scrape

scrape

Fast web scraping

Table of Contents

• Description
• Output Format
• Usage as a CLI Application
• Usage as a Server
  • Web Interface
  • API
  • Healthchecks
• Building and Developing
  • Building
  • Using the Docker
• Roadmap

Description

scrape provides a self-contained low-to-no-setup tool to grab metadata and text content from web pages at medium scale.

Results are stored, so subsequent fetches of a particular URL are fast. Install the binary, and operate it as a shell command or a server with a REST API. The default SQLite storage backend is performance-optimized and can store to disk or in memory. Scraped resources are stored on a 30-day TTL, but you can clear the database at any time (in-memory DBs are wiped whenever the server process dies).

RSS and Atom feeds are supported via an endpoint in scrape-server. Loading a feed returns the parsed results for all item links in the feed.

The scrape and scrape-server binaries should be buildable and runnable in any cgo-enabled environment where SQLite3 is present. A docker build is also included.

Acknowledgements

scrape is powered by:

• go-trafilatura HTML parsing
• gofeed Atom and RSS parsing
• sqlite data storage

Output Format

JSON output is a superset of Trafilatura fields. Empty fields may be omitted in responses.

Parsed field content is largely dependent on metadata included in the page. GIGO/YMMV.

Here's an example, with long fields truncated:

{
  "url": "https://www.nasa.gov/missions/webb/nasas-webb-stuns-with-new-high-definition-look-at-exploded-star/",
  "requested_url": "https://www.nasa.gov/missions/webb/nasas-webb-stuns-with-new-high-definition-look-at-exploded-star/",
  "original_url": "https://www.nasa.gov/missions/webb/nasas-webb-stuns-with-new-high-definition-look-at-exploded-star/",
  "fetch_time": "2024-01-09T03:57:44Z",
  "status_code": 200,
  "hostname": "www.nasa.gov",
  "date": "2023-12-10T00:00:00Z",
  "sitename": "NASA",
  "title": "NASA’s Webb Stuns With New High-Definition Look at Exploded Star - NASA",
  "author": "Steve Sabia",
  "description": "Like a shiny, round ornament ready to be placed in the perfect spot on a holiday tree, supernova remnant Cassiopeia A (Cas A) gleams in a new image from",
  "categories": [
    "Astrophysics",
    "Goddard Space Flight Center",
    "James Webb Space Telescope (JWST)",
    "Missions",
    "Nebulae",
    "Science \u0026 Research",
    "Stars",
    "Supernovae",
    "The Universe"
  ],
  "tags": [
    "Astrophysics",
    "Goddard Space Flight Center",
    "James Webb Space Telescope (JWST)",
    "Missions",
    "Nebulae",
    "Science \u0026 Research",
    "Stars",
    "Supernovae",
    "The Universe"
  ],
  "language": "en",
  "image": "https://www.nasa.gov/wp-content/uploads/2023/12/webb-stsci-01hggzdyh8ghhssnwzd71mf0xh-2k.png",
  "page_type": "article",
  "content_text": "Mysterious features hide in near-infrared light Like a shiny, round ornament ready to be placed in the perfect spot on a holiday tree, supernova remnant Cassiopeia A (Cas A) gleams in a new image from NASA’s James Webb Space Telescope. As part of the 2023...(there's about 10x more content in this example, truncated in the docs for readability)",
}

Usage as a CLI Application

Installing for shell usage

go install github.com/efixler/scrape/cmd/scrape@latest

The scrape command provides single and batch retrieval, using or bypassing the connected storage db. It also provide command to manage the backing store.

Quickstart

> scrape http://www.foo.com/some/url/path

That's actually it. The database will be created if it doesn't exist already.

scrape % ./scrape -h
Usage: 
        scrape [flags] :url [...urls]
 
  -h
        Show this help message
  -clear
        Clear the database and exit
  -csv string
        CSV file path
  -csv-column int
        The index of the column in the CSV that contains the URLs (default 1)
  -database string
        Database file path (default "scrape_data/scrape.db")
  -maintain
        Execute database maintenance and exit
  -notext
        Skip text content

Usage as a Server

The server provides a REST API to get resource data one-at-a-time or in bulk. The root URL serves up a page that can be used to spot check results for any url.

scrape-server is intended for use in closed environments at medium scale. There's no authentication, rate limiting or url sanitization beyond encoding checks. Don't deploy this on an open public network. Do deploy it as a sidecar, in a firewalled environment, or another environment that won't get unbounded quantities of hits.

Installation

go install github.com/efixler/scrape/cmd/scrape-server@latest

scrape % ./build/scrape-server -h

Usage:
-----
scrape-server [-port nnnn] [-h]

Some options have environment variable equivalents. Invalid environment settings
are ignored. Command line options override environment variables.

If environment variables are set, they'll override the defaults displayed in this 
help message.
 
Command line options:
--------------------

  -h
        Show this help message
  -database string
        Database path. If the database doesn't exist, it will be created.
        Use ':memory:' for an in-memory database
        Environment variable equivalent: SCRAPE_DB
         (default "scrape_data/scrape.db")
  -log-level value
        Set the log level [debug|error|info|warn]
         (default info)
  -port int
        Port to run the server on
        Environment variable equivalent: SCRAPE_PORT
         (default 8080)
  -profile
        Enable profiling at /debug/pprof
         (default off)
  -s    Show current settings and exit
         (default false)
  -ttl duration
        TTL for fetched resources
        Environment variable equivalent: SCRAPE_TTL
         (default 720h0m0s)
  -user-agent string
        The user agent to use for fetching
        Environment variable equivalent: SCRAPE_USER_AGENT
         (default "Mozilla/5.0 (X11; Linux x86_64; rv:88.0) Gecko/20100101 Firefox/88.0")

Use caution when using the in-memory database: There are currently no constraints on database size.

Web Interface

The root path of the server (/) is browsable and provides a simple url to test URLs and results.

The pulldown on the right lets you select between loading results for a page url or for a feed.

API

batch [POST]

Returns the metadata for the supplied list of URLs. Returned metadatas are not guaranteed to be in the same order as the request.

The batch endpoint behaves indentically to the extract endpoint in all ways except two:

1. The endpoint returns an array of the JSON payload described above
2. When individual items have errors, the request will still return with a 200 status code. Inspect the payload for individual items to determine the status of an individual item request.

extract [GET, POST]

Fetch the metadata and text content for the specified URL. Returns JSON payload as decribed above.

If the server encounters an error fetching a requested URL, the status code for the request will be set to 422 (Unprocessable Entity). This may change.

The returned JSON payload will include a StatusCode field in all cases, along with an Error field when there's an error fetching or parsing the requested content.

In all other cases, requests should return a 200 status code, and any errors received when fetching a resource will be included in the returned JSON payload.

feed [GET]

Feed parses an RSS or Atom feed and returns the parsed results for each of the item links in the feed.

Global Params

These params work for any endpoint

Healthchecks

scrape currently supports two healthchecks

/.well-known/health

This is a JSON endpoint that returns data on the application's state, including memory and database runtime info.

/.well-known/heartbeat

This just returns a status 200 with the content OK

Building and Developing

Building

Best to build with make. The Makefile has a help target, here is its output:

scrape % make help

Usage:
  make 
  build            build the binaries, to the build/ folder (default target)
  clean            clean the build directory
  docker-build     build a docker image on the current platform, for local use
  docker-push      push an amd64/arm64 image to Docker Hub or to a registry specfied by CONTAINER_REGISTRY
  docker-run       run the docker image, binding to port 8080, or the env value of SCRAPE_PORT
  test             run the tests
  vet              fmt, vet, and staticcheck
  cognitive        run the cognitive complexity checker
  help             show this help message

Using the Docker

The docker-build target will build a docker on the current architecture. Run this image with docker-run to bring up a local instance of the service for testing. You don't need any Go tooling installed locally to build and run via the Docker.

To push a image to a registry, use docker-push. This will build a multiplatform amd64/arm64 image and deploy it upstream. This image is appropriate for cloud platform deployment. The registry username or organization should match the username or organization of the working repo, and you need the appropriate permissions.

The docker builds with local sources so use caution when pushing to registries.

By default, the Docker will run using an in-memory database. This can be changed via the SCRAPE_DB environment variable.

The docker-run make target will mount a local folder called docker/data and bind that to the container for file storage. If you want to use a file-based db you can use this directory, or update the Makefile to mount the desired local directory.

Roadmap

• Enforce TTLs and DB capacity limits for record eviction (TTLs are enforced, but not proactively flushed)
• Expose Request Timeout configuration
• Outbound same-domain request pacing
• Headless fallback for pages that require Javascript
• Add test coverage to cmd/.../main.go files
• Explore performance optimizations if needed, e.g.
  • Batch request parallelization
  • zstd compression for stored resources
• Explore alternate fetch/parse/storage backends

Feature request or bug? Post issues here.