Dockerfile: Rework generation of kas images

While kas and kas-isar surely have a common ground like the kas tool
itself, kas-isar does not need all the toolchain packages that are
essential Yocto dependencies. Splitting up the images earlier allows to
shrink kas-isar by almost 400 MB.

Use this chance to model both images as different build stages of the
same Dockerfile. That is simpler than creating a temporary "kas-base"
image via a separate Dockerfile.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>

.github/workflows/master.yml

@@ -41,7 +41,7 @@ jobs:
       - name: Build kas-isar image
         uses: docker/build-push-action@v2
         with:
-          file: Dockerfile.isar
+          target: kas-isar
           platforms: linux/amd64,linux/arm64
           push: ${{ env.PUSH_MASTER }}
           tags: ghcr.io/siemens/kas/kas-isar

.github/workflows/next.yml

@@ -96,9 +96,8 @@ jobs:
       - name: Build kas-isar image
         uses: docker/build-push-action@v2
         with:
-          file: Dockerfile.isar
+          target: kas-isar
           load: true
-          build-args: KAS_TAG=next
           tags: ghcr.io/siemens/kas/kas-isar:next
       - name: Test kas-isar image
         run: |
@@ -107,8 +106,7 @@ jobs:
       - name: Complete build and deploy kas-isar image
         uses: docker/build-push-action@v2
         with:
-          file: Dockerfile.isar
+          target: kas-isar
           platforms: linux/amd64,linux/arm64
-          build-args: KAS_TAG=next
           tags: ghcr.io/siemens/kas/kas-isar:next
           push: true

.github/workflows/release.yml

@@ -36,7 +36,7 @@ jobs:
       - name: Build kas-isar image
         uses: docker/build-push-action@v2
         with:
-          file: Dockerfile.isar
+          target: kas-isar
           platforms: linux/amd64,linux/arm64
           push: true
           tags: |

Dockerfile

@@ -1,6 +1,6 @@
 # This image builds Yocto jobs using the kas tool
 
-FROM debian:bullseye-slim
+FROM debian:bullseye-slim as kas-base
 
 ARG TARGETPLATFORM
 ARG DEBIAN_FRONTEND=noninteractive
@@ -9,17 +9,10 @@ RUN apt-get update && \
     apt-get install -y locales && \
     localedef -i en_US -c -f UTF-8 -A /usr/share/locale/locale.alias en_US.UTF-8 && \
     apt-get install --no-install-recommends -y \
-        gawk wget git diffstat unzip texinfo \
-        gcc build-essential chrpath socat cpio python3 python3-pip python3-pexpect \
-        xz-utils debianutils iputils-ping python3-git python3-jinja2 libegl1-mesa libsdl1.2-dev \
-        pylint3 xterm python3-subunit mesa-common-dev zstd liblz4-tool \
-        python3-setuptools python3-wheel python3-yaml python3-distro python3-jsonschema python3-newt \
-        gosu lsb-release file vim less procps tree tar bzip2 zstd pigz tmux libncurses-dev \
-        dosfstools mtools parted lz4 \
-        git-lfs mercurial iproute2 ssh-client telnet curl rsync gnupg awscli sudo && \
-    if [ "$TARGETPLATFORM" = "linux/amd64" ]; then \
-        apt-get install --no-install-recommends -y gcc-multilib g++-multilib syslinux; \
-    fi && \
+        python3-pip python3-setuptools python3-wheel python3-yaml python3-distro python3-jsonschema python3-newt \
+        gosu lsb-release file vim less procps tree tar bzip2 zstd pigz lz4 tmux libncurses-dev \
+        git-lfs mercurial iproute2 ssh-client telnet curl rsync gnupg awscli sudo \
+        socat bash-completion && \
     apt-get clean && \
     rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
 
@@ -40,3 +33,32 @@ RUN echo "Defaults env_keep += \"ftp_proxy http_proxy https_proxy no_proxy\"" \
     > /etc/sudoers.d/env_keep && chmod 660 /etc/sudoers.d/env_keep
 
 ENTRYPOINT ["/kas/container-entrypoint"]
+
+FROM kas-base as kas-isar
+
+ENV LC_ALL=en_US.UTF-8
+RUN apt-get update && \
+    apt-get install -y -f --no-install-recommends \
+            binfmt-support debootstrap dosfstools dpkg-dev gettext-base git \
+            mtools parted python3 quilt qemu-user-static reprepro sudo \
+            git-buildpackage pristine-tar sbuild schroot \
+            umoci skopeo && \
+    apt-get clean && \
+    rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
+
+RUN sed -i 's|\tGOSU="gosu builder"|\0\n\tsbuild-adduser builder >/dev/null 2>\&1|' /kas/container-entrypoint
+RUN sed -i 's|#!/bin/bash|\0\n\nupdate-binfmts --enable \&\& [ -f /proc/sys/fs/binfmt_misc/status ]|' /kas/container-entrypoint
+
+FROM kas-base as kas
+
+RUN apt-get update && \
+    apt-get install --no-install-recommends -y \
+        gawk wget git diffstat unzip texinfo \
+        gcc build-essential chrpath socat cpio python3 python3-pip python3-pexpect \
+        xz-utils debianutils iputils-ping python3-git python3-jinja2 libegl1-mesa libsdl1.2-dev \
+        pylint3 xterm python3-subunit mesa-common-dev zstd liblz4-tool && \
+    if [ "$TARGETPLATFORM" = "linux/amd64" ]; then \
+        apt-get install --no-install-recommends -y gcc-multilib g++-multilib; \
+    fi && \
+    apt-get clean && \
+    rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*

Dockerfile.isar

@@ -1,21 +0,0 @@
-# This image builds Isar jobs using the kas tool
-
-ARG KAS_TAG=latest
-
-FROM ghcr.io/siemens/kas/kas:$KAS_TAG
-
-ARG DEBIAN_FRONTEND=noninteractive
-
-ENV LC_ALL=en_US.UTF-8
-RUN apt-get update && \
-    apt-get install -y -f --no-install-recommends \
-            gdisk bash-completion \
-            reprepro python3 binfmt-support \
-            umoci skopeo \
-            git-buildpackage pristine-tar schroot sbuild \
-            qemu-user-static debootstrap quilt && \
-    apt-get clean && \
-    rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
-
-RUN sed -i 's|\tGOSU="gosu builder"|\0\n\tsbuild-adduser builder >/dev/null 2>\&1|' /kas/container-entrypoint
-RUN sed -i 's|#!/bin/bash|\0\n\nupdate-binfmts --enable \&\& [ -f /proc/sys/fs/binfmt_misc/status ]|' /kas/container-entrypoint