templates: improve docker build layers caching

Signed-off-by: Adphi <philippe.adrien.nousse@gmail.com>

templates/centos.Dockerfile

@@ -16,12 +16,6 @@ RUN yum install -y \
     kernel \
     systemd \
     NetworkManager \
-{{- if .GrubBIOS }}
-    grub2 \
-{{- end }}
-{{- if .GrubEFI }}
-    grub2 grub2-efi-x64 grub2-efi-x64-modules \
-{{- end }}
     e2fsprogs \
     sudo && \
     systemctl enable NetworkManager && \
@@ -29,6 +23,13 @@ RUN yum install -y \
     systemctl unmask getty.target && \
     find /boot -type l -exec rm {} \;
 
+{{- if .GrubBIOS }}
+RUN yum install -y grub2
+{{- end }}
+{{- if .GrubEFI }}
+RUN yum install -y grub2 grub2-efi-x64 grub2-efi-x64-modules
+{{- end }}
+
 {{ if .Luks }}
 RUN yum install -y cryptsetup && \
     dracut --no-hostonly --regenerate-all --force --install="/usr/sbin/cryptsetup"

templates/debian.Dockerfile

@@ -19,21 +19,22 @@ RUN ARCH="$([ "$(uname -m)" = "x86_64" ] && echo amd64 || echo arm64)"; \
     DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
       systemd-sysv \
       systemd \
-    {{- if .Grub }}
-      grub-common \
-      grub2-common \
-    {{- end }}
-    {{- if .GrubBIOS }}
-      grub-pc-bin \
-    {{- end }}
-    {{- if .GrubEFI }}
-      grub-efi-${ARCH}-bin \
-    {{- end }}
       dbus \
       iproute2 \
       isc-dhcp-client \
       iputils-ping
 
+{{- if .Grub }}
+RUN DEBIAN_FRONTEND=noninteractive apt install -y grub-common grub2-common
+{{- end }}
+{{- if .GrubBIOS }}
+RUN DEBIAN_FRONTEND=noninteractive apt install -y grub-pc-bin
+{{- end }}
+{{- if .GrubEFI }}
+RUN ARCH="$([ "$(uname -m)" = "x86_64" ] && echo amd64 || echo arm64)"; \
+    DEBIAN_FRONTEND=noninteractive apt install -y grub-efi-${ARCH}-bin
+{{- end }}
+
 RUN systemctl preset-all
 
 {{ if .Password }}RUN echo "root:{{ .Password }}" | chpasswd {{ end }}