Add buildMaven

pkgs/build-support/build-maven.nix

@@ -0,0 +1,58 @@
+{ stdenv, maven, runCommand, writeText, fetchurl, lib }:
+/* Takes an info file generated by mvn2nix
+ * (https://github.com/shlevy/mvn2nix-maven-plugin) and builds the maven
+ * project with it.
+ *
+ * repo: A local maven repository with the project's dependencies.
+ *
+ * settings: A settings.xml to pass to maven to use the repo.
+ *
+ * build: A simple build derivation that uses mvn compile and package to build
+ *        the project.
+ */
+infoFile: let
+  info = builtins.fromJSON (builtins.readFile infoFile);
+
+  repo = runCommand "maven-repository" {} ''
+    ${lib.concatStrings (map (dep: let
+      inherit (dep) url sha1 groupId artifactId version;
+
+      fetch = fetchurl { inherit url sha1; };
+    in ''
+      dir=$out/$(echo ${groupId} | sed 's|\.|/|g')/${artifactId}/${version}
+      mkdir -p $dir
+      ln -sv ${fetch} $dir/${fetch.name}
+    '') info.dependencies)}
+  '';
+
+  settings = writeText "settings.xml" ''
+    <settings xmlns="http://maven.apache.org/SETTINGS/1.0.0"
+      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+      xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.0.0
+                          http://maven.apache.org/xsd/settings-1.0.0.xsd">
+      <localRepository>${repo}</localRepository>
+    </settings>
+  '';
+
+  src = dirOf infoFile;
+in {
+  inherit repo settings;
+
+  build = stdenv.mkDerivation {
+    name = "${info.project.artifactId}-${info.project.version}.jar";
+
+    src = builtins.filterSource (path: type:
+      (toString path) != (toString (src + "/target")) &&
+        (toString path) != (toString (src + "/.git"))
+    ) src;
+
+    buildInputs = [ maven ];
+
+    buildPhase = "mvn --offline --settings ${settings} compile";
+
+    installPhase = ''
+      mvn --offline --settings ${settings} package
+      mv target/*.jar $out
+    '';
+  };
+}

pkgs/top-level/all-packages.nix

@@ -280,6 +280,8 @@ let
     runScript = args.runScript;
   };
 
+  buildMaven = callPackage ../build-support/build-maven.nix {};
+
   dotnetenv = import ../build-support/dotnetenv {
     inherit stdenv;
     dotnetfx = dotnetfx40;