Lint by piping files to the linters instead of bind-mounting

`make lint` passed locally but failed in Gitea Actions with every Dockerfile
reported as missing:

    hadolint: images/node-agent/Dockerfile: withBinaryFile: does not exist

The job itself runs in a container, and the checkout lives in a docker volume
rather than on the host filesystem. Starting hadolint as a sibling container
through the host's docker socket meant `-v "$(CURDIR)":/repo` was resolved
against the HOST, where /workspace/... does not exist — so Docker created an
empty directory and mounted that.

Stream each file in on stdin instead. No shared filesystem is involved, so the
same command works locally and in CI. The linters then only ever see "-" as the
filename, so hack/lint.sh prints the real path itself, and only on failure.

Reproduced the original error and verified the fix against a faithful local
simulation: the repo in a docker volume at a path absent from the host, with
the socket mounted, running the real runner image.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>

Makefile

@@ -14,10 +14,6 @@ TARGETS := $(if $(IMAGE),$(IMAGE),$(IMAGES))
 # CI overrides REF with the real published ref so the smoke test runs against it.
 REF ?=
 
-HADOLINT   ?= hadolint/hadolint:latest-alpine
-SHELLCHECK ?= koalaman/shellcheck:stable
-SCRIPTS    := $(wildcard hack/*.sh images/*/test.sh template/test.sh)
-
 .DEFAULT_GOAL := help
 .PHONY: help list check lint hadolint shellcheck build test all
 
@@ -40,13 +36,10 @@ check: ## Verify each image directory follows the expected layout
 	exit $$rc
 
 hadolint: ## Lint every Dockerfile
-	@docker run --rm -v "$(CURDIR)":/repo:ro -w /repo $(HADOLINT) \
+	@hack/lint.sh dockerfiles
-	  hadolint $(addprefix images/,$(addsuffix /Dockerfile,$(IMAGES))) template/Dockerfile
-	@echo "hadolint ok"
 
 shellcheck: ## Lint every shell script
-	@docker run --rm -v "$(CURDIR)":/repo:ro -w /repo $(SHELLCHECK) $(SCRIPTS)
+	@hack/lint.sh scripts
-	@echo "shellcheck ok"
 
 lint: hadolint shellcheck ## Run all linters
 

hack/lint.sh

@@ -0,0 +1,70 @@
+#!/usr/bin/env bash
+# Lint Dockerfiles with hadolint and shell scripts with shellcheck.
+#
+# Each file is streamed into the linter container on stdin instead of bind-mounting
+# the repository. That is deliberate: in Gitea Actions the job itself runs in a
+# container, and the checkout lives in a docker volume rather than on the host
+# filesystem. A sibling container started through the host's docker socket resolves
+# `-v "$PWD":/repo` against the HOST, where that path does not exist — Docker then
+# silently creates an empty directory and the linter reports every file as missing.
+# Piping needs no shared filesystem, so one command works locally and in CI.
+#
+# The linters therefore only ever see "-" as the filename, so the real path is
+# printed here. Note this also means shellcheck cannot follow `source` directives;
+# none of these scripts use them.
+#
+# Usage: lint.sh [dockerfiles|scripts|all]
+set -euo pipefail
+cd "$(dirname "$0")/.."
+
+HADOLINT_IMAGE=${HADOLINT_IMAGE:-hadolint/hadolint:latest-alpine}
+SHELLCHECK_IMAGE=${SHELLCHECK_IMAGE:-koalaman/shellcheck:stable}
+
+rc=0
+
+report() {
+	local file=$1 out=$2 ok=$3
+	if [ "$ok" = 0 ]; then
+		printf '  ok   %s\n' "$file"
+	else
+		printf '  FAIL %s\n' "$file"
+		[ -n "$out" ] && printf '%s\n' "$out" | sed 's/^/       /'
+		rc=1
+	fi
+}
+
+dockerfiles() {
+	local file out ok
+	for file in images/*/Dockerfile template/Dockerfile; do
+		[ -f "$file" ] || continue
+		ok=0
+		out=$(docker run --rm --interactive "$HADOLINT_IMAGE" \
+			hadolint --no-color - <"$file" 2>&1) || ok=$?
+		report "$file" "$out" "$ok"
+	done
+}
+
+scripts() {
+	local file out ok
+	for file in hack/*.sh images/*/test.sh template/test.sh; do
+		[ -f "$file" ] || continue
+		ok=0
+		out=$(docker run --rm --interactive "$SHELLCHECK_IMAGE" - <"$file" 2>&1) || ok=$?
+		report "$file" "$out" "$ok"
+	done
+}
+
+case "${1:-all}" in
+	dockerfiles) dockerfiles ;;
+	scripts) scripts ;;
+	all)
+		dockerfiles
+		scripts
+		;;
+	*)
+		echo "usage: ${0##*/} [dockerfiles|scripts|all]" >&2
+		exit 2
+		;;
+esac
+
+exit "$rc"