config: introduce roles

This patch introduces initial support for roles.

Roles are programs that run when a configuration is loaded or reloaded.
Roles can be defined for each instance. On first run, the role is
initialized with the init() method. On each run, the role calls
validate_config() and then apply_config() if validate_config() returns
true. If the roles were removed from the instance on reboot, the role is
stopped using the stop() method.

If a role was added to an instance, then removed from the instance, and
then added again, init() is still not called.

If a role is defined more than once on an instance, it will still only
run once.

Roles must have four methods: init(), validate_config(), apply_config()
and stop().

Each assigned role must be described in the roles_cfg file.

Dependencies are not currently supported for roles.

Part of tarantool#9078

NO_DOC=will be added later.

changelogs/unreleased/gh-9078-roles.md

@@ -0,0 +1,3 @@
+## feature/config
+
+* Added initial support of roles (gh-9078).

src/box/CMakeLists.txt

@@ -44,6 +44,7 @@ lua_source(lua_sources lua/config/applier/console.lua     config_applier_console
 lua_source(lua_sources lua/config/applier/credentials.lua config_applier_credentials_lua)
 lua_source(lua_sources lua/config/applier/fiber.lua       config_applier_fiber_lua)
 lua_source(lua_sources lua/config/applier/mkdir.lua       config_applier_mkdir_lua)
+lua_source(lua_sources lua/config/applier/roles.lua       config_applier_roles_lua)
 lua_source(lua_sources lua/config/applier/sharding.lua    config_applier_sharding_lua)
 lua_source(lua_sources lua/config/cluster_config.lua      config_cluster_config_lua)
 lua_source(lua_sources lua/config/configdata.lua          config_configdata_lua)

src/box/lua/config/applier/roles.lua

@@ -0,0 +1,75 @@
+local log = require('internal.config.utils.log')
+
+local last_loaded = {}
+
+local function apply(_config)
+    log.verbose('roles.apply: do nothing')
+end
+
+local function post_apply(config)
+    local configdata = config._configdata
+    local role_names = configdata:get('roles', {use_default = true})
+    if role_names == nil or next(role_names) == nil then
+        return
+    end
+
+    -- Remove duplicates.
+    local roles = {}
+    local roles_dup = {}
+    local roles_check = {}
+    for _, role_name in pairs(role_names) do
+        table.insert(roles_dup, roles_check[role_name] ~= nil)
+        roles_check[role_name] = true
+    end
+    for id, role_name in pairs(role_names) do
+        if not roles_dup[id] then
+            table.insert(roles, role_name)
+        end
+    end
+
+    -- Run roles.
+    local roles_cfg = configdata:get('roles_cfg', {use_default = true}) or {}
+    local loaded = {}
+    for _, role_name in pairs(roles) do
+        local role_cfg = roles_cfg[role_name]
+        -- All roles must be described in roles_cfg, even if the role does not
+        -- require a cfg.
+        if role_cfg == nil then
+            error('No config for role ' .. role_name, 0)
+        end
+        local role = last_loaded[role_name]
+        if not role then
+            role = require(role_name)
+            local methods = {'init', 'validate_config', 'apply_config', 'stop'}
+            for _, method_name in pairs(methods) do
+                if type(role[method_name]) ~= 'function' then
+                    local err = 'Role %s does not contain method %s'
+                    error(err:format(role_name, method_name), 0)
+                end
+            end
+            log.verbose('roles.post_apply: initialize role ' .. role_name)
+            role.init()
+        end
+        loaded[role_name] = role
+        if not role.validate_config(role_cfg) then
+            error('Wrong config for role ' .. role_name, 0)
+        end
+        log.verbose('roles.post_apply: apply config for role ' .. role_name)
+        role.apply_config(role_cfg)
+    end
+
+    -- Stop removed roles.
+    for role_name, role in pairs(last_loaded) do
+        if not roles_check[role_name] then
+            log.verbose('roles.post_apply: stop role ' .. role_name)
+            role.stop()
+        end
+    end
+    last_loaded = loaded
+end
+
+return {
+    name = 'roles',
+    apply = apply,
+    post_apply = post_apply,
+}

src/box/lua/config/init.lua

@@ -150,6 +150,7 @@ function methods._initialize(self)
     self:_register_applier(require('internal.config.applier.console'))
     self:_register_applier(require('internal.config.applier.fiber'))
     self:_register_applier(require('internal.config.applier.sharding'))
+    self:_register_applier(require('internal.config.applier.roles'))
     self:_register_applier(require('internal.config.applier.app'))
 
     if extras ~= nil then

src/box/lua/config/instance_config.lua

@@ -1802,6 +1802,13 @@ return schema.new('instance_config', schema.record({
             "compatibility",
         }),
     })),
+    roles_cfg = schema.map({
+        key = schema.scalar({type = 'string'}),
+        value = schema.scalar({type = 'any'}),
+    }),
+    roles = schema.array({
+        items = schema.scalar({type = 'string'})
+    }),
 }, {
     -- This kind of validation cannot be implemented as the
     -- 'validate' annotation of a particular schema node. There

src/box/lua/init.c

@@ -144,6 +144,7 @@ extern char session_lua[],
 	config_applier_credentials_lua[],
 	config_applier_fiber_lua[],
 	config_applier_mkdir_lua[],
+	config_applier_roles_lua[],
 	config_applier_sharding_lua[],
 	config_cluster_config_lua[],
 	config_configdata_lua[],
@@ -387,6 +388,10 @@ static const char *lua_sources[] = {
 	"internal.config.applier.sharding",
 	config_applier_sharding_lua,
 
+	"config/applier/roles",
+	"internal.config.applier.roles",
+	config_applier_roles_lua,
+
 	"config/init",
 	"config",
 	config_init_lua,

test/config-luatest/app_test.lua

@@ -78,6 +78,7 @@ g.test_reload_failure = function(g)
         script = '',
         options = {['app.file'] = 'main.lua'},
         verify = function() end,
+        options_2 = {['app.file'] = 'main.lua'},
         script_2 = ([[
             error('%s', 0)
         ]]):format(err_msg),
@@ -101,6 +102,7 @@ g.test_reload_success = function(g)
         script_2 = ([[
             error('%s', 0)
         ]]):format(err_msg),
+        options_2 = {['app.module'] = 'main'},
         verify_2 = function()
             local config = require('config')
             local info = config:info()

test/config-luatest/helpers.lua

@@ -88,13 +88,20 @@ local simple_config = {
 
 local function prepare_case(g, opts)
     local dir = opts.dir
+    local roles = opts.roles
     local script = opts.script
     local options = opts.options
 
     if dir == nil then
         dir = treegen.prepare_directory(g, {}, {})
     end
 
+    if roles ~= nil and next(roles) ~= nil then
+        for name, body in pairs(roles) do
+            treegen.write_script(dir, name .. '.lua', body)
+        end
+    end
+
     if script ~= nil then
         treegen.write_script(dir, 'main.lua', script)
     end
@@ -135,6 +142,10 @@ end
 -- Start a server with the given script and the given
 -- configuration, run a verification function on it.
 --
+-- * opts.roles
+--
+--   Role codes for writing into corresponding files.
+--
 -- * opts.script
 --
 --   Code write into the main.lua file.
@@ -164,6 +175,7 @@ end
 -- Start tarantool process with the given script/config and check
 -- the error.
 --
+-- * opts.roles
 -- * opts.script
 -- * opts.options
 --
@@ -185,31 +197,43 @@ end
 -- Start a server, write a new script/config, reload, run a
 -- verification function.
 --
+-- * opts.roles
 -- * opts.script
 -- * opts.options
 -- * opts.verify
 --
 --   Same as in success_case().
 --
+-- * opts.roles_2
+--
+--   A new list of roles to prepare before config:reload().
+--
 -- * opts.script_2
 --
 --   A new script to write into the main.lua file before
 --   config:reload().
 --
+-- * opts.options_2
+--
+--   A new options for config:reload().
+--
 -- * opts.verify_2
 --
 --   Verify test invariants after config:reload().
 local function reload_success_case(g, opts)
+    assert(opts.options)
+    local roles_2 = opts.roles_2
     local script_2 = opts.script_2
-    local options = assert(opts.options)
+    local options_2 = opts.options_2
     local verify_2 = assert(opts.verify_2)
 
     local prepared = success_case(g, opts)
 
     prepare_case(g, {
         dir = prepared.dir,
+        roles = roles_2,
         script = script_2,
-        options = options,
+        options = options_2,
     })
     g.server:exec(function()
         local config = require('config')
@@ -221,31 +245,42 @@ end
 -- Start a server, write a new script/config, reload, run a
 -- verification function.
 --
+-- * opts.roles
 -- * opts.script
 -- * opts.options
 -- * opts.verify
 --
 --   Same as in success_case().
 --
+-- * opts.roles_2
+--
+--   A new list of roles to prepare before config:reload().
+--
 -- * opts.script_2
 --
 --   A new script to write into the main.lua file before
 --   config:reload().
 --
+-- * opts.options_2
+--
+--   A new options for config:reload().
+--
 -- * opts.exp_err
 --
 --   An error that config:reload() must raise.
 local function reload_failure_case(g, opts)
-    local script_2 = assert(opts.script_2)
-    local options = assert(opts.options)
+    local roles_2 = opts.roles_2
+    local script_2 = opts.script_2
+    local options_2 = opts.options_2
     local exp_err = assert(opts.exp_err)
 
     local prepared = success_case(g, opts)
 
     prepare_case(g, {
         dir = prepared.dir,
+        roles = roles_2,
         script = script_2,
-        options = options,
+        options = options_2,
     })
     t.assert_error_msg_equals(exp_err, g.server.exec, g.server, function()
         local config = require('config')

test/config-luatest/mkdir_test.lua

@@ -49,24 +49,28 @@ g.test_work_dir = function(g)
     ]]):format(dir))
 
     local data_dir = fio.pathjoin(dir, '{{ instance_name }}')
+
+    local options = {
+        ['process.work_dir'] = 'a/b/c',
+
+        -- Place all the necessary directories and files into
+        -- a location outside of the work_dir.
+        --
+        -- It allows to test the work_dir creation logic
+        -- independently of creation of other directories.
+        ['process.pid_file'] = fio.pathjoin(dir, '{{ instance_name }}.pid'),
+        ['vinyl.dir'] = data_dir,
+        ['wal.dir'] = data_dir,
+        ['snapshot.dir'] = data_dir,
+        ['console.socket'] = fio.pathjoin(dir,
+            '{{ instance_name }}.control'),
+        ['iproto.listen'] = fio.pathjoin(dir, '{{ instance_name }}.iproto'),
+    }
+
     helpers.reload_success_case(g, {
         dir = dir,
-        options = {
-            ['process.work_dir'] = 'a/b/c',
-
-            -- Place all the necessary directories and files into
-            -- a location outside of the work_dir.
-            --
-            -- It allows to test the work_dir creation logic
-            -- independently of creation of other directories.
-            ['process.pid_file'] = fio.pathjoin(dir, '{{ instance_name }}.pid'),
-            ['vinyl.dir'] = data_dir,
-            ['wal.dir'] = data_dir,
-            ['snapshot.dir'] = data_dir,
-            ['console.socket'] = fio.pathjoin(dir,
-                '{{ instance_name }}.control'),
-            ['iproto.listen'] = fio.pathjoin(dir, '{{ instance_name }}.iproto'),
-        },
+        options = options,
+        options_2 = options,
         verify = verify,
         verify_2 = verify,
     })
@@ -106,24 +110,27 @@ g.test_dirs_are_relative_to_work_dir = function(g)
         assert(not fio.path.exists(fio.pathjoin(work_dir, 'a')))
     ]]):format(dir))
 
+    local options = {
+        ['process.work_dir'] = 'a/b/c',
+        ['process.pid_file'] = 'd/{{ instance_name }}.pid',
+        ['vinyl.dir'] = 'e',
+        ['wal.dir'] = 'f',
+        ['snapshot.dir'] = 'g',
+        ['console.socket'] = 'h/{{ instance_name }}.control',
+        ['log.to'] = 'file',
+        ['log.file'] = 'i/{{ instance_name }}.log',
+
+        -- Set the binary protocol socket as an absolute path
+        -- to don't confuse the testing helpers and allows
+        -- them to connect to the instance and execute
+        -- necessary commands (such as `config:reload()`).
+        ['iproto.listen'] = fio.pathjoin(dir, '{{ instance_name }}.iproto'),
+    }
+
     helpers.reload_success_case(g, {
         dir = dir,
-        options = {
-            ['process.work_dir'] = 'a/b/c',
-            ['process.pid_file'] = 'd/{{ instance_name }}.pid',
-            ['vinyl.dir'] = 'e',
-            ['wal.dir'] = 'f',
-            ['snapshot.dir'] = 'g',
-            ['console.socket'] = 'h/{{ instance_name }}.control',
-            ['log.to'] = 'file',
-            ['log.file'] = 'i/{{ instance_name }}.log',
-
-            -- Set the binary protocol socket as an absolute path
-            -- to don't confuse the testing helpers and allows
-            -- them to connect to the instance and execute
-            -- necessary commands (such as `config:reload()`).
-            ['iproto.listen'] = fio.pathjoin(dir, '{{ instance_name }}.iproto'),
-        },
+        options = options,
+        options_2 = options,
         verify = verify,
         verify_2 = verify,
     })