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fix: don't remove active node if master is dead #262

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fix: don't remove active node if master is dead #262

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27 changes: 25 additions & 2 deletions internal/app/app.go
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Original file line number Diff line number Diff line change
Expand Up @@ -1133,7 +1133,11 @@ func (app *App) updateActiveNodes(clusterState, clusterStateDcs map[string]*node
node := app.cluster.Get(host)
app.disableSemiSyncIfNonNeeded(node, state)
}
// than update DCS
// then update DCS
if !app.canShrinkActiveNodes(masterNode, oldActiveNodes, activeNodes) {
app.logger.Error().Err(err).Msg("update active nodes: failed to update active nodes, master is dead")
return nil
}
err = app.dcs.Set(pathActiveNodes, activeNodes)
if err != nil {
app.logger.Error().Err(err).Msg("update active nodes: failed to update active nodes in dcs")
Expand Down Expand Up @@ -1208,7 +1212,11 @@ func (app *App) updateActiveNodes(clusterState, clusterStateDcs map[string]*node
}
}

// than update DCS
// then update DCS
if !app.canShrinkActiveNodes(masterNode, oldActiveNodes, activeNodes) {
app.logger.Error().Err(err).Msg("update active nodes: failed to update active nodes in dcs, master is dead")
return nil
}
err = app.dcs.Set(pathActiveNodes, activeNodes)
if err != nil {
app.logger.Error().Err(err).Msg("update active nodes: failed to update active nodes in dcs")
Expand All @@ -1218,6 +1226,21 @@ func (app *App) updateActiveNodes(clusterState, clusterStateDcs map[string]*node
return nil
}

// Check that we can safely remove nodes from active nodes
// Can't switch if master is dying, because we won't be able
// to perform failovers
func (app *App) canShrinkActiveNodes(masterNode *mysql.Node, oldActiveNodes, newActiveNodes []string) bool {
removed := filterOut(oldActiveNodes, newActiveNodes)
if len(removed) == 0 {
return true // no shrink - safe
}
if ok, err := masterNode.Ping(); !ok {
app.logger.Error().Err(err).Msgf("update active nodes: master %s is not alive, will not evict %v from active nodes", masterNode.Host(), removed)
return false
}
return true
}

func (app *App) adjustSemiSyncOnMaster(node *mysql.Node, state *nodestate.NodeState, waitSlaveCount int) error {
if state.SemiSyncState == nil {
return fmt.Errorf("semi-sync state is empty for %s", node.Host())
Expand Down
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