services.libvirtd.autoSnapshot: init (92d5ef97) · Commits · nix / nixpkgs

ci/OWNERS

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		@@ -121,6 +121,7 @@ nixos/modules/installer/tools/nix-fallback-paths.nix @NixOS/nix-team @raitobeza

		# NixOS QEMU virtualisation
		/nixos/modules/virtualisation/qemu-vm.nix @raitobezarius
		/nixos/modules/services/backup/libvirtd-autosnapshot.nix @6543

		# ACME
		/nixos/modules/security/acme @NixOS/acme

nixos/doc/manual/release-notes/rl-2511.section.md

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		@@ -116,6 +116,8 @@
		developers to build scalable applications without sacrificing productivity or
		reliability. Available as [services.temporal](#opt-services.temporal.enable).

		- `services.libvirtd.autoSnapshot`, a backup service for libvirt managed vms.

		## Backward Incompatibilities {#sec-release-25.11-incompatibilities}

		<!-- To avoid merge conflicts, consider adding your item at an arbitrary place in the list instead. -->

nixos/modules/module-list.nix

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		@@ -449,6 +449,7 @@
		./services/backup/btrbk.nix
		./services/backup/duplicati.nix
		./services/backup/duplicity.nix
		./services/backup/libvirtd-autosnapshot.nix
		./services/backup/mysql-backup.nix
		./services/backup/pgbackrest.nix
		./services/backup/postgresql-backup.nix

nixos/modules/services/backup/libvirtd-autosnapshot.nix

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		{
		config,
		lib,
		pkgs,
		...
		}:

		let
		cfg = config.services.libvirtd.autoSnapshot;

		# Function to get VM config with defaults
		getVMConfig =
		vm:
		if lib.isString vm then
		{
		name = vm;
		inherit (cfg) snapshotType keep;
		}
		else
		{
		inherit (vm) name;
		snapshotType = if vm.snapshotType != null then vm.snapshotType else cfg.snapshotType;
		keep = if vm.keep != null then vm.keep else cfg.keep;
		};

		# Main backup script combining all VM scripts
		backupScript = ''
		set -eo pipefail

		# Initialize failure tracking
		failed=""

		# Define the VM snapshot function
		function snap_vm() {
		local vmName="$1"
		local snapshotType="$2"
		local keep="$3"

		# Add validation for VM name
		if ! echo "$vmName" \| ${pkgs.gnugrep}/bin/grep -qE '^[a-zA-Z0-9_.-]+$'; then
		echo "Invalid VM name: '$vmName'"
		failed="$failed $vmName"
		return
		fi

		echo "Processing VM: $vmName"

		# Check if VM exists
		if ! ${pkgs.libvirt}/bin/virsh dominfo "$vmName" >/dev/null 2>&1; then
		echo "VM '$vmName' does not exist, skipping"
		return
		fi

		# Create new snapshot
		local snapshot_name
		snapshot_name="${cfg.prefix}_$(date +%Y-%m-%d_%H%M%S)"
		local snapshot_opts=""
		[[ "$snapshotType" == "external" ]] && snapshot_opts="--disk-only"
		if ! ${pkgs.libvirt}/bin/virsh snapshot-create-as \
		"$vmName" \
		"$snapshot_name" \
		"Automatic backup snapshot" \
		$snapshot_opts \
		--atomic; then
		echo "Failed to create snapshot for $vmName"
		failed="$failed $vmName"
		return
		fi

		# List all automatic snapshots for this VM
		readarray -t SNAPSHOTS < <(${pkgs.libvirt}/bin/virsh snapshot-list "$vmName" --name \| ${pkgs.gnugrep}/bin/grep "^${cfg.prefix}_")

		# Count snapshots
		local snapshot_count=''${#SNAPSHOTS[@]}

		# Delete old snapshots if we have more than the keep limit
		if [[ $snapshot_count -gt $keep ]]; then
		# Sort snapshots by date (they're named with date prefix)
		readarray -t TO_DELETE < <(printf '%s\n' "''${SNAPSHOTS[@]}" \| ${pkgs.coreutils}/bin/sort \| ${pkgs.coreutils}/bin/head -n -$keep)
		for snap in "''${TO_DELETE[@]}"; do
		echo "Removing old snapshot $snap from $vmName"

		# Check if snapshot is internal or external
		local snapshot_location
		snapshot_location=$(${pkgs.libvirt}/bin/virsh snapshot-info "$vmName" --snapshotname "$snap" \| ${pkgs.gnugrep}/bin/grep "Location:" \| ${pkgs.gawk}/bin/awk '{print $2}')

		local delete_opts=""
		[[ "$snapshot_location" == "internal" ]] && delete_opts="--metadata"

		if ! ${pkgs.libvirt}/bin/virsh snapshot-delete "$vmName" "$snap" $delete_opts; then
		echo "Failed to remove snapshot $snap from $vmName"
		failed="$failed $vmName(cleanup)"
		fi
		done
		fi
		}

		${
		if cfg.vms == null then
		''
		# Process all VMs
		${pkgs.libvirt}/bin/virsh list --all --name \| while read -r vm; do
		# Skip empty lines
		[ -z "$vm" ] && continue

		# Call snap_vm function with default settings
		snap_vm "$vm" ${cfg.snapshotType} ${toString cfg.keep}
		done
		''
		else
		''
		# Process specific VMs from the list
		${lib.concatMapStrings (
		vm: with getVMConfig vm; "snap_vm '${name}' ${snapshotType} ${toString keep}\n"
		) cfg.vms}
		''
		}

		# Report any failures
		if [ -n "$failed" ]; then
		echo "Snapshot operation failed for:$failed"
		exit 1
		fi

		exit 0
		'';
		in
		{
		options = {
		services.libvirtd.autoSnapshot = {
		enable = lib.mkEnableOption "LibVirt VM snapshots";

		calendar = lib.mkOption {
		type = lib.types.str;
		default = "04:15:00";
		description = ''
		When to create snapshots (systemd calendar format).
		Default is 4:15 AM.
		'';
		};

		prefix = lib.mkOption {
		type = lib.types.str;
		default = "autosnap";
		description = ''
		Prefix for automatic snapshot names.
		This is used to identify and manage automatic snapshots
		separately from manual ones.
		'';
		};

		keep = lib.mkOption {
		type = lib.types.int;
		default = 2;
		description = "Default number of snapshots to keep for VMs that don't specify a keep value.";
		};

		snapshotType = lib.mkOption {
		type = lib.types.enum [
		"internal"
		"external"
		];
		default = "internal";
		description = "Type of snapshot to create (internal or external).";
		};

		vms = lib.mkOption {
		type = lib.types.nullOr (
		lib.types.listOf (
		lib.types.oneOf [
		lib.types.str
		(lib.types.submodule {
		options = {
		name = lib.mkOption {
		type = lib.types.str;
		description = "Name of the VM";
		};
		snapshotType = lib.mkOption {
		type = lib.types.nullOr (
		lib.types.enum [
		"internal"
		"external"
		]
		);
		default = null;
		description = ''
		Type of snapshot to create (internal or external).
		If not specified, uses global snapshotType (${toString cfg.snapshotType}).
		'';
		};
		keep = lib.mkOption {
		type = lib.types.nullOr lib.types.int;
		default = null;
		description = ''
		Number of snapshots to keep for this VM.
		If not specified, uses global keep (${toString cfg.keep}).
		'';
		};
		};
		})
		]
		)
		);
		default = null;
		description = ''
		If specified only the list of VMs will be snapshotted else all existing one. Each entry can be either:
		- A string (VM name, uses default settings)
		- An attribute set with VM configuration
		'';
		example = lib.literalExpression ''
		[
		"myvm1" # Uses defaults
		{
		name = "myvm2";
		keep = 30; # Override retention
		}
		]
		'';
		};
		};
		};

		config = lib.mkIf cfg.enable {
		assertions = [
		{
		assertion = (cfg.vms == null) \|\| (lib.isList cfg.vms && cfg.vms != [ ]);
		message = "'services.libvirtd.autoSnapshot.vms' must either be null for all VMs or a non-empty list of VM configurations";
		}
		{
		assertion = config.virtualisation.libvirtd.enable;
		message = "virtualisation.libvirtd must be enabled to use services.libvirtd.autoSnapshot";
		}
		];

		systemd = {
		timers.libvirtd-autosnapshot = {
		description = "LibVirt VM snapshot timer";
		wantedBy = [ "timers.target" ];
		timerConfig = {
		OnCalendar = cfg.calendar;
		AccuracySec = "5m";
		Unit = "libvirtd-autosnapshot.service";
		};
		};

		services.libvirtd-autosnapshot = {
		description = "LibVirt VM snapshot service";
		after = [ "libvirtd.service" ];
		requires = [ "libvirtd.service" ];
		serviceConfig = {
		Type = "oneshot";
		User = "root";
		};
		script = backupScript;
		};
		};
		};

		meta.maintainers = [ lib.maintainers._6543 ];
		}