by sbt in `--no-share` mode.
 - `overrideDepsAttrs` now takes two parameters, `final` and `prev`, instead of just `prev`.
 
 ### New options

lib/archival-strategies.nix

@@ -9,7 +9,7 @@
     fileExtension = "";
     packerFragment = ''
       mkdir -p $out
-      cp -ar project/{.sbtboot,.boot,.ivy,.coursier} $out
+      cp -ar $SBT_DEPS/project/. $out
     '';
   };
 in {
@@ -20,7 +20,7 @@ in {
     packerFragment = ''
       tar --owner=0 --group=0 --numeric-owner --format=gnu \
         --sort=name --mtime="@$SOURCE_DATE_EPOCH" \
-        -C project -cf "$out" .sbtboot .boot .ivy .coursier
+        -C $SBT_DEPS/project -cf $out .
     '';
     extractorFragment = deps: ''
       tar -C "$target/project" -xpf ${deps}
@@ -34,7 +34,7 @@ in {
       tar --owner=0 --group=0 --numeric-owner --format=gnu \
         --sort=name --mtime="@$SOURCE_DATE_EPOCH" \
         -I 'zstd -c --fast=3 -' \
-        -C project -cf "$out" .sbtboot .boot .ivy .coursier
+        -C $SBT_DEPS/project -cf $out .
     '';
     extractorFragment = deps: ''
       tar -I zstd -C "$target/project" -xpf ${deps}
@@ -53,7 +53,6 @@ in {
     // {
       nativeBuildInputs = [stow];
       extractorFragment = deps: ''
-        mkdir -p "$target/project"
         stow -t "$target/project" -d ${builtins.dirOf deps} --no-folding ${builtins.baseNameOf deps}
       '';
     };

lib/dependencies.nix

@@ -13,7 +13,7 @@
   writeShellScript,
 }: {
   namePrefix,
-  sbtEnv,
+  sbtEnvSetupCmds,
   src,
   patches ? [],
   sha256,
@@ -25,8 +25,7 @@
 } @ args: let
   archivalStrategy = (callPackage ./archival-strategies.nix {}).${args.archivalStrategy};
 
-  mkAttrs = drv: (sbtEnv
-    // {
+  mkAttrs = drv: ({
       inherit src patches;
 
       name = namePrefix + archivalStrategy.fileExtension;
@@ -49,6 +48,8 @@
       buildPhase = ''
         runHook preBuild
 
+        ${sbtEnvSetupCmds}
+
         echo "running:"
         ${let
           matches = builtins.match ''
@@ -63,32 +64,31 @@
         ${warmupCommand}
 
         echo "stripping out comments containing dates"
-        find project -name '*.properties' -type f -exec sed -i '/^#/d' {} \;
+        find $SBT_DEPS/project -name '*.properties' -type f -exec sed -i '/^#/d' {} \;
 
         echo "removing non-reproducible accessory files"
-        find project -name '*.lock' -type f -print0 | xargs -r0 rm -rfv
-        find project -name '*.log' -type f -print0 | xargs -r0 rm -rfv
+        find $SBT_DEPS/project -name '*.lock' -type f -print0 | xargs -r0 rm -rfv
+        find $SBT_DEPS/project -name '*.log' -type f -print0 | xargs -r0 rm -rfv
 
         echo "fixing-up the compiler bridge and interface"
-        find project -name 'org.scala-sbt-compiler-bridge_*' -type f -print0 | xargs -r0 strip-nondeterminism
-        find project -name 'org.scala-sbt-compiler-interface_*' -type f -print0 | xargs -r0 strip-nondeterminism
+        find $SBT_DEPS/project -name 'org.scala-sbt-compiler-bridge_*' -type f -print0 | xargs -r0 strip-nondeterminism
+        find $SBT_DEPS/project -name 'org.scala-sbt-compiler-interface_*' -type f -print0 | xargs -r0 strip-nondeterminism
 
         echo "removing runtime jar"
-        find project -name rt.jar -delete
+        find $SBT_DEPS/project -name rt.jar -delete
 
         echo "removing empty directories"
-        find project -type d -empty -delete
+        find $SBT_DEPS/project -type d -empty -delete
 
         runHook postBuild
       '';
 
       installPhase = ''
         runHook preInstall
 
-        mkdir -p project/{.sbtboot,.boot,.ivy,.coursier}
         ${lib.optionalString optimize ''
-          ${rdfind}/bin/rdfind -makesymlinks true -outputname /dev/null project/{.coursier,.ivy,.boot,.sbtboot}
-          ${symlinks}/bin/symlinks -rc project
+          ${rdfind}/bin/rdfind -makesymlinks true -outputname /dev/null $SBT_DEPS/project/{.sbtboot,.boot,.ivy,.coursier}
+          ${symlinks}/bin/symlinks -rc $SBT_DEPS/project
         ''}
         ${archivalStrategy.packerFragment}
 
@@ -108,6 +108,7 @@
         target="$1"
 
         echo "extracting dependencies in $target"
+        mkdir -p "$target/project"
 
         start="$(date +%s.%N)"
         ${archivalStrategy.extractorFragment drv}

lib/sbt-derivation.nix

@@ -34,15 +34,20 @@
   drvAttrs =
     removeAttrs args ["overrideDepsAttrs" "depsSha256" "depsWarmupCommand" "depsPackingStrategy" "depsOptimize"];
 
-  depsDir = ".nix";
-
-  sbtEnv = {
-    SBT_OPTS = (args.SBT_OPTS or "") + " --no-share";
-    COURSIER_CACHE = "project/.coursier";
-  };
+  # create a random temporary directory and configure sbt using environment
+  # variables to use directories within it as a cache dir. we use the "project"
+  # subdirectory so that all the dependencies can be extracted to the directory
+  # with build.sbt and sbt will use them in --no-share mode, if the user finds
+  # this convenient for testing.
+  sbtEnvSetupCmds = ''
+    export SBT_DEPS=$(mktemp -d)
+    export SBT_OPTS="-Dsbt.global.base=$SBT_DEPS/project/.sbtboot -Dsbt.boot.directory=$SBT_DEPS/project/.boot -Dsbt.ivy.home=$SBT_DEPS/project/.ivy $SBT_OPTS"
+    export COURSIER_CACHE=$SBT_DEPS/project/.coursier
+    mkdir -p $SBT_DEPS/project/{.sbtboot,.boot,.ivy,.coursier}
+  '';
 
   dependencies = (callPackage ./dependencies.nix {}) {
-    inherit src patches nativeBuildInputs sbtEnv;
+    inherit src patches nativeBuildInputs sbtEnvSetupCmds;
 
     namePrefix = "${pname}-sbt-dependencies";
     sha256 = depsSha256;
@@ -52,8 +57,7 @@
     overrideAttrs = overrideDepsAttrs;
   };
 in
-  stdenv.mkDerivation (sbtEnv
-    // drvAttrs
+  stdenv.mkDerivation (drvAttrs
     // {
       nativeBuildInputs = [sbt] ++ nativeBuildInputs;
 
@@ -62,7 +66,8 @@ in
       configurePhase = ''
         runHook preConfigure
 
-        ${dependencies.extractor} .
+        ${sbtEnvSetupCmds}
+        ${dependencies.extractor} $SBT_DEPS
 
         runHook postConfigure
       '';