Rework the Dockerfile to produce a proper multi-arch manifest from a
single `docker buildx build --platform linux/amd64,linux/arm64`. The
builder stage runs on the host's native arch ($BUILDPLATFORM) and Go
cross-compiles to each requested $TARGETARCH via the Makefile's
build-$TARGETARCH targets — no qemu-emulated builder, no per-arch
Dockerfile duplication. VERSION/COMMIT/DATE flow from --build-arg
through to the -ldflags -X injection so images stamp the same metadata
as `make build` on bare metal.
docker-compose.yml gains Docker Compose "profiles" (collector,
aggregator, frontend) and an `env_file: .env`, mirroring vpp-maglev's
pattern. All three services ship from one multi-arch image and select
their binary via `command:`. Collector uses network_mode: host so UDP
from host nginx on 127.0.0.1 actually reaches it; aggregator/frontend
bridge-network with published ports.
.env.example documents every COLLECTOR_*, AGGREGATOR_*, FRONTEND_* env
var with its default plus COMPOSE_PROFILES and notes for Docker-specific
cases (service DNS names, AGGREGATOR_COLLECTORS spelling). .gitignore
excludes /.env so local tunables stay local.
Verified: `docker buildx build --platform linux/amd64,linux/arm64` goes
through cleanly from one invocation; local --load build's four binaries
report version 0.9.1 with the injected commit/date.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
