com.squareup.rack.examples.dropwizard.ExampleService.java Source code

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Here is the source code for com.squareup.rack.examples.dropwizard.ExampleService.java

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/*
 * Copyright (C) 2013 Square, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.squareup.rack.examples.dropwizard;

import com.google.common.io.Resources;
import com.squareup.rack.examples.dropwizard.health.FakeHealthCheck;
import com.squareup.rack.examples.dropwizard.resources.EmptyResource;
import com.squareup.rack.jruby.JRubyRackApplication;
import com.squareup.rack.servlet.RackServlet;
import com.yammer.dropwizard.Service;
import com.yammer.dropwizard.config.Bootstrap;
import com.yammer.dropwizard.config.Configuration;
import com.yammer.dropwizard.config.Environment;
import java.io.IOException;
import org.jruby.embed.ScriptingContainer;
import org.jruby.runtime.builtin.IRubyObject;

import static com.google.common.base.Throwables.propagate;
import static com.google.common.io.Resources.getResource;
import static java.nio.charset.Charset.defaultCharset;

public class ExampleService extends Service<Configuration> {
    @Override
    public void initialize(Bootstrap<Configuration> bootstrap) {
        // Nothing to do here.
    }

    @Override
    public void run(Configuration config, Environment environment) {
        // Suppress the "THIS SERVICE HAS NO HEALTHCHECKS" warning.
        // A real service would have proper health checks.
        environment.addHealthCheck(new FakeHealthCheck());

        // Suppress the "ResourceConfig instance does not contain any root resource classes" error.
        // A real service would probably provide a Jersey resource or two.
        environment.addResource(EmptyResource.class);

        // Here's the interesting part:
        // Mount the Rack application defined in the config.ru file on the classpath at /rack.
        environment.addServlet(createRackServlet(), "/rack/*");
    }

    private RackServlet createRackServlet() {
        return new RackServlet(new JRubyRackApplication(createApplication()));
    }

    private IRubyObject createApplication() {
        // There's a lot you could do here; for now, we just read a rackup file from the classpath,
        // then build a Rack application based on it.
        ScriptingContainer container = new ScriptingContainer();
        container.put("builder_script", readResource("config.ru"));
        return container.parse("require 'rack'; Rack::Builder.new_from_string(builder_script)").run();
    }

    private String readResource(String path) {
        try {
            return Resources.toString(getResource(path), defaultCharset());
        } catch (IOException e) {
            throw propagate(e);
        }
    }
}