support ubuntu12

Signed-off-by: LEI WANG <ssst0n3@gmail.com>

templates/ubuntu12.Dockerfile

@@ -0,0 +1,67 @@
+FROM {{ .Image }}
+
+USER root
+
+RUN ARCH="$([ "$(uname -m)" = "x86_64" ] && echo amd64 || echo arm64)"; \
+  apt-get update && \
+  DEBIAN_FRONTEND=noninteractive apt-get -y install --no-install-recommends \
+  linux-image-virtual \
+  initramfs-tools \
+{{- if .Grub }}
+  grub-common \
+  grub2-common \
+{{- end }}
+{{- if .GrubBIOS }}
+  grub-pc-bin \
+{{- end }}
+{{- if .GrubEFI }}
+  grub-efi-${ARCH}-bin \
+{{- end }}
+  dbus \
+  isc-dhcp-client \
+  iputils-ping && \
+  find /boot -type l -exec rm {} \;
+
+{{ if gt .Release.VersionID "16.04" }}
+RUN systemctl preset-all
+{{ end }}
+
+{{ if .Password }}RUN echo "root:{{ .Password }}" | chpasswd {{ end }}
+
+{{ if eq .NetworkManager "netplan" }}
+RUN apt install -y netplan.io
+RUN mkdir -p /etc/netplan && printf '\
+network:\n\
+  version: 2\n\
+  renderer: networkd\n\
+  ethernets:\n\
+    eth0:\n\
+      dhcp4: true\n\
+      dhcp-identifier: mac\n\
+      nameservers:\n\
+        addresses:\n\
+        - 8.8.8.8\n\
+        - 8.8.4.4\n\
+' > /etc/netplan/00-netcfg.yaml
+{{ else if eq .NetworkManager "ifupdown"}}
+RUN if [ -z "$(apt-cache madison ifupdown-ng 2> /dev/nul)" ]; then apt-get install -y ifupdown; else apt-get install -y ifupdown-ng; fi
+RUN mkdir -p /etc/network && printf '\
+auto eth0\n\
+allow-hotplug eth0\n\
+iface eth0 inet dhcp\n\
+' > /etc/network/interfaces
+{{ end }}
+
+{{- if .Luks }}
+RUN DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends cryptsetup-initramfs && \
+    update-initramfs -u -v
+{{- end }}
+
+# needs to be after update-initramfs
+{{- if not .Grub }}
+RUN mv $(find /boot -name 'vmlinuz-*') /boot/vmlinuz && \
+      mv $(find /boot -name 'initrd.img-*') /boot/initrd.img
+{{- end }}
+
+RUN apt-get clean && \
+    rm -rf /var/lib/apt/lists/*