408 lines
15 KiB
Nix
408 lines
15 KiB
Nix
{ config, lib, options, pkgs, utils, ... }:
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with lib;
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let
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gcfg = config.services.tarsnap;
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opt = options.services.tarsnap;
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configFile = name: cfg: ''
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keyfile ${cfg.keyfile}
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${optionalString (cfg.cachedir != null) "cachedir ${cfg.cachedir}"}
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${optionalString cfg.nodump "nodump"}
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${optionalString cfg.printStats "print-stats"}
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${optionalString cfg.printStats "humanize-numbers"}
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${optionalString (cfg.checkpointBytes != null) ("checkpoint-bytes "+cfg.checkpointBytes)}
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${optionalString cfg.aggressiveNetworking "aggressive-networking"}
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${concatStringsSep "\n" (map (v: "exclude ${v}") cfg.excludes)}
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${concatStringsSep "\n" (map (v: "include ${v}") cfg.includes)}
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${optionalString cfg.lowmem "lowmem"}
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${optionalString cfg.verylowmem "verylowmem"}
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${optionalString (cfg.maxbw != null) "maxbw ${toString cfg.maxbw}"}
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${optionalString (cfg.maxbwRateUp != null) "maxbw-rate-up ${toString cfg.maxbwRateUp}"}
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${optionalString (cfg.maxbwRateDown != null) "maxbw-rate-down ${toString cfg.maxbwRateDown}"}
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'';
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in
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{
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imports = [
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(mkRemovedOptionModule [ "services" "tarsnap" "cachedir" ] "Use services.tarsnap.archives.<name>.cachedir")
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];
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options = {
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services.tarsnap = {
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enable = mkEnableOption "periodic tarsnap backups";
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keyfile = mkOption {
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type = types.str;
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default = "/root/tarsnap.key";
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description = ''
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The keyfile which associates this machine with your tarsnap
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account.
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Create the keyfile with <command>tarsnap-keygen</command>.
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Note that each individual archive (specified below) may also have its
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own individual keyfile specified. Tarsnap does not allow multiple
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concurrent backups with the same cache directory and key (starting a
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new backup will cause another one to fail). If you have multiple
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archives specified, you should either spread out your backups to be
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far apart, or specify a separate key for each archive. By default
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every archive defaults to using
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<literal>"/root/tarsnap.key"</literal>.
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It's recommended for backups that you generate a key for every archive
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using <literal>tarsnap-keygen(1)</literal>, and then generate a
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write-only tarsnap key using <literal>tarsnap-keymgmt(1)</literal>,
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and keep your master key(s) for a particular machine off-site.
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The keyfile name should be given as a string and not a path, to
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avoid the key being copied into the Nix store.
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'';
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};
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archives = mkOption {
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type = types.attrsOf (types.submodule ({ config, options, ... }:
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{
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options = {
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keyfile = mkOption {
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type = types.str;
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default = gcfg.keyfile;
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defaultText = literalExpression "config.${opt.keyfile}";
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description = ''
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Set a specific keyfile for this archive. This defaults to
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<literal>"/root/tarsnap.key"</literal> if left unspecified.
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Use this option if you want to run multiple backups
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concurrently - each archive must have a unique key. You can
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generate a write-only key derived from your master key (which
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is recommended) using <literal>tarsnap-keymgmt(1)</literal>.
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Note: every archive must have an individual master key. You
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must generate multiple keys with
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<literal>tarsnap-keygen(1)</literal>, and then generate write
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only keys from those.
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The keyfile name should be given as a string and not a path, to
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avoid the key being copied into the Nix store.
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'';
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};
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cachedir = mkOption {
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type = types.nullOr types.path;
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default = "/var/cache/tarsnap/${utils.escapeSystemdPath config.keyfile}";
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defaultText = literalExpression ''
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"/var/cache/tarsnap/''${utils.escapeSystemdPath config.${options.keyfile}}"
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'';
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description = ''
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The cache allows tarsnap to identify previously stored data
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blocks, reducing archival time and bandwidth usage.
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Should the cache become desynchronized or corrupted, tarsnap
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will refuse to run until you manually rebuild the cache with
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<command>tarsnap --fsck</command>.
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Set to <literal>null</literal> to disable caching.
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'';
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};
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nodump = mkOption {
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type = types.bool;
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default = true;
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description = ''
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Exclude files with the <literal>nodump</literal> flag.
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'';
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};
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printStats = mkOption {
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type = types.bool;
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default = true;
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description = ''
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Print global archive statistics upon completion.
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The output is available via
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<command>systemctl status tarsnap-archive-name</command>.
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'';
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};
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checkpointBytes = mkOption {
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type = types.nullOr types.str;
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default = "1GB";
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description = ''
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Create a checkpoint every <literal>checkpointBytes</literal>
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of uploaded data (optionally specified using an SI prefix).
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1GB is the minimum value. A higher value is recommended,
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as checkpointing is expensive.
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Set to <literal>null</literal> to disable checkpointing.
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'';
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};
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period = mkOption {
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type = types.str;
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default = "01:15";
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example = "hourly";
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description = ''
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Create archive at this interval.
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The format is described in
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<citerefentry><refentrytitle>systemd.time</refentrytitle>
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<manvolnum>7</manvolnum></citerefentry>.
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'';
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};
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aggressiveNetworking = mkOption {
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type = types.bool;
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default = false;
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description = ''
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Upload data over multiple TCP connections, potentially
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increasing tarsnap's bandwidth utilisation at the cost
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of slowing down all other network traffic. Not
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recommended unless TCP congestion is the dominant
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limiting factor.
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'';
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};
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directories = mkOption {
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type = types.listOf types.path;
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default = [];
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description = "List of filesystem paths to archive.";
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};
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excludes = mkOption {
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type = types.listOf types.str;
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default = [];
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description = ''
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Exclude files and directories matching these patterns.
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'';
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};
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includes = mkOption {
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type = types.listOf types.str;
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default = [];
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description = ''
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Include only files and directories matching these
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patterns (the empty list includes everything).
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Exclusions have precedence over inclusions.
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'';
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};
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lowmem = mkOption {
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type = types.bool;
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default = false;
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description = ''
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Reduce memory consumption by not caching small files.
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Possibly beneficial if the average file size is smaller
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than 1 MB and the number of files is lower than the
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total amount of RAM in KB.
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'';
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};
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verylowmem = mkOption {
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type = types.bool;
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default = false;
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description = ''
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Reduce memory consumption by a factor of 2 beyond what
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<literal>lowmem</literal> does, at the cost of significantly
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slowing down the archiving process.
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'';
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};
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maxbw = mkOption {
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type = types.nullOr types.int;
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default = null;
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description = ''
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Abort archival if upstream bandwidth usage in bytes
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exceeds this threshold.
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'';
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};
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maxbwRateUp = mkOption {
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type = types.nullOr types.int;
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default = null;
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example = literalExpression "25 * 1000";
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description = ''
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Upload bandwidth rate limit in bytes.
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'';
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};
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maxbwRateDown = mkOption {
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type = types.nullOr types.int;
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default = null;
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example = literalExpression "50 * 1000";
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description = ''
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Download bandwidth rate limit in bytes.
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'';
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};
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verbose = mkOption {
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type = types.bool;
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default = false;
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description = ''
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Whether to produce verbose logging output.
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'';
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};
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explicitSymlinks = mkOption {
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type = types.bool;
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default = false;
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description = ''
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Whether to follow symlinks specified as archives.
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'';
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};
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followSymlinks = mkOption {
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type = types.bool;
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default = false;
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description = ''
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Whether to follow all symlinks in archive trees.
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'';
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};
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};
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}
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));
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default = {};
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example = literalExpression ''
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{
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nixos =
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{ directories = [ "/home" "/root/ssl" ];
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};
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gamedata =
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{ directories = [ "/var/lib/minecraft" ];
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period = "*:30";
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};
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}
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'';
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description = ''
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Tarsnap archive configurations. Each attribute names an archive
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to be created at a given time interval, according to the options
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associated with it. When uploading to the tarsnap server,
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archive names are suffixed by a 1 second resolution timestamp,
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with the format <literal>%Y%m%d%H%M%S</literal>.
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For each member of the set is created a timer which triggers the
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instanced <literal>tarsnap-archive-name</literal> service unit. You may use
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<command>systemctl start tarsnap-archive-name</command> to
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manually trigger creation of <literal>archive-name</literal> at
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any time.
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'';
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};
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};
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};
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config = mkIf gcfg.enable {
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assertions =
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(mapAttrsToList (name: cfg:
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{ assertion = cfg.directories != [];
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message = "Must specify paths for tarsnap to back up";
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}) gcfg.archives) ++
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(mapAttrsToList (name: cfg:
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{ assertion = !(cfg.lowmem && cfg.verylowmem);
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message = "You cannot set both lowmem and verylowmem";
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}) gcfg.archives);
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systemd.services =
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(mapAttrs' (name: cfg: nameValuePair "tarsnap-${name}" {
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description = "Tarsnap archive '${name}'";
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requires = [ "network-online.target" ];
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after = [ "network-online.target" ];
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path = with pkgs; [ iputils tarsnap util-linux ];
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# In order for the persistent tarsnap timer to work reliably, we have to
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# make sure that the tarsnap server is reachable after systemd starts up
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# the service - therefore we sleep in a loop until we can ping the
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# endpoint.
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preStart = ''
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while ! ping -4 -q -c 1 v1-0-0-server.tarsnap.com &> /dev/null; do sleep 3; done
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'';
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script = let
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tarsnap = ''tarsnap --configfile "/etc/tarsnap/${name}.conf"'';
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run = ''${tarsnap} -c -f "${name}-$(date +"%Y%m%d%H%M%S")" \
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${optionalString cfg.verbose "-v"} \
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${optionalString cfg.explicitSymlinks "-H"} \
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${optionalString cfg.followSymlinks "-L"} \
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${concatStringsSep " " cfg.directories}'';
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cachedir = escapeShellArg cfg.cachedir;
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in if (cfg.cachedir != null) then ''
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mkdir -p ${cachedir}
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chmod 0700 ${cachedir}
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( flock 9
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if [ ! -e ${cachedir}/firstrun ]; then
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( flock 10
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flock -u 9
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${tarsnap} --fsck
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flock 9
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) 10>${cachedir}/firstrun
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fi
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) 9>${cachedir}/lockf
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exec flock ${cachedir}/firstrun ${run}
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'' else "exec ${run}";
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serviceConfig = {
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Type = "oneshot";
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IOSchedulingClass = "idle";
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NoNewPrivileges = "true";
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CapabilityBoundingSet = [ "CAP_DAC_READ_SEARCH" ];
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PermissionsStartOnly = "true";
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};
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}) gcfg.archives) //
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(mapAttrs' (name: cfg: nameValuePair "tarsnap-restore-${name}"{
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description = "Tarsnap restore '${name}'";
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requires = [ "network-online.target" ];
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path = with pkgs; [ iputils tarsnap util-linux ];
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script = let
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tarsnap = ''tarsnap --configfile "/etc/tarsnap/${name}.conf"'';
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lastArchive = "$(${tarsnap} --list-archives | sort | tail -1)";
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run = ''${tarsnap} -x -f "${lastArchive}" ${optionalString cfg.verbose "-v"}'';
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cachedir = escapeShellArg cfg.cachedir;
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in if (cfg.cachedir != null) then ''
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mkdir -p ${cachedir}
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chmod 0700 ${cachedir}
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( flock 9
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if [ ! -e ${cachedir}/firstrun ]; then
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( flock 10
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flock -u 9
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${tarsnap} --fsck
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flock 9
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) 10>${cachedir}/firstrun
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fi
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) 9>${cachedir}/lockf
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exec flock ${cachedir}/firstrun ${run}
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'' else "exec ${run}";
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serviceConfig = {
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Type = "oneshot";
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IOSchedulingClass = "idle";
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NoNewPrivileges = "true";
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CapabilityBoundingSet = [ "CAP_DAC_READ_SEARCH" ];
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PermissionsStartOnly = "true";
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};
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}) gcfg.archives);
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# Note: the timer must be Persistent=true, so that systemd will start it even
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# if e.g. your laptop was asleep while the latest interval occurred.
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systemd.timers = mapAttrs' (name: cfg: nameValuePair "tarsnap-${name}"
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{ timerConfig.OnCalendar = cfg.period;
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timerConfig.Persistent = "true";
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wantedBy = [ "timers.target" ];
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}) gcfg.archives;
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environment.etc =
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mapAttrs' (name: cfg: nameValuePair "tarsnap/${name}.conf"
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{ text = configFile name cfg;
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}) gcfg.archives;
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environment.systemPackages = [ pkgs.tarsnap ];
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};
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}
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