brozzler/README.rst

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===============
"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 <https://github.com/rg3/youtube-dl>`_ to enhance media
capture capabilities.

Brozzler is designed to work in conjunction with
`warcprox <https://github.com/internetarchive/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 <https://github.com/ikreymer/pywb>`_, 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 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 --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/

Job Configuration
-----------------

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,
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

See ``brozzler-dashboard --help`` for configuration options.

Brozzler Wayback
----------------

Brozzler comes with a customized version of
`pywb <https://github.com/ikreymer/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)
--------------------------------

`Headless Chromium <https://chromium.googlesource.com/chromium/src/+/master/headless/README.md>`_
is now available in stable Chrome releases for 64-bit Linux and may be
used to run the browser without a visibe window or X11 at all.

To try this out, create a wrapper script like ~/bin/chrome-headless.sh:

::

    #!/bin/bash
    exec /opt/google/chrome/chrome --headless --disable-gpu "$@"

Run brozzler passing the path to the wrapper script as the ``--chrome-exe``
option:

::

    chmod +x ~/bin/chrome-headless.sh
    brozzler-worker --chrome-exe ~/bin/chrome-headless.sh

Beware: Chrome's headless mode is still very new and has a number of
`unresolved issues. <https://bugs.chromium.org/p/chromium/issues/list?can=2&q=Proj%3DHeadless>`_
You may experience hangs or crashes with some types of content. Brozzler
has not had much testing with it. For the moment we recommend using
Chrome's regular mode instead.

License
-------

Copyright 2015-2017 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.