#!/bin/sh
# script/lint: run the linter. golangci-lint is never installed on a
# host: it runs via docker only, one way, everywhere — this builds
# Dockerfile.lint, which COPYs the repo into the digest-pinned
# golangci-lint image and lints as a build step, so a successful build
# is a clean lint. The only prerequisite is a working docker. The gate
# steps make no network calls of their own, but Dockerfile.lint runs
# `go mod download` above them, so a cold cache does reach the network
# (as does pulling the pinned image); that layer stays cached, and once
# it is warm this runs offline until go.mod or go.sum changes.
#
# CHECK_EPOCH is what makes the result mean anything. Without it docker
# serves the gate layers from cache on an unchanged tree and this exits
# 0 in well under a second having run no linter. The PID is in the value
# as well as the epoch because two lint runs land inside the same second
# easily, and `date +%s` alone would cache the second one.
set -eu

ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"

main() {
    cd "$ROOT"
    docker build \
        --build-arg CHECK_EPOCH="$(date +%s)-$$" \
        -f Dockerfile.lint \
        .
}

main "$@"