nixos-config/hosts/pinix/localServices/prosody

Prosody

Prosody runs on pinix. Public XMPP traffic reaches port 5222 on blunix, where Traefik forwards it through the Headscale/Tailscale network to 100.64.0.3:5222.

The service uses the upstream NixOS Prosody module. LDAP authentication is enabled by adding lualdap to the Prosody package's Lua environment in setup-prosody.nix; no store paths or copied NixOS module are required.

The LDAP password and MOTD are included from agenix files at runtime. Consequently, the module's build-time configuration check is disabled and the live configuration must be checked after activation.

Anonymous web chat

xmpp-web.nix serves the pinned xmpp-web release on pinix. nginx terminates TLS on the Tailscale address 100.64.0.3:8443, serves the static frontend, and proxies /xmpp-websocket to Prosody on 127.0.0.1:5280.

On blunix, traefik-xmpp-web.nix uses TCP TLS passthrough for chat.0ff.space. TLS is therefore terminated on pinix; blunix neither receives the certificate key nor sees XMPP message contents.

Guests authenticate anonymously against anon.0ff.space and join lobby@muc.0ff.space. The room is persistent and lukas@0ff.space is its owner, so the normal LDAP-backed account can join and administer it from Monal without a second account.

The MUC archive is retained for 30 days and cleaned every four hours. mod_muc_moderation is installed from the Prosody community-modules revision pinned by nixpkgs and enabled only on muc.0ff.space. Clients supporting XEP-0425 can therefore retract abusive messages from the room and its archive; the moderator must join with an owner or administrator account.

Update notifications

Forgejo sends push and pull-request events to the local webhook receiver on pinix. The receiver posts short notifications as forgeBot to update@muc.0ff.space using vikunja@bot.0ff.space. The repository hook targets http://127.0.0.1:9000/hooks/wiki-update; Forgejo permits that exact loopback address in addition to its default external targets.

The update room is members-only. The bot therefore needs a member affiliation in the room; its password remains in go-sendxmpp.age.

Second channel: agent@bot.0ff.space

Vikunja updates additionally go out as a direct (1:1) message from vikunja to agent@bot.0ff.space, alongside the existing vikunja@muc.0ff.space post. Unlike a MUC room, a 1:1 JID needs no room creation or affiliation dance — Prosody delivers chat messages between local accounts regardless of roster subscription. The point of the separate account is to have a single-JID message archive that only carries this one event stream, instead of parsing it back out of the shared MUC room log.

agent@bot.0ff.space is intentionally never added to a human XMPP client: go-sendxmpp sends plaintext (no OMEMO), so a client like Monal shows this conversation unencrypted next to otherwise-encrypted chats.

The listener now runs on blunix, where the persistent Codex checkout and CLI authentication already live. hosts/blunix/localServices/agent-codex.nix keeps go-sendxmpp --listen connected as agent, archives its stdout in the journal, and only queues messages from the explicit sender allowlist:

journalctl -u agent-xmpp-listener

Accepted messages are atomically written below /var/lib/agent-codex/inbox. Messages from the same sender that arrive within a three-second quiet window are combined into one queue job. Sending /neu is handled immediately after any already pending text and resets the sender's active conversation.

agent-codex-worker.path starts a separate oneshot worker, which invokes codex exec in /home/drone/nixos-config/agents/platform. The nested agents/platform/AGENTS.md supplies the XMPP role in addition to the root repository instructions.

The first turn uses JSONL output to capture Codex's thread.started ID. Successful replies store the sender-to-thread mapping below /var/lib/agent-codex/sessions; later turns use codex exec resume <SESSION_ID>. A mapping expires after 30 minutes without a successful turn. /neu removes it explicitly, so the next content message starts a fresh thread. Codex's own session rollout files remain in the isolated /var/lib/agent-codex/codex-home.

Every invocation ignores personal Codex configuration, uses the isolated CODEX_HOME containing only the copied authentication, explicitly selects a read-only sandbox, and sends only the final agent message back to the original XMPP sender. systemd serializes the queue; tmux is not involved. Failed jobs remain in /var/lib/agent-codex/failed for inspection.

The first successful reply to each allowlisted sender includes a one-time usage note. In normal use:

• send related short fragments within three seconds to combine them;
• wait for the reply before beginning a different request;
• send /neu to discard the current conversational context;
• wait 30 minutes to let the active mapping expire automatically.

The account password lives in agentXmpp.age, decrypted at runtime to /run/agenix/agentXmpp on blunix, owner drone. It is not decrypted on pinix after the listener migration. The listener reads it through a mode-0600 runtime configuration, so it is not exposed in process arguments.

Useful checks on blunix:

systemctl status agent-xmpp-listener agent-codex-worker.path
journalctl -u agent-xmpp-listener -u agent-codex-worker
find /var/lib/agent-codex -maxdepth 2 -type f

Run the unit tests from the repository root:

nix shell --inputs-from . nixpkgs#python3 --command \
  python3 -m unittest discover \
    -s hosts/blunix/localServices/agent-codex \
    -p 'test_*.py' -v

Enable and deploy

Enable the Prosody configuration in ../default.nix:

./prosody/setup-prosody.nix

Build locally on tnix, copy the closure to pinix, and activate it:

nrsp

Refresh the TLS certificate

Traefik renews the wildcard Let's Encrypt certificate on blunix, but Prosody reads separate certificate files on pinix. Copy the current certificate manually before the previous one expires. Let's Encrypt certificates are normally valid for about 90 days.

Run all commands from tnix.

1. Check source and installed certificates

Check the current Traefik certificate without exposing the private key:

ssh -T blunix \
  'sudo jq -r '"'"'.cloudflare.Certificates[] |
    select(.domain.main == "0ff.space") | .certificate'"'"' \
    /var/lib/traefik/acme.json |
    base64 -d |
    openssl x509 -noout -subject -issuer -dates -fingerprint -sha256'

Check the certificate currently installed on pinix:

ssh -T pinix \
  'sudo openssl x509 \
    -in /var/lib/prosody/certs/0ff.space.crt.pem \
    -noout -subject -issuer -dates -fingerprint -sha256'

2. Transfer certificate and key

Transfer both files directly over SSH. The private key is never written to the tnix filesystem or printed to the terminal.

set -o pipefail
ssh -T blunix \
  'sudo jq -r '"'"'.cloudflare.Certificates[] |
    select(.domain.main == "0ff.space") | .certificate'"'"' \
    /var/lib/traefik/acme.json | base64 -d' |
ssh -T pinix \
  'sudo sh -c '"'"'umask 022
    tee /var/lib/prosody/certs/0ff.space.crt.pem.new >/dev/null
    chown prosody:prosody /var/lib/prosody/certs/0ff.space.crt.pem.new'"'"''

set -o pipefail
ssh -T blunix \
  'sudo jq -r '"'"'.cloudflare.Certificates[] |
    select(.domain.main == "0ff.space") | .key'"'"' \
    /var/lib/traefik/acme.json | base64 -d' |
ssh -T pinix \
  'sudo sh -c '"'"'umask 077
    tee /var/lib/prosody/certs/0ff.space.key.pem.new >/dev/null
    chown prosody:prosody /var/lib/prosody/certs/0ff.space.key.pem.new'"'"''

3. Validate and install

Validate the certificate, private key, and file permissions on pinix:

ssh -T pinix 'sudo sh -c '"'"'
  set -eu
  cert=/var/lib/prosody/certs/0ff.space.crt.pem.new
  key=/var/lib/prosody/certs/0ff.space.key.pem.new

  openssl x509 -in "$cert" -noout -dates -fingerprint -sha256
  openssl pkey -in "$key" -check -noout

  cert_hash=$(openssl x509 -in "$cert" -pubkey -noout |
    openssl pkey -pubin -outform DER 2>/dev/null |
    sha256sum | cut -d" " -f1)
  key_hash=$(openssl pkey -in "$key" -pubout -outform DER 2>/dev/null |
    sha256sum | cut -d" " -f1)
  test "$cert_hash" = "$key_hash"

  stat -c "%U:%G %a %n" "$cert" "$key"
'"'"''

Expected permissions:

prosody:prosody 644 ...crt.pem.new
prosody:prosody 600 ...key.pem.new

Back up the existing files, install the validated files, and restart Prosody:

ssh -T pinix 'sudo sh -c '"'"'
  set -eu
  dir=/var/lib/prosody/certs
  stamp=$(date -u +%Y%m%dT%H%M%SZ)

  cp -a "$dir/0ff.space.crt.pem" \
    "$dir/0ff.space.crt.pem.previous-$stamp"
  cp -a "$dir/0ff.space.key.pem" \
    "$dir/0ff.space.key.pem.previous-$stamp"
  mv "$dir/0ff.space.crt.pem.new" "$dir/0ff.space.crt.pem"
  mv "$dir/0ff.space.key.pem.new" "$dir/0ff.space.key.pem"
  chmod 640 "$dir/0ff.space.key.pem"
  systemctl restart prosody
  systemctl restart nginx
'"'"''

The installed key is 0640 prosody:prosody: nginx is a supplementary member of the prosody group and receives read-only access. The temporary key remains 0600 while it is being transferred and validated.

4. Verify

Check the service and listeners:

ssh -T pinix \
  'systemctl is-active prosody
   ss -lnt | grep -E ":(5222|5269|5280|5281)[[:space:]]"'

Verify the certificate delivered through the public XMPP endpoint:

set -o pipefail
timeout 20 openssl s_client \
  -starttls xmpp \
  -connect 23.88.33.137:5222 \
  -xmpphost 0ff.space \
  -servername 0ff.space \
  </dev/null 2>/dev/null |
openssl x509 -noout -subject -issuer -dates -fingerprint -sha256