added hadolint-checks (#5)

Co-authored-by: Michael Grote <michael.grote@posteo.de>
Reviewed-on: mg/miniflux-filter#5
Co-authored-by: mg <michael.grote@posteo.de>
Co-committed-by: mg <michael.grote@posteo.de>

build.sh

@@ -11,6 +11,12 @@ if ! shellcheck ./filter.sh; then
     exit 1
 fi
 
+if ! docker run --rm -i ghcr.io/hadolint/hadolint < dockerfile; then
+    echo "-----------------------------------"
+    echo "warning: fix hadolint errors"
+    exit 1
+fi
+
 # pruefe ob kw gesetzt ist
 if [[ -z "$MF_DOCKERHUB_PASS" ]]; then
     # shellcheck disable=SC2016

dockerfile

@@ -1,5 +1,6 @@
 FROM ubuntu:focal
 
+# hadolint ignore=DL3008
 RUN apt-get update \
     && apt-get install -y --no-install-recommends bash curl ca-certificates jq \
     && apt-get clean \