Steven Hé (Sīchàng)'s recursive scraper

The scraper scrapes recursively, at constant frequency (requests per time), asynchronously, and write the results continuously to disk. It is simple to use, while providing flexible configurations.

This scraper is an open source rewrite of the proprietary scraper used for SSO in DKU.

Objective

The scraper is designed for recursive scraping, that is, by default, the scraper process every href and img from the HTML it gets to know even more URLs, and then process those URLs as well. One obvious usage of recursive scraping is full site scraping.

If you want to scrape only the URLs you provide, just provide a tricky filter such as "#" and it will function as a non-recursive scraper. One usage of non-recursive scraping is bulk image scraping.

Features

Constant frequency

The scraper guarantees that eventually the number of requests sent per time is constant. This constant depends on the delay set between each request.

The delay needs to be set in milliseconds. It has a default value of 500.

Regex filter and blacklist

The scraper does not process any new URLs that does not match given filter regex or does match given blacklist regex.

Any urls specified by the user are not checked. If not specified, filter defaults to ".*" to match any URLs, and blacklist defaults to "#" to match no URLs. (URLs processed do not include # because the scraper strips it to avoid repetition.)

Adjustable connection timeout

The scraper times out a request if it fails to connect after 10 seconds. You can set custom timeout in milliseconds.

Under the hood, the scraper also uses a timeout eight times as long as the connection timeout for the request and response to finish.

Continuously-updating record

The scrape record is written to disk as summary.toml in the log directory. The record is updated once in a while as the scraper goes.

In [urls], each URL is mapped to an id based on their order of discovery. [scrapes] records the ids to the URLs that are scraped. [fails] records the the ids to the URLs that the scraper failed to process. [redirections] records if one URL (whose id is on the left) was redirected to another URL (on the right).

Usage

``shell $ ./scraper --help recursive_scraper 0.2.1 Steven Hé (Sīchàng) Scrapes given urls (separated by commas) recursively. Saves the results to html/andother/, the log tolog/`, or other directories if specified.

USAGE: recursive_scraper [OPTIONS]

ARGS:

OPTIONS: -b, --blacklist -c, --connection-timeout -d, --delay -f, --filter -h, --help Print help information -i, --disregard-html -l, --log-dir -o, --other-dir -s, --disregard-other -t, --html-dir -V, --version Print version information ```

Recursively scrape the whole https://example.com/:

shell ./scraper -f "https://example.com/.*" https://example.com/

Same as above except I don't want images:

shell ./scraper -f "https://example.com/.*" -s https://example.com/

Only scrape the URLs I provide (separated by commas):

shell ./scraper -f "#" https://example.com/blah,https://example.com/blahblah,https://example.com/bla

Scrape everything into one folder result/:

shell ./scraper -f "https://example.com/.*" -l result/ -o result/ -t result/ https://example.com/