diff options
Diffstat (limited to 'nixos/modules/services/backup/tarsnap.nix')
-rw-r--r-- | nixos/modules/services/backup/tarsnap.nix | 66 |
1 files changed, 60 insertions, 6 deletions
diff --git a/nixos/modules/services/backup/tarsnap.nix b/nixos/modules/services/backup/tarsnap.nix index 57121e238553..78776786468b 100644 --- a/nixos/modules/services/backup/tarsnap.nix +++ b/nixos/modules/services/backup/tarsnap.nix @@ -5,9 +5,9 @@ with lib; let cfg = config.services.tarsnap; - configFile = cfg: '' - cachedir ${config.services.tarsnap.cachedir} - keyfile ${config.services.tarsnap.keyfile} + configFile = name: cfg: '' + cachedir ${config.services.tarsnap.cachedir}/${name} + keyfile ${cfg.keyfile} ${optionalString cfg.nodump "nodump"} ${optionalString cfg.printStats "print-stats"} ${optionalString cfg.printStats "humanize-numbers"} @@ -41,6 +41,20 @@ in account. Create the keyfile with <command>tarsnap-keygen</command>. + Note that each individual archive (specified below) may also have its + own individual keyfile specified. Tarsnap does not allow multiple + concurrent backups with the same cache directory and key (starting a + new backup will cause another one to fail). If you have multiple + archives specified, you should either spread out your backups to be + far apart, or specify a separate key for each archive. By default + every archive defaults to using + <literal>"/root/tarsnap.key"</literal>. + + It's recommended for backups that you generate a key for every archive + using <literal>tarsnap-keygen(1)</literal>, and then generate a + write-only tarsnap key using <literal>tarsnap-keymgmt(1)</literal>, + and keep your master key(s) for a particular machine off-site. + The keyfile name should be given as a string and not a path, to avoid the key being copied into the Nix store. ''; @@ -57,6 +71,12 @@ in will refuse to run until you manually rebuild the cache with <command>tarsnap --fsck</command>. + Note that each individual archive (specified below) has its own cache + directory specified under <literal>cachedir</literal>; this is because + tarsnap locks the cache during backups, meaning multiple services + archives cannot be backed up concurrently or overlap with a shared + cache. + Set to <literal>null</literal> to disable caching. ''; }; @@ -65,6 +85,28 @@ in type = types.attrsOf (types.submodule ( { options = { + keyfile = mkOption { + type = types.str; + default = config.services.tarsnap.keyfile; + description = '' + Set a specific keyfile for this archive. This defaults to + <literal>"/root/tarsnap.key"</literal> if left unspecified. + + Use this option if you want to run multiple backups + concurrently - each archive must have a unique key. You can + generate a write-only key derived from your master key (which + is recommended) using <literal>tarsnap-keymgmt(1)</literal>. + + Note: every archive must have an individual master key. You + must generate multiple keys with + <literal>tarsnap-keygen(1)</literal>, and then generate write + only keys from those. + + The keyfile name should be given as a string and not a path, to + avoid the key being copied into the Nix store. + ''; + }; + nodump = mkOption { type = types.bool; default = true; @@ -242,15 +284,23 @@ in systemd.services."tarsnap@" = { description = "Tarsnap archive '%i'"; - requires = [ "network.target" ]; + requires = [ "network-online.target" ]; + after = [ "network-online.target" ]; + + path = [ pkgs.iputils pkgs.tarsnap pkgs.coreutils ]; - path = [ pkgs.tarsnap pkgs.coreutils ]; + # In order for the persistent tarsnap timer to work reliably, we have to + # make sure that the tarsnap server is reachable after systemd starts up + # the service - therefore we sleep in a loop until we can ping the + # endpoint. + preStart = "while ! ping -q -c 1 betatest-server.tarsnap.com &> /dev/null; do sleep 3; done"; scriptArgs = "%i"; script = '' mkdir -p -m 0755 ${dirOf cfg.cachedir} mkdir -p -m 0700 ${cfg.cachedir} chown root:root ${cfg.cachedir} chmod 0700 ${cfg.cachedir} + mkdir -p -m 0700 ${cfg.cachedir}/$1 DIRS=`cat /etc/tarsnap/$1.dirs` exec tarsnap --configfile /etc/tarsnap/$1.conf -c -f $1-$(date +"%Y%m%d%H%M%S") $DIRS ''; @@ -259,17 +309,21 @@ in IOSchedulingClass = "idle"; NoNewPrivileges = "true"; CapabilityBoundingSet = "CAP_DAC_READ_SEARCH"; + PermissionsStartOnly = "true"; }; }; + # Note: the timer must be Persistent=true, so that systemd will start it even + # if e.g. your laptop was asleep while the latest interval occurred. systemd.timers = mapAttrs' (name: cfg: nameValuePair "tarsnap@${name}" { timerConfig.OnCalendar = cfg.period; + timerConfig.Persistent = "true"; wantedBy = [ "timers.target" ]; }) cfg.archives; environment.etc = (mapAttrs' (name: cfg: nameValuePair "tarsnap/${name}.conf" - { text = configFile cfg; + { text = configFile name cfg; }) cfg.archives) // (mapAttrs' (name: cfg: nameValuePair "tarsnap/${name}.dirs" { text = concatStringsSep " " cfg.directories; |