brozzler

Distributed web crawling with browsers

Project description

brozzler

“browser” | “crawler” = “brozzler”

Brozzler is a distributed web crawler (爬虫) that uses a real browser (Chrome or Chromium) to fetch pages and embedded URLs and to extract links. It employs youtube-dl to enhance media capture capabilities and rethinkdb to manage crawl state.

Brozzler is designed to work in conjuction with warcprox for web archiving.

Requirements

Python 3.4 or later
RethinkDB deployment
Chromium or Google Chrome >= version 64

Note: The browser requires a graphical environment to run. When brozzler is run on a server, this may require deploying some additional infrastructure, typically X11. Xvnc4 and Xvfb are X11 variants that are suitable for use on a server, because they don’t display anything to a physical screen. The vagrant configuration in the brozzler repository has an example setup using Xvnc4. (When last tested, chromium on Xvfb did not support screenshots, so Xvnc4 is preferred at this time.)

Getting Started

The easiest way to get started with brozzler for web archiving is with brozzler-easy. Brozzler-easy runs brozzler-worker, warcprox, brozzler wayback, and brozzler-dashboard, configured to work with each other in a single process.

Mac instructions:

# install and start rethinkdb
brew install rethinkdb
# no brew? try rethinkdb's installer: https://www.rethinkdb.com/docs/install/osx/
rethinkdb &>>rethinkdb.log &

# install brozzler with special dependencies pywb and warcprox
pip install brozzler[easy]  # in a virtualenv if desired

# queue a site to crawl
brozzler-new-site http://example.com/

# or a job
brozzler-new-job job1.yml

# start brozzler-easy
brozzler-easy

At this point brozzler-easy will start archiving your site. Results will be immediately available for playback in pywb at http://localhost:8880/brozzler/.

Brozzler-easy demonstrates the full brozzler archival crawling workflow, but does not take advantage of brozzler’s distributed nature.

Installation and Usage

To install brozzler only:

pip install brozzler  # in a virtualenv if desired

Launch one or more workers: [*]

brozzler-worker --warcprox-auto

Submit jobs:

brozzler-new-job myjob.yaml

Submit sites not tied to a job:

brozzler-new-site --time-limit=600 http://example.com/

[*] A note about --warcprox-auto: this option tells brozzler to look for a healthy warcprox instance in the rethinkdb service registry. For this to work you need to have at least one instance of warcprox running, with the --rethinkdb-services-url option pointing to the same rethinkdb services table that brozzler is using. Using --warcprox-auto is recommended for clustered deployments.

Job Configuration

Brozzler jobs are defined using YAML files. Options may be specified either at the top-level or on individual seeds. At least one seed URL must be specified, however everything else is optional. For details, see job-conf.rst.

id: myjob
time_limit: 60 # seconds
proxy: 127.0.0.1:8000 # point at warcprox for archiving
ignore_robots: false
warcprox_meta: null
metadata: {}
seeds:
  - url: http://one.example.org/
  - url: http://two.example.org/
    time_limit: 30
  - url: http://three.example.org/
    time_limit: 10
    ignore_robots: true
    scope:
      surt: http://(org,example,

Brozzler Dashboard

Brozzler comes with a rudimentary web application for viewing crawl job status. To install the brozzler with dependencies required to run this app, run

pip install brozzler[dashboard]

To start the app, run

brozzler-dashboard

At this point Brozzler Dashboard will be accessible at http://localhost:8000/.

See brozzler-dashboard --help for configuration options.

Brozzler Wayback

Brozzler comes with a customized version of pywb, which supports using the rethinkdb “captures” table (populated by warcprox) as its index.

To use, first install dependencies.

pip install brozzler[easy]

Write a configuration file pywb.yml.

# 'archive_paths' should point to the output directory of warcprox
archive_paths: warcs/  # pywb will fail without a trailing slash
collections:
  brozzler:
    index_paths: !!python/object:brozzler.pywb.RethinkCDXSource
      db: brozzler
      table: captures
      servers:
      - localhost
enable_auto_colls: false
enable_cdx_api: true
framed_replay: true
port: 8880

Run pywb like so:

$ PYWB_CONFIG_FILE=pywb.yml brozzler-wayback

Then browse http://localhost:8880/brozzler/.

Headless Chrome (experimental)

Brozzler is known to work nominally with Chrome/Chromium in headless mode, but this has not yet been extensively tested.

License

Licensed under the Apache License, Version 2.0 (the “License”); you may not use this software 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.