580 lines
20 KiB
Nix
580 lines
20 KiB
Nix
{ config, lib, pkgs, ... }:
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with lib;
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let
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isLocalPath = x:
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builtins.substring 0 1 x == "/" # absolute path
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|| builtins.substring 0 1 x == "." # relative path
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|| builtins.match "[.*:.*]" == null; # not machine:path
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mkExcludeFile = cfg:
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# Write each exclude pattern to a new line
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pkgs.writeText "excludefile" (concatStringsSep "\n" cfg.exclude);
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mkKeepArgs = cfg:
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# If cfg.prune.keep e.g. has a yearly attribute,
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# its content is passed on as --keep-yearly
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concatStringsSep " "
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(mapAttrsToList (x: y: "--keep-${x}=${toString y}") cfg.prune.keep);
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mkBackupScript = cfg: ''
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on_exit()
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{
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exitStatus=$?
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# Reset the EXIT handler, or else we're called again on 'exit' below
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trap - EXIT
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${cfg.postHook}
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exit $exitStatus
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}
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trap 'on_exit' INT TERM QUIT EXIT
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archiveName="${cfg.archiveBaseName}-$(date ${cfg.dateFormat})"
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archiveSuffix="${optionalString cfg.appendFailedSuffix ".failed"}"
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${cfg.preHook}
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'' + optionalString cfg.doInit ''
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# Run borg init if the repo doesn't exist yet
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if ! borg list > /dev/null; then
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borg init \
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--encryption ${cfg.encryption.mode} \
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$extraInitArgs
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${cfg.postInit}
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fi
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'' + ''
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borg create \
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--compression ${cfg.compression} \
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--exclude-from ${mkExcludeFile cfg} \
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$extraCreateArgs \
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"::$archiveName$archiveSuffix" \
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${escapeShellArgs cfg.paths}
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'' + optionalString cfg.appendFailedSuffix ''
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borg rename "::$archiveName$archiveSuffix" "$archiveName"
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'' + ''
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${cfg.postCreate}
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'' + optionalString (cfg.prune.keep != { }) ''
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borg prune \
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${mkKeepArgs cfg} \
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--prefix ${escapeShellArg cfg.prune.prefix} \
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$extraPruneArgs
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${cfg.postPrune}
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'';
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mkPassEnv = cfg: with cfg.encryption;
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if passCommand != null then
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{ BORG_PASSCOMMAND = passCommand; }
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else if passphrase != null then
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{ BORG_PASSPHRASE = passphrase; }
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else { };
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mkBackupService = name: cfg:
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let
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userHome = config.users.users.${cfg.user}.home;
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in nameValuePair "borgbackup-job-${name}" {
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description = "BorgBackup job ${name}";
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path = with pkgs; [
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borgbackup openssh
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];
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script = mkBackupScript cfg;
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serviceConfig = {
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User = cfg.user;
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Group = cfg.group;
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# Only run when no other process is using CPU or disk
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CPUSchedulingPolicy = "idle";
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IOSchedulingClass = "idle";
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ProtectSystem = "strict";
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ReadWritePaths =
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[ "${userHome}/.config/borg" "${userHome}/.cache/borg" ]
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# Borg needs write access to repo if it is not remote
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++ optional (isLocalPath cfg.repo) cfg.repo;
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PrivateTmp = true;
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};
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environment = {
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BORG_REPO = cfg.repo;
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inherit (cfg) extraInitArgs extraCreateArgs extraPruneArgs;
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} // (mkPassEnv cfg) // cfg.environment;
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inherit (cfg) startAt;
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};
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# Paths listed in ReadWritePaths must exist before service is started
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mkActivationScript = name: cfg:
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let
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install = "install -o ${cfg.user} -g ${cfg.group}";
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in
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nameValuePair "borgbackup-job-${name}" (stringAfter [ "users" ] (''
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# Eensure that the home directory already exists
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# We can't assert createHome == true because that's not the case for root
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cd "${config.users.users.${cfg.user}.home}"
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${install} -d .config/borg
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${install} -d .cache/borg
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'' + optionalString (isLocalPath cfg.repo) ''
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${install} -d ${escapeShellArg cfg.repo}
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''));
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mkPassAssertion = name: cfg: {
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assertion = with cfg.encryption;
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mode != "none" -> passCommand != null || passphrase != null;
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message =
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"passCommand or passphrase has to be specified because"
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+ '' borgbackup.jobs.${name}.encryption != "none"'';
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};
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mkRepoService = name: cfg:
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nameValuePair "borgbackup-repo-${name}" {
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description = "Create BorgBackup repository ${name} directory";
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script = ''
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mkdir -p ${escapeShellArg cfg.path}
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chown ${cfg.user}:${cfg.group} ${escapeShellArg cfg.path}
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'';
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serviceConfig = {
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# The service's only task is to ensure that the specified path exists
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Type = "oneshot";
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};
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wantedBy = [ "multi-user.target" ];
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};
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mkAuthorizedKey = cfg: appendOnly: key:
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let
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# Because of the following line, clients do not need to specify an absolute repo path
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cdCommand = "cd ${escapeShellArg cfg.path}";
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restrictedArg = "--restrict-to-${if cfg.allowSubRepos then "path" else "repository"} .";
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appendOnlyArg = optionalString appendOnly "--append-only";
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quotaArg = optionalString (cfg.quota != null) "--storage-quota ${cfg.quota}";
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serveCommand = "borg serve ${restrictedArg} ${appendOnlyArg} ${quotaArg}";
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in
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''command="${cdCommand} && ${serveCommand}",restrict ${key}'';
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mkUsersConfig = name: cfg: {
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users.${cfg.user} = {
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openssh.authorizedKeys.keys =
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(map (mkAuthorizedKey cfg false) cfg.authorizedKeys
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++ map (mkAuthorizedKey cfg true) cfg.authorizedKeysAppendOnly);
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useDefaultShell = true;
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};
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groups.${cfg.group} = { };
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};
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mkKeysAssertion = name: cfg: {
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assertion = cfg.authorizedKeys != [ ] || cfg.authorizedKeysAppendOnly != [ ];
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message =
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"borgbackup.repos.${name} does not make sense"
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+ " without at least one public key";
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};
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in {
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meta.maintainers = with maintainers; [ dotlambda ];
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###### interface
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options.services.borgbackup.jobs = mkOption {
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description = "Deduplicating backups using BorgBackup.";
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default = { };
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example = literalExample ''
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{
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rootBackup = {
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paths = "/";
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exclude = [ "/nix" ];
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repo = "/path/to/local/repo";
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encryption = {
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mode = "repokey";
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passphrase = "secret";
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};
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compression = "auto,lzma";
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startAt = "weekly";
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};
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}
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'';
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type = types.attrsOf (types.submodule (let globalConfig = config; in
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{ name, config, ... }: {
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options = {
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paths = mkOption {
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type = with types; either path (nonEmptyListOf path);
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description = "Path(s) to back up.";
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example = "/home/user";
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apply = x: if isList x then x else [ x ];
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};
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repo = mkOption {
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type = types.str;
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description = "Remote or local repository to back up to.";
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example = "user@machine:/path/to/repo";
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};
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archiveBaseName = mkOption {
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type = types.strMatching "[^/{}]+";
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default = "${globalConfig.networking.hostName}-${name}";
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defaultText = "\${config.networking.hostName}-<name>";
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description = ''
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How to name the created archives. A timestamp, whose format is
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determined by <option>dateFormat</option>, will be appended. The full
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name can be modified at runtime (<literal>$archiveName</literal>).
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Placeholders like <literal>{hostname}</literal> must not be used.
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'';
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};
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dateFormat = mkOption {
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type = types.str;
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description = ''
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Arguments passed to <command>date</command>
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to create a timestamp suffix for the archive name.
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'';
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default = "+%Y-%m-%dT%H:%M:%S";
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example = "-u +%s";
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};
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startAt = mkOption {
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type = with types; either str (listOf str);
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default = "daily";
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description = ''
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When or how often the backup should run.
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Must be in the format described in
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<citerefentry><refentrytitle>systemd.time</refentrytitle>
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<manvolnum>7</manvolnum></citerefentry>.
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If you do not want the backup to start
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automatically, use <literal>[ ]</literal>.
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'';
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};
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user = mkOption {
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type = types.str;
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description = ''
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The user <command>borg</command> is run as.
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User or group need read permission
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for the specified <option>paths</option>.
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'';
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default = "root";
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};
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group = mkOption {
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type = types.str;
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description = ''
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The group borg is run as. User or group needs read permission
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for the specified <option>paths</option>.
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'';
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default = "root";
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};
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encryption.mode = mkOption {
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type = types.enum [
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"repokey" "keyfile"
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"repokey-blake2" "keyfile-blake2"
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"authenticated" "authenticated-blake2"
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"none"
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];
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description = ''
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Encryption mode to use. Setting a mode
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other than <literal>"none"</literal> requires
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you to specify a <option>passCommand</option>
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or a <option>passphrase</option>.
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'';
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};
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encryption.passCommand = mkOption {
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type = with types; nullOr str;
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description = ''
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A command which prints the passphrase to stdout.
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Mutually exclusive with <option>passphrase</option>.
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'';
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default = null;
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example = "cat /path/to/passphrase_file";
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};
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encryption.passphrase = mkOption {
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type = with types; nullOr str;
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description = ''
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The passphrase the backups are encrypted with.
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Mutually exclusive with <option>passCommand</option>.
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If you do not want the passphrase to be stored in the
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world-readable Nix store, use <option>passCommand</option>.
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'';
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default = null;
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};
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compression = mkOption {
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# "auto" is optional,
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# compression mode must be given,
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# compression level is optional
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type = types.strMatching "none|(auto,)?(lz4|zstd|zlib|lzma)(,[[:digit:]]{1,2})?";
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description = ''
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Compression method to use. Refer to
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<command>borg help compression</command>
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for all available options.
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'';
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default = "lz4";
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example = "auto,lzma";
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};
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exclude = mkOption {
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type = with types; listOf str;
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description = ''
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Exclude paths matching any of the given patterns. See
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<command>borg help patterns</command> for pattern syntax.
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'';
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default = [ ];
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example = [
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"/home/*/.cache"
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"/nix"
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];
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};
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doInit = mkOption {
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type = types.bool;
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description = ''
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Run <command>borg init</command> if the
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specified <option>repo</option> does not exist.
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You should set this to <literal>false</literal>
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if the repository is located on an external drive
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that might not always be mounted.
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'';
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default = true;
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};
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appendFailedSuffix = mkOption {
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type = types.bool;
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description = ''
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Append a <literal>.failed</literal> suffix
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to the archive name, which is only removed if
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<command>borg create</command> has a zero exit status.
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'';
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default = true;
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};
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prune.keep = mkOption {
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# Specifying e.g. `prune.keep.yearly = -1`
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# means there is no limit of yearly archives to keep
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# The regex is for use with e.g. --keep-within 1y
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type = with types; attrsOf (either int (strMatching "[[:digit:]]+[Hdwmy]"));
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description = ''
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Prune a repository by deleting all archives not matching any of the
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specified retention options. See <command>borg help prune</command>
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for the available options.
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'';
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default = { };
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example = literalExample ''
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{
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within = "1d"; # Keep all archives from the last day
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daily = 7;
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weekly = 4;
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monthly = -1; # Keep at least one archive for each month
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}
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'';
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};
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prune.prefix = mkOption {
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type = types.str;
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description = ''
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Only consider archive names starting with this prefix for pruning.
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By default, only archives created by this job are considered.
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Use <literal>""</literal> to consider all archives.
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'';
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default = config.archiveBaseName;
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defaultText = "\${archiveBaseName}";
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};
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environment = mkOption {
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type = with types; attrsOf str;
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description = ''
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Environment variables passed to the backup script.
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You can for example specify which SSH key to use.
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'';
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default = { };
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example = { BORG_RSH = "ssh -i /path/to/key"; };
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};
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preHook = mkOption {
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type = types.lines;
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description = ''
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Shell commands to run before the backup.
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This can for example be used to mount file systems.
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'';
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default = "";
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example = ''
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# To add excluded paths at runtime
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extraCreateArgs="$extraCreateArgs --exclude /some/path"
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'';
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};
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postInit = mkOption {
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type = types.lines;
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description = ''
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Shell commands to run after <command>borg init</command>.
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'';
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default = "";
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};
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postCreate = mkOption {
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type = types.lines;
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description = ''
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Shell commands to run after <command>borg create</command>. The name
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of the created archive is stored in <literal>$archiveName</literal>.
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'';
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default = "";
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};
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postPrune = mkOption {
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type = types.lines;
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description = ''
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Shell commands to run after <command>borg prune</command>.
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'';
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default = "";
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};
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postHook = mkOption {
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type = types.lines;
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description = ''
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Shell commands to run just before exit. They are executed
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even if a previous command exits with a non-zero exit code.
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The latter is available as <literal>$exitStatus</literal>.
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'';
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default = "";
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};
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extraInitArgs = mkOption {
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type = types.str;
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description = ''
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Additional arguments for <command>borg init</command>.
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Can also be set at runtime using <literal>$extraInitArgs</literal>.
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'';
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default = "";
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example = "--append-only";
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};
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extraCreateArgs = mkOption {
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type = types.str;
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description = ''
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Additional arguments for <command>borg create</command>.
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Can also be set at runtime using <literal>$extraCreateArgs</literal>.
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'';
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default = "";
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example = "--stats --checkpoint-interval 600";
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};
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extraPruneArgs = mkOption {
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type = types.str;
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description = ''
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Additional arguments for <command>borg prune</command>.
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Can also be set at runtime using <literal>$extraPruneArgs</literal>.
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'';
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default = "";
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example = "--save-space";
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};
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};
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}
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));
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};
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options.services.borgbackup.repos = mkOption {
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description = ''
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Serve BorgBackup repositories to given public SSH keys,
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restricting their access to the repository only.
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Also, clients do not need to specify the absolute path when accessing the repository,
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i.e. <literal>user@machine:.</literal> is enough. (Note colon and dot.)
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'';
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default = { };
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type = types.attrsOf (types.submodule (
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{ name, config, ... }: {
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options = {
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path = mkOption {
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type = types.path;
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description = ''
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Where to store the backups. Note that the directory
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is created automatically, with correct permissions.
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'';
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default = "/var/lib/borgbackup";
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};
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user = mkOption {
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type = types.str;
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description = ''
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The user <command>borg serve</command> is run as.
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User or group needs write permission
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for the specified <option>path</option>.
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'';
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default = "borg";
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};
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group = mkOption {
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type = types.str;
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description = ''
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The group <command>borg serve</command> is run as.
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User or group needs write permission
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for the specified <option>path</option>.
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'';
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default = "borg";
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};
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authorizedKeys = mkOption {
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type = with types; listOf str;
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description = ''
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Public SSH keys that are given full write access to this repository.
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You should use a different SSH key for each repository you write to, because
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the specified keys are restricted to running <command>borg serve</command>
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and can only access this single repository.
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'';
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default = [ ];
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};
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authorizedKeysAppendOnly = mkOption {
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type = with types; listOf str;
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description = ''
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Public SSH keys that can only be used to append new data (archives) to the repository.
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Note that archives can still be marked as deleted and are subsequently removed from disk
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upon accessing the repo with full write access, e.g. when pruning.
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'';
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default = [ ];
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};
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allowSubRepos = mkOption {
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type = types.bool;
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description = ''
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Allow clients to create repositories in subdirectories of the
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specified <option>path</option>. These can be accessed using
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<literal>user@machine:path/to/subrepo</literal>. Note that a
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<option>quota</option> applies to repositories independently.
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Therefore, if this is enabled, clients can create multiple
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repositories and upload an arbitrary amount of data.
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'';
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default = false;
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};
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quota = mkOption {
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# See the definition of parse_file_size() in src/borg/helpers/parseformat.py
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type = with types; nullOr (strMatching "[[:digit:].]+[KMGTP]?");
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description = ''
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Storage quota for the repository. This quota is ensured for all
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sub-repositories if <option>allowSubRepos</option> is enabled
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|
but not for the overall storage space used.
|
|
'';
|
|
default = null;
|
|
example = "100G";
|
|
};
|
|
|
|
};
|
|
}
|
|
));
|
|
};
|
|
|
|
###### implementation
|
|
|
|
config = mkIf (with config.services.borgbackup; jobs != { } || repos != { })
|
|
(with config.services.borgbackup; {
|
|
assertions =
|
|
mapAttrsToList mkPassAssertion jobs
|
|
++ mapAttrsToList mkKeysAssertion repos;
|
|
|
|
system.activationScripts = mapAttrs' mkActivationScript jobs;
|
|
|
|
systemd.services =
|
|
# A job named "foo" is mapped to systemd.services.borgbackup-job-foo
|
|
mapAttrs' mkBackupService jobs
|
|
# A repo named "foo" is mapped to systemd.services.borgbackup-repo-foo
|
|
// mapAttrs' mkRepoService repos;
|
|
|
|
users = mkMerge (mapAttrsToList mkUsersConfig repos);
|
|
|
|
environment.systemPackages = with pkgs; [ borgbackup ];
|
|
});
|
|
}
|