avoid hard-coded /bin paths

based in part on #8 and addressing part of #10

default.nix

@@ -32,7 +32,9 @@ packs = import ./packs {
      etc.  These can be string paths to the system or to packages/environments
      from nixpkgs or similar, but regardless need to be external to nixpacks. */
   spackPython = "/usr/bin/python3";
-  spackPath = "/bin:/usr/bin";
+  spackEnv = {
+    PATH = "/bin:/usr/bin";
+  };
 
   /* packs can optionally include nixpkgs for additional packages or bootstrapping.
      omit to disable. */

fi/default.nix

@@ -33,7 +33,9 @@ corePacks = import ../packs {
     };
   };
   spackPython = "/usr/bin/python3";
-  spackPath = "/bin:/usr/bin";
+  spackEnv = {
+    PATH = "/bin:/usr/bin";
+  };
 
   nixpkgsSrc = {
     /* -------- upstream nixpkgs version -------- */

fi/lmod/builder.sh

@@ -1,7 +1,7 @@
 #!/bin/sh -eu
-/bin/mkdir -p $out
-/bin/ln -s $mod $out/modules.lua
+mkdir -p $out
+ln -s $mod $out/modules.lua
 # these are just temporary stubs until /etc/profile.d/modules.sh is updated everywhere:
 for f in setup.sh setup.csh ; do
-	/bin/cp $src/$f $out/$f
+	cp $src/$f $out/$f
 done

fi/lmod/default.nix

@@ -1,9 +1,9 @@
 gitrev: packs: mods:
 # this just wraps modules.nix in a directory/symlink layer for nix-env
-derivation {
+derivation (packs.spackEnv // {
   name = "lmodSite";
   inherit (mods) system;
   mod = import ./modules.nix gitrev packs mods;
   src = ./.;
   builder = ./builder.sh;
-}
+})

fi/lmod/modules.nix

@@ -1,10 +1,10 @@
 gitrev: packs: mods:
 # a simple modules.lua meta-module for adding modules
-derivation {
+derivation (packs.spackEnv // {
   name = "modules.lua";
   inherit (mods) system;
   mods = "${mods}/${packs.platform}-${packs.os}-${packs.target}";
   src = ./modules.lua;
   git = gitrev;
   builder = ./modules.sh;
-}
+})

packs/default.nix

@@ -60,7 +60,7 @@ prefsUpdate = let
       spackSrc = scalar;
       spackConfig = lib.recursiveUpdate;
       spackPython = scalar;
-      spackPath = scalar;
+      spackEnv = a: b: a // b;
       nixpkgsSrc = scalar;
       verbose = scalar;
       repoPatch = a: b: a // b;
@@ -77,7 +77,9 @@ packsWithPrefs =
   , spackSrc ? {}
   , spackConfig ? {}
   , spackPython ? "/usr/bin/python3"
-  , spackPath ? "/bin:/usr/bin"
+  , spackEnv ? {
+      PATH = "/bin:/usr/bin";
+    }
   , nixpkgsSrc ? null
   , repos ? [ ../spack/repo ]
   , repoPatch ? {}
@@ -99,22 +101,21 @@ lib.fix (packs: with packs; {
 
   makeSpackConfig = import ../spack/config.nix packs;
 
-  inherit spackPython spackPath;
+  inherit spackPython spackEnv;
   spackConfig = makeSpackConfig (lib.recursiveUpdate defaultSpackConfig packPrefs.spackConfig);
 
-  spackNixLib = derivation {
+  spackNixLib = derivation (spackEnv // {
     name = "nix-spack-py";
     inherit system;
     builder = ../spack/install.sh;
     src = ../spack/nixpack.py;
-  };
+  });
 
   /* common attributes for running spack */
-  spackBuilder = attrs: builtins.removeAttrs (derivation ({
+  spackBuilder = attrs: builtins.removeAttrs (derivation (spackEnv // {
     inherit (packs) system os spackConfig;
     builder = spackPython;
     PYTHONPATH = "${spackNixLib}:${spack}/lib/spack:${spack}/lib/spack/external";
-    PATH = spackPath;
     LC_ALL = "en_US.UTF-8"; # work around spack bugs processing log files
     repos = if attrs ? withRepos
       then if attrs.withRepos

packs/lmodCache.nix

@@ -1,10 +1,9 @@
 packs:
 src:
-derivation {
+derivation (packs.spackEnv // {
   inherit (packs) system;
   name = "lmodCache";
   builder = ./lmodCache.sh;
-  PATH = packs.spackPath;
   lmod = packs.pkgs.lmod;
   MODULEPATH = "${src}/${packs.platform}-${packs.os}-${packs.target}/Core";
-}
+})

spack/bin.sh

@@ -21,4 +21,4 @@ EOF
 
 }
 gen > $out
-/bin/chmod +x $out
+chmod +x $out

spack/config.nix

@@ -3,4 +3,5 @@ packs: config: derivation ({
   name = "spackConfig";
   builder = ./config.sh;
   sections = builtins.attrNames config;
-} // builtins.mapAttrs (n: v: builtins.toJSON { "${n}" = v; }) config)
+} // builtins.mapAttrs (n: v: builtins.toJSON { "${n}" = v; }) config
+  // packs.spackEnv)

spack/config.sh

@@ -1,6 +1,6 @@
 #!/bin/sh -eu
 
-/bin/mkdir -p $out
+mkdir -p $out
 for section in $sections ; do
 	eval "echo \"\$$section\"" > $out/$section.yaml
 done

spack/install.sh

@@ -1,3 +1,3 @@
 #!/bin/sh -e
-/bin/mkdir -p $out
-/bin/cp $src $out/nixpack.py
+mkdir -p $out
+cp $src $out/nixpack.py