Distributed web crawling with browsers
Project description
“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 also uses youtube-dl to enhance media capture capabilities.
Brozzler is designed to work in conjunction with warcprox for web archiving.
Requirements
Python 3.4 or later
RethinkDB deployment
Chromium or Google Chrome browser
Worth noting is that the browser requires a graphical environment to run. You already have this on your laptop, but on a server it will probably require deploying some additional infrastructure (typically X11). The vagrant configuration in the brozzler repository (still a work in progress) has an example setup.
Getting Started
The easiest way to get started with brozzler for web archiving is with brozzler-easy. Brozzler-easy runs brozzler-worker, warcprox, pywb, and brozzler-webconsole, configured to work with each other, in a single process.
Mac instructions:
# install and start rethinkdb brew install rethinkdb 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 brozzling 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
Submit jobs:
brozzler-new-job myjob.yaml
Submit sites not tied to a job:
brozzler-new-site --proxy=localhost:8000 --enable-warcprox-features \ --time-limit=600 http://example.com/
Job Configuration
Jobs are defined using yaml files. Options may be specified either at the top-level or on individual seeds. A job id and at least one seed url must be specified, 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 enable_warcprox_features: 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 Web Console
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[webconsole]
To start the app, run
brozzler-webconsole
See brozzler-webconsole --help for configuration options.
Headless Chromium
Headless Chromium may optionally be used instead of Chromium or Chrome to run Brozzler without a visisble browser window or X11 server. At the time of writing headless_shell is a separate Linux-only executable and must be compiled from source. Beware that compiling Chromium requires 10 GB of disk space, several GB of RAM and patience.
Start by installing the dependencies listed in Chromium’s Linux-specific build instructions.
Next install the build tools and fetch the source code:
mkdir -p ~/chromium cd ~/chromium git clone https://chromium.googlesource.com/chromium/tools/depot_tools.git export $PATH=$PWD/depot_tools:$PATH fetch --no-history chromium --nosvn=True
Configure a headless release build (the debug builds are much larger):
cd src mkdir -p out/release echo 'import("//build/args/headless.gn")' > out/release/args.gn echo 'is_debug = false' >> out/release/args.gn gn gen out/release
Run the compile:
ninja -C out/release headless_shell
This will produce an out/release/headless_shell executable. Unfortunately this cannot be used with Brozzler as-is as the --window-size command-line option expects a different syntax in Headless Chromium. As a workaround create a wrapper shell script headless_chromium.sh which replaces the misbehaving option:
#!/bin/bash exec ~/chromium/src/out/release/headless_shell "${@//--window-size=1100,900/--window-size=1100x900}"
Run brozzler passing the path to the wrapper script as the --chrome-exe option:
chmod +x ~/bin/headless_chromium.sh brozzler-worker --chrome-exe ~/bin/headless_chromium.sh
The Pepper Flash plugin libpepflashplayer.so from an official Google Chrome release may be used with Headless Chromium by adding this option to the wrapper script:
--register-pepper-plugins=/opt/google/chrome/PepperFlash/libpepflashplayer.so;application/x-shockwave-flash
License
Copyright 2015-2016 Internet Archive
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.