K8s pods have IPv4-only egress; without :inet in the gen_tcp opts,
BEAM was picking mqtt.pskreporter.info's AAAA record and the
kernel's connect() returned EINVAL, surfacing as :einval and a
30-second retry loop.
emqtt's transitive `quicer` dep needs CMake + msquic submodule
clones to build, which the slim Debian builder image doesn't ship —
the prod CI build was failing inside `mix deps.compile`. Tortoise311
is the obvious pure-Elixir alternative but it bundles a
gen_state_machine + retry/inflight stack we don't use because we're
subscribe-only at QoS 0.
Implementing the wire protocol inline is ~150 lines in
`Microwaveprop.Pskr.Mqtt` (CONNECT/SUBSCRIBE/PINGREQ/DISCONNECT
builders, CONNACK/PUBLISH/SUBACK/PINGRESP parser, varint codec).
Pskr.Client now uses :gen_tcp with `active: :once` framing,
buffers partial reads, schedules its own keepalive, and parses
inbound packets in a tight loop.
Drops `BUILD_WITHOUT_QUIC=1` from the Dockerfile — no longer
relevant since there's no native dep at all in the build chain
now.
Subscribes to mqtt.pskreporter.info:1883 over plain TCP and folds
every reception report into hourly aggregates per
(band, sender_grid_4, receiver_grid_4). Each spot is the empirical
"propagation actually occurred on this path right now" signal we'll
correlate against HRRR atmospheric state to recalibrate the scoring
weights. Aggregating at the path-hour bucket collapses 50-reporter
QSOs to one row instead of 50.
Topic filter anchors on USA (DXCC 291) on either sender or receiver
side so the broker pre-filters out everything outside our HRRR
domain. Bands subscribed: VHF and up (6m, 2m, 70cm, 23cm, +
microwave) — HF is dominated by ionospheric propagation, which this
project doesn't model.
Pskr.Client cluster-elects a singleton via :global.register_name —
all replicas start the GenServer but only one connects to MQTT;
the rest stay in :standby and watch for the leader's nodedown to
re-run election. Off in dev/test, on by default in prod
(PSKR_MQTT_ENABLED=false as kill-switch).
Pskr.Aggregator buffers in memory keyed by Pskr.path_key/1 and
flushes every 60s via Repo.insert_all/3 with an additive
ON CONFLICT (count summed, SNR envelope by GREATEST/LEAST,
modes unioned via unnest+DISTINCT). Idempotent across overlapping
flushes and across leader handover.
Dockerfile sets BUILD_WITHOUT_QUIC=1 — emqtt's transitive quicer
dep wants CMake + OpenSSL headers we'd otherwise have to add to
the builder image just to never use QUIC over plain MQTT. Base
image is unchanged; the new dep compiles cleanly into the existing
prop-base runtime.
