Merge pull request '26-install-zfs-only-when-needed' (#27) from 26-install-zfs-only-when-needed into main

Reviewed-on: #27

.gitignore

@@ -0,0 +1,2 @@
+archzbm_settings.env
+.idea

README.md

@@ -99,7 +99,9 @@ The script will create a single ZFS zpool `zpool` on the zpool partition with da
 
 ## Options
 
-The following options can be given either by exporting them as shell variables prior to script execution or in a file named `archzbm_settings.env` that lives in your current working directory where you're about to execute the script. File format is identical to shell variable assignments of the form `VAR=value` or `VAR='value'`.
+The following options can be given either by exporting them as shell variables prior to script execution or in a file named `archzbm_settings.env` that lives in your current working directory where you're about to execute the script. You can walk yourself through an interactive questionnaire that helps create a valid `archzbm_settings.env` file. Check out [Command line setup help](#command-line-setup-help) for details on the questionnaire.
+
+If you instead want to define settings yourself with an `archzbm_settings.env` file its file format is identical to shell variable assignments of the form `VAR=value` or `VAR='value'`.
 
 If `./archzbm_settings.env` exists the script will `source` its content and `export` all variables for use in future steps.
 
@@ -107,6 +109,30 @@ In cases where a variable is both exported prior to script execution and specifi
 
 Known options are as follows.
 
+### Kernel downgrade
+
+By default we install newest `linux` and `linux-headers` packages into a `chroot`. Once we're in that `chroot` we then install newest [AUR zfs-dkms package](https://aur.archlinux.org/packages/zfs-dkms). You may want to override `linux` and `linux-headers` versions to ensure you end up with a compatible mix between them and `zfs-dkms`.
+
+For example:
+```
+export ARCHZBM_KERNEL_VER=6.5.9.arch2
+```
+
+In our `chroot` this will trigger execution of:
+```
+downgrade --ala-only 'linux=6.5.9.arch2' 'linux-headers=6.5.9.arch2' --ignore always
+```
+
+Where `downgrade` is the [AUR downgrade package](https://aur.archlinux.org/packages/downgrade). This will downgrade `linux` and `linux-headers` and will add a setting to your `/etc/pacman.conf`:
+```
+[options]
+IgnorePkg = linux linux-headers
+```
+
+Setting `ARCHZBM_KERNEL_VER` to an empty string `''` or keeping it undefined are both valid and will retain newest versions instead of downgrading.
+
+Also read [Kernel selection](#kernel-selection) for details.
+
 ### Compression
 
 By default we create a zpool with ZFS property `compression=on`. If the `lz4_compress` pool feature is active this will by default enable `compression=lz4`. See `man 7 zfsprops` for example in ZFS 2.1.9 for details. See `zpool get feature@lz4_compress <pool>` to check this feature's status on your `<pool>`.
@@ -149,6 +175,8 @@ By default the script configures plain ZFSBootMenu without networking nor an SSH
 
 #### IP address
 
+> IPv6 addresses are untested. Script has been confirmed working with IPv4 addresses.
+
 ```
 ARCHZBM_NET_CLIENT_IP=''
 ARCHZBM_NET_SERVER_IP=''
@@ -159,7 +187,7 @@ ARCHZBM_NET_DEVICE=''
 ARCHZBM_NET_AUTOCONF=''
 ```
 
-By default none of the variables are set to any value and no networking will be available in ZFSBootMenu. If you want networking as in an IP address bound to a network interace set at least one of these variables or one of the [SSH](#ssh) variables listed further down. Setting one or more `ARCHZBM_NET_*` variables to an empty string is valid. If at least one variable is given either from this paragraph or from [SSH](#ssh) we're assuming that you want networking. Unspecified values and values set to the empty string `''` use defaults.
+By default none of the variables are set to any value and no networking will be available in ZFSBootMenu. If you want networking as in an IP address bound to a network interface set at least one of these variables or one of the [SSH](#ssh) variables listed further down. Setting one or more `ARCHZBM_NET_*` variables to an empty string is valid. If at least one variable is given either from this paragraph or from [SSH](#ssh) we're assuming that you want networking. Unspecified values and values set to the empty string `''` use defaults.
 
 For networking we rely on the [mkinitcpio-nfs-utils](https://archlinux.org/packages/core/x86_64/mkinitcpio-nfs-utils/) package with its `net` hook. Please refer to its [initcpio-install-net](https://gitlab.archlinux.org/archlinux/packaging/packages/mkinitcpio-nfs-utils/-/blob/main/initcpio-install-net) script file for usage hints on above variables. The hook implements a subset of the [ip Kernel Command Line argument](https://docs.kernel.org/admin-guide/nfs/nfsroot.html).
 
@@ -203,6 +231,18 @@ ARCHZBM_NET_DEVICE='eth0'
 ARCHZBM_NET_AUTOCONF='dhcp'
 ```
 
+> In ZFSBootMenu the device names that go into `ARCHZBM_NET_DEVICE` are raw unchanged kernel device names such as `eth0`. If you're unsure which device name to use in your Arch Linux live CD ISO image check `dmesg` output. During boot typically a kernel module will first assign the raw kernel device name then later `systemd` will enforce [Predictable Network Interface Names](https://www.freedesktop.org/wiki/Software/systemd/PredictableNetworkInterfaceNames/).
+>
+> In `dmesg | grep` on a physical PC with an MSI B550-A Pro mainboard from 2020 that comes with one onboard Realtek RTL8111H network adapter governed by the Realtek RTL-8169 Gigabit Ethernet driver from the `r8169` kernel module you will for example see:
+> ```
+> # dmesg -T | grep eth
+> [time] r8169 0000:2a:00.0 eth0: RTL8168h/8111h, 04:7c:16:00:01:02, XID 541, IRQ 95
+> [time] r8169 0000:2a:00.0 eth0: jumbo features [frames: 9194 bytes, tx checksumming: ko]
+> [time] r8169 0000:2a:00.0 enp42s0: renamed from eth0
+> ```
+>
+> Notice how a Predictable Network Interface Name comes in on line 3. What *__you__* need here is the `eth0` part.
+
 #### SSH
 
 If you want networking indicated by the fact that at least one of the `ARCHZBM_NET_*` variables is set or one of the `ARCHZBM_SSH_*` vars we assume that you want an SSH daemon as well. This comes in the form of a `dropbear` daemon with minimal configurability. Use the following variables to define Dropbear's behavior.
@@ -223,6 +263,24 @@ ssh-rsa Eahajei8,,ssh-ed25519 kaeD0mas ...
 
 This syntax crutch allows you to use the full range of Dropbear-supported `authorized_keys` stanzas, see [man 8 dropbear](https://man.archlinux.org/man/extra/dropbear/dropbear.8.en) for what's available. Whether or not this is useful to you is another topic :) At least the functionality for stanzas is there by separating values in `ARCHZBM_SSH_AUTH_KEYS` with double-commas.
 
+## Command line setup help
+
+An interactive questionnaire can guide you through settings and goes like this:
+
+![Command line setup questionnaire](https://i.imgur.com/OXG75GH.gif)
+
+To do the questionnaire yourself start this script with the `setup` argument:
+
+```
+export SCRIPT_URL='https://quico.space/quico-os-setup/arch-zbm/raw/branch/main/setup.sh' && curl -s "${SCRIPT_URL}" | bash -s -- setup
+```
+
+When done rerun it without that argument:
+
+```
+export SCRIPT_URL='https://quico.space/quico-os-setup/arch-zbm/raw/branch/main/setup.sh' && curl -s "${SCRIPT_URL}" | bash
+```
+
 # Steps
 
 The script takes the following installation steps.
@@ -262,6 +320,24 @@ When it comes to the point that your SSH client sends an are-your-still-there me
 
 This effectively configures your SSH client to remain connected even through somewhat lossy hops to the Dropbear daemon; and to cleanly disconnect 3 seconds and some change after you've executed whatever you needed to do in ZFSBootMenu.
 
+# Kernel selection
+
+This script compiles ZFS via Arch Linux' [Dynamic Kernel Module Support](https://wiki.archlinux.org/title/Dynamic_Kernel_Module_Support) (DKMS). Not all kernels allow for successful compilation, in some instances a particularly recent kernel version may change APIs to such a degree that ZFS compilation simply fails.
+
+We strongly suggest to that you:
+
+- Firstly, refer to a resource such as the [Arch Linux Archive package version list](https://archive.archlinux.org/packages/l/linux/) to find out what newest kernel version this script will install.
+- Secondly, research if newest [AUR zfs-dkms package](https://aur.archlinux.org/packages/zfs-dkms) is compatible with that kernel. Two reasonable points of contact are AUR and its comments section for `zfs-dkms` where users quickly report issues; and the [github.com/openzfs/zfs issues list](https://github.com/openzfs/zfs/issues).
+
+An example for this is that `linux-6.6.1.arch1-1-x86_64` came out on Wednesday, November 8, 2023 at a time when newest `zfs-dkms` package version [was 2.2.0](https://aur.archlinux.org/cgit/aur.git/commit/?h=zfs-dkms&id=da1b6372c57b16f2781a7fda2b95971bb392c5ee) which did not compile against `linux` 6.6.x.
+
+You'd then set for example:
+```
+export ARCHZBM_KERNEL_VER=6.5.9.arch2
+```
+
+Where any 6.5.x version is known to work well with `zfs-dkms`. See also [Kernel downgrade](#kernel-downgrade) for details on how to configure this.
+
 # Flavor choices
 
 We make the following opinionated flavor choices. Feel free to change them to your liking.
@@ -286,7 +362,7 @@ After installation you're going to want to at least touch these points in your n
 - Unless you had a settings file or exported shell env vars per [Passwords](#passwords) you're going to want to change passwords now:
     - ZFS: The password for all datasets underneath `zpool` is `password`.
     - Local `root` account: The local `root` account's password is `password`.
-- Arch User Repository (AUR) helper: We installed [paru](https://github.com/Morganamilo/paru) as our AUR helper, we installed from GitHub via `makepkg -si` then replaced it with its [paru-bin](https://aur.archlinux.org/packages/paru-bin) version from AUR.
+- Arch User Repository (AUR) helper: We installed [paru](https://github.com/Morganamilo/paru) as our AUR helper, we installed from AUR as [paru-bin](https://aur.archlinux.org/packages/paru-bin).
 - In `/etc/systemd/network/50-wired.network` instead of a DHCP-based network config you can get a static one. The DHCP-based one for reference looks like:
     ```
     ...
@@ -384,7 +460,7 @@ In order to generate a new master key after you've changed your user key as ment
         --large-block \
         --compressed \
         'zpool/root/archlinux-sxu@rekey' | \
-
+    \
     zfs receive \
         -Fvu \
         -o 'encryption=on' \

setup.sh

@@ -19,9 +19,10 @@ exec 3>&1
 declare this_script_url
 this_script_url="${SCRIPT_URL:?}"
 
-declare zpool_name zfs_arch_dataset_name
+declare zpool_name zfs_arch_dataset_name settings_file
 zpool_name='zpool'
 zfs_arch_dataset_name='archlinux'
+settings_file='archzbm_settings.env'
 
 declare -A partition_types
 partition_types[gpt_zfs]='6a85cf4d-1dd2-11b2-99a6-080020736631'
@@ -35,6 +36,363 @@ trap '[ "$?" -ne 77 ] || exit 77' ERR
 
 declare zpool_drive efi_drive boot_drive part_schema
 
+function calculate_prefix_from_netmask () {
+    # https://stackoverflow.com/a/50419919
+    c='0'
+    x='0'"$(printf -- '%o' ${1//./ })"
+    while [ "${x}" -gt '0' ]; do
+        # Modulo then bitwise-shift x and store as new x
+        let c+="$(( x % 2 ))" 'x>>=1'
+    done
+    printf -- '%s' '/'"${c}";
+}
+
+function setup_env_vars () {
+    printf -- '%s\n' \
+        'We will go over a series of questions to create an answer file with' \
+        'options you want the script to use.' \
+        '' \
+        'Current working directory is:'\
+        "$(pwd)" \
+        '' \
+        'After we'"'"'re done answer file will be written to current working dir:' \
+        './'"${settings_file}" \
+        '' \
+        'Press <Ctrl>+C to abort this process. No answer file will' \
+        'be written to ./'"${settings_file}"' if you abort the script.' \
+        '' \
+        'When done rerun the same command you just did without '"'"'setup'"'"' argument.' \
+        ''
+    read -u3 -n 1 -s -r -p "Press any key to begin questionnaire"
+    echo
+    echo '----------------------------------------'
+    echo
+
+    read -u3 -p 'Please type kernel version to use, leave empty for latest, confirm with <Enter>: ' ARCHZBM_KERNEL_VER
+    echo
+
+    echo 'Do you want compressed datasets?'
+    select arg_compressed in 'Compressed' 'Uncompressed'; do
+        case "${arg_compressed}" in
+            'Compressed')
+                break
+                ;;
+            'Uncompressed')
+                ARCHZBM_ZFSPROPS_NO_COMPRESSION='true'
+                break
+                ;;
+        esac
+    done <&3 && echo
+
+    echo 'Do you want encrypted datasets?'
+    select arg_encrypted in 'Encrypted' 'Unencrypted'; do
+        case "${arg_encrypted}" in
+            'Encrypted')
+                break
+                ;;
+            'Unencrypted')
+                ARCHZBM_ZFSPROPS_NO_ENCRYPTION='true'
+                break
+                ;;
+        esac
+    done <&3 && echo
+
+    if [[ "${arg_encrypted}" = 'Encrypted' ]]; then
+        echo 'Do you want a custom dataset decryption password?'
+        select arg_custom_dataset_pw in 'Yes' 'No (use '"'"'password'"'"')'; do
+            case "${arg_custom_dataset_pw}" in
+                'Yes')
+                    want_custom_dataset_pw='true'
+                    break
+                    ;;
+                'No (use '"'"'password'"'"')')
+                    break
+                    ;;
+            esac
+        done <&3 && echo
+
+        if [[ "${want_custom_dataset_pw}" ]]; then
+            read -u3 -p 'Please type password, confirm with <Enter>: ' -s ARCHZBM_ZPOOL_PASSWORD
+            echo
+            echo
+        fi
+    fi
+
+    echo 'Do you want a custom '"'"'root'"'"' user password?'
+    select arg_custom_root_pw in 'Yes' 'No (use '"'"'password'"'"')'; do
+        case "${arg_custom_root_pw}" in
+            'Yes')
+                want_custom_root_pw='true'
+                break
+                ;;
+            'No (use '"'"'password'"'"')')
+                break
+                ;;
+        esac
+    done <&3 && echo
+
+    if [[ "${want_custom_root_pw}" ]]; then
+        read -u3 -p 'Please type password, confirm with <Enter>: ' -s ARCHZBM_ROOT_PASSWORD
+        echo
+        echo
+    fi
+
+    echo 'Do you want an SSH daemon in ZFSBootMenu?'
+    select arg_ssh_in_zbm in "Yes" "No"; do
+        case "${arg_ssh_in_zbm}" in
+            Yes)
+                want_ssh_in_zbm='true'
+                break
+                ;;
+            No)
+                break
+                ;;
+        esac
+    done <&3 && echo
+
+    if [[ "${want_ssh_in_zbm}" ]]; then
+        echo 'How do you want to assign an IP address in ZFSBootMenu?'
+        select arg_ip_autoconf_method in 'Statically' 'Dynamically, DHCP' 'Dynamically, BOOTP' 'Dynamically, RARP'; do
+            case "${arg_ip_autoconf_method}" in
+                'Statically')
+                    ARCHZBM_NET_AUTOCONF='none'
+                    break
+                    ;;
+                'Dynamically, DHCP')
+                    ARCHZBM_NET_AUTOCONF='dhcp'
+                    break
+                    ;;
+                'Dynamically, BOOTP')
+                    ARCHZBM_NET_AUTOCONF='bootp'
+                    break
+                    ;;
+                'Dynamically, RARP')
+                    ARCHZBM_NET_AUTOCONF='rarp'
+                    break
+                    ;;
+            esac
+        done <&3 && echo
+
+        read -u3 -p 'Which device to configure (eth0 is a good guess): ' ARCHZBM_NET_DEVICE
+        echo
+
+        if [[ "${arg_ip_autoconf_method}" = 'Statically' ]]; then
+            read -u3 -p 'Interface IP address: ' ARCHZBM_NET_CLIENT_IP
+            echo
+
+            read -u3 -p 'Netmask: ' ARCHZBM_NET_NETMASK
+            echo
+
+            read -u3 -p 'Gateway IP address: ' ARCHZBM_NET_GATEWAY_IP
+            echo
+        fi
+
+        echo 'Do you want a custom SSH listening port?'
+        select arg_custom_ssh_port in 'Yes (let me specify)' 'No (keep port 22)'; do
+            case "${arg_custom_ssh_port}" in
+                'Yes (let me specify)')
+                    want_custom_ssh_port='true'
+                    break
+                    ;;
+                'No (keep port 22)')
+                    break
+                    ;;
+            esac
+        done <&3 && echo
+
+        if [[ "${want_custom_ssh_port}" ]]; then
+            read -u3 -p 'Please type SSH port, confirm with <Enter>: ' ARCHZBM_SSH_PORT
+            echo
+        fi
+
+        echo 'Do you want the SSH daemon to use a custom keepalive send interval?'
+        select arg_custom_ssh_keepalive_intvl in 'Yes (let me specify)' 'No (keep 1)'; do
+            case "${arg_custom_ssh_keepalive_intvl}" in
+                'Yes (let me specify)')
+                    want_custom_keepalive_intvl='true'
+                    break
+                    ;;
+                'No (keep 1)')
+                    break
+                    ;;
+            esac
+        done <&3 && echo
+
+        if [[ "${want_custom_keepalive_intvl}" ]]; then
+            read -u3 -p 'Please type server keepalive send interval, confirm with <Enter>: ' ARCHZBM_SSH_KEEPALIVE_INTVL
+            echo
+        fi
+
+        read -u3 -p 'Please type SSH pub keys on one line separated by double-commas (,,) and confirm with <Enter>: ' ARCHZBM_SSH_AUTH_KEYS
+        echo
+    fi
+
+    if [[ "${want_ssh_in_zbm}" ]]; then
+        echo 'Do you want to define operating system'"'"'s IP address?'
+        select arg_os_ip in 'Yes (let me specify)' 'Yes (use ZBM addresses)' 'No (DHCP is fine)'; do
+            case "${arg_os_ip}" in
+                'Yes (let me specify)')
+                    want_custom_ip_in_os='true'
+                    want_dns_and_ntp='true'
+                    break
+                    ;;
+                'Yes (use ZBM addresses)')
+                    ARCHZBM_OS_CLIENT_IP="${ARCHZBM_NET_CLIENT_IP}"
+                    ARCHZBM_NET_CLIENT_IP_PREFIX="$(calculate_prefix_from_netmask "${ARCHZBM_NET_NETMASK}")"
+                    ARCHZBM_OS_CLIENT_IP+="${ARCHZBM_NET_CLIENT_IP_PREFIX}"
+                    ARCHZBM_OS_GATEWAY_IP="${ARCHZBM_NET_GATEWAY_IP}"
+                    want_dns_and_ntp='true'
+                    break
+                    ;;
+                'No (DHCP is fine)')
+                    break
+                    ;;
+            esac
+        done <&3 && echo
+
+        if [[ "${want_custom_ip_in_os}" ]]; then
+            read -u3 -p 'Interface IP address with CIDR prefix (a.b.c.d/nn): ' ARCHZBM_OS_CLIENT_IP
+            echo
+
+            read -u3 -p 'Gateway IP address: ' ARCHZBM_OS_GATEWAY_IP
+            echo
+        fi
+    else
+        echo 'Do you want to define operating system'"'"'s IP address?'
+        select arg_os_ip in 'Yes (let me specify)' 'No (DHCP is fine)'; do
+            case "${arg_os_ip}" in
+                'Yes (let me specify)')
+                    want_own_ip_in_os='true'
+                    want_dns_and_ntp='true'
+                    break
+                    ;;
+                'No (DHCP is fine)')
+                    break
+                    ;;
+            esac
+        done <&3 && echo
+
+        if [[ "${want_own_ip_in_os}" ]]; then
+            read -u3 -p 'Interface IP address with CIDR prefix (a.b.c.d/nn): ' ARCHZBM_OS_CLIENT_IP
+            echo
+
+            read -u3 -p 'Gateway IP address: ' ARCHZBM_OS_GATEWAY_IP
+            echo
+        fi
+    fi
+
+    if [[ "${want_ssh_in_zbm}" ]]; then
+        echo 'Do you want to define OS '"'"'root'"'"' user'"'"'s SSH pub key?'
+        select arg_root_pub_keys in 'Yes (let me specify)' 'Yes (use ZBM pub keys)' 'No (don'"'"'t enable sshd.service)'; do
+            case "${arg_root_pub_keys}" in
+                'Yes (let me specify)')
+                    want_custom_pub_keys_in_os='true'
+                    break
+                    ;;
+                'Yes (use ZBM pub keys)')
+                    ARCHZBM_OS_SSH_AUTH_KEYS="${ARCHZBM_SSH_AUTH_KEYS}"
+                    break
+                    ;;
+                'No (don'"'"'t enable sshd.service)')
+                    break
+                    ;;
+            esac
+        done <&3 && echo
+
+        if [[ "${want_custom_pub_keys_in_os}" ]]; then
+            read -u3 -p 'Please type SSH pub keys on one line separated by double-commas (,,) and confirm with <Enter>: ' ARCHZBM_OS_SSH_AUTH_KEYS
+            echo
+        fi
+    else
+        echo 'Do you want to define OS root user'"'"'s SSH pub key?'
+        select arg_root_pub_keys in 'Yes (let me specify)' 'No (don'"'"'t enable sshd.service)'; do
+            case "${arg_root_pub_keys}" in
+                'Yes (let me specify)')
+                    want_own_pub_key_in_os='true'
+                    break
+                    ;;
+                'No (don'"'"'t enable sshd.service)')
+                    break
+                    ;;
+            esac
+        done <&3 && echo
+
+        if [[ "${want_own_pub_key_in_os}" ]]; then
+            read -u3 -p 'Please type SSH pub keys on one line separated by double-commas (,,) and confirm with <Enter>: ' ARCHZBM_OS_SSH_AUTH_KEYS
+            echo
+        fi
+    fi
+
+    if [[ "${want_dns_and_ntp}" ]]; then
+        read -u3 -p 'Specify one or more comma-separated DNS IPs: ' ARCHZBM_OS_DNS_IP
+        echo
+
+        echo 'Do you want to override Arch Linux'"'"' NTP servers?'
+        select arg_custom_ntp in 'Yes' 'No'; do
+            case "${arg_custom_ntp}" in
+                'Yes')
+                    want_own_ntp='true'
+                    break
+                    ;;
+                'No')
+                    break
+                    ;;
+            esac
+        done <&3 && echo
+
+        if [[ "${want_own_ntp}" ]]; then
+            read -u3 -p 'Specify one or more comma-separated NTP hostnames or IPs: ' ARCHZBM_OS_NTP_IP
+            echo
+        fi
+    fi
+
+    for env_var in 'ARCHZBM_KERNEL_VER' 'ARCHZBM_ZFSPROPS_NO_COMPRESSION' 'ARCHZBM_ZFSPROPS_NO_ENCRYPTION' 'ARCHZBM_ZPOOL_PASSWORD' 'ARCHZBM_ROOT_PASSWORD' 'ARCHZBM_NET_AUTOCONF' 'ARCHZBM_NET_DEVICE' 'ARCHZBM_NET_CLIENT_IP' 'ARCHZBM_NET_NETMASK' 'ARCHZBM_NET_GATEWAY_IP' 'ARCHZBM_SSH_PORT' 'ARCHZBM_SSH_KEEPALIVE_INTVL' 'ARCHZBM_SSH_AUTH_KEYS' 'ARCHZBM_OS_CLIENT_IP' 'ARCHZBM_OS_GATEWAY_IP' 'ARCHZBM_OS_SSH_AUTH_KEYS' 'ARCHZBM_OS_DNS_IP' 'ARCHZBM_OS_NTP_IP'; do
+        if [[ "${!env_var}" ]]; then
+            printf -- '%s='"'"'%s'"'"'\n' \
+                "${env_var}" "${!env_var}" \
+                >> "${settings_file}"
+        fi
+    done
+
+    printf -- '%s\n' \
+        'Done, please rerun script now with just' \
+        '... | bash' \
+        'so without the '"'"'setup'"'"' argument'
+    exit 77
+}
+
+function arg_parse () {
+    [[ "${1}" ]] && while :; do
+        case "${1}" in
+            -[[:alnum:]]*)
+                >&3 printf -- '%s\n' \
+                    'Short options '"'${1}'"' detected. Only known option is' \
+                    'literal string '"'"'setup'"'"'. No idea what '"'${1}'"' is.' \
+                    'Exiting ...'
+                    exit 77
+                ;;
+            --*)
+                >&3 printf -- '%s\n' \
+                    'Long-form option '"'${1}'"' detected. Only known option is' \
+                    'literal string '"'"'setup'"'"'. No idea what '"'${1}'"' is.' \
+                    'Exiting ...'
+                    exit 77
+                ;;
+            setup)
+                setup_env_vars
+                return
+                ;;
+            *)
+                >&3 printf -- '%s\n' \
+                    'Argument '"'${1}'"' detected. Only known option is literal' \
+                    'string '"'"'setup'"'"'. No idea what '"'${1}'"' is.' \
+                    'Exiting ...'
+                    exit 77
+                ;;
+            esac
+    done
+}
+
 function we_are_changerooted () {
     if [ "$(stat -c '%d:%i' '/')" != "$(stat -c '%d:%i' '/proc/1/root/.')" ]; then
         return 0
@@ -71,19 +429,34 @@ function update_pacman_db () {
     systemctl start reflector
     # In an ISO and for the minimal number of packages we need we do not
     # care about partial upgrades
-    pacman -Syyuu --noconfirm
+    #
+    # Are we better off not attempting an upgrade inside the ISO?
+    # Let's try and find out.
+    # while ! pacman -Syyuu --needed --noconfirm --downloadonly; do
+    #     sleep 5
+    # done
+    # pacman -Syyuu --needed --noconfirm
+    pacman -Syy
 }
 
 function install_pkgs () {
     #1.5
     printf -- '%s\n' 'Installing packages ...'
+    while ! pacman -S --needed --noconfirm --downloadonly "${@}"; do
+        sleep 5
+    done
     pacman -S --needed --noconfirm "${@}"
 }
 
 function install_zfs () {
     #1.6
     declare reset_colors='\033[0m'
-    curl -s 'https://raw.githubusercontent.com/eoli3n/archiso-zfs/master/init' | bash
+    if modinfo 'zfs' &>/dev/null; then
+        >&3 printf -- '%s\n' \
+            'ZFS kernel module is loaded, no need to install ...'
+    else
+        curl -s 'https://raw.githubusercontent.com/eoli3n/archiso-zfs/master/init' | bash
+    fi
     printf -- "${reset_colors}"
 }
 
@@ -328,9 +701,8 @@ function export_pool () {
 
 function load_settings_file () {
     #1.8
-    local working_dir settings_file settings_abs
+    local working_dir settings_abs
     working_dir="$(pwd)"
-    settings_file='archzbm_settings.env'
     settings_abs="${working_dir}"'/'"${settings_file}"
     if [[ -r "${settings_abs}" ]]; then
         set -a
@@ -406,27 +778,29 @@ function install_archlinux () {
     #1.12
     pacman_dl_parallel
     pacman_dont_check_space
-    pacstrap /mnt              \
-        base                   \
-        base-devel             \
-        linux                  \
-        linux-headers          \
-        linux-firmware         \
-        amd-ucode              \
-        efibootmgr             \
-        vim                    \
-        git                    \
-        iwd                    \
-        networkmanager         \
-        network-manager-applet \
-        dialog                 \
-        os-prober              \
-        reflector              \
-        bluez                  \
-        bluez-utils            \
-        man-db                 \
-        xdg-utils              \
-        xdg-user-dirs
+    while ! pacstrap /mnt              \
+                base                   \
+                base-devel             \
+                linux                  \
+                linux-headers          \
+                linux-firmware         \
+                amd-ucode              \
+                efibootmgr             \
+                vim                    \
+                git                    \
+                iwd                    \
+                networkmanager         \
+                network-manager-applet \
+                dialog                 \
+                os-prober              \
+                reflector              \
+                bluez                  \
+                bluez-utils            \
+                man-db                 \
+                xdg-utils              \
+                xdg-user-dirs; do
+        sleep 5
+    done
 }
 
 function gen_fstab () {
@@ -677,56 +1051,17 @@ function get_aur_helper () {
     usermod --append --groups 'wheel' 'build'
     printf -- '%s\n' '%wheel ALL=(ALL:ALL) NOPASSWD: ALL' > '/etc/sudoers.d/10-wheel-group-no-passwd-prompt'
     pushd /tmp
-    git clone 'https://aur.archlinux.org/paru.git'
-    chown -R 'build:' 'paru'
-    pushd 'paru'
+    git clone https://aur.archlinux.org/paru-bin.git
+    chown -R 'build:' 'paru-bin'
+    pushd 'paru-bin'
     sudo --user 'build' makepkg -si --noconfirm
     popd
-    rm -rf 'paru'
+    rm -rf 'paru-bin'
     popd
 }
 
 function paru_install () {
-    declare -a paru_install_packages
-    [[ "${1}" ]] && while :; do
-        case "${1}" in
-            -[[:alnum:]]*)
-                >&3 printf -- '%s\n' \
-                    'Short-form argument '"'${1}'"' not supported for function '"'${FUNCNAME[0]}()'"'. Only known accepted argument' \
-                    'is '"'"'--replace-conflicting'"'"' without a value given. Exiting ...'
-                exit 77
-                ;;
-            --replace-conflicting)
-                pacman_force_yes='true'
-                shift
-                continue
-                ;;
-            --*)
-                >&3 printf -- '%s\n' \
-                    'Long-form argument '"'${1}'"' not supported for function '"'${FUNCNAME[0]}()'"'. Only known accepted argument' \
-                    'is '"'"'--replace-conflicting'"'"' without a value given. Exiting ...'
-                exit 77
-                ;;
-            '')
-                # All arguments processed
-                break
-                ;;
-            *)
-                paru_install_packages+=("${1}")
-                shift
-                ;;
-            esac
-    done || {
-        >&3 printf -- '%s\n' \
-            'No argument '"'${1}'"' given for function '"'${FUNCNAME[0]}'"'. Exiting ...'
-        exit 77
-    }
-    if [[ "${pacman_force_yes}" ]]; then
-        yes 'y' | sudo --user 'build' paru -S "${paru_install_packages[@]}"
-        unset -v pacman_force_yes
-    else
-        sudo --user 'build' paru -S --noconfirm "${paru_install_packages[@]}"
-    fi
+    sudo --user build paru -S --noconfirm "${@}"
 }
 
 function configure_syslinux () {
@@ -774,7 +1109,6 @@ EFI:
   ImageDir: /efi/EFI/ZBM
   Versions: false
   Enabled: true
-  Stub: /usr/share/zfsbootmenu/stubs/linuxx64.efi.stub/linuxx64.efi.stub  # workaround: https://github.com/zbm-dev/zfsbootmenu/discussions/501
 Kernel:
   CommandLine: ro loglevel=0 zbm.import_policy=hostid
   Prefix: vmlinuz
@@ -971,6 +1305,10 @@ function get_disks_with_one_efipart () {
 
 function install_os_in_chroot () {
     #2.2
+    dd if='/dev/zero' of='/swapfile' bs='1M' count='2048'
+    losetup '/dev/loop9' '/swapfile'
+    mkswap '/dev/loop9'
+    swapon '/dev/loop9'
     ### Reinit keyring
     # As keyring is initialized at boot, and copied to the install dir with pacstrap, and ntp is running
     # Time changed after keyring initialization, it leads to malfunction
@@ -978,6 +1316,9 @@ function install_os_in_chroot () {
     rm -rf '/etc/pacman.d/gnupg'
     pacman-key --init
     pacman-key --populate archlinux
+    while ! pacman -S archlinux-keyring --noconfirm --downloadonly; do
+        sleep 5
+    done
     pacman -S archlinux-keyring --noconfirm
 
     locale-gen
@@ -988,7 +1329,13 @@ function install_os_in_chroot () {
     unleash_makepkg                             #2.5
     add_motd_getting_started_msg                #2.6
     get_aur_helper                              #2.7
-    paru_install --replace-conflicting 'paru-bin'
+    if [[ "${ARCHZBM_KERNEL_VER}" ]]; then
+        paru_install 'downgrade'
+        yes | downgrade --ala-only \
+            'linux='"${ARCHZBM_KERNEL_VER}" \
+            'linux-headers='"${ARCHZBM_KERNEL_VER}" \
+            --ignore always
+    fi
     paru_install 'zfs-dkms' 'zfs-utils' 'jq'
     hwclock --systohc
     mkinitcpio -P
@@ -1008,6 +1355,9 @@ function install_os_in_chroot () {
         add_syslinux_pacman_hook
     fi
     add_zbm_pacman_hook
+    swapoff '/dev/loop9'
+    losetup -d '/dev/loop9'
+    rm '/swapfile'
 }
 
 function set_root_pw () {
@@ -1023,11 +1373,54 @@ function set_root_pw () {
 
 function configure_networking () {
     #3.3
+    local -a dns_addresses ntp_addresses
+
+    # Begin network unit file with a default top section
     cat > '/mnt/etc/systemd/network/50-wired.network' <<"EOF"
 [Match]
 Name=en*
 
 [Network]
+EOF
+
+    # Decide on what comes next in network unit file
+    if  [[ "${ARCHZBM_OS_CLIENT_IP}" ]]  || \
+        [[ "${ARCHZBM_OS_GATEWAY_IP}" ]] || \
+        [[ "${ARCHZBM_OS_DNS_IP}" ]]     || \
+        [[ "${ARCHZBM_OS_NTP_IP}" ]]; then
+
+        cat >> '/mnt/etc/systemd/network/50-wired.network' <<EOF
+Address=${ARCHZBM_OS_CLIENT_IP}
+Gateway=${ARCHZBM_OS_GATEWAY_IP}
+EOF
+
+        if [[ "${ARCHZBM_OS_DNS_IP}" ]]; then
+            mapfile -t dns_addresses < <(<<<"${ARCHZBM_OS_DNS_IP}" tr ',' '\n' | sed '/^$/d')
+        else
+            dns_addresses+=('8.8.8.8')
+            dns_addresses+=('8.8.4.4')
+        fi
+        for dns_addr in "${dns_addresses[@]}"; do
+            cat >> '/mnt/etc/systemd/network/50-wired.network' <<EOF
+DNS=${dns_addr}
+EOF
+        done
+
+        if [[ "${ARCHZBM_OS_NTP_IP}" ]]; then
+            mapfile -t ntp_addresses < <(<<<"${ARCHZBM_OS_NTP_IP}" tr ',' '\n' | sed '/^$/d')
+            for ntp_addr in "${ntp_addresses[@]}"; do
+                cat >> '/mnt/etc/systemd/network/50-wired.network' <<EOF
+NTP=${ntp_addr}
+EOF
+            done
+        fi
+
+        cat >> '/mnt/etc/systemd/network/50-wired.network' <<"EOF"
+IPForward=yes
+Domains=~.
+EOF
+    else
+        cat >> '/mnt/etc/systemd/network/50-wired.network' <<"EOF"
 DHCP=ipv4
 IPForward=yes
 
@@ -1035,33 +1428,56 @@ IPForward=yes
 UseDNS=yes
 RouteMetric=10
 EOF
+    fi
+
     systemctl enable 'systemd-networkd' --root='/mnt'
     systemctl disable 'systemd-networkd-wait-online' --root='/mnt'
 }
 
-function configure_dns () {
+function configure_sshd () {
     #3.4
+    local pub_key_line
+
+    cat >> '/mnt/etc/ssh/sshd_config.d/40-defaults.conf' <<"EOF"
+PasswordAuthentication no
+PermitRootLogin yes
+EOF
+
+    while IFS= read -r pub_key_line; do
+        printf -- '%s\n' "${pub_key_line}" >> '/mnt/root/.ssh/authorized_keys'
+    done < <(<<<"${ARCHZBM_OS_SSH_AUTH_KEYS}" sed -r -e 's/,,/\n/g')
+
+    systemctl enable 'sshd.service' --root='/mnt'
+}
+
+function configure_dns () {
+    #3.5
     rm '/mnt/etc/resolv.conf'
     ln -s '/run/systemd/resolve/stub-resolv.conf' '/mnt/etc/resolv.conf'
 
     # Optionally you may want /etc/systemd/network/50-wired.network to use
     # UseDNS=no and hardcode DNS server(s) here:
     # sed -i 's/^#DNS=.*/DNS=1.1.1.1/' /mnt/etc/systemd/resolved.conf
-    systemctl enable 'systemd-resolved' --root='/mnt'
+    systemctl enable 'systemd-resolved.service' --root='/mnt'
+}
+
+function configure_ntp () {
+    #3.6
+    systemctl enable 'systemd-timesyncd.service' --root='/mnt'
 }
 
 function configure_reflector () {
-    #3.5
+    #3.7
     systemctl enable 'reflector.service' 'reflector.timer' --root='/mnt'
 }
 
 function configure_zfs () {
-    #3.6
-    systemctl enable 'zfs-import-cache' 'zfs-mount' 'zfs-import.target' 'zfs.target' --root='/mnt'
+    #3.8
+    systemctl enable 'zfs-import-cache.service' 'zfs-mount.service' 'zfs-import.target' 'zfs.target' --root='/mnt'
 }
 
 function configure_zfs_mount_gen () {
-    #3.7
+    #3.9
     mkdir -p '/mnt/etc/zfs/zfs-list.cache'
     touch '/mnt/etc/zfs/zfs-list.cache/'"${zpool_name}"
     zfs list -H -o name,mountpoint,canmount,atime,relatime,devices,exec,readonly,setuid,nbmand | sed 's/\/mnt//' > '/mnt/etc/zfs/zfs-list.cache/'"${zpool_name}"
@@ -1069,7 +1485,7 @@ function configure_zfs_mount_gen () {
 }
 
 function set_new_uefi_boot_entries () {
-    #3.8
+    #3.10
     declare -a uefi_images
     mapfile -t uefi_images < \
         <(find '/mnt/efi/EFI/ZBM' -type f -iname '*.efi' -print0 | \
@@ -1112,7 +1528,7 @@ function set_new_uefi_boot_entries () {
 }
 
 function umount_all () {
-    #3.9
+    #3.11
     if [[ "${part_schema}" = 'mbr' ]]; then
         umount '/mnt/boot/syslinux'
     else
@@ -1124,44 +1540,51 @@ function umount_all () {
 
 function finalize_os_setup () {
     #3.1
-    set_root_pw                                 #3.2
-    configure_networking                        #3.3
-    configure_dns                               #3.4
-    configure_reflector                         #3.5
-    configure_zfs                               #3.6
-    configure_zfs_mount_gen                     #3.7
-    if [[ "${part_schema}" = 'gpt' ]]; then
-        set_new_uefi_boot_entries               #3.8
+    set_root_pw                                     #3.2
+    configure_networking                            #3.3
+    if [[ "${ARCHZBM_OS_SSH_AUTH_KEYS}" ]]; then
+        configure_sshd                              #3.4
     fi
-    umount_all                                  #3.9
+    configure_dns                                   #3.5
+    configure_ntp                                   #3.6
+    configure_reflector                             #3.7
+    configure_zfs                                   #3.8
+    configure_zfs_mount_gen                         #3.9
+    if [[ "${part_schema}" = 'gpt' ]]; then
+        set_new_uefi_boot_entries                   #3.10
+    fi
+    umount_all                                      #3.11
 }
 
 function main () {
+    if [[ "${#@}" -gt '0' ]]; then
+        arg_parse "${@}"
+    fi
     if we_are_changerooted; then
-        install_os_in_chroot                    #2.2
+        install_os_in_chroot                        #2.2
     else
-        no_kernel_update_in_iso                 #1.1
-        set_ntp                                 #1.2
-        resize_cow_space                        #1.3
-        update_pacman_db                        #1.4
-        install_pkgs 'jq'                       #1.5
-        install_zfs                             #1.6
-        uefi_or_bios                            #1.7
-        load_settings_file                      #1.8
-        setup_zpool                             #1.9
-        mount_system                            #1.10
-        copy_zpool_cache                        #1.11
-        install_archlinux                       #1.12
-        gen_fstab                               #1.13
-        set_hostname                            #1.14
-        set_locale                              #1.15
-        add_zfs_hook_to_initramfs               #1.16
-        set_initramfs_build_list                #1.17
-        add_zfs_files_to_new_os                 #1.18
-        enter_chroot                            #2.1
+        no_kernel_update_in_iso                     #1.1
+        set_ntp                                     #1.2
+        resize_cow_space                            #1.3
+        update_pacman_db                            #1.4
+        install_pkgs 'jq'                           #1.5
+        install_zfs                                 #1.6
+        uefi_or_bios                                #1.7
+        load_settings_file                          #1.8
+        setup_zpool                                 #1.9
+        mount_system                                #1.10
+        copy_zpool_cache                            #1.11
+        install_archlinux                           #1.12
+        gen_fstab                                   #1.13
+        set_hostname                                #1.14
+        set_locale                                  #1.15
+        add_zfs_hook_to_initramfs                   #1.16
+        set_initramfs_build_list                    #1.17
+        add_zfs_files_to_new_os                     #1.18
+        enter_chroot                                #2.1
         # We're done in chroot
-        finalize_os_setup                       #3.1
+        finalize_os_setup                           #3.1
     fi
 }
 
-main
+main "${@}"