#!/bin/sh
# script/lint: run the linter. Linting is a phase of the Dockerfile and
# this builds that phase; the linter is never installed or run on
# a developer host, where a shared result cache and a host-global lock
# make its answer untrustworthy.
#
# --target builds the lint phase and the stages it depends on, nothing
# else. A new CACHEBUST value reruns every RUN step after
# the ARG CACHEBUST line, since a cached lint layer is a lint that did
# not run; unlike --no-cache, it keeps the layers above that line and
# the cache mounts. This relies on every stage of the Dockerfile
# declaring ARG CACHEBUST before every step that lints, tests or
# compiles; a stage without that line is served from cache on an
# unchanged tree, with no warning.
# --output type=cacheonly writes no image, since nothing uses one.
set -eu

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

main() {
    cd "$ROOT"
    docker build --build-arg CACHEBUST="$(date +%s)-$$" \
        --target lint \
        --output type=cacheonly .
}

main "$@"