config: process section for instance config

This section describes the instance process configuration.

Part of #8778

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

src/box/lua/config/instance_config.lua

@@ -82,6 +82,50 @@ return schema.new('instance_config', schema.record({
             default = 'auto',
         }),
     }),
+    process = schema.record({
+        strip_core = schema.scalar({
+            type = 'boolean',
+            box_cfg = 'strip_core',
+            box_cfg_nondynamic = true,
+            default = true,
+        }),
+        coredump = schema.scalar({
+            type = 'boolean',
+            box_cfg = 'coredump',
+            box_cfg_nondynamic = true,
+            default = false,
+        }),
+        background = schema.scalar({
+            type = 'boolean',
+            box_cfg = 'background',
+            box_cfg_nondynamic = true,
+            default = false,
+        }),
+        title = schema.scalar({
+            type = 'string',
+            box_cfg = 'custom_proc_title',
+            default = 'tarantool - {{ instance_name }}',
+        }),
+        username = schema.scalar({
+            type = 'string',
+            box_cfg = 'username',
+            box_cfg_nondynamic = true,
+            default = box.NULL,
+        }),
+        work_dir = schema.scalar({
+            type = 'string',
+            box_cfg = 'work_dir',
+            box_cfg_nondynamic = true,
+            default = box.NULL,
+        }),
+        pid_file = schema.scalar({
+            type = 'string',
+            box_cfg = 'pid_file',
+            box_cfg_nondynamic = true,
+            mk_parent_dir = true,
+            default = '{{ instance_name }}.pid',
+        }),
+    }),
 }, {
     -- Any configuration data should contain a version of the
     -- config schema for which it is written.

test/config-luatest/instance_config_schema_test.lua

@@ -52,3 +52,31 @@ g.test_config = function()
     local res = instance_config:apply_default({}).config
     t.assert_equals(res, exp)
 end
+
+g.test_process = function()
+    local iconfig = {
+        process = {
+            strip_core = true,
+            coredump = true,
+            background = true,
+            title = 'one',
+            username = 'two',
+            work_dir = 'three',
+            pid_file = 'four',
+        },
+    }
+    instance_config:validate(iconfig)
+    validate_fields(iconfig.process, instance_config.schema.fields.process)
+
+    local exp = {
+        strip_core = true,
+        coredump = false,
+        background = false,
+        title = 'tarantool - {{ instance_name }}',
+        username = box.NULL,
+        work_dir = box.NULL,
+        pid_file = '{{ instance_name }}.pid',
+    }
+    local res = instance_config:apply_default({}).process
+    t.assert_equals(res, exp)
+end