Cannot reconnect to Nats cluster

I have a Nats cluster setup. When the Nats server that is being used by the java app is terminated, the app tries to reconnect but it throws the following exception.

java.io.IOException: java.net.URISyntaxException: Illegal character in scheme name at index 0: 172.18.0.101:4222
	at io.nats.client.impl.SocketDataPort.connect(SocketDataPort.java:60)
	at io.nats.client.impl.NatsConnection.tryToConnect(NatsConnection.java:299)
	at io.nats.client.impl.NatsConnection.reconnect(NatsConnection.java:225)
	at io.nats.client.impl.NatsConnection.closeSocket(NatsConnection.java:471)
	at io.nats.client.impl.NatsConnection.lambda$handleCommunicationIssue$2(NatsConnection.java:428)
	at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: java.net.URISyntaxException: Illegal character in scheme name at index 0: 172.18.0.101:4222
	at java.base/java.net.URI$Parser.fail(URI.java:2915)
	at java.base/java.net.URI$Parser.checkChars(URI.java:3086)
	at java.base/java.net.URI$Parser.checkChar(URI.java:3096)
	at java.base/java.net.URI$Parser.parse(URI.java:3111)
	at java.base/java.net.URI.<init>(URI.java:600)
	at io.nats.client.impl.SocketDataPort.connect(SocketDataPort.java:47)
	... 5 more

From what I can see, Nats publishes all addresses of Nats servers in the cluster in the following format ip-address:port without the scheme. Check the connect_urls values below.

{"server_id":"iHAhz9B35WdjjgYytJ35ze","version":"1.3.0","proto":1,"git_commit":"eed4fbc","go":"go1.11","host":"0.0.0.0","port":4222,"max_payload":1048576,"client_id":8,"connect_urls":["172.18.0.100:4222","172.18.0.101:4222","172.18.0.102:4222"]}

When the Nats client tries to reconnect, it will use one of those addresses and create a java.net.URI instance from it. Looks like the URI class does not accept a ip-address:port format. Running the code below, will throws the same exception.

URI url = new URI("172.18.0.1:4222");

However, if the nats scheme is added, the URI will work fine.

URI url = new URI("nats://172.18.0.1:4222");

Should the nats:// scheme be always used when building the server list in NatsConnection#getServers()?

Actually, it is not possible to a Nats server by addressing it without the scheme because looks like java.net.URI requires a scheme. None of the following code works.

Nats.connect("localhost:4222");
Nats.connect("127.0.0.1:4222");

[sasbury]

ok, it turns out blindly adding nats:// is not necessarily bad, because the place that was failing doesn’t care about the protocol. BUT, i did a new fix that is a bit more careful and checks the URI in all the places we use it. I am re-running tests and will commit momentarily into v2.4.0 branch. Hoping to release that branch this week, but if you get a chance to try before I release it would be awesome just in case the tests miss something.

Oh, i also fixed the unit test that was for servers in info to remove the nats:// to test this.

[sasbury]

Should get this fixed this week, I have other tasks in there anyway

On Sun, Nov 25, 2018, 12:26 PM Ivan Kozlovic <[e-mail] wrote:

@sasbury https://github.com/sasbury This is correct analysis. The server sends connect URLs of all servers in the cluster in the form IP:port, without a scheme (or username and password for that matter). The client library is responsible for adding it.

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