passing grunt parameters from one task to another

Question

I'm trying to pass the configuration values returned from the server(zookeeper) into compass (cdnHost, environment, etc) and seem to be having a hard time using the right approach.

I looked at ways to pass around args from one task to another on this page as a starting point

http://gruntjs.com/frequently-asked-questions#how-can-i-share-parameters-across-multiple-tasks

module.exports = function(grunt) {
    grunt.initConfig({
        compass: {
            dist: {
                //options: grunt.option('foo')
                //options: global.bar
                options: grunt.config.get('baz')
            }
        },

    ...

    grunt.registerTask('compassWithConfig', 'Run compass with external async config loaded first', function () {
        var done = this.async();
        someZookeeperConfig( function () {
            // some global.CONFIG object from zookeeper
            var config = CONFIG;
            // try grunt.option
            grunt.option('foo', config);
            // try config setting
            grunt.config.set('bar', config);
            // try global
            global['baz'] = config;
            done(true);
        });
    });

    ...

    grunt.registerTask('default', ['clean', 'compassWithConfig', 'compass']);

I also tried calling the compass task directly, and it made no difference.

grunt.task.run('compass');

Any insights would be greatly appreciated. (e.g. way to use initConfig and have the value be available).

Thanks

Answer 1

When you write:

grunt.initConfig({
    compass: {
        dist: {
            options: grunt.config.get('baz')
        }
    }

... grunt.config is called right away, and returns the value of baz as it is right now. Altering it (later) in another task simply won't get picked-up.

How to solve that?

#1: update compass.dist.options instead of updating baz

grunt.registerTask('compassWithConfig', 'Run compass with external async config loaded first', function () {
    var done = this.async();
    someZookeeperConfig( function () {
        // some global.CONFIG object from zookeeper
        var config = CONFIG;
        grunt.config.set('compass.dist.options', config);
        done();
    });
});

Now, running task compassWithConfig first, then task compass will get the result you expect.

#2: wrap-up compass task execution in order to abstract away config mapping

grunt.registerTask('wrappedCompass', '', function () {
    grunt.config.set('compass.dist.options', grunt.config.get('baz'));
    grunt.task.run('compass');
});

// Then, you can manipulate 'baz' without knowing how it needs to be mapped for compass

grunt.registerTask('globalConfigurator', '', function () {
    var done = this.async();
    someZookeeperConfig( function () {
        // some global.CONFIG object from zookeeper
        var config = CONFIG;
        grunt.config.set('baz', config);
        done();
    });
});

Finally, running task globalConfigurator then wrappedCompass will get you to the result.