build.gradle

plugins {
    id "com.jfrog.bintray" version "1.1"
    id "com.github.jruby-gradle.base" version "0.1.5"
    id "java"
}
import com.github.jrubygradle.JRubyExec
repositories {
    mavenCentral()
    jcenter()
}
configurations {
    provided
}

version = "0.1.0"

dependencies {
    compile  "org.embulk:embulk-core:0.4.9"
    provided "org.embulk:embulk-core:0.4.9"
    compile("com.google.apis:google-api-services-storage:v1-rev27-1.19.1") { exclude module: 'guava-jdk5' }
    testCompile "junit:junit:4.+"
}

task classpath(type: Copy, dependsOn: ["jar"]) {
    doFirst { file("classpath").deleteDir() }
    from (configurations.runtime - configurations.provided + files(jar.archivePath))
    into "classpath"
}
clean { delete 'classpath' }

task gem(type: JRubyExec, dependsOn: ["build", "gemspec", "classpath"]) {
    jrubyArgs "-rrubygems/gem_runner", "-eGem::GemRunner.new.run(ARGV)", "build"
    script "build/gemspec"
    doLast { ant.move(file: "${project.name}-${project.version}.gem", todir: "pkg") }
}

task gemspec << { file("build/gemspec").write($/
Gem::Specification.new do |spec|
  spec.name          = "${project.name}"
  spec.version       = "${project.version}"
  spec.authors       = ["Sadayuki Furuhashi"]
  spec.summary       = %[Gapi input plugin for Embulk]
  spec.description   = %["Loads records from Gapi."]
  spec.email         = ["frsyuki@gmail.com"]
  spec.licenses      = ["MIT"]
  # TODO: spec.homepage      = "https://github.com/frsyuki/embulk-input-gapi"

  spec.files         = `git ls-files`.split("\n") + Dir["classpath/*.jar"]
  spec.test_files    = spec.files.grep(%r"^(test|spec)/")
  spec.require_paths = ["lib"]

  #spec.add_dependency 'YOUR_GEM_DEPENDENCY', ['~> YOUR_GEM_DEPENDENCY_VERSION']
  spec.add_development_dependency 'bundler', ['~> 1.0']
  spec.add_development_dependency 'rake', ['>= 10.0']
end
/$)
}

GapiInputPlugin.java

package org.embulk.input;

import java.util.List;
import java.util.ArrayList;
import com.google.common.base.Optional;
import org.embulk.config.CommitReport;
import org.embulk.config.Config;
import org.embulk.config.ConfigDefault;
import org.embulk.config.ConfigDiff;
import org.embulk.config.ConfigSource;
import org.embulk.config.Task;
import org.embulk.config.TaskSource;
import org.embulk.spi.Exec;
import org.embulk.spi.InputPlugin;
import org.embulk.spi.PageOutput;
import org.embulk.spi.Schema;
import org.embulk.spi.Column;
import org.embulk.spi.SchemaConfig;

public class GapiInputPlugin
        implements InputPlugin
{
    public interface PluginTask
            extends Task
    {
        @Config("last_path")
        @ConfigDefault("null")
        public Optional<String> getLastPath();
    }

    public ConfigDiff transaction(ConfigSource config,
            InputPlugin.Control control)
    {
        PluginTask task = config.loadConfig(PluginTask.class);

        Schema schema = new Schema(new ArrayList<Column>());
        int taskCount = 1;  // number of run() method calls

        return resume(task.dump(), schema, taskCount, control);
    }

    public ConfigDiff resume(TaskSource taskSource,
            Schema schema, int taskCount,
            InputPlugin.Control control)
    {
        control.run(taskSource, schema, taskCount);
        return Exec.newConfigDiff();
    }

    public void cleanup(TaskSource taskSource,
            Schema schema, int taskCount,
            List<CommitReport> successCommitReports)
    {
    }

    public CommitReport run(TaskSource taskSource,
            Schema schema, int taskIndex,
            PageOutput output)
    {
        PluginTask task = taskSource.loadTask(PluginTask.class);

        // TODO
        throw new UnsupportedOperationException("The 'run' method needs to be implemented");
    }
}