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selfhostblocks/modules/blocks/restic.nix
2024-08-29 07:12:45 +00:00

296 lines
11 KiB
Nix

{ config, pkgs, lib, utils, ... }:
let
cfg = config.shb.restic;
shblib = pkgs.callPackage ../../lib {};
instanceOptions = {
enable = lib.mkEnableOption "shb restic. A disabled instance will not backup data anymore but still provides the helper tool to introspect and rollback snapshots";
passphraseFile = lib.mkOption {
description = "Encryption key for the backups.";
type = lib.types.path;
};
user = lib.mkOption {
description = ''
Unix user doing the backups. Must be the user owning the files to be backed up.
'';
type = lib.types.str;
};
sourceDirectories = lib.mkOption {
description = "Source directories.";
type = lib.types.nonEmptyListOf lib.types.str;
};
excludePatterns = lib.mkOption {
description = "Exclude patterns.";
type = lib.types.listOf lib.types.str;
default = [];
};
repositories = lib.mkOption {
description = "Repositories to back this instance to.";
type = lib.types.nonEmptyListOf (lib.types.submodule {
options = {
path = lib.mkOption {
type = lib.types.str;
description = "Repository location";
};
secrets = lib.mkOption {
type = lib.types.attrsOf shblib.secretFileType;
default = {};
description = ''
Secrets needed to access the repository where the backups will be stored.
See [s3 config](https://restic.readthedocs.io/en/latest/030_preparing_a_new_repo.html#amazon-s3) for an example
and [list](https://restic.readthedocs.io/en/latest/040_backup.html#environment-variables) for the list of all secrets.
'';
example = lib.literalExpression ''
{
AWS_ACCESS_KEY_ID = <path/to/secret>;
AWS_SECRET_ACCESS_KEY = <path/to/secret>;
}
'';
};
timerConfig = lib.mkOption {
type = lib.types.attrsOf utils.systemdUtils.unitOptions.unitOption;
default = {
OnCalendar = "daily";
Persistent = true;
};
description = ''When to run the backup. See {manpage}`systemd.timer(5)` for details.'';
example = {
OnCalendar = "00:05";
RandomizedDelaySec = "5h";
Persistent = true;
};
};
};
});
};
retention = lib.mkOption {
description = "For how long to keep backup files.";
type = lib.types.attrsOf (lib.types.oneOf [ lib.types.int lib.types.nonEmptyStr ]);
default = {
keep_within = "1d";
keep_hourly = 24;
keep_daily = 7;
keep_weekly = 4;
keep_monthly = 6;
};
};
hooks = lib.mkOption {
description = "Hooks to run before or after the backup.";
default = {};
type = lib.types.submodule {
options = {
before_backup = lib.mkOption {
description = "Hooks to run before backup";
type = lib.types.listOf lib.types.str;
default = [];
};
after_backup = lib.mkOption {
description = "Hooks to run after backup";
type = lib.types.listOf lib.types.str;
default = [];
};
};
};
};
limitUploadKiBs = lib.mkOption {
type = lib.types.nullOr lib.types.int;
description = "Limit upload bandwidth to the given KiB/s amount.";
default = null;
example = 8000;
};
limitDownloadKiBs = lib.mkOption {
type = lib.types.nullOr lib.types.int;
description = "Limit download bandwidth to the given KiB/s amount.";
default = null;
example = 8000;
};
};
repoSlugName = name: builtins.replaceStrings ["/" ":"] ["_" "_"] (lib.strings.removePrefix "/" name);
backupName = name: repository: "${name}_${repoSlugName repository.path}";
fullName = name: repository: "restic-backups-${name}_${repoSlugName repository.path}";
in
{
options.shb.restic = {
instances = lib.mkOption {
description = "Each instance is a backup setting";
default = {};
type = lib.types.attrsOf (lib.types.submodule {
options = instanceOptions;
});
};
# Taken from https://github.com/HubbeKing/restic-kubernetes/blob/73bfbdb0ba76939a4c52173fa2dbd52070710008/README.md?plain=1#L23
performance = lib.mkOption {
description = "Reduce performance impact of backup jobs.";
default = {};
type = lib.types.submodule {
options = {
niceness = lib.mkOption {
type = lib.types.ints.between (-20) 19;
description = "nice priority adjustment, defaults to 15 for ~20% CPU time of normal-priority process";
default = 15;
};
ioSchedulingClass = lib.mkOption {
type = lib.types.enum [ "idle" "best-effort" "realtime" ];
description = "ionice scheduling class, defaults to best-effort IO. Only used for `restic backup`, `restic forget` and `restic check` commands.";
default = "best-effort";
};
ioPriority = lib.mkOption {
type = lib.types.nullOr (lib.types.ints.between 0 7);
description = "ionice priority, defaults to 7 for lowest priority IO. Only used for `restic backup`, `restic forget` and `restic check` commands.";
default = 7;
};
};
};
};
};
config = lib.mkIf (cfg.instances != {}) (
let
enabledInstances = lib.attrsets.filterAttrs (k: i: i.enable) cfg.instances;
in lib.mkMerge [
{
environment.systemPackages = lib.optionals (enabledInstances != {}) [ pkgs.restic ];
systemd.tmpfiles.rules =
let
mkRepositorySettings = name: instance: repository: lib.optionals (lib.hasPrefix "/" repository.path) [
"d '${repository.path}' 0750 ${instance.user} root - -"
];
mkSettings = name: instance: builtins.map (mkRepositorySettings name instance) instance.repositories;
in
lib.flatten (lib.attrsets.mapAttrsToList mkSettings cfg.instances);
services.restic.backups =
let
mkRepositorySettings = name: instance: repository: {
"${name}_${repoSlugName repository.path}" = {
inherit (instance) user;
repository = repository.path;
paths = instance.sourceDirectories;
passwordFile = toString instance.passphraseFile;
initialize = true;
inherit (repository) timerConfig;
pruneOpts = lib.mapAttrsToList (name: value:
"--${builtins.replaceStrings ["_"] ["-"] name} ${builtins.toString value}"
) instance.retention;
backupPrepareCommand = lib.strings.concatStringsSep "\n" instance.hooks.before_backup;
backupCleanupCommand = lib.strings.concatStringsSep "\n" instance.hooks.after_backup;
} // lib.attrsets.optionalAttrs (builtins.length instance.excludePatterns > 0) {
exclude = instance.excludePatterns;
extraBackupArgs =
(lib.optionals (instance.limitUploadKiBs != null) [
"--limit-upload=${toString instance.limitUploadKiBs}"
])
++ (lib.optionals (instance.limitDownloadKiBs != null) [
"--limit-download=${toString instance.limitDownloadKiBs}"
]);
};
};
mkSettings = name: instance: builtins.map (mkRepositorySettings name instance) instance.repositories;
in
lib.mkMerge (lib.flatten (lib.attrsets.mapAttrsToList mkSettings enabledInstances));
systemd.services =
let
mkRepositorySettings = name: instance: repository:
let
serviceName = fullName name repository;
in
{
${serviceName} = lib.mkMerge [
{
serviceConfig = {
Nice = cfg.performance.niceness;
IOSchedulingClass = cfg.performance.ioSchedulingClass;
IOSchedulingPriority = cfg.performance.ioPriority;
BindReadOnlyPaths = instance.sourceDirectories;
};
}
(lib.attrsets.optionalAttrs (repository.secrets != {})
{
serviceConfig.EnvironmentFile = [
"/run/secrets_restic/${serviceName}"
];
after = [ "${serviceName}-pre.service" ];
requires = [ "${serviceName}-pre.service" ];
})
];
"${serviceName}-pre" = lib.mkIf (repository.secrets != {})
(let
script = shblib.genConfigOutOfBandSystemd {
config = repository.secrets;
configLocation = "/run/secrets_restic/${serviceName}";
generator = name: v: pkgs.writeText "template" (lib.generators.toINIWithGlobalSection {} { globalSection = v; });
user = instance.user;
};
in
{
script = script.preStart;
serviceConfig.Type = "oneshot";
serviceConfig.LoadCredential = script.loadCredentials;
});
};
mkSettings = name: instance: builtins.map (mkRepositorySettings name instance) instance.repositories;
in
lib.mkMerge (lib.flatten (lib.attrsets.mapAttrsToList mkSettings enabledInstances));
}
{
system.activationScripts = let
mkEnv = name: instance: repository:
lib.nameValuePair "${fullName name repository}_gen"
(shblib.replaceSecrets {
userConfig = repository.secrets // {
RESTIC_PASSWORD_FILE = instance.passphraseFile;
RESTIC_REPOSITORY = repository.path;
};
resultPath = "/run/secrets_restic_env/${fullName name repository}";
generator = name: v: pkgs.writeText (fullName name repository) (lib.generators.toINIWithGlobalSection {} { globalSection = v; });
user = instance.user;
});
mkSettings = name: instance: builtins.map (mkEnv name instance) instance.repositories;
in
lib.listToAttrs (lib.flatten (lib.attrsets.mapAttrsToList mkSettings cfg.instances));
environment.systemPackages = let
mkResticBinary = name: instance: repository:
pkgs.writeShellScriptBin (fullName name repository) ''
export $(grep -v '^#' "/run/secrets_restic_env/${fullName name repository}" \
| xargs -d '\n')
${pkgs.restic}/bin/restic $@
'';
mkSettings = name: instance: builtins.map (mkResticBinary name instance) instance.repositories;
in
lib.flatten (lib.attrsets.mapAttrsToList mkSettings cfg.instances);
}
]);
}