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chore(seismic)!: replace nginx and certbot with an unprivileged Caddy - #81
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samlaf merged 1 commit intoOct 9, 2026
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The public proxy ran as root: the nginx master, certbot (a root Python
process that talks to the network and rewrites nginx's config) and the
nginx-ssl-setup script. In-guest root can read root_key out of the
custodian's memory, so the most exposed process on the node should hold
no privilege it does not need. Caddy takes and renews its certificate
in-process, as User=caddy with only CAP_NET_BIND_SERVICE, from a static
Caddyfile in the measured image.
- certificates: Let's Encrypt, falling back to ZeroSSL, over TLS-ALPN-01
only, so nothing listens on :80; no admin endpoint, HTTP/3 off
- routes match their exact path (trailing slash allowed) and forward to
/, since every backend serves one endpoint whatever the path; any
other path is a 404, and WebSocket upgrades reach /ws only
- caddy.service: ordered after tdx-init and persistent-luks-setup and
required by nothing, with NoNewPrivileges, ProtectSystem=strict,
PrivateTmp, PrivateDevices and RestrictAddressFamilies; all Caddy
state lives in /persistent/caddy, which replaces /persistent/nginx
- caddy v2.11.7 built from source in mkosi.build, with a pinned Go
(go1.26.9) fetched through GOTOOLCHAIN, since Debian's is too old;
static and reproducible
- enclave pin to 74a6185: Caddy pastes {$DOMAIN_NAME} into its config
as raw text, so tdx-init's domain validation is what keeps an
operator's domain from injecting Caddyfile syntax
- python3, nginx and certbot leave the image
- CI validates the Caddyfile with the image's own caddy and expects four
source pins; image.json and the release notes record the caddy commit
- README: the endpoint table describes Caddy, and /summit is read-only
JSON-RPC (getDepositSignature is on summit's localhost admin listener)
BREAKING CHANGE: existing nodes take a fresh certificate on their first
boot on this image, which counts against Let's Encrypt's 5-a-week limit
for an exact name set. Nothing answers on :80.
Refs: SEI-629
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October 9, 2026 21:25
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Oct 9, 2026
Describes SeismicSystems/seismic-images#81 architecture.md: the process table, lifecycle diagram, ports table (:443 only), keys table and the /persistent section describe Caddy, and a design-rationale entry explains an unprivileged Caddy over nginx and certbot. network-founding.md, trust-model.md and the node-processes and key-families diagrams follow. The seismic-tee CLI's comments and its configure summary name the node's HTTPS proxy generically. Refs: SEI-629
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The public proxy ran as root: the nginx master, certbot (a root Python process that talks to the network and rewrites nginx's config) and the nginx-ssl-setup script. In-guest root can read root_key out of the custodian's memory, so the most exposed process on the node should hold no privilege it does not need. Caddy takes and renews its certificate in-process, as User=caddy with only CAP_NET_BIND_SERVICE, from a static Caddyfile in the measured image.
BREAKING CHANGE: existing nodes take a fresh certificate on their first boot on this image, which counts against Let's Encrypt's 5-a-week limit for an exact name set. Nothing answers on :80.
Refs: SEI-629