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Parley: Federated, decentralised chat that speaks plain IRC

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Federated, decentralised chat that speaks plain IRC.

Parley is a chat network with no centre. Every person (or team) runs a small instance for their own domain. Instances find each other through DNS and well-known identity documents, exchange signed messages over HTTPS, and present the whole federated network to ordinary IRC clients such as irssi, WeeChat or Textual, with no plugins.

Identities look like email: alice@foo.com runs on foo.com, bob@bar.com on bar.com. Bob types /msg alice@foo.com hi and it just works, even if the two instances have never heard of each other before.

Status: working proof of concept. It demonstrates the design end to end and runs a real instance, but it is not hardened yet. See Limitations.

It works with the client you already have

Two instances (foo.com and bar.com), two stock irssi sessions.

Alice connects to her instance; Bob connects to his:

Alice connects to foo.com Bob connects to bar.com

Bob opens a query with /msg alice@foo.com and the two instances federate on the spot. Alice sees Bob as bob on bar.com; Bob sees Alice as alice on foo.com:

Alice's query window with bob@bar.com Bob's query window with alice@foo.com

Both join #lobby, a global channel replicated across their instances:

Alice in #lobby Bob in #lobby

What it does

Quick start (two instances on one machine, no DNS)

Then, in two terminals:

-insecure and -resolve exist only for local development. In production each instance has a real domain, a TLS certificate, an SRV record, and finds peers via DNS.

The real thing: DNS + TLS demo

demo/ brings up CoreDNS (authoritative for foo.com and bar.com, with _parley._tcp SRV records), a local demo CA, and both instances in Docker, then runs scripted IRC sessions and prints the evidence:

See demo/README.md.

Running your own instance

The container image is prologic/parley, and docker-compose.example.yml is a starting point. An instance for example.com, reachable at chat.example.com, needs:

  1. A place to run it, with /data on persistent storage (it holds the instance key, the peer cache, the channel logs and the accounts):

    Then create accounts with parleyctl (it is in the image too) or the admin page:

    Without an admin token and with no accounts yet, parleyd logs a one-time /setup URL that creates the first admin in the browser. Single sign-on through OpenID Connect or a reverse proxy's identity headers is described in docs/AUTH.md; SSO users mint IRC tokens for their clients on their settings page.

  2. HTTPS in front of port 8443 on chat.example.com. Any reverse proxy that terminates TLS will do; parleyd itself serves plain HTTP unless you give it -tls-cert and -tls-key.

  3. An SRV record so other instances can find you:

    Without it, peers fall back to https://example.com/.well-known/parley/.

  4. IRC over TLS for your clients. parleyd's IRC listener is plaintext, so terminate TLS in front of it. With Caddy's layer4 module, for example:

    Then, in irssi: /connect -tls -tls_verify chat.example.com 6697 <password-or-token> alice.

    The port here is whatever your proxy listens on. If it is not 6697, start parleyd with -irc-port (and -irc-host, if IRC is on a different name to the endpoint), or set PARLEY_IRC_PORT / PARLEY_IRC_HOST:

    The landing page, the settings page, parleyctl and the instance document all print a connect line from it, and the settings page prints a live token on that line. A wrong port under a right hostname still passes certificate verification, so the token would go to whatever else is listening there.

  5. Check it from the outside. parleyctl check probes an instance the way a peer does — SRV record, well-known documents, the advertised endpoint, the inbox, and the IRC TLS port — and says what to fix:

    It needs no token and works against anyone's instance, so it is also how you tell a peer what is wrong with theirs. The common failure is a missing SRV record: the instance is perfectly reachable at its own host, but nobody resolving the identity domain can find it. Add -resolve https://chat.example.com to probe the host directly while DNS is still wrong, and -json for a machine-readable report. It exits non-zero if any check fails.

How it fits together

  1. Bob's client sends PRIVMSG alice@foo.com :hi.
  2. bar.com looks up _parley._tcp.foo.com, fetches the instance document from the host it names, and caches the key.
  3. bar.com signs the event and POSTs it to foo.com's inbox.
  4. foo.com discovers bar.com the same way to verify the signature, delivers the message to Alice's clients, and since bar.com is a stranger, sends a hello back. Both sides now exchange channel rosters and peer lists.

The wire format is documented in docs/PROTOCOL.md.

Configuration

There is no config file. Configuration is in two places and each thing is in exactly one of them.

Flags, each with an environment variable, for what the process needs before it can open its database, what describes the machine and network it sits on, and the secrets and trust decisions about who may assert an identity. A flag wins over its variable. Only -domain is required.

flag env meaning default
-domain PARLEY_DOMAIN identity domain this instance serves required
-data PARLEY_DATA_DIR identity key, databases, peer and membership state ./data
-endpoint PARLEY_ENDPOINT advertised base URL https://<domain>
-irc PARLEY_IRC_LISTEN IRC listener (plaintext; terminate TLS in front) :6667
-http PARLEY_HTTP_LISTEN HTTP(S) listener for the web UI, discovery, inbox and feeds :8443
-irc-host, -irc-port PARLEY_IRC_HOST, PARLEY_IRC_PORT where clients reach IRC over TLS endpoint host, 6697
-tls-cert, -tls-key PARLEY_TLS_CERT, PARLEY_TLS_KEY serve HTTPS directly off
-admin-token PARLEY_ADMIN_TOKEN bearer token for the admin API and parleyctl off
-admin (repeatable) PARLEY_ADMINS nicks that are admins regardless of their stored role none
-seed (repeatable) PARLEY_SEEDS peer domains to link with at startup none
-irc-proxy (repeatable) PARLEY_IRC_PROXIES CIDRs allowed to prepend a PROXY header to an IRC connection none
-http-proxy (repeatable) PARLEY_HTTP_PROXIES CIDRs whose X-Forwarded-For the web listener believes none
PARLEY_TRUSTED_PROXIES and PARLEY_TRUSTED_* identity headers from listed proxies (see docs/AUTH.md) off
PARLEY_OIDC_* OpenID Connect provider (see docs/AUTH.md) off
HAVEN_SOCKET Home Cloud app socket for household sync off
-ca, -insecure, -resolve, -debug PARLEY_DEBUG local development off

Settings, in the database, for everything an administrator might change while the instance runs. They take effect the moment they are saved, with no restart, and have no flag and no environment variable. Change them on the admin page, through PUT /api/v1/settings (docs/API.md), or with parleyctl:

Only what differs from the defaults is stored, so an upgrade that changes a default changes it for every instance that never touched that key.

setting meaning default
motd message of the day (empty means the built-in text) built-in
history_replay messages replayed on JOIN (channels and DMs alike), unread DMs on login, and the backlog a second client attaching to the same account is shown 50
history_retention how long channel and DM history is kept (-1 forever) 8760h
message_rate, message_burst how much one account may say: messages per second, and how many at once. A rate of 0 is no limit. Bots are exempt 1, 20
max_conns concurrent IRC connections to the instance (-1 unlimited) 1024
max_conns_per_account concurrent IRC connections per account (-1 unlimited) 8
max_conns_per_addr concurrent IRC connections per client address (0 off) 0
federation.policy open, or allowlist to federate only by invitation open
federation.inbox_rate, federation.inbox_burst inbox deliveries per peer and per address 20, 200
federation.feed_rate, federation.feed_burst feed reads per address 2, 20
federation.catch_up_window how far back a reconnecting instance asks for 168h
auth.local show the username/password login form true
auth.auto_link a first SSO login may claim an unlinked local nick true
auth.session_ttl web login lifetime 720h
auth.rate_limit.* login rate limiting (see docs/AUTH.md) on
metrics_public serve /metrics without authentication false
network_name what this instance calls itself, on IRC and on the web (empty means the domain on IRC, "Parley" on the web) empty
theme_color the colour a phone tints its browser bar with, as #rrggbb built-in
operator who runs this instance, shown in the web footer empty

People set their own picture under Settings in the web interface, or it comes from their identity provider's picture claim at login and is re-hosted here. It is published to IRC clients as the IRCv3 avatar metadata key and to other instances in the well-known user document; see docs/PROTOCOL.md.

The instance's logo is not in this table, because it is not text: upload one PNG of at least 512 pixels along its longest side under Settings -> Logo in the admin page and Parley derives the favicon, the home-screen icon and the square an IRC client shows beside the network. A square is ideal, and a wordmark is fine -- anything up to three times as long as it is tall is centred on a transparent square rather than refused. Until then every instance shows Parley's own icon, which is why two of them look alike in a client's network list.

Chat help. /help (or /quote HELP <topic>) serves the pages in help/*.txt, which are compiled into the binary. Edit a page and rebuild to change it; the first line is its title. A new file is a new topic -- list it in help/index.txt, which make test checks.

Endpoints: /healthz for liveness, /api/v1/status for a JSON status of peers and channels, /metrics for Prometheus, and the API in docs/API.md.

Upgrading from a config file. parleyd -config config.json no longer reads the file: it prints, for every key in it, the flag, variable or setting that key has become, and exits. Move the process-level keys to your unit file or compose file, start the instance, then parleyctl settings import config.json applies the rest in one go and names what it skipped.

Real client addresses behind a TCP proxy

With TLS terminated in front of the IRC listener, every client arrives from the proxy: the logs name the wrong host, and per-address limits either do nothing or lock everybody out at once. List the proxy in irc_proxies and it must then prepend a PROXY protocol header (v1 or v2) to each connection.

This is two changes, and neither works alone. Listing a proxy that does not send a header drops every connection from it; sending a header from an address that is not listed feeds it to the IRC parser as garbage. There is no safe order, so change both together and be ready to put both back.

The default is empty, which is the whole thing switched off. 127.0.0.1/32 below is an example, not a default -- substitute the address your own connections actually arrive from:

Note the name: PARLEY_TRUSTED_PROXIES is the web listener's equivalent and a different decision entirely.

To find the address to list, connect once and read the log. Every client address is reported the first time it is seen:

Behind a proxy every client shares one address, so that is a single line naming exactly what belongs in irc_proxies. It is always the address on the socket, never the one a header carries -- the header address could never match the list, so reporting it would hand you a value guaranteed to fail. Once the proxy is listed and sending headers, the line reappears for it with trusted_proxy=true, which is the confirmation that the two halves now agree.

Only listed addresses are believed, and a connection from one of them that does not carry a header is dropped rather than treated as a direct connection -- accepting both shapes from the same place hands back the address forgery the header exists to stop. Those drops are counted in parley_irc_proxy_rejected_total, which is the metric to watch while making the change.

The web listener has the same blindness and its own setting. Behind a reverse proxy every request arrives from that proxy, so the per-address gates on web login, the federation inbox and feed reads all share one bucket -- a global rate limit wearing a per-address name. List the proxy in http_proxies and X-Forwarded-For is believed from it, and nothing else changes.

Use that rather than auth.trusted_headers.proxies, which looks like it would do the job and does far more: a proxy on that list may assert who the user is, so a request to /login carrying Remote-User is logged in without a password. Fixing a rate limit is no reason to turn on passwordless login. The identity list does imply the address one, since a proxy trusted that far is not one to doubt about an address.

The step-by-step version, including the order that costs one outage instead of two, is in docs/PROXY.md.

With real addresses in hand, max_conns_per_addr becomes safe to turn on, and turning it on also applies the per-address login bucket to IRC. Leave it at 0 while the listener sits behind an unlisted proxy: every client shares one address there, so the cap would not limit anybody in particular, it would lock out everybody at once. It is a setting, so turning it on is parleyctl settings set max_conns_per_addr 8 and needs no restart. The per-account login backoff applies either way -- see docs/AUTH.md.

Metrics

/metrics serves the Prometheus text format: connections, accounts online, channels, peers linked, and counters for pushes, inbox events, feed reads, tag messages and what was refused. It needs an admin token by default, since how many people are on an instance is the operator's business; set the metrics_public setting to serve it openly. Every sample is a count -- no nicks, no channel names, no peer domains.

Back up the instance key

<data_dir>/identity.key is the one file that cannot be regenerated. The domain's identity is the keypair: lose it and every peer that has cached the old public key refuses the instance, and the only fix is a new key that everyone has to re-trust. Back it up on the host, off the host:

If the key ever leaks, replacing it is a supported operation rather than a disaster:

Peers recover by themselves. A signature they cannot verify makes them re-read the instance document once, which is where they find the new public key, so the cost is one failed request each -- and if that request was a hello, a few minutes of backoff before they try again. The old key is kept as identity.key.<fingerprint>.bak because the only unrecoverable mistake here is replacing a key you still needed. Restart parleyd afterwards to serve the new one.

These read and write the data directory directly rather than going through the API, because an admin token must never be able to fetch the private key over the network. Run them on the instance host, with -data-dir or PARLEY_DATA_DIR pointing at the data directory.

Upgrading

Nothing to run: the database gains its new tables on first start and the old ones are untouched. What follows is the handful of things that changed under you, newest first.

To v0.6.0

How much one account may say is now bounded. message_rate (1 a second) and message_burst (20 at once) apply to everybody but bots, keyed by the account, so a person's clients share one budget. A refused message is answered 439 naming the target and is delivered nowhere. Every instance before this had no bound at all, so if yours has a room busier than that, raise the numbers or set message_rate to 0, which is the old behaviour:

It is a setting, so it lands without a restart.

To v0.5.0

Somebody on another instance is alice:foo.com, not alice/foo.com. The separator was borrowed from draft/relaymsg, and it was the wrong half of the convention to copy: a strict client guards against mistaking a server name for a nick by requiring both a . and a : or neither, and a name with a domain has a dot and no colon. Such a client read the whole prefix as a server name and dropped every JOIN, PART, QUIT, NICK and AWAY from a remote user, while PRIVMSG degraded quietly -- which is why chat looked fine and no roster ever updated. PARLEYSEP in ISUPPORT says which character is in use, so a bot should read it from there rather than hardcode one.

The trap while a network is mid-upgrade: mention text crosses federation as bytes. Somebody on a peer that is still on / types alice/foo.com, and it does not match anything here until they upgrade. Tell your peers rather than letting them find it.

A reaction sent to a peer older than v0.5.0 is lost, not queued. Those versions answer an event type they do not implement with a 422, and a refusal is final to the sender's outbox: the event is dropped and the sender is told the send failed. From v0.5.0 on, an unimplemented type is answered 200 {"unsupported": true} instead, so this is the last change that has to wait for the whole mesh. Reactions between people here, and between upgraded instances, are unaffected.

GET /api/v1/status no longer publishes channel rosters. It is the only unauthenticated endpoint, and it was naming every member of every global channel -- our peers' users included, on their behalf, when their own landing page publishes counts and never names. A channel still carries name, a members count and on, the other domains with members in it. Nothing in federation read it: peers exchange members in signed hello snapshots.

history_replay now defaults to 50, up from 20. Only settings you have never set follow a default, so an instance that has chosen a number keeps it.

From a version that took -user or PARLEY_USERS

Those are gone. Start the new version, then import the old list once:

Project layout

make test runs in-process end-to-end scenarios covering global and local channels, direct messages with automatic peering, peer exchange, catch-up after downtime, signature rejection and IRC basics.

Limitations

Known gaps, roughly in the order they should be closed:

Roadmap ideas

License

MIT, see LICENSE.