move to alpine

Dockerfile

@@ -1,18 +1,15 @@
-FROM ubuntu:focal
-
-ENV DEBIAN_FRONTEND=noninteractive
-
-# hadolint ignore=DL3008,DL3028
-RUN apt-get update && \
-	apt-get -y --no-install-recommends install \
-		build-essential \
-		wget \
-		rsync \
-		openssh-client \
-		ca-certificates \
-		debhelper \
-		git \
-		curl \
-		yamllint \
-	&& apt-get clean && \
-	rm -rf /var/lib/apt/lists/* /var/tmp/* /tmp/*
+# hadolint ignore=DL3007
+FROM alpine:latest
+# hadolint ignore=DL3018
+RUN apk update --no-cache && \
+    apk add --no-cache \
+				build-essential \
+				wget \
+				rsync \
+				openssh-client \
+				ca-certificates \
+				debhelper \
+				git \
+				curl \
+				yamllint \
+				bash \