Starting Neo4j in HA giving network error back

Question

I'm currently trying to run Neo4j 3.0.3 in our on-premise cloud.

I have 3 nodes whose local IPs are:

172.16.1.8
172.16.1.74
172.16.1.79

The neo4j.conf file is identical to all nodes, except the ha.server_id parameter:

# Database mode
# Allowed values:
# HA - High Availability
# SINGLE - Single mode, default.
# To run in High Availability mode uncomment this line:
dbms.mode=HA

# ha.server_id is the number of each instance in the HA cluster. It should be
# an integer (e.g. 1), and should be unique for each cluster instance.
ha.server_id=1 # 2 or 3, depending on which server it's running

# ha.initial_hosts is a comma-separated list (without spaces) of the host:port
# where the ha.host.coordination of all instances will be listening. Typically
# this will be the same for all cluster instances.
ha.initial_hosts=172.16.1.8:5001,172.16.1.74:5001,172.16.1.79:5001

# HTTP Connector
dbms.connector.http.type=HTTP
dbms.connector.http.enabled=true
#dbms.connector.http.encryption=NONE
# To have HTTP accept non-local connections, uncomment this line
dbms.connector.http.address=0.0.0.0:7474

This is the exact same configuration suggested by the docs. I'm just using IP addresses instead of the hostnames.

Then I run neo4j start and go to the logs. This is what I get:

2016-08-02 19:17:01.211+0000 ERROR Failed to start Neo4j: Starting Neo4j failed:
 Component 'org.neo4j.server.database.LifecycleManagingDatabase@25a55713' was su
ccessfully initialized, but failed to start. Please see attached cause exception
. Starting Neo4j failed: Component 'org.neo4j.server.database.LifecycleManagingD
atabase@25a55713' was successfully initialized, but failed to start. Please see
attached cause exception.
org.neo4j.server.ServerStartupException: Starting Neo4j failed: Component 'org.n
eo4j.server.database.LifecycleManagingDatabase@25a55713' was successfully initia
lized, but failed to start. Please see attached cause exception.

The exceptions are chained until this one:

Caused by: java.lang.RuntimeException: java.net.UnknownHostException: npc_cvalor_v1_db3-a923e8d7-0e02-4209-9bac-c5a55d7a09c6.arq.lab: npc_cvalor_v1_db3-a923e8d7-0e02-4209-9bac-c5a55d7a09c6.arq.lab: unknown error

Strange thing is that both nodes can see each other (tested via ping), so I don't know what can be causing this issue, but I believe it has something to do with Java.

Any thoughts?

Additional information: I'm running RHEL 7 with Java 1.8.0 (IBM's distribution)

score 0 · Answer 1 · answered Aug 03 '16 at 13:08

I found out the problem.

For some reason I don't know yet, the java.net.* components could not resolve the hostname into IP of the server they are running in.

I had to add an entry in the /etc/hosts file pointing the server IP to the hostname:

# On Server 1
172.16.1.8 <full.hostname> <hostname>

# On Server 2
172.16.1.74 <full.hostname> <hostname>

# On Server 3
172.16.1.79 <full.hostname> <hostname>

Starting Neo4j in HA giving network error back

1 Answers1