bicep/mysql: split backups into one file per db

base/services/irqbalance.nix

@@ -1,4 +1,22 @@
-{ ... }:
+{ config, pkgs, lib, ... }:
+let
+  cfg = config.services.irqbalance;
+in
 {
   services.irqbalance.enable = true;
-}
+
+  # irqbalance only has meaningful work to do on multi-socket machines, so
+  # skip starting it pointlessly everywhere else.
+  systemd.services.irqbalance.serviceConfig.ExecCondition = let
+    isMultiSocket = pkgs.writeShellApplication {
+      name = "irqbalance-is-multi-socket";
+      runtimeInputs = [ pkgs.coreutils ];
+      text = ''
+        sockets=$(cat /sys/devices/system/cpu/cpu*/topology/physical_package_id | sort -u | wc -l)
+        [ "$sockets" -gt 1 ]
+      '';
+    };
+  in lib.mkIf cfg.enable [
+    (lib.getExe isMultiSocket)
+  ];
+}

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/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

@@ -14,6 +14,7 @@ in
     extensions = ps: with ps; [ pg_repack ];
     enableTCPIP = true;
 
+    # NOTE: md5 accepts both md5 and scram-sha-256
     authentication = ''
       host all all ${values.ipv4-space} md5
       host all all ${values.ipv6-space} md5
@@ -76,6 +77,15 @@ in
       maintenance_io_concurrency = 100;
       wal_recycle = true;
 
+      # -------------------------------- #
+
+      # Authentication
+      password_encryption = "scram-sha-256";
+
+      # Logging
+      log_connections = "authorization";
+      log_disconnections = true;
+
       # SSL
       ssl = true;
       ssl_cert_file = "/run/credentials/postgresql.service/cert";