Only defer client.Logout if client has been successfully returned.

[lucaszhangyz]

Hi Adrian,
Thanks for sharing these codes.
I found a bug which arised in the scenarios when error occured in vcenter.Connect(). Then when go exec the defer client.Logout(ctx) codes, a null point panic arised since client has never been initialized. A better idea is to move defer client.Logout(ctx) afer if err != nil codes. Here is the codes.

--- a/vsphere-influxdb.go
+++ b/vsphere-influxdb.go
@@ -131,12 +131,12 @@ func (vcenter *VCenter) Init(config Configuration) {
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
client, err := vcenter.Connect()

•   defer client.Logout(ctx)
  if err != nil {
          errlog.Println("Could not connect to vcenter: ", vcenter.Hostname)
          errlog.Println("Error: ", err)
          return
  }
  

•   defer client.Logout(ctx)
  var perfmanager mo.PerformanceManager
  

Best wishes
lucas

[sofixa]

Thanks a lot for this MR :)

Cheers,
Adrian

[cblomart]

Don't hesitate to report also to vsphere-graphite.
I've patched this back into it.