chore: Dockerfile - Adopt HereDoc syntax

Dockerfile

@@ -6,42 +6,53 @@ ARG INSTALL_ROOT=/rootfs
 FROM opensuse/leap:${LEAP_VERSION} AS builder
 ARG CACHE_ZYPPER=/tmp/cache/zypper
 ARG INSTALL_ROOT
-RUN \
+RUN <<HEREDOC
-  # /etc/os-release provides ${VERSION_ID} for usage in ZYPPER_OPTIONS:
+  # Remove the `openh264` the `non-oss` repos to save on sync time, they're not needed:
-  source /etc/os-release \
+  zypper removerepo repo-openh264 repo-non-oss repo-update-non-oss
-  # We don't need the openh264.repo and the non-oss repos, just costs build time (repo caches).
+  # `/etc/os-release` provides the `VERSION_ID` variable for usage in `ZYPPER_OPTIONS`:
-  && zypper removerepo repo-openh264 repo-non-oss repo-update-non-oss \
+  source /etc/os-release
-  && export ZYPPER_OPTIONS=( --releasever "${VERSION_ID}" --installroot "${INSTALL_ROOT}" --cache-dir "${CACHE_ZYPPER}" ) \
+  export ZYPPER_OPTIONS=( --releasever "${VERSION_ID}" --installroot "${INSTALL_ROOT}" --cache-dir "${CACHE_ZYPPER}" )
-  && zypper "${ZYPPER_OPTIONS[@]}" --gpg-auto-import-keys refresh \
+
-  && zypper "${ZYPPER_OPTIONS[@]}" --non-interactive install --download-in-advance --no-recommends \
+  # Install packages to a custom root-fs location (defined in `ZYPPER_OPTIONS`):
-       bash procps grep gawk sed coreutils busybox ldns libidn2-0 socat openssl curl \
+  zypper "${ZYPPER_OPTIONS[@]}" --gpg-auto-import-keys refresh
-  && zypper "${ZYPPER_OPTIONS[@]}" clean --all \
+  zypper "${ZYPPER_OPTIONS[@]}" --non-interactive install --download-in-advance --no-recommends \
-  ## Cleanup (reclaim approx 13 MiB):
+       bash procps grep gawk sed coreutils busybox ldns libidn2-0 socat openssl curl
+
+  # Optional - Avoid `CACHE_ZYPPER` from being redundantly cached in this RUN layer:
+  # (doesn't improve `INSTALL_ROOT` size thanks to `--cache-dir`)
+  zypper "${ZYPPER_OPTIONS[@]}" clean --all
+
+  # Cleanup (reclaim approx 13 MiB):
   # None of this content should be relevant to the container:
-  && rm -r "${INSTALL_ROOT}/usr/share/"{licenses,man,locale,doc,help,info} \
+  rm -r "${INSTALL_ROOT}/usr/share/"{licenses,man,locale,doc,help,info} \
-           "${INSTALL_ROOT}/usr/share/misc/termcap" \
+    "${INSTALL_ROOT}/usr/share/misc/termcap" \
-           "${INSTALL_ROOT}/usr/lib/sysimage/rpm"
+    "${INSTALL_ROOT}/usr/lib/sysimage/rpm"
+HEREDOC
 
 
 # Create a new image with the contents of ${INSTALL_ROOT}
 FROM scratch AS base-leap
 ARG INSTALL_ROOT
 COPY --link --from=builder ${INSTALL_ROOT} /
-RUN \
+RUN <<HEREDOC
   # Creates symlinks for any other commands that busybox can provide that
   # aren't already provided by coreutils (notably hexdump + tar, see #2403):
   # NOTE: `busybox --install -s` is not supported via the leap package, manually symlink commands.
-  ln -s /usr/bin/busybox /usr/bin/tar \
+  ln -s /usr/bin/busybox /usr/bin/tar
-  && ln -s /usr/bin/busybox /usr/bin/hexdump \
+  ln -s /usr/bin/busybox /usr/bin/hexdump
-  && ln -s /usr/bin/busybox /usr/bin/xxd \
+  ln -s /usr/bin/busybox /usr/bin/xxd
+
   # Add a non-root user `testssl`, this is roughly equivalent to the `useradd` command:
   # useradd --uid 1000 --user-group --create-home --shell /bin/bash testssl
-  && echo 'testssl:x:1000:1000::/home/testssl:/bin/bash' >> /etc/passwd \
+  echo 'testssl:x:1000:1000::/home/testssl:/bin/bash' >> /etc/passwd
-  && echo 'testssl:x:1000:' >> /etc/group \
+  echo 'testssl:x:1000:' >> /etc/group
-  && echo 'testssl:!::0:::::' >> /etc/shadow \
+  echo 'testssl:!::0:::::' >> /etc/shadow
-  && install --mode 2755 --owner testssl --group testssl --directory /home/testssl \
+  install --mode 2755 --owner testssl --group testssl --directory /home/testssl
-  # The home directory will install a copy of `testssl.sh`, symlink the script to be used as a command:
+
-  && ln -s /home/testssl/testssl.sh /usr/local/bin/testssl.sh
+  # A copy of `testssl.sh` will be added to the home directory,
+  # symlink to that file so it can be treated as a command:
+  ln -s /home/testssl/testssl.sh /usr/local/bin/testssl.sh
+HEREDOC
 
 # Runtime config:
 USER testssl
@@ -49,7 +60,7 @@ ENTRYPOINT ["testssl.sh"]
 CMD ["--help"]
 
 # Final image stage (add `testssl.sh` project files)
-# Choose either one as the final stage (defaults to last stage, `dist-local`)
+# Choose either one as the final stage (defaults to the last stage, `dist-local`)
 
 # 62MB Image (Remote repo clone, cannot filter content through `.dockerignore`):
 FROM base-leap AS dist-git

Dockerfile.alpine

@@ -1,8 +1,20 @@
+# syntax=docker.io/docker/dockerfile:1
+
 FROM alpine:3.21 AS base-alpine
-RUN apk add --no-cache bash procps drill coreutils libidn curl socat openssl xxd \
+RUN <<HEREDOC
-    && addgroup testssl \
+  apk add --no-cache bash procps drill coreutils libidn curl socat openssl xxd
-    && adduser -G testssl -g "testssl user" -s /bin/bash -D testssl \
+
-    && ln -s /home/testssl/testssl.sh /usr/local/bin/testssl.sh
+  # Add a non-root user `testssl`, this is roughly equivalent to the `adduser` command:
+  # addgroup testssl && adduser -G testssl -g "testssl user" -s /bin/bash -D testssl
+  echo 'testssl:x:1000:1000::/home/testssl:/bin/bash' >> /etc/passwd
+  echo 'testssl:x:1000:' >> /etc/group
+  echo 'testssl:!::0:::::' >> /etc/shadow
+  install --mode 2755 --owner testssl --group testssl --directory /home/testssl
+
+  # A copy of `testssl.sh` will be added to the home directory,
+  # symlink to that file so it can be treated as a command:
+  ln -s /home/testssl/testssl.sh /usr/local/bin/testssl.sh
+HEREDOC
 
 # Runtime config:
 USER testssl
@@ -10,7 +22,7 @@ ENTRYPOINT ["testssl.sh"]
 CMD ["--help"]
 
 # Final image stage (add `testssl.sh` project files)
-# Choose either one as the final stage (defaults to last stage, `dist-git`)
+# Choose either one as the final stage (defaults to the last stage, `dist-local`)
 
 # 35MB Image (Remote repo clone, cannot filter content through `.dockerignore`):
 FROM base-alpine AS dist-git