Dockerfile.backend

# syntax=docker/dockerfile:1.7
#
# ForecastLabAI backend image.
#
# Multi-stage:
#   base  — python:3.12-slim-bookworm + curl (for healthcheck) + uv installer
#   deps  — `uv sync --frozen --extra dev --no-install-project` against pyproject.toml/uv.lock
#           ONLY (no `app/` yet — keeps the dep layer cacheable across source edits)
#   dev   — copies the project, installs it, runs alembic+uvicorn with --reload
#   prod  — re-syncs without dev extras, no --reload (smaller, immutable)
#
# Build:
#   docker build -t forecastlab-backend:dev --target dev -f Dockerfile.backend .
#   docker build -t forecastlab-backend:prod --target prod -f Dockerfile.backend .
#
# Gotchas (verified on this host):
#   * asyncpg talks the Postgres wire protocol directly — NO libpq needed.
#   * uv 0.11.8 supports `--no-install-project` (verified via `uv sync --help`).
#   * Inside the container the Postgres DNS name is `postgres:5432`, NOT
#     `localhost:5433` (that's the host-side published port).

ARG PYTHON_VERSION=3.12-slim-bookworm

# ---------- base ----------
FROM python:${PYTHON_VERSION} AS base

# curl for the healthcheck; ca-certificates for the uv install over HTTPS.
# build-essential is intentionally NOT installed — every Python dep in uv.lock
# ships a manylinux wheel, asyncpg includes a binary distribution, and pure-Python
# packages need no compiler.
RUN apt-get update \
    && apt-get install -y --no-install-recommends \
        curl \
        ca-certificates \
    && rm -rf /var/lib/apt/lists/*

# Install uv (pinned by the official installer's stable URL; the binary lands
# in /root/.local/bin which we add to PATH).
ENV UV_INSTALL_DIR=/root/.local/bin
RUN curl -LsSf https://astral.sh/uv/install.sh | sh
ENV PATH="/root/.local/bin:${PATH}"

# Don't write .pyc files or buffer stdout — keeps logs clean and the image small.
ENV PYTHONDONTWRITEBYTECODE=1 \
    PYTHONUNBUFFERED=1 \
    UV_LINK_MODE=copy \
    UV_PROJECT_ENVIRONMENT=/opt/venv

WORKDIR /app

# ---------- deps ----------
FROM base AS deps

# Bring in JUST the dependency manifests. `--no-install-project` keeps uv from
# trying to install the workspace itself when `app/` isn't present yet.
COPY pyproject.toml uv.lock README.md ./

RUN --mount=type=cache,target=/root/.cache/uv \
    uv sync --frozen --extra dev --no-install-project

# ---------- dev (default target) ----------
FROM deps AS dev

# Project source. Keep these in their own layer so an `app/` edit doesn't
# invalidate the (much heavier) deps layer above.
COPY app/ ./app/
COPY alembic/ ./alembic/
COPY alembic.ini ./
COPY scripts/ ./scripts/

# Now register the project itself against the existing venv. Cheap — deps are
# cached above, only the project's editable install runs.
RUN --mount=type=cache,target=/root/.cache/uv \
    uv sync --frozen --extra dev

EXPOSE 8123

# Inline entrypoint:
#   1. Wait for Postgres? — handled by `depends_on: condition: service_healthy`
#      in docker-compose; the container only starts after pg_isready is green.
#   2. Run migrations (forward-only — idempotent if already applied).
#   3. Hand off to uvicorn with --reload for the dev hot-loop.
ENTRYPOINT ["sh", "-c", "uv run alembic upgrade head && exec uv run uvicorn app.main:app --host 0.0.0.0 --port 8123 --reload"]

# ---------- prod ----------
FROM dev AS prod

# Re-sync WITHOUT the dev extra to drop pytest/ruff/mypy/pyright from the image.
RUN --mount=type=cache,target=/root/.cache/uv \
    uv sync --frozen

# No --reload in prod. The migration step stays — first container of a new
# release applies migrations idempotently; subsequent containers see "no-op".
ENTRYPOINT ["sh", "-c", "uv run alembic upgrade head && exec uv run uvicorn app.main:app --host 0.0.0.0 --port 8123"]