Add script for running checkton locally

If you don't want to push to a PR just to re-run the linter, you can use
this script.

Won't work on ARM Macs, sorry!

Signed-off-by: Adam Cmiel <[email protected]>

hack/checkton-local.sh

@@ -0,0 +1,31 @@
+#!/bin/bash
+set -o errexit -o nounset -o pipefail
+
+get_checkton_image_based_on_action_version() {
+    sed -nE \
+        's;^\s*uses: (.*)/checkton.*(v[0-9]\S*);ghcr.io/\1/checkton:\2;p' \
+        .github/workflows/checkton.yaml
+}
+
+mapfile -t checkton_env_vars < <(
+    env CHECKTON_FIND_COPIES_HARDER="${CHECKTON_FIND_COPIES_HARDER:-true}" | grep '^CHECKTON_'
+)
+CHECKTON_IMAGE=${CHECKTON_IMAGE:-$(get_checkton_image_based_on_action_version)}
+
+{
+    echo "Checkton image: $CHECKTON_IMAGE"
+
+    echo "CHECKTON_* variables:"
+    printf "  %s\n" "${checkton_env_vars[@]}"
+} >&2
+
+
+if command -v getenforce >/dev/null && [[ "$(getenforce)" == Enforcing ]]; then
+    z=":z"
+else
+    z=""
+fi
+
+mapfile -t env_flags < <(printf -- "--env=%s\n" "${checkton_env_vars[@]}")
+
+podman run --rm --tty -v "$PWD:/code${z}" -w /code "${env_flags[@]}" "$CHECKTON_IMAGE"