services.mysqlBackup: add option to change compression tool

NixOS · Dec 12, 2024 · 23ed34c · 23ed34c
1 parent f98a28c
commit 23ed34c
Showing 1 changed file with 101 additions and 33 deletions.
diff --git a/nixos/modules/services/backup/mysql-backup.nix b/nixos/modules/services/backup/mysql-backup.nix
@@ -1,16 +1,52 @@
-{
-  config,
-  lib,
-  pkgs,
-  ...
-}:
+{ config, lib, pkgs, ... }:
 let
-
-  inherit (pkgs) mariadb gzip;
+  inherit (pkgs) mariadb gzip p7zip zstd zip;
 
   cfg = config.services.mysqlBackup;
   defaultUser = "mysqlbackup";
 
+  compressionPkg = {
+    "gzip" = pkgs.gzip;
+    "zstd" = pkgs.zstd;
+    "7z" = pkgs.p7zip;
+    "zip" = pkgs.zip;
+  }.${cfg.compression};
+
+  fileExt = {
+    "gzip" = ".gz";
+    "zstd" = ".zst";
+    "7z" = ".7z";
+    "zip" = ".zip";
+  }.${cfg.compression};
+
+  validCompressionLevels = {
+    "zstd" = range: 1 <= range && range <= 19;
+    "7z" = range: 0 <= range && range <= 9;
+    "zip" = range: 0 <= range && range <= 9;
+    "gzip" = range: false; # gzip doesn't use compressionLevel
+  };
+
+  compressionCmd = let
+    zstdFlags = if cfg.compressionLevel != null then
+      "-${toString cfg.compressionLevel}"
+    else
+      "";
+    sevenZipFlags = if cfg.compressionLevel != null then
+      "-mx=${toString cfg.compressionLevel}"
+    else
+      "";
+    zipFlags = if cfg.compressionLevel != null then
+      "-${toString cfg.compressionLevel}"
+    else
+      "";
+  in {
+    "gzip" = "${gzip}/bin/gzip -c ${cfg.gzipOptions}";
+    "zstd" = "${zstd}/bin/zstd ${zstdFlags} -";
+    "7z" = "${p7zip}/bin/7z a -si -t7z ${sevenZipFlags}";
+    "zip" = ''
+      TMPFILE=$(mktemp).sql && cat > "$TMPFILE" && ${zip}/bin/zip ${zipFlags} - "$TMPFILE" && rm -f "$TMPFILE"'';
+  }.${cfg.compression};
+
   backupScript = ''
     set -o pipefail
     failed=""
@@ -20,9 +56,12 @@ let
       exit 1
     fi
   '';
+
   backupDatabaseScript = db: ''
-    dest="${cfg.location}/${db}.gz"
-    if ${mariadb}/bin/mysqldump ${lib.optionalString cfg.singleTransaction "--single-transaction"} ${db} | ${gzip}/bin/gzip -c ${cfg.gzipOptions} > $dest.tmp; then
+    dest="${cfg.location}/${db}${fileExt}"
+    if ${mariadb}/bin/mysqldump ${
+      lib.optionalString cfg.singleTransaction "--single-transaction"
+    } ${db} | ${compressionCmd} > $dest.tmp; then
       mv $dest.tmp $dest
       echo "Backed up to $dest"
     else
@@ -32,13 +71,9 @@ let
     fi
   '';
 
-in
-
-{
+in {
   options = {
-
     services.mysqlBackup = {
-
       enable = lib.mkEnableOption "MySQL backups";
 
       calendar = lib.mkOption {
@@ -49,6 +84,27 @@ in
         '';
       };
 
+      compression = lib.mkOption {
+        type = lib.types.enum [ "gzip" "zstd" "7z" "zip" ];
+        default = "gzip";
+        description = ''
+          Compression algorithm to use for database dumps.
+          Available options: gzip, zstd, 7z, zip
+        '';
+      };
+
+      compressionLevel = lib.mkOption {
+        type = lib.types.nullOr lib.types.int;
+        default = null;
+        description = ''
+          Compression level to use for zstd or 7z.
+          For zstd: 1-19
+          For 7z: 0-9
+          For zip: 0-9
+          Ignored for gzip (use gzipOptions instead)
+        '';
+      };
+
       user = lib.mkOption {
         type = lib.types.str;
         default = defaultUser;
@@ -69,7 +125,7 @@ in
         type = lib.types.path;
         default = "/var/backup/mysql";
         description = ''
-          Location to put the gzipped MySQL database dumps.
+          Location to put the compressed MySQL database dumps.
         '';
       };
 
@@ -86,13 +142,29 @@ in
         type = lib.types.str;
         description = ''
           Command line options to use when invoking `gzip`.
+          Only used when compression is set to "gzip".
         '';
       };
     };
-
   };
 
   config = lib.mkIf cfg.enable {
+    # assert config to be correct
+    assertions = [{
+      assertion = cfg.compressionLevel == null
+        || validCompressionLevels.${cfg.compression} cfg.compressionLevel;
+      message = let
+        rangeMsg = {
+          "zstd" = "zstd compression level must be between 1 and 19";
+          "7z" = "7z compression level must be between 0 and 9";
+          "zip" = "zip compression level must be between 0 and 9";
+          "gzip" =
+            "gzip does not support compression level option, use gzipOptions instead";
+        };
+      in rangeMsg.${cfg.compression};
+    }];
+
+    # ensure unix user to be used to perform backup exist.
     users.users = lib.optionalAttrs (cfg.user == defaultUser) {
       ${defaultUser} = {
         isSystemUser = true;
@@ -102,18 +174,17 @@ in
       };
     };
 
-    services.mysql.ensureUsers = [
-      {
-        name = cfg.user;
-        ensurePermissions =
-          with lib;
-          let
-            privs = "SELECT, SHOW VIEW, TRIGGER, LOCK TABLES";
-            grant = db: lib.nameValuePair "${db}.*" privs;
-          in
-          lib.listToAttrs (map grant cfg.databases);
-      }
-    ];
+    # add the compression tool to the system environment.
+    environment.systemPackages = [ compressionPkg ];
+
+    # ensure database user to be used to perform backup exist.
+    services.mysql.ensureUsers = [{
+      name = cfg.user;
+      ensurePermissions = let
+        privs = "SELECT, SHOW VIEW, TRIGGER, LOCK TABLES";
+        grant = db: lib.nameValuePair "${db}.*" privs;
+      in lib.listToAttrs (map grant cfg.databases);
+    }];
 
     systemd = {
       timers.mysql-backup = {
@@ -134,10 +205,7 @@ in
         };
         script = backupScript;
       };
-      tmpfiles.rules = [
-        "d ${cfg.location} 0700 ${cfg.user} - - -"
-      ];
+      tmpfiles.rules = [ "d ${cfg.location} 0700 ${cfg.user} - - -" ];
     };
   };
-
 }