config: wal section for instance config

This section describes the instance WAL configuration.

Part of #8778

NO_DOC=will be added later
NO_CHANGELOG=will be added later

src/box/lua/config/instance_config.lua

@@ -414,6 +414,45 @@ return schema.new('instance_config', schema.record({
             default = 1024 * 1024,
         }),
     }),
+    wal = schema.record({
+        dir = schema.scalar({
+            type = 'string',
+            box_cfg = 'wal_dir',
+            box_cfg_nondynamic = true,
+            mkdir = true,
+            default = '{{ instance_name }}',
+        }),
+        mode = schema.enum({
+            'none',
+            'write',
+            'fsync',
+        }, {
+            box_cfg = 'wal_mode',
+            box_cfg_nondynamic = true,
+            default = 'write',
+        }),
+        max_size = schema.scalar({
+            type = 'integer',
+            box_cfg = 'wal_max_size',
+            box_cfg_nondynamic = true,
+            default = 256 * 1024 * 1024,
+        }),
+        dir_rescan_delay = schema.scalar({
+            type = 'number',
+            box_cfg = 'wal_dir_rescan_delay',
+            default = 2,
+        }),
+        queue_max_size = schema.scalar({
+            type = 'integer',
+            box_cfg = 'wal_queue_max_size',
+            default = 16 * 1024 * 1024,
+        }),
+        cleanup_delay = schema.scalar({
+            type = 'number',
+            box_cfg = 'wal_cleanup_delay',
+            default = 4 * 3600,
+        }),
+    }),
 }, {
     -- Any configuration data should contain a version of the
     -- config schema for which it is written.

test/config-luatest/instance_config_schema_test.lua

@@ -326,3 +326,29 @@ g.test_vinyl = function()
     local res = instance_config:apply_default({}).vinyl
     t.assert_equals(res, exp)
 end
+
+g.test_wal = function()
+    local iconfig = {
+        wal = {
+            dir = 'one',
+            mode = 'none',
+            max_size = 1,
+            dir_rescan_delay = 1,
+            queue_max_size = 1,
+            cleanup_delay = 1,
+        },
+    }
+    instance_config:validate(iconfig)
+    validate_fields(iconfig.wal, instance_config.schema.fields.wal)
+
+    local exp = {
+        dir = '{{ instance_name }}',
+        mode = 'write',
+        max_size = 268435456,
+        dir_rescan_delay = 2,
+        queue_max_size = 16777216,
+        cleanup_delay = 14400,
+    }
+    local res = instance_config:apply_default({}).wal
+    t.assert_equals(res, exp)
+end