Ubuntu preseed to install an 18.04 Desktop OS with disk encryption

bionic-crypt.cfg

#### Contents of the preconfiguration file (for bionic)
### Localization
# Preseeding only locale sets language, country and locale.
d-i debian-installer/locale string en_GB

# Keyboard selection.
# Disable automatic (interactive) keymap detection.
d-i console-setup/ask_detect boolean false
d-i keyboard-configuration/xkb-keymap select gb

### Network configuration
# netcfg will choose an interface that has link if possible. This makes it
# skip displaying a list if there is more than one interface.
d-i netcfg/choose_interface select auto
d-i netcfg/get_hostname string <default-hostname>

# If non-free firmware is needed for the network or other hardware, you can 
# configure the installer to always try to load it, without prompting. Or
# change to false to disable asking.
d-i hw-detect/load_firmware boolean true

### Mirror settings
# If you select ftp, the mirror/country string does not need to be set.
d-i mirror/country string manual
d-i mirror/http/hostname string <mirror-of-choice>
d-i mirror/http/directory string /ubuntu
d-i mirror/http/proxy string

# Suite to install.
#d-i mirror/suite string xenial
# Suite to use for loading installer components (optional).
#d-i mirror/udeb/suite string xenial
# Components to use for loading installer components (optional).
d-i mirror/udeb/components multiselect main, restricted

### Account setup

d-i passwd/root-login boolean true
d-i passwd/root-password-crypted password <crypted-password>
d-i passwd/make-user boolean false

### Clock and time zone setup
# Controls whether or not the hardware clock is set to UTC.
d-i clock-setup/utc boolean true

# You may set this to any valid setting for $TZ; see the contents of
# /usr/share/zoneinfo/ for valid values.
d-i time/zone string <TZ-string>

# Controls whether to use NTP to set the clock during the install
d-i clock-setup/ntp boolean true
# NTP server to use. The default is almost always fine here.
d-i clock-setup/ntp-server string <NTP-server-of-choice>

### Partitioning
#Get around the prompt for UEFI-only
d-i partman-efi/non_efi_system boolean true
d-i partman/default_filesystem string ext4
#If the machine may have mutliple disks, set the default root disk here
d-i partman-auto/disk string /dev/nvme0n1

# In addition, you'll need to specify the method to use.
# The presently available methods are:
# - regular: use the usual partition types for your architecture
# - lvm:     use LVM to partition the disk
# - crypto:  use LVM within an encrypted partition
d-i partman-auto/method string crypto
d-i partman-crypto/passphrase password <disk-encryption-password>
d-i partman-crypto/passphrase-again password <disk-encryption-password>

# If one of the disks that are going to be automatically partitioned
# contains an old LVM configuration, the user will normally receive a
# warning. This can be preseeded away...
d-i partman-lvm/device_remove_lvm boolean true
# The same applies to pre-existing software RAID array:
d-i partman-md/device_remove_md boolean true
# And the same goes for the confirmation to write the lvm partitions.
d-i partman-lvm/confirm boolean true
d-i partman-lvm/confirm_nooverwrite boolean true

# For LVM partitioning, you can select how much of the volume group to use
# for logical volumes.
d-i partman-auto-lvm/guided_size string max

# You can choose one of the three predefined partitioning recipes:
# - atomic: all files in one partition
# - home:   separate /home partition
# - multi:  separate /home, /var, and /tmp partitions
d-i partman-auto/choose_recipe select atomic

# This makes partman automatically partition without confirmation, provided
# that you told it what to do using one of the methods above.
d-i partman-partitioning/confirm_write_new_label boolean true
d-i partman/choose_partition select finish
d-i partman/confirm boolean true
d-i partman/confirm_nooverwrite boolean true

### Base system installation
### Apt setup
# You can choose to install restricted and universe software, or to install
# software from the backports repository.
d-i apt-setup/restricted boolean true
d-i apt-setup/universe boolean true
d-i apt-setup/backports boolean true

# Select which update services to use; define the mirrors to be used.
# Values shown below are the normal defaults.
d-i apt-setup/services-select multiselect security
d-i apt-setup/security_host string security.ubuntu.com
d-i apt-setup/security_path string /ubuntu

# Additional repositories, local[0-9] available
d-i apt-setup/local0/repository string <deb-string>
d-i apt-setup/local0/comment string <comment>
d-i apt-setup/local0/key string <GPG-signing-key-URL>

### Package selection
tasksel tasksel/first multiselect ubuntu-desktop

# Whether to upgrade packages after debootstrap.
# Allowed values: none, safe-upgrade, full-upgrade
d-i pkgsel/upgrade select full-upgrade

# Policy for applying updates. May be "none" (no automatic updates),
# "unattended-upgrades" (install security updates automatically), or
# "landscape" (manage system with Landscape).
d-i pkgsel/update-policy select unattended-upgrades

ubiquity ubiquity/success_command string <post-install-command>

# Some versions of the installer can report back on what software you have
# installed, and what software you use. The default is not to report back,
# but sending reports helps the project determine what software is most
# popular and include it on CDs.
popularity-contest popularity-contest/participate boolean false

# By default, the system's locate database will be updated after the
# installer has finished installing most packages. This may take a while, so
# if you don't want it, you can set this to "false" to turn it off.
d-i pkgsel/updatedb boolean true

### Boot loader installation
# This is fairly safe to set, it makes grub install automatically to the MBR
# if no other operating system is detected on the machine.
d-i grub-installer/only_debian boolean true

# This one makes grub-installer install to the MBR if it also finds some other
# OS, which is less safe as it might not be able to boot that other OS.
d-i grub-installer/with_other_os boolean true

### Finishing up the installation
# Avoid that last message about the install being complete.
d-i finish-install/reboot_in_progress note