# Lint phase
# golangci/golangci-lint:v2.14.0, 2026-10-06
FROM golangci/golangci-lint@sha256:ad862ba6b3798cbe0fd9fd7408d498fd74fbd2623a92406b2fd3898faf0bf98f AS lint
WORKDIR /src
COPY go.mod go.sum ./
RUN go mod download
COPY . .
RUN golangci-lint run --config .golangci.yml ./...

# Test phase. -race needs cgo and so a C compiler, which the Debian Go
# image ships and the alpine one does not. The tests run as an
# unprivileged user: root can read a file with mode 0000, so the
# permission tests would fail.
# golang:1.25.7-trixie, 2026-10-06
FROM golang@sha256:2b174ffcf56c7ad0c47d30d2630693265639ddf2a5141149c2da34db921791b4 AS test
RUN useradd --create-home testuser
USER testuser
WORKDIR /src
COPY go.mod go.sum ./
RUN go mod download
COPY . .
RUN go test -timeout 90s -race -cover ./... || \
    { echo "--- Rerunning with -v for details ---"; \
      go test -timeout 90s -race -v ./...; exit 1; }

# Build stage. Nothing is wanted from either phase above; the copies
# are what make BuildKit build them first, so this stage cannot run
# unless lint and test passed.
# golang 1.25-alpine, 2026-02-28
FROM golang@sha256:f6751d823c26342f9506c03797d2527668d095b0a15f1862cddb4d927a7a4ced AS builder
COPY --from=lint /src/go.sum /dev/null
COPY --from=test /src/go.sum /dev/null
RUN apk add --no-cache git make
# A tar-stream context keeps the sender's file owners, which git refuses.
RUN git config --system --add safe.directory /src
WORKDIR /src
COPY go.mod go.sum ./
RUN go mod download
COPY . .

# The version stamped into the binary: the VERSION build argument when one
# is given, otherwise `git describe --tags --always` of the .git the build
# context carries: the tag on a tagged commit, tag-N-gHASH on a commit after
# one, the short commit when no tag is reachable. A context that carries .git
# and still yields no version fails the build. With neither, as from a source
# tarball, the binary reports dev.
ARG VERSION
RUN version="${VERSION:-$(git describe --tags --always)}"; \
    if [ -e .git ] && { [ -z "$version" ] || [ "$version" = dev ] || \
        [ "$version" = unknown ]; }; then \
        echo "version is '$version' although .git is present" >&2; \
        exit 1; \
    fi; \
    make build VERSION="${version:-dev}"

# Runtime stage
# alpine 3.21, 2026-02-28
FROM alpine@sha256:c3f8e73fdb79deaebaa2037150150191b9dcbfba68b4a46d70103204c53f4709

RUN apk add --no-cache ca-certificates tzdata

WORKDIR /app

COPY --from=builder /src/attrsum /app/attrsum

ENTRYPOINT ["/app/attrsum"]