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C0: black-hole /mirrors/* at Fly edge + name-and-shame scrapers
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A $29.60 Fly bill traced to ~1.25 TB/30d egress on forge.eblu.me (99.95% of
all proxy egress), ~71% of it AI scrapers (Meta meta-externalagent, OpenAI
GPTBot, Amazonbot, Bytespider) crawling the public mirror repos' infinite
git-history URL space and timing out Forgejo. robots.txt already disallowed
/mirrors/ but those agents ignore it, so enforce at the edge: return 403 (^~
to beat the regex asset locations), served as a roll-of-dishonour page with an
X-Naughty-Scrapers header. Mirrors stay reachable on the tailnet via
forge.ops.eblu.me. Tier 2 (UA denylist + Anubis) and the Cloudflare rejection
are documented in docs/explanation/ai-scraper-mitigation.md.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
This commit is contained in:
Erich Blume 2026-06-01 20:52:20 -07:00
commit a36a18aaa6
7 changed files with 302 additions and 0 deletions
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27
fly/nginx.conf
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@ -215,6 +215,33 @@ http {
return 403 "API documentation is only available at forge.ops.eblu.me (tailnet).\n";
}
# Black-hole the mirror repositories on WAN. These are mirrors of
# already-public upstreams (tailscale, prometheus, mealie, …) kept
# for supply-chain control; CI, gilbert, and tailnet clients consume
# them via forge.ops.eblu.me. Their web UI served no public purpose
# but AI scrapers, which crawled the near-infinite git-history URL
# space (src/commit, commits, blame, raw) and drove ~70% of Fly
# egress (1.24 TB/30d → a surprise bill) plus enough upstream load to
# time out Forgejo. robots.txt already Disallows /mirrors/, but
# meta-externalagent and GPTBot ignore it — so enforce at the edge.
# `^~` makes this win over the regex locations below (e.g. *.css), so
# static assets under /mirrors/ can't leak through. We also name and
# shame: blocked requests get a "roll of dishonour" page (403 status
# preserved) and an X-Naughty-Scrapers header. See
# docs/explanation/ai-scraper-mitigation.md.
location ^~ /mirrors/ {
error_page 403 /naughty.html;
return 403;
}
# Roll of dishonour — served on the /mirrors/ 403, status kept at 403.
location = /naughty.html {
internal;
root /usr/share/nginx/html;
add_header X-Naughty-Scrapers "OpenAI/GPTBot, Meta/meta-externalagent, Amazonbot, ByteDance/Bytespider — robots.txt ignorers" always;
add_header X-Clacks-Overhead "GNU Terry Pratchett" always;
}
# Redirect archive endpoints to tailnet — archive requests generate full
# git bundles on demand. Unauthenticated crawlers hitting unique commit
# SHAs cause unbounded CPU and disk usage (DoS vector). Legitimate users