Could not get connection while getPartitionedTopicMetadata - io.netty.channel.ConnectTimeoutException: connection timed out - apache-pulsar

Question

I have a basic Pulsar app, and when I try to connect to Pulsar, I get this exception:
2021-03-10 14:38:26.107 WARN 7 --- [r-client-io-1-1]
o.a.pulsar.client.impl.ConnectionPool : Failed to open connection
to my-pulsar-server-ms-tls.domain.com:6651 :
io.netty.channel.ConnectTimeoutException: connection timed out:
my-pulsar-server-ms-tls.domain.com/10.80.13.38:6651 2021-03-10
14:38:26.212 WARN 7 --- [al-listener-3-1]
o.a.pulsar.client.impl.PulsarClientImpl : [topic:
persistent://myTenant/myNamespace/myTopic]
Could not get connection while getPartitionedTopicMetadata -- Will try
again in 100 ms
My Pulsar client is pretty basic:
PulsarClient.builder()
.serviceUrl(serviceUrl)
.authentication(AuthenticationFactory.token(authToken))
.tlsTrustCertsFilePath(serverCertificateFilePath.toString())
.enableTlsHostnameVerification(false)
.allowTlsInsecureConnection(false)
.build();
The producer is also pretty basic and looks like this:
pulsarClient.newProducer(Schema.STRING)
.topic(topic)
.create();
I've verified that the token and TLS cert are correct. I've also tried connecting a consumer from this same environment and got a similar exception, and I know that others with the same code are able to connect to the same Pulsar cluster from other environments. What is the issue?

Answer 1

Your connection is getting blocked by a firewall or network issue.
Verify that you can establish a connection to your endpoint my-pulsar-server-ms-tls.domain.com:6651 from your environment.
If you're able to run a network packet dump (like tcpdump), that should make it obvious if you're not able to establish a connection.
You can also try running curl my-pulsar-server-ms-tls.domain.com:6651, and if you get back some html, that means you were able to reach the server. However, if you get Could not resolve host, then you were blocked by the network configuration (such as a missing route) or firewall.