Files
continuum-proxy/README.md
T
octoturge 07f49f0c5b Stop a go2rtc that outlived a hard-killed proxy
SIGTERM already stops go2rtc (the signal handler), but SIGKILL and the OOM
killer give the proxy no chance to, and the orphan keeps :1984/:8555 bound
and a printer's access code in memory.

Two layers, neither needing unsafe or a new dependency:

- The watchdog records go2rtc's pid next to its config and, on startup,
  stops a leftover. It acts only if /proc confirms the pid is still *our*
  go2rtc - the configured binary on our own `-config` path - so a reused pid
  or another proxy's go2rtc is never touched; without /proc it does nothing.
  The pid file is removed when the supervisor goes away.
- deploy/continuum-proxy.service, whose KillMode=control-group (written out,
  with the reason) makes systemd kill the whole cgroup when the proxy dies.
  Syntax-checked with systemd-analyze only; not run under a real systemd.

Tests: the identity check, and a real stand-in process - a leftover is
terminated while an unrelated `sleep` survives. Making the identity check
always say yes fails both, so they do guard the behaviour.
2026-10-29 10:47:26 +00:00

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8.0 KiB
Markdown

# continuum-proxy
Edge gateway daemon for the Continuum print farm platform. Runs on a Linux
SBC on-site, talks to printers over the LAN, and keeps a connection to the
cloud control plane (`continuum-backend`).
## What's real right now
- **Bambu MQTT** - a real client for both protocol generations (MQTT
v3.1.1+BambuMQTT v1 on older firmware, MQTT v5+BambuMQTT v2 on current
firmware), auto-detected per printer on connect (a firmware update can
move the same physical printer between them, so this isn't something
config can hard-code once and forget - see `printer/bambu.rs`'s
`BambuProtocolPreference::Auto`). Request/reply correlation via
`sequence_id`, an in-memory `print.push_status` cache that merges v1's
partial updates and replaces on v2's full ones, and TLS trust that
auto-pins a printer's certificate via trust-on-first-connect the first
time the bundled CA doesn't verify (`printer/bambu.rs`'s
`ensure_trusted`) - see `printer/bambu_mqtt.rs`'s doc comment for the
full protocol write-up.
- **Marlin/RepRap serial** - a real held-open serial connection that paces
gcode lines by Marlin's own "ok" acknowledgment (`printer/marlin_serial.rs`).
- **Wire shapes from schemas, not hand duplication** - Bambu's raw MQTT
JSON is built straight from `continuum-schemas`' JSON Schema files via
`continuum-schema-instance`, instead of a second hand-written copy of
every request shape drifting out of sync with the schema.
- **Cloud uplink** - a WebSocket client to `continuum-backend` that
connects, sends a heartbeat on a timer, and reconnects on drop
(`src/uplink/`).
- **Camera restreaming** - generates go2rtc's configuration from the camera
URLs the printers report, and restarts go2rtc when it changes
(`src/camera.rs` + `src/go2rtc.rs`). Only the X1/H2 class publishes an
RTSP URL: confirmed against two real machines, an H2C reports
`rtsps://<ip>:322/streaming/live/1` and a P1P reports a camera with no URL
for it. A P1/A1 camera needs Bambu's proprietary port-6000 JPEG stream,
which this crate does not speak, so those printers advertise no stream
rather than one that will not play. Note the stream is reachable on the
gateway's LAN only - there is no relay.
- **Bambu file upload** - implicit FTPS (port 990) into the printer's own
`cache/` directory (`src/printer/bambu_ftps.rs`, via
`BambuPrinter::upload_file`). **Confirmed live against a P1P on
2026-10-03**: login, binary mode, and the transfer all work, byte count
matched exactly.
- **Print status** - `print.push_status` parsed into `PrintReport` with real
job progress, temperatures, fans and HMS entries. Confirmed live on both
generations (idle P1P on v1, H2C 20% into a job on v2); regression
fixtures from those captures are in `tests/fixtures/`.
## Examples worth knowing
- `cargo run --example live_reports [printer-id]` - **read-only**, safe
against a printer that is mid-print. Connects, reports firmware, and
watches the status stream. Redirect stderr to capture raw payloads.
- `cargo run --example bambu_idle_checks -- <printer-id>` - **writes**
(FTPS upload, fan speed). Requires an explicit printer id and refuses to
run unless that printer reports `gcode_state: "IDLE"`.
## What routes between the cloud and the printers
The uplink and the printer fleet are wired together, in both directions
(`uplink/mod.rs`):
- **Up:** every 5s, one `PrinterTelemetry` snapshot per printer that has
reported, batched into a single `Telemetry` message. Verified live against
a P1P and an H2C.
- **Down:** a `Command` from the cloud is looked up by our own printer id,
executed, and answered with a `CommandResult`. The set of commands is
deliberately small - a fan speed and a single gcode line - and deliberately
has no "start a print" variant; see `PrinterCommand`.
One quirk worth knowing: a Bambu on protocol v1 only sends a *complete*
status when asked, so each telemetry tick also fires a `pushing.pushall` for
the next one. A v1 printer's telemetry is therefore one tick behind, which
is why it shows up on the second frame rather than the first.
## What's still a stub
`start_uploaded_file` - the MQTT command that actually *starts* a print from
an uploaded file - is written but has deliberately never been fired, since
that commits a machine to hours of work. Its doc comment lists the three
details to confirm on the first real attempt. `upload_file` is proven, but
only with a small text file, not a multi-megabyte sliced `.3mf`.
PrusaLink (REST) and Klipper/Moonraker (WebSocket) - `printer/prusa.rs`
and `printer/klipper.rs` just `println!` what they'd send. Also not built
yet: local buffering for telemetry across connectivity gaps (so telemetry
produced while the uplink is down is simply lost), LAN printer discovery
(SSDP/mDNS), and the mechanical plate-changer interface.
## Getting started
```bash
cp .env.example .env
cargo run # the daemon: connects every configured printer, then runs the cloud uplink + go2rtc watchdog
cp printers.example.toml printers.toml # fill in your real printers (gitignored)
cargo run --example auto_connect_bambu # checks/auto-pins each Bambu printer's certificate, no MQTT needed
cargo run --example test_bambu_certs # narrower: just the raw TLS handshake, no auto-pinning
cargo run --example printer_polymorphism # standalone trait+enum demo, fake data, no network/env needed
cargo run --example bambu_commands_demo # round-trips hand-written structs against real captured Bambu JSON
```
## Structure
```
src/
main.rs Loads+connects the printer fleet, then runs the uplink, camera config, watchdog and completion watcher side by side
config.rs Loads settings from environment variables
fleet.rs Loads printers.toml into ready-to-use PrinterHandles
uplink/ WebSocket client to continuum-backend: connect, heartbeat, reconnect on drop
camera.rs Writes go2rtc's config from the camera URLs the printers report
go2rtc.rs Restarts the go2rtc camera-restreaming process if it dies, or when the config changes
and stops one a hard-killed proxy left behind (pid file next to its config)
deploy/ systemd unit template; its KillMode=control-group is what stops go2rtc outliving a SIGKILL'd proxy
printer/
mod.rs GenericPrinter trait + PrinterBase + PrinterHandle enum - the trait+enum
"inheritance" pattern this project uses instead of class inheritance
bambu.rs The real Bambu printer type: cert trust, protocol version auto-detect, commands
bambu_mqtt.rs The real MQTT wiring underneath bambu.rs - see its doc comment for the protocol details
bambu_commands/ Hand-written serde structs mirroring continuum-schemas' bambulab/ shapes
marlin_serial.rs A real held-open Marlin/RepRap serial connection
prusa.rs, klipper.rs Still stubs - see "What's still a stub" above
examples/
auto_connect_bambu.rs Checks/auto-pins every Bambu printer's certificate (no MQTT)
test_bambu_certs.rs Narrower: just a raw TLS handshake per Bambu printer
printer_polymorphism.rs Standalone trait+enum demo, five fake printers, no network needed
bambu_commands_demo.rs Round-trips bambu_commands' structs against real captured Bambu JSON
```
`printers.toml` (gitignored - copy from `printers.example.toml`) holds real
per-printer connection details: host, access code/API key/serial port
depending on vendor, and - for Bambu - an optional per-printer CA
certificate override (see `certs/README.md`; most printers don't need one,
since `connect()` auto-pins automatically).
## Learning Rust through this repo
`src/printer/mod.rs`'s doc comment is where the "how do I do inheritance
without classes" question lives - trait (shared behavior) + struct
(shared fields) + enum (the closed set of concrete types), instead of
`GenericPrinter -> BambuPrinter/PrusaLinkPrinter/...` class inheritance.
Run `printer_polymorphism` to see it work end to end without needing any
real printer on the network.