Janusgraph connect to remove server cannot instantiate implementation of CQLStoreManager

Question

I am running a cassandara cluster on ec2 and janusgraph node as another ec2 instance as well. I have these properties file for janus graph(janusgraph.properties)

storage.backend = cassandra
storage.hostname = [xxx.xx.xx.xx] #its valid ip and is correct, just hidden

and from gremlin coonsole i do

graph = JanusGraphFactory.open('janusgraph.properties')

It seems like it is not being able to connect with cassandra and error is

Could not instantiate implementation: org.janusgraph.diskstorage.cql.CQLStoreManager

I am not able to understand it.

Detailed error is:

java.lang.IllegalArgumentException: Could not instantiate implementation: org.janusgraph.diskstorage.cql.CQLStoreManager    at org.janusgraph.util.system.ConfigurationUtil.instantiate(ConfigurationUtil.java:64)  at org.janusgraph.diskstorage.Backend.getImplementationClass(Backend.java:440)  at org.janusgraph.diskstorage.Backend.getStorageManager(Backend.java:411)   at org.janusgraph.graphdb.configuration.builder.GraphDatabaseConfigurationBuilder.build(GraphDatabaseConfigurationBuilder.java:50)  at org.janusgraph.core.JanusGraphFactory.open(JanusGraphFactory.java:161)   at org.janusgraph.core.JanusGraphFactory.open(JanusGraphFactory.java:132)   at org.janusgraph.core.JanusGraphFactory.open(JanusGraphFactory.java:79)    at org.janusgraph.core.JanusGraphFactory$open.call(Unknown Source)  at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:47)    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:115)    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:127)    at groovysh_evaluate.run(groovysh_evaluate:3)   at groovysh_evaluate$run.call(Unknown Source)   at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:47)    at groovysh_evaluate$run.call(Unknown Source)   at org.codehaus.groovy.tools.shell.Interpreter.evaluate(Interpreter.groovy:77)  at org.codehaus.groovy.tools.shell.Evaluator$evaluate.call(Unknown Source)  at org.codehaus.groovy.tools.shell.Groovysh.execute(Groovysh.groovy:199)    at org.apache.tinkerpop.gremlin.console.GremlinGroovysh.super$3$execute(GremlinGroovysh.groovy)     at sun.reflect.GeneratedMethodAccessor20.invoke(Unknown Source)     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)    at java.lang.reflect.Method.invoke(Method.java:498)     at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:101)    at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:323)   at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1217)  at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeMethodOnSuperN(ScriptBytecodeAdapter.java:144)   at org.apache.tinkerpop.gremlin.console.GremlinGroovysh.execute(GremlinGroovysh.groovy:72)  at org.codehaus.groovy.tools.shell.Shell.leftShift(Shell.groovy:120)    at org.codehaus.groovy.tools.shell.Shell$leftShift$1.call(Unknown Source)   at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:47)    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:115)    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:127)    at org.codehaus.groovy.tools.shell.ShellRunner.work(ShellRunner.groovy:93)  at org.codehaus.groovy.tools.shell.InteractiveShellRunner.super$2$work(InteractiveShellRunner.groovy)   at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)  at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)    at java.lang.reflect.Method.invoke(Method.java:498)     at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:101)    at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:323)   at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1217)  at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeMethodOnSuperN(ScriptBytecodeAdapter.java:144)   at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeMethodOnSuper0(ScriptBytecodeAdapter.java:164)   at org.codehaus.groovy.tools.shell.InteractiveShellRunner.work(InteractiveShellRunner.groovy:138)   at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)  at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)    at java.lang.reflect.Method.invoke(Method.java:498)     at org.codehaus.groovy.runtime.callsite.PlainObjectMetaMethodSite.doInvoke(PlainObjectMetaMethodSite.java:43)   at org.codehaus.groovy.runtime.callsite.PogoMetaMethodSite$PogoCachedMethodSiteNoUnwrapNoCoerce.invoke(PogoMetaMethodSite.java:190)     at org.codehaus.groovy.runtime.callsite.PogoMetaMethodSite.callCurrent(PogoMetaMethodSite.java:58)  at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCallCurrent(CallSiteArray.java:51)     at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:156)     at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:160)     at org.codehaus.groovy.tools.shell.ShellRunner.run(ShellRunner.groovy:57)   at org.codehaus.groovy.tools.shell.InteractiveShellRunner.super$2$run(InteractiveShellRunner.groovy)    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)  at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)    at java.lang.reflect.Method.invoke(Method.java:498)     at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:101)    at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:323)   at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1217)  at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeMethodOnSuperN(ScriptBytecodeAdapter.java:144)   at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeMethodOnSuper0(ScriptBytecodeAdapter.java:164)   at org.codehaus.groovy.tools.shell.InteractiveShellRunner.run(InteractiveShellRunner.groovy:97)     at org.codehaus.groovy.vmplugin.v7.IndyInterface.selectMethod(IndyInterface.java:234)   at org.apache.tinkerpop.gremlin.console.Console.<init>(Console.groovy:153)  at org.codehaus.groovy.vmplugin.v7.IndyInterface.selectMethod(IndyInterface.java:234)   at org.apache.tinkerpop.gremlin.console.Console.main(Console.groovy:466) Caused by: java.lang.reflect.InvocationTargetException     at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)     at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)     at java.lang.reflect.Constructor.newInstance(Constructor.java:423)  at org.janusgraph.util.system.ConfigurationUtil.instantiate(ConfigurationUtil.java:58)  ... 69 more Caused by: com.datastax.driver.core.exceptions.NoHostAvailableException: All host(s) tried for query failed (tried: []:9042 (com.datastax.driver.core.exceptions.TransportException: [[]:9042] Cannot connect))     at com.datastax.driver.core.ControlConnection.reconnectInternal(ControlConnection.java:268)     at com.datastax.driver.core.ControlConnection.connect(ControlConnection.java:107)   at com.datastax.driver.core.Cluster$Manager.negotiateProtocolVersionAndConnect(Cluster.java:1652)   at com.datastax.driver.core.Cluster$Manager.init(Cluster.java:1571)     at com.datastax.driver.core.Cluster.init(Cluster.java:208)  at com.datastax.driver.core.Cluster.connectAsync(Cluster.java:376)  at com.datastax.driver.core.Cluster.connectAsync(Cluster.java:355)  at com.datastax.driver.core.Cluster.connect(Cluster.java:305)   at org.janusgraph.diskstorage.cql.CQLStoreManager.initializeSession(CQLStoreManager.java:302)   at org.janusgraph.diskstorage.cql.CQLStoreManager.<init>(CQLStoreManager.java:174)  ... 74 more

Answer 1

I faced the similar issue but the EC2 instances were brought down by administrator and hence the issue. Once I restarted the EC2 instances, the issue was resolved.

Answer 2

So i figured it out.

Janusgraph documentation says to put one of the node in cluster as

storage.hostname = [IP-address-of-one-Cassandra-EC2-instance]

Since it wasnt in form, i thought its an array syntax

Replacing [xx.xx.xx.xx] with xx.xx.xx.xx worked