Systemd service for backing up via ZFS snapshot with send/recv

[Mark Gardner]

Goal: schedule ZFS snapshots and use send/recv to replicate to a backup server.

Options: I considered sanoid/syncoid, zfsnap, zap, zrep, and znapzend. I chose the latter because it is the only one already in NixOS.

Issue: installing znapzend package doesn't start the daemon. I am trying to create a config that will generate the znapzend.service file following the example in github (https://github.com/oetiker/znapzend/blob/master/init/znapzend.service) but my NixOS and systemd foo are not up to the task. Here is what I have so far:

systemd.services.znapzend = {

  description = "ZnapZend - ZFS Backup Service";

  documentation = "man:znapzend";

  after = [ "zfs-import-dpool.service" ];

  wants = [ "zfs-import-dpool.service" ];

  wantedBy = [ "multi-user.target" ];

  serviceConfig = {

    Type = "forking";

    ExecStart = "${pkgs.znapzend}/bin/znapzend --daemonize";

    ExecReload = "${pkgs.coreutils}/bin/kill -HUP $MAINPID";

    Restart = "on-failure";

  };

};

Also, I am not happy with this because the pool name (dpool) is hard-coded into the service file. (I found the dependency on dpool by "systemctl list-units | grep zfs".) I don't know how to generalize the dependency to the import of all pools. How should I be doing it? More generally, what do you do to start the znapzen daemon?

Second question: how do you specify the setup rather than running znapzendzetup by hand?

Note: I am willing to entertain other ways of accomplishing the goal. Please enlighten me if you know of a alternate/better way...

​Mark

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Mark Gardner
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[Silvan Mosberger]

You're in luck! There is already a znapzend service available, you don't need to create one yourself. And: My PR that let's you specify the znapzenzetup in configuration.nix just got merged last week! Check it out here: https://github.com/NixOS/nixpkgs/pull/32914 Also contains an example.

Silvan

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[Silvan Mosberger]

Oh actually correction: it is not merged yet, but I am very sure it's ready for that

On 30 Dec 2017, at 23:23, Mark Gardner <m...@vt.edu> wrote:

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