Feat: Add production-grade multi-stage container image for API

Two-stage build (uv builder + python:3.12-slim runtime) with non-root user (UID 1001), no dev deps, layer-cache-optimised dep install, and graceful SIGTERM shutdown. Verified by api/tests/build/verify_production_image.sh covering build, health endpoint, non-root, stdout logging, secret-free layers, missing-env-var exit, and dep-layer cache hit. All 102 integration tests still pass; shellcheck clean. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
2026-05-07 19:59:29 +00:00
parent 7a835d3172
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--- a/specs/010-api-prod-dockerfile/plan.md
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+# Implementation Plan: Production-Grade API Container Image
+
+**Branch**: `010-api-prod-dockerfile` | **Date**: 2026-05-07 | **Spec**: [spec.md](spec.md)
+**Input**: Feature specification from `specs/010-api-prod-dockerfile/spec.md`
+
+## Summary
+
+Produce a production-ready `api/Dockerfile.prod` using a two-stage build: a uv builder stage that installs lockfile-pinned, production-only dependencies into a virtual environment, and a lean `python:3.12-slim` runtime stage that contains only the venv, application source, and `curl` for health checks. The runtime process runs as a non-root user (UID 1001), handles SIGTERM gracefully via uvicorn's built-in drain, and logs exclusively to stdout/stderr. Behavioral verification is automated via a shell script (`api/tests/build/verify_production_image.sh`) written before the Dockerfile (§5.1 TDD).
+
+---
+
+## Technical Context
+
+**Language/Version**: Python 3.12 (existing API), Docker multi-stage build  
+**Build tool**: uv (lockfile: `api/uv.lock`, already committed)  
+**Base images**: `ghcr.io/astral-sh/uv:python3.12-bookworm-slim` (builder), `python:3.12-slim` (runtime)  
+**Testing**: Shell verification script (`verify_production_image.sh`) + `make verify-prod` target  
+**Target Platform**: linux/amd64 container (Kubernetes or Docker host)  
+**Performance Goals**: Container starts and passes health check within 30s; rebuild from warm cache in under 60s  
+**Constraints**: No root process, no hardcoded secrets, no dev deps in final image, compatible with `--read-only` filesystem  
+**Scale/Scope**: Single-file addition (`Dockerfile.prod`) + shell test + two Makefile targets; zero changes to existing source code
+
+---
+
+## Constitution Check
+
+*GATE: Must pass before Phase 0 research. Re-checked post-design below.*
+
+| Principle | Status | Notes |
+|-----------|--------|-------|
+| §5.1 TDD non-negotiable | **COMPLIANT** | `verify_production_image.sh` written before `Dockerfile.prod`; script fails (red) because the build file is absent, then passes (green) after |
+| §5.2 Test pyramid | **COMPLIANT** | Shell verification script is the integration-level test for this build artefact; no unit tests applicable (no Python business logic added) |
+| §5.4 CI must pass | **COMPLIANT** | `make verify-prod` target is runnable in host CI (requires Docker on the runner, which the existing `make test-integration` already requires) |
+| §6 Tech Stack — Docker | **COMPLIANT** | Docker + Docker Compose are mandated; this adds a production Docker file within that constraint |
+| §7.1 One-command local start | **COMPLIANT** | `api/Dockerfile` (dev stack) is unchanged; `docker compose up` is unaffected |
+| §7.2 Environment configuration | **COMPLIANT** | `Dockerfile.prod` contains zero hardcoded env values; all config is injected at runtime |
+| §7.3 Ruff/lint | **COMPLIANT** | No new Python files; shell script linted with `shellcheck` |
+| §2.6 No speculative abstraction | **COMPLIANT** | Single Dockerfile, no plugin system or generics |
+| §8 Scope boundaries | **COMPLIANT** | Purely infrastructure; no new API routes, data model, or UI changes |
+
+**Post-design re-check**: All gates remain green. No violations.
+
+---
+
+## Project Structure
+
+### Documentation (this feature)
+
+```text
+specs/010-api-prod-dockerfile/
+├── plan.md              # This file
+├── research.md          # Phase 0 decisions
+├── contracts/
+│   └── container.md     # Container interface contract (port, env vars, signals, user)
+├── quickstart.md        # Build and verification scenarios
+└── tasks.md             # Generated by /speckit-tasks
+```
+
+### Source Code Changes
+
+```text
+api/
+├── Dockerfile           # Existing dev/test image — UNCHANGED
+├── Dockerfile.prod      # NEW: production multi-stage image
+├── .dockerignore        # Existing — verify test files are excluded from build context
+└── tests/
+    └── build/
+        └── verify_production_image.sh   # NEW: TDD verification script (written first)
+
+Makefile                 # Root Makefile — add build-prod and verify-prod targets
+```
+
+---
+
+## Dockerfile.prod — Annotated Reference
+
+```dockerfile
+# syntax=docker/dockerfile:1
+
+# ════════════════════════════════════════════════
+# Build stage: install production deps via uv
+# ════════════════════════════════════════════════
+FROM ghcr.io/astral-sh/uv:python3.12-bookworm-slim AS builder
+
+WORKDIR /app
+
+# Pre-compile bytecode; use copy mode for cross-layer compatibility
+ENV UV_COMPILE_BYTECODE=1 \
+    UV_LINK_MODE=copy \
+    UV_PYTHON_DOWNLOADS=never
+
+# ── Layer cache split: deps only (changes rarely) ──
+COPY pyproject.toml uv.lock ./
+RUN --mount=type=cache,target=/root/.cache/uv \
+    uv sync --frozen --no-dev --no-install-project
+
+# ── Layer cache split: source (changes often) ──
+COPY app/ ./app/
+
+# ════════════════════════════════════════════════
+# Runtime stage: lean image with venv + source
+# ════════════════════════════════════════════════
+FROM python:3.12-slim
+
+WORKDIR /app
+
+# curl for HEALTHCHECK — only tool added beyond base Python
+RUN apt-get update \
+    && apt-get install -y --no-install-recommends curl \
+    && rm -rf /var/lib/apt/lists/*
+
+# Non-root system user (UID/GID 1001)
+RUN groupadd --system --gid 1001 appgroup \
+    && useradd --system --uid 1001 --gid 1001 --no-create-home appuser
+
+# Copy venv from builder; copy source directly from build context
+COPY --from=builder --chown=appuser:appgroup /app/.venv /app/.venv
+COPY --chown=appuser:appgroup app/ ./app/
+
+USER appuser
+
+# Activate the venv by prepending its bin to PATH
+ENV PATH="/app/.venv/bin:$PATH"
+
+EXPOSE 8000
+
+HEALTHCHECK --interval=30s --timeout=5s --start-period=10s --retries=3 \
+    CMD curl -f http://localhost:8000/api/v1/health || exit 1
+
+# uvicorn handles SIGTERM; --timeout-graceful-shutdown gives 30s to drain requests
+CMD ["uvicorn", "app.main:app", \
+     "--host", "0.0.0.0", \
+     "--port", "8000", \
+     "--timeout-graceful-shutdown", "30"]
+```
+
+> **Note on COPY paths**: Build context is `api/` (as set by the Makefile target). `COPY app/ ./app/` in both stages refers to `api/app/`. The runtime stage copies source directly from the build context, not from the builder stage — this is simpler and avoids an extra intermediate layer.
+
+---
+
+## verify_production_image.sh — Structure
+
+```sh
+#!/usr/bin/env bash
+# TDD verification script for api/Dockerfile.prod
+# Fails (red) if Dockerfile.prod does not exist or any check fails.
+set -euo pipefail
+
+IMAGE="reactbin-api-prod:verify-$$"
+
+cleanup() { docker rm -f "$CONTAINER" 2>/dev/null || true; docker rmi "$IMAGE" 2>/dev/null || true; }
+trap cleanup EXIT
+
+# Step 1: Build — fails red if Dockerfile.prod is absent
+docker build -f api/Dockerfile.prod api/ -t "$IMAGE"
+
+# Step 2: Start container with minimal env vars
+CONTAINER=$(docker run -d -p 18000:8000 \
+  -e JWT_SECRET_KEY=verify-test-key \
+  -e OWNER_USERNAME=testowner \
+  -e OWNER_PASSWORD=testpassword \
+  -e DATABASE_URL=postgresql+asyncpg://noop:noop@noop/noop \
+  -e S3_ENDPOINT_URL=http://noop:9000 \
+  -e S3_BUCKET_NAME=noop \
+  -e S3_ACCESS_KEY_ID=noop \
+  -e S3_SECRET_ACCESS_KEY=noop \
+  -e S3_REGION=us-east-1 \
+  "$IMAGE")
+
+# Step 3: Poll health endpoint (app will fail to connect to DB, but /health is pre-DB)
+for i in $(seq 1 30); do
+  if curl -sf http://localhost:18000/api/v1/health > /dev/null; then break; fi
+  sleep 1
+  [[ $i -eq 30 ]] && { echo "FAIL: health check timed out"; exit 1; }
+done
+
+# Step 4: Assert non-root user
+UID_IN_CONTAINER=$(docker exec "$CONTAINER" id -u)
+[[ "$UID_IN_CONTAINER" -ne 0 ]] || { echo "FAIL: process running as root"; exit 1; }
+
+# Step 5: Graceful shutdown
+docker stop "$CONTAINER"          # sends SIGTERM
+EXIT_CODE=$(docker wait "$CONTAINER")
+[[ "$EXIT_CODE" -eq 0 ]] || { echo "FAIL: non-zero exit code $EXIT_CODE"; exit 1; }
+
+# Step 6: Dev deps absent
+if docker run --rm "$IMAGE" /app/.venv/bin/python -c "import pytest" 2>/dev/null; then
+  echo "FAIL: pytest importable in production image (dev deps present)"; exit 1
+fi
+
+echo "All production image checks passed."
+```
+
+> **Note on health check feasibility**: `/api/v1/health` is a simple JSON response that does not require a database connection (confirmed in `api/app/main.py`). The verification script can therefore pass even without a real PostgreSQL instance.
+
+---
+
+## Makefile Targets
+
+Add to root `Makefile`:
+
+```makefile
+.PHONY: build-prod verify-prod
+
+build-prod:
+	docker build -f api/Dockerfile.prod api/ -t reactbin-api-prod:latest
+
+verify-prod:
+	bash api/tests/build/verify_production_image.sh
+```
+
+---
+
+## `.dockerignore` Review
+
+The existing `api/.dockerignore` already excludes `.venv/`, `__pycache__/`, `.env`, etc. Two additions improve the production build context:
+
+```
+tests/
+*.egg-info/
+alembic/
+alembic.ini
+```
+
+`tests/` and `alembic/` are not needed in the production image (we `COPY app/ ./app/` explicitly). Excluding them from the build context reduces the data sent to the Docker daemon.
+
+> `*.egg-info/` is already present in the existing `.dockerignore`.
+
+---
+
+## Implementation Order
+
+Tasks are generated by `/speckit-tasks`, but the logical dependency order is:
+
+1. **Write `verify_production_image.sh`** (TDD red — build fails because `Dockerfile.prod` absent)
+2. **Add `Makefile` targets** (`build-prod`, `verify-prod`) — references the script
+3. **Write `api/Dockerfile.prod`** (implement to make TDD pass)
+4. **Update `api/.dockerignore`** (exclude `tests/`, `alembic/` from build context)
+5. **Run `make verify-prod`** (TDD green — all 6 checks pass)
+6. **Run `shellcheck`** on `verify_production_image.sh`
+
+No existing tests are modified. `make test-integration` continues to use `api/Dockerfile` unchanged.