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cluster: drop instances removed from config in cluster.sync #424

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3 changes: 3 additions & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,9 @@

- Fixed a bug when `server:grep_log()` failed to find a string logged in
`server:exec()` called immediately before it (gh-421).
- Fixed `cluster:sync()` to drop instances removed from the config. It is
now possible to reload the config with `cluster:reload()` after removing
an instance (gh-423).

## 1.1.0

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21 changes: 16 additions & 5 deletions luatest/cluster.lua
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Expand Up @@ -197,6 +197,7 @@ end
--
-- * Write the new config into the config file.
-- * Update the internal list of instances.
-- * Drops instances removed from the config.
--
-- @tab config New config.
function Cluster:sync(config)
Expand All @@ -206,16 +207,26 @@ function Cluster:sync(config)

treegen.write_file(self._dir, self._config_file_rel, yaml.encode(config))

for i, name in ipairs(instance_names) do
if self._server_map[name] == nil then
local iserver = server:new(fun.chain(self._server_opts, {
local old_server_map = self._server_map
self._server_map = {}
self._servers = {}

for _, name in ipairs(instance_names) do
local iserver = old_server_map[name]
if iserver == nil then
iserver = server:new(fun.chain(self._server_opts, {
alias = name,
}):tomap())
table.insert(self._servers, i, iserver)
self._server_map[name] = iserver
else
old_server_map[name] = nil
end
self._server_map[name] = iserver
table.insert(self._servers, iserver)
end

for _, iserver in pairs(old_server_map) do
iserver:drop()
end
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That's interesting. We don't start new instances in :sync(), just create server objects in Lua. So, it looks like we shouldn't stop them too.

But,

  1. If we don't stop the server, it remains running after the test case.
  2. A user may want some automation about synchronization of the configured and present instances.

The first point is simple: just track the excluded server objects in some list to call :drop() on it in the after_each hook. self._excluded_server_map or something like this. We can also reuse the server object from this mapping if a previously deleted server is added again.

The second point is really interesting. Since tarantool 3.3 a user can configure autoexpelling if needed. So, we really need just update the config and start/stop processes to manage the cluster.

It looks like we really have two suitable methods:

  • update config + update server objects
  • update config + update server objects + start/stop processes

The first one is what :sync() do now. We can implement the second as a :sync() option. What do you think?

end

--- Reload configuration on all the instances.
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23 changes: 15 additions & 8 deletions test/cluster_test.lua
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Expand Up @@ -133,34 +133,41 @@ g.test_sync = function()
:use_group('g-001')
:use_replicaset('r-001')
:add_instance('i-001', {})
:use_replicaset('r-002')
:add_instance('i-002', {})
:config()

local c = cluster:new(config, server_opts)

t.assert_equals(c:size(), 1)
t.assert_equals(c:size(), 2)

c:start()
assert_instance_running(c, 'i-001')

c:stop()
assert_instance_stopped(c, 'i-001')
local server1 = c['i-001']
local server2 = c['i-002']
t.assert_is_not(server1.process, nil)
t.assert_is_not(server2.process, nil)

local config2 = cbuilder:new()
:use_group('g-001')
:use_replicaset('r-001')
:use_replicaset('r-002')
:add_instance('i-002', {})

:use_group('g-002')
:use_replicaset('r-002')
:use_replicaset('r-003')
:add_instance('i-003', {})

:config()

c:sync(config2)

t.assert_equals(c:size(), 3)
t.assert_is(c['i-001'], nil)
t.assert_is(c['i-002'], server2)
t.assert_is(server1.process, nil)
t.assert_is_not(server2.process, nil)

t.assert_equals(c:size(), 2)

c:start_instance('i-002')
c:start_instance('i-003')
assert_instance_running(c, 'i-002')
assert_instance_running(c, 'i-003')
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