Both apps demanded a domain and Traefik. That was over-constrained: LibrePortal
ships WireGuard, Headscale and private ports, so LAN and VPN-only is a
first-class deployment here, and Rocket.Chat and Mattermost already prove chat
apps work fine on http://<lan-ip>:<port>.
The gate on Matrix rested on a mistake of mine: server_name being permanent.
server_name and public_baseurl are independent — the identity can be a domain
you own with no DNS behind it while clients reach the server on a LAN address,
so federation can be switched on later by adding DNS and TLS, with no rebuild
and no lost history. CFG_MATRIX_SERVER_NAME now exposes exactly that, and the
install warns when it falls back to the machine's IP.
What is genuinely lost without a domain is stated where it belongs, at install:
Matrix cannot federate and Element's mobile apps want HTTPS; Stoat cannot do
camera or microphone, because browsers gate getUserMedia on a secure context
and a VPN does not change that, the check being on the URL scheme.
Both now derive their URL from the port that was actually allocated. Since ports
are only assigned during compose-up, each writes a best guess before start and
corrects it afterwards, restarting only when the value really changed.
Three bugs found while proving it works end to end:
- The Synapse image writes /data as its UID/GID env, default 991, which under
rootless is a host sub-UID owning nothing — so the generated signing key could
not be moved by the install user. Both the generate container and the service
now run as the same identity USER_TAG resolves to.
- Element's config.json is bind-mounted as a file, and docker silently creates a
DIRECTORY when the source is missing. An early return left exactly that
landmine, which then broke every later run. It is written first now, and a
stale directory is cleared.
- A successful admin registration was reported as an error: checkSuccess read $?
after an intervening [[ ]] test rather than the command's own status.
Verified with no domain and no Traefik installed: Synapse answers
/_matrix/client/versions and /health on http://<ip>:<port>, admin login returns
a token, and Element is configured against the corrected base_url.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Synapse on Postgres plus the Element web client, on two subdomains: the
homeserver on matrix.<domain> (which becomes server_name, so IDs read
@alice:matrix.<domain>) and Element on element.<domain>.
Two hosts rather than one because server_name then matches the host Traefik
already terminates TLS for, so 'serve_server_wellknown: true' is all the
federation delegation needed and nothing has to be published at the apex
domain — which this app has no way to configure.
CFG_MATRIX_AUTHELIA is pinned false and documented: forward-auth in front of
/_matrix locks out every client and every federating peer, since they carry
Matrix access tokens and cannot follow a redirect. Real SSO goes through the
OIDC block in resources/homeserver.yaml instead.
The install hook generates the signing key once via upstream's own 'generate'
command and refuses to regenerate it over an existing install — a new key would
be rejected by every server that had cached the old one.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
