Scrapy Cluster

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This Scrapy project uses Redis and Kafka to create a distributed on demand scraping cluster.

The goal is to distribute seed URLs among many waiting spider instances, whose requests are coordinated via Redis. Any other crawls those trigger, as a result of frontier expansion or depth traversal, will also be distributed among all workers in the cluster.

The input to the system is a set of Kafka topics and the output is a set of Kafka topics. Raw HTML and assets are crawled interactively, spidered, and output to the log. For easy local development, you can also disable the Kafka portions and work with the spider entirely via Redis, although this is not recommended due to the serialization of the crawl requests.

Dependencies

Please see the requirements.txt within each sub project for Pip package dependencies.

Other important components required to run the cluster

Core Concepts

This project tries to bring together a bunch of new concepts to Scrapy and large scale distributed crawling in general. Some bullet points include:

Scrapy Cluster test environment

To set up a pre-canned Scrapy Cluster test environment, make sure you have the latest Virtualbox + Vagrant >= 1.7.4 installed. Vagrant will automatically mount the base scrapy-cluster directory to the /vagrant directory, so any code changes you make will be visible inside the VM. Please note that at time of writing this will not work on a Windows machine.

Steps to launch the test environment:

  1. vagrant up in base scrapy-cluster directory.
  2. vagrant ssh to ssh into the VM.
  3. sudo supervisorctl status to check that everything is running.
  4. virtualenv sc to create a virtual environment
  5. source sc/bin/activate to activate the virtual environment
  6. cd /vagrant to get to the scrapy-cluster directory.
  7. pip install -r requirements.txt to install Scrapy Cluster dependencies.
  8. ./run_offline_tests.sh to run offline tests.
  9. ./run_online_tests.sh to run online tests (relies on kafka, zookeeper, redis).

Documentation

Please check out the official Scrapy Cluster 1.2.1 documentation for more information on how everything works!

Branches

The master branch of this repository contains the latest stable release code for Scrapy Cluster 1.2.1.

The dev branch contains bleeding edge code and is currently working towards Scrapy Cluster 1.3. Please note that not everything may be documented, finished, tested, or finalized but we are happy to help guide those who are interested.