Merge pull request #250501 from miallo/nixos-rebuild/list-generations

- LXD now supports virtual machine instances to complement the existing container support

- The `nixos-rebuild` command has been given a `list-generations` subcommand. See `man nixos-rebuild` for more details.

## New Services {#sec-release-23.11-new-services}

- [MCHPRS](https://github.com/MCHPR/MCHPRS), a multithreaded Minecraft server built for redstone. Available as [services.mchprs](#opt-services.mchprs.enable).

, coreutils

, gnused

, gnugrep

, jq

, util-linux

, nix

, lib

, nixosTests

  nix_x86_64_linux = fallback.x86_64-linux;

  nix_i686_linux = fallback.i686-linux;

  nix_aarch64_linux = fallback.aarch64-linux;

  path = lib.makeBinPath [ coreutils gnused gnugrep ];

  path = lib.makeBinPath [ coreutils gnused gnugrep jq util-linux ];

  nativeBuildInputs = [

    installShellFiles

  ];

.Sh SYNOPSIS

.Nm

.Bro

.Cm switch | boot | test | build | dry-build | dry-activate | edit | build-vm | build-vm-with-bootloader

.Cm switch | boot | test | build | dry-build | dry-activate | edit | build-vm | build-vm-with-bootloader | list-generations Op Fl -json

.Brc

.br

.Op Fl -upgrade | -upgrade-all

containing a

.Pa /boot

partition.

.

.It Cm list-generations Op Fl -json

List the available generations in a similar manner to the boot loader

menu. It shows the generation number, build date and time, NixOS version,

kernel version and the configuration revision. This is useful to get

information e.g. for which generation to roll back to with

.Ic nixos-rebuild switch Fl -generation Ar N

There is also a json version of output available.

.El

.

.

noFlake=

# comma separated list of vars to preserve when using sudo

preservedSudoVars=NIXOS_INSTALL_BOOTLOADER

json=

# log the given argument to stderr

log() {

      --help)

        showSyntax

        ;;

      switch|boot|test|build|edit|dry-build|dry-run|dry-activate|build-vm|build-vm-with-bootloader)

      switch|boot|test|build|edit|dry-build|dry-run|dry-activate|build-vm|build-vm-with-bootloader|list-generations)

        if [ "$i" = dry-run ]; then i=dry-build; fi

        # exactly one action mandatory, bail out if multiple are given

        if [ -n "$action" ]; then showSyntax; fi

        k="$1"; shift 1

        lockFlags+=("$i" "$j" "$k")

        ;;

      --json)

        json=1

        ;;

      *)

        log "$0: unknown option \`$i'"

        exit 1

    extraBuildFlags+=(--dry-run)

fi

if [ "$action" = list-generations ]; then

    if [ ! -L "$profile" ]; then

        log "No profile \`$(basename "$profile")' found"

        exit 1

    fi

    generation_from_dir() {

        generation_dir="$1"

        generation_base="$(basename "$generation_dir")" # Has the format "system-123-link" for generation 123

        no_link_gen="${generation_base%-link}"  # remove the "-link"

        echo "${no_link_gen##*-}" # remove everything before the last dash

    }

    describe_generation(){

        generation_dir="$1"

        generation_number="$(generation_from_dir "$generation_dir")"

        nixos_version="$(cat "$generation_dir/nixos-version" 2> /dev/null || echo "Unknown")"

        kernel_dir="$(dirname "$(realpath "$generation_dir/kernel")")"

        kernel_version="$(ls "$kernel_dir/lib/modules" || echo "Unknown")"

        configurationRevision="$("$generation_dir/sw/bin/nixos-version" --configuration-revision 2> /dev/null || true)"

        # Old nixos-version output ignored unknown flags and just printed the version

        # therefore the following workaround is done not to show the default output

        nixos_version_default="$("$generation_dir/sw/bin/nixos-version")"

        if [ "$configurationRevision" == "$nixos_version_default" ]; then

             configurationRevision=""

        fi

        # jq automatically quotes the output => don't try to quote it in output!

        build_date="$(stat "$generation_dir" --format=%W | jq 'todate')"

        pushd "$generation_dir/specialisation/" > /dev/null || :

        specialisation_list=(*)

        popd > /dev/null || :

        specialisations="$(jq --compact-output --null-input '$ARGS.positional' --args -- "${specialisation_list[@]}")"

        if [ "$(basename "$generation_dir")" = "$(readlink "$profile")" ]; then

            current_generation_tag="true"

        else

            current_generation_tag="false"

        fi

        # Escape userdefined strings

        nixos_version="$(jq -aR <<< "$nixos_version")"

        kernel_version="$(jq -aR <<< "$kernel_version")"

        configurationRevision="$(jq -aR <<< "$configurationRevision")"

        cat << EOF

{

  "generation": $generation_number,

  "date": $build_date,

  "nixosVersion": $nixos_version,

  "kernelVersion": $kernel_version,

  "configurationRevision": $configurationRevision,

  "specialisations": $specialisations,

  "current": $current_generation_tag

}

EOF

    }

    find "$(dirname "$profile")" -regex "$profile-[0-9]+-link" |

        sort -Vr |

        while read -r generation_dir; do

            describe_generation "$generation_dir"

        done |

        if [ -z "$json" ]; then

            jq --slurp -r '.[] | [

                    ([.generation, (if .current == true then "current" else "" end)] | join(" ")),

                    (.date | fromdate | strflocaltime("%Y-%m-%d %H:%M:%S")),

                    .nixosVersion, .kernelVersion, .configurationRevision,

                    (.specialisations | join(" "))

                ] | @tsv' |

                column --separator $'\t' --table --table-columns "Generation,Build-date,NixOS version,Kernel,Configuration Revision,Specialisation" |

                ${PAGER:cat}

        else

            jq --slurp .

        fi

    exit 0

fi

# Either upgrade the configuration in the system profile (for "switch"

# or "boot"), or just build it and create a symlink "result" in the