create-datastore.fcc

variant: fcos
version: 1.1.0

storage:
  files:
    - path: /usr/local/bin/create-datastore
      mode: 0755
      contents:
        inline: |
          #!/bin/bash

          LABEL=datastore
          OFFSET=2G

          set -euo pipefail

          cmdline=( $(</proc/cmdline) )
          karg() {
              local name="$1" value="${2:-}"
              for arg in "${cmdline[@]}"; do
                  if [[ "${arg%%=*}" == "${name}" ]]; then
                      value="${arg#*=}"
                  fi
              done
              echo "${value}"
          }

          # Get install device
          device="$(karg coreos.inst.install_dev)"
          if [[ -z $device ]]; then
              echo "Install device not specified."
              exit 1
          fi
          # Append /dev/ if missing
          device="/dev/${device##/dev/}"

          # Wait for device nodes
          udevadm settle

          # Check for partitions other than the system ones
          if lsblk --pairs --output NAME,TYPE,PARTLABEL "${device}" |\
              awk '/TYPE="part"/ && !/PARTLABEL="(boot|EFI-SYSTEM|BIOS-BOOT|root|luks_root)"/ {print; exit 1}'
          then
              echo "Creating data partition \"${LABEL}\""

              # Relocate second GPT header to end of disk and create partition
              sgdisk --move-second-header \
                  --new=0:+"${OFFSET}":0 --change-name=0:"${LABEL}" \
                  "${device}"

              # Wait for device node
              udevadm settle

              # Get the device node
              partition=$(lsblk "${device}" --paths --pairs --output NAME,PARTLABEL |\
                  awk '/PARTLABEL="'${LABEL}'"/ && match($0, "NAME=\"([a-zA-Z0-9/_-]+)\"", a) {print a[1]; exit 0}')

              # Create ext4 filesystem in it
              mkfs.ext4 -F -L "${LABEL}" "${partition}"
          else
              echo "Found existing data partition; not creating a new one"
          fi

systemd:
  units:
    - name: create-datastore.service
      enabled: true
      contents: |
        [Unit]
        Description=Create data partition if one doesn't already exist
        After=coreos-installer.service
        Before=coreos-installer.target
        ConditionKernelCommandLine=create-datastore

        [Service]
        Type=oneshot
        ExecStart=/usr/local/bin/create-datastore

        [Install]
        WantedBy=coreos-installer.target