ArangoDB - Asymmetrical clustering doesn't work - configuration

Question

i've installed an arangodb instance on a virtual machine of Google Cloud (tcp://10.240.0.2). I would setup an asymmetrical cluster with another vm where i've installed arangodb (tcp://10.240.0.3).
I follow the official guide to config the production scenario: 1 coordinator and 1 DBServer on the same machine
I tried also a second configuration to cluster with two vm instances, but it doesn't work, showing this error in the GoogleChromeConsole :
{"error":true,"code":500,"errorNum":500,
"errorMessage":"Cannot check port on dispatcher tcp://10.240.0.3:8529"}
Here you can find the configurations that I have tried
What could be the error?
PS: I've open in the firewall the ports: 8529,8530,8629
Thanks in advance.
Daniele

Answer 1

Have you installed ArangoDB on both virtual machines and changed the configuration (on both) to set
[cluster]
disable-dispatcher-kickstarter = false
disable-dispatcher-frontend = false
and then restarted the database servers? I assume so, since you get "Connection OK" for both servers. Your browser would then talk to the first dispatcher, which in turn will contact the second one. The error message you get suggests that this latter step does not work, since checking ports is the first request the first dispatcher would send to the second one.
Is it possible that processes in the first VM cannot access tcp://10.240.0.3:8529 on the second VM? Maybe the respective other subnets are not routed from within the VMs?
Furthermore, when you have got this to work, you will almost certainly also need port 4001 on the first VM, because that is where our etcd (Agency) will listen. In addition, the ports 8530 and 8629 are the defaults which are tried first. If they are not usable for some reason, the dispatchers will use subsequent port numbers instead to assign them to the coordinators and DBservers. In that case you would have to open these as well, at least from the respective other VM.