# syntax=docker/dockerfile:1
FROM golang:1.26.1-alpine AS builder
WORKDIR /app

# Download modules into the BuildKit cache so they survive across builds.
# This layer is only invalidated when go.mod or go.sum changes.
COPY go.mod go.sum ./
RUN --mount=type=cache,target=/root/go/pkg/mod \
    go mod download

COPY . .

ARG VERSION=dev
ARG COMMIT=unknown

# Build all three binaries in a single layer so the Go compiler can reuse
# intermediate object files.  Both cache mounts are preserved between builds:
#   /root/go/pkg/mod   — downloaded module source
#   /root/.cache/go-build — compiled package objects (incremental recompile)
RUN --mount=type=cache,target=/root/go/pkg/mod \
    --mount=type=cache,target=/root/.cache/go-build \
    CGO_ENABLED=0 GOOS=linux go build \
      -ldflags="-s -w -X main.version=${VERSION} -X main.commit=${COMMIT}" \
      -o /out/backend ./cmd/backend && \
    CGO_ENABLED=0 GOOS=linux go build \
      -ldflags="-s -w -X main.version=${VERSION} -X main.commit=${COMMIT}" \
      -o /out/runner ./cmd/runner && \
    CGO_ENABLED=0 GOOS=linux go build \
      -ldflags="-s -w" \
      -o /out/healthcheck ./cmd/healthcheck

# ── backend service ──────────────────────────────────────────────────────────
FROM gcr.io/distroless/static:nonroot AS backend
COPY --from=builder /out/healthcheck /healthcheck
COPY --from=builder /out/backend /backend
ENTRYPOINT ["/backend"]

# ── runner service ───────────────────────────────────────────────────────────
FROM gcr.io/distroless/static:nonroot AS runner
COPY --from=builder /out/healthcheck /healthcheck
COPY --from=builder /out/runner /runner
ENTRYPOINT ["/runner"]