Duc-Tam Nguyen
a871265cbe
Crawling keyed off the raw URL, so the same page reached over http and https, or as /index.html versus /, was a different frontier entry that nonetheless wrote to the same file. A clone of paulgraham.com did 948 render passes for 474 files. Key pages and assets by the local path they write instead, and collapse a directory-index document to its directory, so each page is fetched exactly once. Add --refresh to re-render a mirror in place (re-fetch every page, keep the directory, overwrite) and make --no-resume truly stateless by not persisting state.json. The default remains a resumable, idempotent crawl that skips work already on disk.
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3.1 KiB
title, description, weight
| title | description | weight |
|---|---|---|
| Configuration | Environment variables kage reads, and the layout of a cloned mirror on disk. | 20 |
kage is configured almost entirely through command-line flags (see the CLI reference). It reads a couple of environment variables for locating the browser.
Environment variables
| Variable | Meaning |
|---|---|
KAGE_CHROME |
Path to the Chrome/Chromium binary. Takes precedence over autodetection. Equivalent to --chrome. |
CHROME_BIN |
Fallback Chrome path, read if KAGE_CHROME is unset. |
If neither is set and no system Chrome is found in the usual install locations, kage's launcher can download a private copy of Chromium on first use.
Output layout
A clone of example.com lands under $HOME/data/kage/example.com/ (override the
root with -o/--out):
kage-out/example.com/
├── index.html # the home page (/), scripts stripped
├── about/index.html # /about
├── blog/
│ ├── index.html # /blog
│ └── a-post/index.html # /blog/a-post
├── _kage/ # reserved directory
│ ├── example.com/
│ │ ├── site.css # localised stylesheet, url() rewritten
│ │ ├── logo.png
│ │ └── fonts/body.woff2
│ ├── cdn.example.com/ # assets from other hosts, by host
│ └── state.json # visited set, for --resume
└── ...
Key points:
- Pages become directories. A page at
/aboutis written asabout/index.html, so a link to/aboutresolves to a real file when served. - Assets live under the reserved directory. Everything kage downloads, CSS,
images, fonts, media, goes under
_kage/<asset-host>/, mirroring the path it had on its origin. Cross-origin assets are grouped by their own host. - Query strings are folded into the filename. An asset like
style.css?v=3is saved with a short hash suffix so two versions never collide. - State lives in the mirror.
_kage/state.jsonrecords every page written, which is what lets a repeated run skip completed work. Rename the reserved directory with--reservedif_kagewould clash with a real path on the site.
Resume, refresh, and re-crawl
A clone is idempotent: every page is keyed by the file it writes, so the same
page reached over http and https, with or without a trailing slash, or as
/index.html versus /, is fetched exactly once. Re-running picks the work back
up rather than starting over.
| You want to… | Use | What happens |
|---|---|---|
| Continue an interrupted crawl | (default) | Loads state.json, skips pages already written, fetches only what is missing |
| Pull in content that changed on the site | --refresh |
Keeps the mirror, re-renders every page in place, overwrites with the new DOM |
| Start completely clean | --force |
Deletes the host's mirror, then crawls from scratch |
| Run once and leave no trace | --no-resume |
Skips nothing, writes no state.json |