Grunt create war file using compress and rename.

Gruntfile.js

var app = {
  build: 'build',
  root: '',
  dist: 'build/dist'
};

grunt.initConfig({
  app: app,
  //create a war file in zip format. compress does not support it currently.
  compress: {
    war: {
      options: {
          archive: '<%=app.build%>/app.war.zip'
      },
      files: [
          {expand: true, cwd: '<%=app.root%>', src: ['WEB-INF/web.xml'], dest: ''},
          {expand: true, cwd: '<%=app.dist%>', src: ['**/*'], dest: ''}
      ]
    }
  },
  //rename war.zip to war
  rename: {
      war: {
          files: [
              {src: ['<%=app.build%>/app.war.zip'], dest: '<%=app.build%>/app.war'}
          ]
      }
  }
});
grunt.loadNpmTasks('grunt-contrib-compress');
grunt.loadNpmTasks('grunt-contrib-rename');

grunt.registerTask('war', ['compress:war', 'rename:war']);

//run grunt war