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MXS-2158 Relax requirements for manual rejoin

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The operation is now allowed even if the rejoining server has empty gtid:s.
Auto-rejoin keeps the safeties on.
This commit is contained in:
Esa Korhonen 2018-11-12 12:53:54 +02:00
parent 6a1cfddb43
commit bba0bc0f31
2 changed files with 42 additions and 19 deletions
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17
Documentation/Monitors/MariaDB-Monitor.md
View File

@ -368,12 +368,17 @@ operations.
### Manual activation
Cluster operations can be activated manually through the REST API, MaxCtrl or
MaxAdmin. The commands are only performed when MaxScale is in active mode. All
commands require the monitor instance name as the first parameter. Failover
MaxAdmin. The commands are only performed when MaxScale is in active mode. The
commands generally match their automatic versions. The exception is _rejoin_, in
which the manual command allows rejoining even when the joining server has empty
gtid:s. This rule allows the user to force a rejoin on a server without binary
logs.
All commands require the monitor instance name as the first parameter. Failover
selects the new master server automatically and does not require additional
parameters. Rejoin requires the name of the joining server as second parameter.
Replication reset accepts the name of the new master server as second
parameter. If not given, the current master is selected.
Replication reset accepts the name of the new master server as second parameter.
If not given, the current master is selected.
Switchover takes one to three parameters. If only the monitor name is given,
switchover will autoselect both the slave to promote and the current master as
@ -401,8 +406,8 @@ to demote (OldMasterServ). For rejoin, the server to join (OldMasterServ) is
required. Replication reset requires the server to promote (NewMasterServ).
It is safe to perform manual operations even with automatic failover, switchover
or rejoin enabled since the automatic operations cannot happen simultaneously
with the manual one.
or rejoin enabled since automatic operations cannot happen simultaneously
with manual ones.
If a switchover or failover fails, automatic failover is disabled to prevent
master changes to a possibly malfunctioning cluster. Automatic failover can be

44
server/modules/monitor/mariadbmon/cluster_manipulation.cc
View File

@ -115,17 +115,42 @@ bool MariaDBMonitor::manual_rejoin(SERVER* rejoin_server, json_t** output)
if (mon_slave_cand)
{
MariaDBServer* slave_cand = get_server_info(mon_slave_cand);
if (server_is_rejoin_suspect(slave_cand, output))
{
string gtid_update_error;
if (m_master->update_gtids(&gtid_update_error))
{
// The manual version of rejoin does not need to be as careful as the automatic one.
// The rules are mostly the same, the only difference is that a server with empty gtid:s
// can be rejoined manually.
// TODO: Add the warning to JSON output.
string no_rejoin_reason;
if (slave_cand->can_replicate_from(m_master, &no_rejoin_reason))
bool safe_rejoin = slave_cand->can_replicate_from(m_master, &no_rejoin_reason);
bool empty_gtid = slave_cand->m_gtid_current_pos.empty();
bool rejoin_allowed = false;
if (safe_rejoin)
{
ServerArray joinable_server;
joinable_server.push_back(slave_cand);
rejoin_allowed = true;
}
else
{
if (empty_gtid)
{
rejoin_allowed = true;
MXB_WARNING("gtid_curren_pos of %s is empty. Manual rejoin is unsafe "
"but allowed.", rejoin_serv_name);
}
else
{
PRINT_MXS_JSON_ERROR(output, "%s cannot replicate from master server %s: %s",
rejoin_serv_name, m_master->name(),
no_rejoin_reason.c_str());
}
}
if (rejoin_allowed)
{
ServerArray joinable_server = {slave_cand};
if (do_rejoin(joinable_server, output) == 1)
{
rval = true;
@ -136,12 +161,6 @@ bool MariaDBMonitor::manual_rejoin(SERVER* rejoin_server, json_t** output)
PRINT_MXS_JSON_ERROR(output, "Rejoin attempted but failed.");
}
}
else
{
PRINT_MXS_JSON_ERROR(output,
"%s cannot replicate from cluster master %s: %s.",
rejoin_serv_name, m_master->name(), no_rejoin_reason.c_str());
}
}
else
{
@ -153,8 +172,7 @@ bool MariaDBMonitor::manual_rejoin(SERVER* rejoin_server, json_t** output)
}
else
{
PRINT_MXS_JSON_ERROR(output,
"The given server '%s' is not monitored by this monitor.",
PRINT_MXS_JSON_ERROR(output, "The given server '%s' is not monitored by this monitor.",
rejoin_serv_name);
}
}
@ -1862,4 +1880,4 @@ MariaDBMonitor::FailoverParams::FailoverParams(const ServerOperation& promotion,
, demotion_target(demotion_target)
, general(general)
{
}
}