Cloning a 1990s/2000s site like paulgraham.com and opening it in Kiwix
on a phone produces microscopic text: the pages use <font size="2">,
table layouts, and no viewport declaration, so the mobile browser shrinks
everything to desktop scale and then the font-size attribute makes it
smaller still.
kage clone --mobile injects two things into every saved page:
- <meta name="viewport" content="width=device-width, initial-scale=1">
so the browser stops shrinking the page
- a <style> block that lifts the base font to 18px, inherits it through
<font> elements (overriding the in-HTML size/face attributes), caps the
content width at 720px, loosens line height to 1.7, and hides
image-map nav elements whose source GIFs 404 offline
The style block goes last in <head> to win specificity ties, and
ensureViewport skips pages that already carry a viewport meta.
Two tests cover the happy path and the no-duplicate case.
An extensionless link is queued as a page, so the page worker navigated to
it in headless Chrome. When such a link served a binary, a zip or a CSV,
Chrome saved the file to the user's Downloads folder, a surprise side effect
of a clone (issue #32).
Deny Chrome-initiated downloads browser-wide, since kage fetches every asset
through its own downloader and never needs the browser to write a file. Then
watch the main document's response, and when it is not HTML, return a typed
ErrNotHTML so the page worker reroutes the URL to the asset downloader, where
the existing size and media policy decides whether to localise it or leave it
on the live web.
Verified against the two URLs from the issue, a zip and a CSV: both land
under the mirror's reserved tree and nothing is written to Downloads.
A developer.apple.com crawl came back at 19 GB, 18 of it assets, most of
that the site's own videos, .dmg/.pkg installers, and PDF manuals pulled
from a couple dozen hosts including unrelated third parties. None of it
helps read the docs offline. This changes what kage localizes by default.
Bulk media, installers, archives, and PDFs are left pointing at their
live URL instead of downloaded. The decision is made from the URL alone,
so the rewritten HTML simply keeps the remote link. --keep-media restores
the old behavior and --skip-ext adds more extensions to leave remote.
Assets are localized only from the seed's registrable domain by default,
so www.apple.com and images.apple.com still come along but a separate
brand domain or an off-topic third party does not. --all-asset-hosts goes
back to downloading from any host.
The size cap was also truncating instead of skipping: it wrapped the body
in a LimitReader, so an over-cap file was saved as exactly the first N MB
of itself, a corrupt fragment that would never play or run. On the apple
crawl that was around a gigabyte of half-downloaded WWDC videos. kage now
checks the response size and leaves an over-cap asset out of the mirror.
Two related changes for crawling faceted sites, where one path spawns
thousands of ?q=.../?page=... URLs that all render the same page.
The progress line was counting every written file, so the page number ran
far ahead of the site's real size. It now shows distinct URL paths as
"pages" and folds the query-string permutations into a separate "variants"
count, so the live counter tracks real pages and is easy to read.
Pages with identical bytes are now stored once. The first page with a given
content is written normally; a later page with the same bytes becomes a hard
link to it, so duplicate content never takes disk twice. Links still resolve
because each variant keeps its own path. When hard links are unsupported the
bytes are written, so correctness never depends on the link. The summary
reports how many pages were deduped.
kage launched Chrome with --no-sandbox unconditionally, which turns off the
browser's main security boundary for every run, including ordinary desktop
use where the sandbox works fine. Since kage renders pages from the open web,
a renderer exploit could then reach the host. Reported in #10.
Keep the sandbox on by default and drop it only where it genuinely cannot
initialize: inside a container, or when running as root (Chrome refuses to
start a sandbox as root). Containers are detected from IN_DOCKER or the
/.dockerenv marker, and there kage also sets --disable-dev-shm-usage because
the default 64 MB /dev/shm is too small for the renderer on large pages.
Whenever the sandbox is dropped kage says so on stderr, so it is never silent.
Thanks to Dimitrios Prasakis for the report and to the commenter on Hacker
News who suggested the IN_DOCKER opt-in.
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.
kage renders every page in headless Chrome, snapshots the final
DOM, strips all JavaScript, and localises CSS, images, and fonts
so a site can be browsed offline as a plain folder of files.
The engine is split into small packages:
urlx deterministic URL to local-path mapping and scope rules
sanitize remove scripts, on* handlers, and javascript: URLs
asset rewrite HTML and CSS references, download assets
browser headless Chrome pool over the DevTools protocol
robots robots.txt matcher
clone the orchestrator: a polite resumable breadth-first crawl
The cli package wires a cobra and fang command surface with two
commands, clone and serve. Every pure package has table tests; the
browser and clone packages add Chrome-driven end-to-end tests that
skip when no browser is present or under -short.
CI runs gofmt, vet, build, race tests, golangci-lint, govulncheck,
and a tidy check on Linux and macOS. A goreleaser config fans one
tag out to archives, deb/rpm/apk, a Chromium-bundled GHCR image,
and the package managers. A tago docs site builds to Pages and
Cloudflare.
Xirui