selfhostblocks/modules/contracts/datasetbackup/docs/default.md

Dataset Backup Contract

This NixOS contract represents a backup job that will backup one ZFS dataset.

It is a contract between a service that manages ZFS datasets and a service that backs up ZFS datasets.

Contract Reference

These are all the options that are expected to exist for this contract to be respected.

id-prefix: contracts-datasetbackup-options-
list-id: selfhostblocks-options
source: @OPTIONS_JSON@

Usage

A service that manages ZFS datasets that can be backed up will provide a datasetbackup option.

Here is an example module defining such a backup option, which defines what directories to backup (sourceDirectories) and the user to backup with (user).

{
  options = {
    myservice.datasetbackup = mkOption {
      type = lib.types.submodule {
        options = shb.contracts.datasetbackup.mkRequester {
          dataset = "root/test";
        };
      };
    };
  };
};

Now, on the other side we have a service that uses this datasetbackup option and actually backs up the dataset. This service is a provider of this contract and will provide a result option.

Let's assume such a module is available under the backupService option and that one can create multiple backup instances under backupService.instances. Then, to actually backup the myservice service, one would write:

backupService.instances.myservice = {
  request = myservice.datasetbackup.request;
  
  settings = {
    enable = true;

    targetDataset = "backup/myservice";

    # ... Other options specific to backupService like scheduling.
  };
};

It is advised to backup files to different location, to improve redundancy. Thanks to using contracts, this can be made easily either with the same backupService:

backupService.instances.myservice_2 = {
  request = myservice.datasetbackup.request;
  
  settings = {
    enable = true;
  
    targetDataset = "backup2/myservice";
  };
};

Or with another module backupService_2!

Providers of the Backup Contract

• Sanoid block.

Requester Blocks and Services

• ZFS.