This library provides a fast, standalone way to read and write WARC Format commonly used in web archives. Supports Python 2.7+ and Python 3.4+ (using six, the only external dependency)
warcio supports reading and writing of WARC files compliant with both the WARC 1.0 and WARC 1.1 ISO standards.
Install with: pip install warcio
This library is a spin-off of the WARC reading and writing component of the pywb high-fidelity replay library, a key component of Webrecorder
The library is designed for fast, low-level access to web archival content, oriented around a stream of WARC records rather than files.
A key feature of the library is to be able to iterate over a stream of
WARC records using the ArchiveIterator.
It includes the following features:
- Reading a WARC 1.0, WARC 1.1 or ARC stream
- On the fly ARC to WARC record conversion
- Decompressing and de-chunking HTTP payload content stored in WARC/ARC files.
For example, the following prints the the url for each WARC response
record:
from warcio.archiveiterator import ArchiveIterator
with open('path/to/file', 'rb') as stream:
for record in ArchiveIterator(stream):
if record.rec_type == 'response':
print(record.rec_headers.get_header('WARC-Target-URI'))The stream object could be a file on disk or a remote network stream.
The ArchiveIterator reads the WARC content in a single pass. The
record is represented by an ArcWarcRecord object which contains
the format (ARC or WARC), record type, the record headers, http headers
(if any), and raw stream for reading the payload.
class ArcWarcRecord(object):
def __init__(self, *args):
(self.format, self.rec_type, self.rec_headers, self.raw_stream,
self.http_headers, self.content_type, self.length) = argsThe raw_stream can be used to read the rest of the payload directly.
A special ArcWarcRecord.content_stream() function provides a stream that
automatically decompresses and de-chunks the HTTP payload, if it is
compressed and/or transfer-encoding chunked.
The library provides support for reading (but not writing ARC) files.
The ARC format is legacy but is important to support in a consistent
matter. The ArchiveIterator can equally iterate over ARC and WARC
files to emit ArcWarcRecord objects. The special arc2warc option
converts ARC records to WARCs on the fly, allowing for them to be
accessed using the same API.
(Special WARCIterator and ARCIterator subclasses of ArchiveIterator
are also available to read only WARC or only ARC files).
For example, here is a snippet for reading an ARC and a WARC using the same API.
The example streams a WARC and ARC file over HTTP using
requests, printing the
warcinfo record (or ARC header) and any response records (or all ARC
records) that contain HTML:
import requests
from warcio.archiveiterator import ArchiveIterator
def print_records(url):
resp = requests.get(url, stream=True)
for record in ArchiveIterator(resp.raw, arc2warc=True):
if record.rec_type == 'warcinfo':
print(record.raw_stream.read())
elif record.rec_type == 'response':
if record.http_headers.get_header('Content-Type') == 'text/html':
print(record.rec_headers.get_header('WARC-Target-URI'))
print(record.content_stream().read())
print('')
# WARC
print_records('https://archive.org/download/ExampleArcAndWarcFiles/IAH-20080430204825-00000-blackbook.warc.gz')
# ARC with arc2warc
print_records('https://archive.org/download/ExampleArcAndWarcFiles/IAH-20080430204825-00000-blackbook.arc.gz')Starting with 1.6, warcio introduces a way to capture HTTP/S traffic directly
to a WARC file, by monkey-patching Python's http.client library.
This approach works well with the popular requests library often used to fetch
HTTP/S content. Note that requests must be imported after the capture_http module.
Fetching the url https://example.com/ while capturing the response and request
into a gzip compressed WARC file named example.warc.gz can be done with the following four lines:
from warcio.capture_http import capture_http
import requests # requests must be imported after capture_http
with capture_http('example.warc.gz'):
requests.get('https://example.com/')The WARC example.warc.gz will contain two records (the response is written first, then the request).
To write to a default in-memory buffer (BufferWARCWriter), don't specify a filename, using with capture_http() as writer:.
Additional requests in the capture_http context and will be appended to the WARC as expected.
The WARC-IP-Address header will also be added for each record if the IP address is available.
The following example (similar to a unit test from the test suite) demonstrates the resulting records created with capture_http:
with capture_http() as writer:
requests.get('http://example.com/')
requests.get('https://google.com/')
expected = [('http://example.com/', 'response', True),
('http://example.com/', 'request', True),
('https://google.com/', 'response', True),
('https://google.com/', 'request', True),
('https://www.google.com/', 'response', True),
('https://www.google.com/', 'request', True)
]
actual = [
(record.rec_headers['WARC-Target-URI'],
record.rec_type,
'WARC-IP-Address' in record.rec_headers)
for record in ArchiveIterator(writer.get_stream())
]
assert actual == expectedThe library provides a simple and extensible interface for writing standards-compliant WARC files.
The library comes with a basic WARCWriter class for writing to a
single WARC file and BufferWARCWriter for writing to an in-memory
buffer. The BaseWARCWriter can be extended to support more complex
operations.
(There is no support for writing legacy ARC files)
For more flexibility, such as to use a custom WARCWriter class,
the above example can be written as:
from warcio.capture_http import capture_http
from warcio import WARCWriter
import requests # requests *must* be imported after capture_http
with open('example.warc.gz', 'wb') as fh:
warc_writer = WARCWriter(fh)
with capture_http(warc_writer):
requests.get('https://example.com/')By default, warcio creates WARC 1.0 records for maximum compatibility with existing tools. To create WARC/1.1 records, simply specify the warc version as follows:
with capture_http('example.warc.gz', warc_version='1.1'):
...WARCWriter(fh, warc_version='1.1)
...When using WARC 1.1, the main difference is that the WARC-Date timestamp header
will be written with microsecond precision, while WARC 1.0 only supports second precision.
WARC 1.0:
WARC/1.0 ... WARC-Date: 2018-12-26T10:11:12Z
WARC 1.1:
WARC/1.1 ... WARC-Date: 2018-12-26T10:11:12.456789Z
When capturing via HTTP, it is possible to provide a custom filter function, which can be used to determine if a particular request and response records should be written to the WARC file or skipped.
The filter function is called with the request and response record before they are written, and can be used to substitute a different record (for example, a revisit instead of a response), or to skip writing altogether by returning nothing, as shown below:
def filter_records(request, response, request_recorder):
# return None, None to indicate records should be skipped
if response.http_headers.get_statuscode() != '200':
return None, None
# the response record can be replaced with a revisit record
elif check_for_dedup():
response = create_revisit_record(...)
return request, response
with capture_http('example.warc.gz', filter_records):
requests.get('https://example.com/')Please refer to
test/test_capture_http.py for additional examples
of capturing requests traffic to WARC.
Before 1.6, this was the primary method for fetching a url and then writing to a WARC. This process is a bit more verbose, but provides for full control of WARC creation and avoid monkey-patching.
The following example loads http://example.com/, creates a WARC
response record, and writes it, gzip compressed, to example.warc.gz
The block and payload digests are computed automatically.
from warcio.warcwriter import WARCWriter
from warcio.statusandheaders import StatusAndHeaders
import requests
with open('example.warc.gz', 'wb') as output:
writer = WARCWriter(output, gzip=True)
resp = requests.get('http://example.com/',
headers={'Accept-Encoding': 'identity'},
stream=True)
# get raw headers from urllib3
headers_list = resp.raw.headers.items()
http_headers = StatusAndHeaders('200 OK', headers_list, protocol='HTTP/1.0')
record = writer.create_warc_record('http://example.com/', 'response',
payload=resp.raw,
http_headers=http_headers)
writer.write_record(record)- The library also includes additional semantics for:
- Creating
warcinfoandrevisitrecords - Writing
responseandrequestrecords together - Writing custom WARC records
- Reading a full WARC record from a stream
- Creating
Please refer to warcwriter.py and test/test_writer.py for additional examples.
The library currently ships with a few simple command line tools.
The warcio index cmd will print a simple index of the records in the
warc file as newline delimited JSON lines (NDJSON).
WARC header fields to include in the index can be specified via the
-f flag, and are included in the JSON block (in order, for
convenience).
warcio index ./test/data/example-iana.org-chunked.warc -f warc-type,warc-target-uri,content-length
{"warc-type": "warcinfo", "content-length": "137"}
{"warc-type": "response", "warc-target-uri": "http://www.iana.org/", "content-length": "7566"}
{"warc-type": "request", "warc-target-uri": "http://www.iana.org/", "content-length": "76"}
HTTP header fields can be included by prefixing them with the prefix
http:. The special field offset refers to the record offset within
the warc file.
warcio index ./test/data/example-iana.org-chunked.warc -f offset,content-type,http:content-type,warc-target-uri
{"offset": "0", "content-type": "application/warc-fields"}
{"offset": "405", "content-type": "application/http;msgtype=response", "http:content-type": "text/html; charset=UTF-8", "warc-target-uri": "http://www.iana.org/"}
{"offset": "8379", "content-type": "application/http;msgtype=request", "warc-target-uri": "http://www.iana.org/"}
(Note: this library does not produce CDX or CDXJ format indexes often associated with web archives. To create these indexes, please see the cdxj-indexer tool which extends warcio indexing to provide this functionality)
The warcio check command will check the payload and block digests
of WARC records, if possible. An exit value of 1 indicates a failure.
warcio check -v will print verbose output for each record in the
WARC file.
The recompress command allows for re-compressing or normalizing WARC
(or ARC) files to a record-compressed, gzipped WARC file.
Each WARC record is compressed individually and concatenated. This is
the 'canonical' WARC storage format used by
Webrecorder and other
web archiving institutions, and usually stored with a .warc.gz
extension.
It can be used to: - Compress an uncompressed WARC - Convert any ARC file to a compressed WARC - Fix an improperly compressed WARC file (eg. a WARC compressed entirely instead of by record)
warcio recompress ./input.arc.gz ./output.warc.gz
The extract command provides a way to extract either the WARC and HTTP headers and/or payload of a WARC record
to stdout. Given a WARC filename and an offset, extract will print the (decompressed) record at that offset
in the file to stdout
Specifying --payload or --headers will output only the payload or only the WARC + HTTP headers (if any), respectively.
warcio extract [--payload | --headers] filename offset
warcio is licensed under the Apache 2.0 License and is part of the
Webrecorder project.