Don't panic when DROPing non-existent nodes

meta/statement_executor.go

@@ -157,12 +157,16 @@ func (e *StatementExecutor) executeShowServersStatement(q *influxql.ShowServersS
 }
 
 func (e *StatementExecutor) executeDropServerStatement(q *influxql.DropServerStatement) *influxql.Result {
-	// Dropping only non-Raft nodes supported.
-	peers, err := e.Store.Peers()
+	ni, err := e.Store.Node(q.NodeID)
 	if err != nil {
 		return &influxql.Result{Err: err}
 	}
-	ni, err := e.Store.Node(q.NodeID)
+	if ni == nil {
+		return &influxql.Result{Err: ErrNodeNotFound}
+	}
+
+	// Dropping only non-Raft nodes supported.
+	peers, err := e.Store.Peers()
 	if err != nil {
 		return &influxql.Result{Err: err}
 	}

meta/statement_executor_test.go

@@ -147,6 +147,19 @@ func TestStatementExecutor_ExecuteStatement_ShowServers(t *testing.T) {
 // Ensure a DROP SERVER statement can be executed.
 func TestStatementExecutor_ExecuteStatement_DropServer(t *testing.T) {
 	e := NewStatementExecutor()
+	e.Store.PeersFn = func() ([]string, error) {
+		return []string{"node1"}, nil
+	}
+
+	// Ensure non-existent nodes do not cause a problem.
+	e.Store.NodeFn = func(id uint64) (*meta.NodeInfo, error) {
+		return nil, nil
+	}
+	if res := e.ExecuteStatement(influxql.MustParseStatement(`DROP SERVER 666`)); res.Err != meta.ErrNodeNotFound {
+		t.Fatalf("unexpected error: %s", res.Err)
+	}
+
+	// Make a node exist.
 	e.Store.NodeFn = func(id uint64) (*meta.NodeInfo, error) {
 		return &meta.NodeInfo{
 			ID: 1, Host: "node1",
@@ -154,9 +167,6 @@ func TestStatementExecutor_ExecuteStatement_DropServer(t *testing.T) {
 	}
 
 	// Ensure Raft nodes cannot be dropped.
-	e.Store.PeersFn = func() ([]string, error) {
-		return []string{"node1"}, nil
-	}
 	if res := e.ExecuteStatement(influxql.MustParseStatement(`DROP SERVER 1`)); res.Err != meta.ErrNodeRaft {
 		t.Fatalf("unexpected error: %s", res.Err)
 	}