bicep/mysql: split backups into one file per db

flake.nix

@@ -197,7 +197,6 @@
             inputs.pvv-calendar-bot.nixosModules.default
             inputs.minecraft-heatmap.nixosModules.default
             self.nixosModules.gickup
-            self.nixosModules.hugepages
             self.nixosModules.matrix-ooye
           ];
           overlays = [
@@ -310,7 +309,6 @@
       bluemap = ./modules/bluemap.nix;
       drumknotty = ./modules/drumknotty;
       gickup = ./modules/gickup;
-      hugepages = ./modules/hugepages.nix;
       matrix-ooye = ./modules/matrix-ooye.nix;
       python-http-handlers = ./modules/python-http-handlers.nix;
       robots-txt = ./modules/robots-txt.nix;

hosts/bicep/services/mysql/backup.nix

@@ -41,24 +41,38 @@ in
     path = with pkgs; [
       cfg.package
       coreutils
+      diffutils
       zstd
     ];
 
-    script = let
-      rotations = 2;
-    in ''
+    script = ''
       set -euo pipefail
 
-      OUT_FILE="$STATE_DIRECTORY/mysql-dump-$(date --iso-8601).sql.zst"
+      dump() {
+        local name="$1" out tmp
+        out="$STATE_DIRECTORY/$name.sql.zst"
+        tmp="$out.tmp"
+        shift
+        "$@" | zstd -9 --rsyncable -f -o "$tmp"
+        if cmp -s "$tmp" "$out" 2>/dev/null; then
+          rm -f "$tmp"
+        else
+          mv -f "$tmp" "$out"
+        fi
+      }
 
-      mysqldump --all-databases | zstd --compress -9 --rsyncable -o "$OUT_FILE"
+      declare -A keep
+      while IFS= read -r db; do
+        [ -n "$db" ] || continue
+        dump "$db" mysqldump --skip-dump-date --databases "$db"
+        keep["$db.sql.zst"]=1
+      done < <(mysql -N -e 'SHOW DATABASES' | grep -vE '^(information_schema|performance_schema)$')
 
-      # NOTE: this needs to be a hardlink for rrsync to allow sending it
-      rm "$STATE_DIRECTORY/mysql-dump-latest.sql.zst" ||:
-      ln -T "$OUT_FILE" "$STATE_DIRECTORY/mysql-dump-latest.sql.zst"
-
-      while [ "$(find "$STATE_DIRECTORY" -type f -printf '.' | wc -c)" -gt '${toString (rotations + 1)}' ]; do
-        rm "$(find "$STATE_DIRECTORY" -type f -printf '%T+ %p\n' | sort | head -n 1 | cut -d' ' -f2)"
+      # drop dumps of databases that no longer exist
+      for f in "$STATE_DIRECTORY"/*.sql.zst; do
+        [ -e "$f" ] || continue
+        base="$(basename "$f")"
+        [ -n "''${keep[$base]:-}" ] || rm -f "$f"
       done
     '';
 

hosts/bicep/services/mysql/default.nix

@@ -2,8 +2,6 @@
 let
   cfg = config.services.mysql;
   dataDir = "/data/mysql";
-
-  innodbBufferPoolMB = 128;
 in
 {
   imports = [ ./backup.nix ];
@@ -28,10 +26,6 @@ in
         # Useful for the mysqld prometheus exporter
         userstat = 1;
 
-        # Memory settings
-        innodb_buffer_pool_size = "${toString innodbBufferPoolMB}M";
-        "large-pages" = 1;
-
         # This was needed in order to be able to use all of the old users
         # during migration from knakelibrak to bicep in Sep. 2023
         secure_auth = 0;
@@ -53,10 +47,6 @@ in
     }];
   };
 
-  boot.kernel.hugepages.reservations.mysql = lib.mkIf cfg.enable (
-    builtins.ceil (innodbBufferPoolMB / config.boot.kernel.hugepages.size)
-  );
-
   networking.firewall.allowedTCPPorts = lib.mkIf cfg.enable [ 3306 ];
 
   systemd.tmpfiles.settings."10-mysql".${dataDir}.d = lib.mkIf cfg.enable {

hosts/bicep/services/postgresql/backup.nix

@@ -41,25 +41,42 @@ in
 
     path = with pkgs; [
       coreutils
+      diffutils
       zstd
       cfg.package
     ];
 
-    script = let
-      rotations = 2;
-    in ''
+    script = ''
       set -euo pipefail
 
-      OUT_FILE="$STATE_DIRECTORY/postgresql-dump-$(date --iso-8601).sql.zst"
+      dump() {
+        local name="$1" out tmp
+        out="$STATE_DIRECTORY/$name.sql.zst"
+        tmp="$out.tmp"
+        shift
+        "$@" | zstd -9 --rsyncable -f -o "$tmp"
+        if cmp -s "$tmp" "$out" 2>/dev/null; then
+          rm -f "$tmp"
+        else
+          mv -f "$tmp" "$out"
+        fi
+      }
 
-      pg_dumpall -U postgres | zstd --compress -9 --rsyncable -o "$OUT_FILE"
+      declare -A keep
+      dump globals pg_dumpall -U postgres --globals-only --restrict-key=backup
+      keep[globals.sql.zst]=1
 
-      # NOTE: this needs to be a hardlink for rrsync to allow sending it
-      rm "$STATE_DIRECTORY/postgresql-dump-latest.sql.zst" ||:
-      ln -T "$OUT_FILE" "$STATE_DIRECTORY/postgresql-dump-latest.sql.zst"
+      while IFS= read -r db; do
+        [ -n "$db" ] || continue
+        dump "$db" pg_dump -U postgres -C -d "$db" --restrict-key=backup
+        keep["$db.sql.zst"]=1
+      done < <(psql -U postgres -tAc "SELECT datname FROM pg_database WHERE datallowconn ORDER BY datname")
 
-      while [ "$(find "$STATE_DIRECTORY" -type f -printf '.' | wc -c)" -gt '${toString (rotations + 1)}' ]; do
-        rm "$(find "$STATE_DIRECTORY" -type f -printf '%T+ %p\n' | sort | head -n 1 | cut -d' ' -f2)"
+      # drop dumps of databases that no longer exist
+      for f in "$STATE_DIRECTORY"/*.sql.zst; do
+        [ -e "$f" ] || continue
+        base="$(basename "$f")"
+        [ -n "''${keep[$base]:-}" ] || rm -f "$f"
       done
     '';
 

hosts/bicep/services/postgresql/default.nix

@@ -1,8 +1,6 @@
 { config, lib, pkgs, values, ... }:
 let
   cfg = config.services.postgresql;
-
-  sharedBuffersMB = 8192;
 in
 {
   imports = [
@@ -31,7 +29,7 @@ in
       superuser_reserved_connections = 3;
 
       # Memory Settings
-      shared_buffers = "${toString sharedBuffersMB} MB";
+      shared_buffers = "8192 MB";
       work_mem = "32 MB";
       maintenance_work_mem = "420 MB";
       effective_cache_size = "22 GB";
@@ -95,10 +93,6 @@ in
     };
   };
 
-  boot.kernel.hugepages.reservations.postgresql = lib.mkIf cfg.enable (
-    builtins.ceil (sharedBuffersMB / config.boot.kernel.hugepages.size)
-  );
-
   systemd.tmpfiles.settings."10-postgresql"."/data/postgresql".d = lib.mkIf cfg.enable {
     user = config.systemd.services.postgresql.serviceConfig.User;
     group = config.systemd.services.postgresql.serviceConfig.Group;

modules/hugepages.nix

@@ -1,38 +0,0 @@
-{ config, lib, ... }:
-let
-  cfg = config.boot.kernel.hugepages;
-in
-{
-  options.boot.kernel.hugepages = {
-    size = lib.mkOption {
-      type = lib.types.enum [ 2 1024 ];
-      default = 2;
-      description = ''
-        Hugepage size in MB.
-
-        You can use this value to calculate the amount of memory you will have available as hugepages.
-      '';
-    };
-
-    reservations = lib.mkOption {
-      type = lib.types.attrsOf lib.types.ints.unsigned;
-      default = { };
-      description = ''
-        Number of hugepages each service wants reserved in vm.nr_hugepages,
-        keyed by service name.
-      '';
-    };
-  };
-
-  config = {
-    boot.kernelParams = let
-      num = {
-        "2" = "2M";
-        "1024" = "1G";
-      }.${toString cfg.size};
-    in [ "hugepagesz=${num}" ];
-
-    boot.kernel.sysctl."vm.nr_hugepages" =
-      lib.foldl' (a: b: a + b) 0 (lib.attrValues cfg.reservations);
-  };
-}