What libraries are needed for spark?

I want to be able to read and write to ES from spark. I've created a elasticsearch-hadoop-with-dependencies library but it's 188Mb!

I've stripped out some stuff that I don't think I need - see my gradle configuration below. What else can be removed?

dependencies {
    // the elastic search library
    compile('org.elasticsearch:elasticsearch-hadoop:2.3.0') {
        // FIXME: there was an issue zipping up this library so excluding it
        exclude group: 'org.apache.curator', module: 'apache-curator'

// create jar file with all dependencies
task('SetupElasticSearchLibs', type: Jar) {
    baseName = 'elastic-search-with-dependencies'
    from {
        configurations.compile.filter( {
                                        !(it.name =~ /spark.*\.jar/ ) &&
                                        !(it.name =~ /jetty-all.*\.jar/ ) &&
                                        !(it.name =~ /servlet-api.*\.jar/ ) &&
                                        !(it.name =~ /pig.*\.jar/ )
                                    }).collect {
            println it
            it.isDirectory() ? it : zipTree(it)
    zip64 = true
    with jar

es-hadoop by itself doesn't require any libraries - it is designed to reuse the ones available in Hadoop and Spark at runtime. Take a look at the docs or better yet, the POM in particular the dependencies scope (which are provided).
In your case, through gradle, you are getting Hadoop and Spark in your uber jar which is really unnecessary.