refactor: separate core and optimizer images

.changeset/fast-cores-split.md

@@ -0,0 +1,5 @@
+---
+"ftw": minor
+---
+
+Make the official core container a small static runtime and keep Python/CVXPY exclusively in the independently updatable optimizer image.

.github/workflows/test.yml

@@ -69,7 +69,7 @@ jobs:
                 drivers/*.lua)
                   drivers=true
                   ;;
-                docker-compose*.yml|scripts/enable-modular-stack.sh|scripts/migrate-legacy-compose.sh|scripts/test-modular-compose.sh|scripts/install-macos.sh)
+                Dockerfile|Dockerfile.optimizer|docker-compose*.yml|scripts/enable-modular-stack.sh|scripts/migrate-legacy-compose.sh|scripts/test-modular-compose.sh|scripts/test-container-boundaries.sh|scripts/install-macos.sh)
                   compose=true
                   ;;
                 Makefile|.github/workflows/test.yml)
@@ -195,13 +195,13 @@ jobs:
           -head "${{ needs.changes.outputs.head_sha }}"
 
   compose:
-    name: compose migration
+    name: module boundaries
     needs: changes
     if: needs.changes.outputs.compose == 'true'
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v5
-      - run: make compose-migration-test
+      - run: make compose-migration-test container-boundary-test
 
   e2e:
     name: full stack

Dockerfile

@@ -1,14 +1,13 @@
-# FTW container — static Go host + Python mathematical planner.
-#
-# Builder uses golang:alpine to keep the Go binary fully static. The runtime is
-# Debian slim because the CVXPY and HiGHS ARM64 wheels target glibc.
+# FTW core container — static Go host plus bundled Lua drivers and web assets.
+# The optional Python/CVXPY optimizer ships as its own independently updatable
+# image from Dockerfile.optimizer. Core falls back safely when it is absent.
 #
 # Multi-arch: linux/amd64 + linux/arm64 via docker buildx TARGETOS /
 # TARGETARCH when available. Plain `docker build` falls back to the
 # native Go arch inside the builder image.
 
 # --- Builder ---------------------------------------------------------------
-FROM golang:1.26-alpine AS builder
+FROM --platform=$BUILDPLATFORM golang:1.26-alpine AS builder
 
 # git is needed by `go build` to resolve VCS info baked into the binary
 # via -X main.Version. Everything else is in the base image.
@@ -33,20 +32,12 @@ RUN cd go && \
     CGO_ENABLED=0 GOOS=${TARGETOS} GOARCH=${target_arch} \
     go build -trimpath -ldflags="-s -w -X main.Version=${VERSION}" \
     -o /out/ftw ./cmd/ftw
-# --- Optimizer -------------------------------------------------------------
-FROM python:3.12-slim-bookworm AS optimizer
-
-COPY optimizer/ /src/optimizer/
-RUN python -m venv /opt/venv && \
-    /opt/venv/bin/pip install --no-cache-dir /src/optimizer
-
 # --- Runtime ---------------------------------------------------------------
-FROM python:3.12-slim-bookworm
+FROM alpine:3.22
 
-# ca-certificates: HTTPS to elprisetjustnu / met.no / ECB FX.
-# tzdata: timezone-aware price + plan windows (Europe/Stockholm etc).
-RUN apt-get update && apt-get install -y --no-install-recommends ca-certificates tzdata && \
-    rm -rf /var/lib/apt/lists/*
+# HTTPS integrations and timezone-aware price/plan windows need these at
+# runtime. BusyBox wget provides the health check without adding Python/curl.
+RUN apk add --no-cache ca-certificates tzdata
 
 # Image layout:
 #   /app/ftw              binary (immutable, replaced on upgrade)
@@ -62,19 +53,15 @@ RUN apt-get update && apt-get install -y --no-install-recommends ca-certificates
 # is no path resolution against the config file's directory; the open
 # call is literally state.Open(cfg.State.Path).
 COPY --from=builder /out/ftw             /app/ftw
-COPY --from=optimizer /opt/venv          /opt/venv
-COPY optimizer/                          /app/optimizer/
 COPY drivers/ /app/drivers/
 COPY web/     /app/web/
 COPY LICENSE NOTICE /usr/share/doc/ftw/
 
 RUN ln -s /app/ftw /app/forty-two-watts && \
     mkdir -p /app/data /app/data/drivers /run/ftw-update /run/ftw-optimizer && \
-    chown -R 100:101 /app /run/ftw-update /run/ftw-optimizer /opt/venv
+    chown -R 100:101 /app /run/ftw-update /run/ftw-optimizer
 
-ENV HOME=/app/data \
-    FTW_OPTIMIZER_PYTHON=/opt/venv/bin/python \
-    FTW_OPTIMIZER_DIR=/app/optimizer
+ENV HOME=/app/data
 
 USER 100:101
 WORKDIR /app/data
@@ -100,7 +87,7 @@ EXPOSE 8080
 # open database file" because SQLite can't create state.db inside
 # a directory it doesn't own.
 HEALTHCHECK --interval=10s --timeout=5s --start-period=20s --retries=12 \
-  CMD python -c "import urllib.request; urllib.request.urlopen('http://127.0.0.1:8080/api/health', timeout=4)" || exit 1
+  CMD wget -q -T 4 -O /dev/null http://127.0.0.1:8080/api/health || exit 1
 
 ENTRYPOINT ["/app/ftw"]
 CMD ["-config", "/app/data/config.yaml", "-web", "/app/web", "-drivers", "/app/drivers", "-user-drivers", "/app/data/drivers"]

Makefile

@@ -11,7 +11,7 @@
 #   make dev                  — start sims + main app (hot-reload workflow)
 #   make clean                — remove all build artifacts
 
-.PHONY: help test optimizer-install optimizer-test compose-migration-test build build-arm64 build-amd64 build-windows-amd64 release \
+.PHONY: help test optimizer-install optimizer-test compose-migration-test container-boundary-test build build-arm64 build-amd64 build-windows-amd64 release \
         run-sim dev fmt vet clean e2e ci ci-ui ci-hw-pi docs \
 		verify verify-all install-hooks driver-repository-validate driver-versions
 
@@ -68,6 +68,9 @@ compose-migration-test:
 	bash -n scripts/enable-modular-stack.sh scripts/migrate-legacy-compose.sh scripts/install-macos.sh
 	bash scripts/test-modular-compose.sh
 
+container-boundary-test:
+	bash scripts/test-container-boundaries.sh
+
 optimizer/.venv/.installed: optimizer/pyproject.toml
 	$(MAKE) optimizer-install
 
@@ -99,7 +102,7 @@ ci-hw-pi:
 # verify-all adds cross-compile checks for all release targets, catching
 # platform-specific syscall/import mistakes before push.
 
-verify: test compose-migration-test
+verify: test compose-migration-test container-boundary-test
 	cd go && go vet ./...
 	cd go && go build ./...
 	@echo "verify: vet + test + build clean"

config.example.yaml

@@ -176,8 +176,9 @@ state:
 #       trusted_keys:
 #         ftw-drivers-2026-01: MX+j27UBkyM099hTyJlmMLK9qlTTDUJsaK/vH12fFKc=
 
-# Mathematical MPC optimizer. The official container includes Python/CVXPY;
-# native installs can set optimizer_command to their venv's Python executable.
+# Mathematical MPC optimizer. Official Compose runs it as the independently
+# updatable ftw-optimizer service; native installs can point optimizer_command
+# at their venv's Python executable.
 # planner:
 #   enabled: true
 #   engine: python

scripts/test-container-boundaries.sh

@@ -0,0 +1,17 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+ROOT=$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)
+cd "$ROOT"
+
+if grep -Eq 'COPY optimizer/|--from=optimizer|/opt/venv|FTW_OPTIMIZER_(PYTHON|DIR)' Dockerfile; then
+  echo "Dockerfile must contain only core, drivers and web assets; use Dockerfile.optimizer for Python/CVXPY" >&2
+  exit 1
+fi
+
+grep -q '^FROM alpine:' Dockerfile
+grep -q '^COPY optimizer/' Dockerfile.optimizer
+grep -q '^  ftw-optimizer:' docker-compose.yml
+grep -q 'FTW_OPTIMIZER_SOCKET: /run/ftw-optimizer/optimizer.sock' docker-compose.yml
+
+echo "container module boundaries verified"