question

@scano_183208 In response to your followup questions, I've generated self-signed certificates locally following the steps in DSE 6.7 Creating local SSL certificate and keystore files.

I've used the keystore and truststore files I've created to enable client-to-node encryption on the DSE nodes. To validate that SSL is working, I've used the root certificate (rootca.crt) to connect to SSL-enabled nodes with cqlsh. For example, on node with IP 10.101.35.27:

$ export SSL_CERTFILE="/path/to/rootca.crt"
$ cqlsh --ssl 10.101.35.27

After confirming that client-to-node encryption is setup correctly, I have configured Gremlin console to use SSL with the same PEM file (signing_request.crt_signed) from when I generated the certificates. Here is my complete remote.yaml:

hosts: [10.101.35.27]
port: 8182
serializer: { className: org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV3d0,
              config: { serializeResultToString: true, ioRegistries: [org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerIoRegistryV3d0] }}
connectionPool: {
  enableSsl: true,
  maxContentLength: 65536000,
  maxInProcessPerConnection: 4,
  maxSimultaneousUsagePerConnection: 16,
  maxSize: 8,
  maxWaitForConnection: 3000,
  maxWaitForSessionClose: 3000,
  minInProcessPerConnection: 1,
  minSimultaneousUsagePerConnection: 8,
  minSize: 2,
  reconnectInterval: 1000,
  resultIterationBatchSize: 64,
  trustCertChainFile: /path/to/signing_request.crt_signed
}

Here's the output from my test connection:

$ dse gremlin-console 10.101.35.27:8182
...
gremlin> system.graph('test').create()
==>null
gremlin> system.graphs()
==>test

I can also see in the system.log that my connection to the server was successful:

INFO  [gremlin-server-worker-1] 2020-01-23 20:08:16,951 GREMLIN Session.java:93 - New session established for 9c1c9069-e371-44cd-bde0-4f22153b62b

Without configuring SSL with a valid trustCertChainFile, you would see an error like this in system.log :

WARN  [gremlin-server-worker-2] 2020-01-23 20:04:00,005  Slf4JLogger.java:151 - An exceptionCaught() event was fired, and it reached at the tail of the pipeline. It usually means the last handler in the pipeline did not handle the exception.
io.netty.handler.codec.DecoderException: io.netty.handler.ssl.NotSslRecordException: not an SSL/TLS record: 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
        at io.netty.handler.codec.ByteToMessageDecoder.callDecode(ByteToMessageDecoder.java:459)
        at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:265)
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340)
        at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1434)
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
        at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:965)
        at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:163)
        at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:647)
        at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:582)
        at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:499)
        at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:461)
        at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:884)
        at java.lang.Thread.run(Thread.java:748)
Caused by: io.netty.handler.ssl.NotSslRecordException: not an SSL/TLS record: 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
        at io.netty.handler.ssl.SslHandler.decodeJdkCompatible(SslHandler.java:1156)
        at io.netty.handler.ssl.SslHandler.decode(SslHandler.java:1221)
        at io.netty.handler.codec.ByteToMessageDecoder.decodeRemovalReentryProtection(ByteToMessageDecoder.java:489)
        at io.netty.handler.codec.ByteToMessageDecoder.callDecode(ByteToMessageDecoder.java:428)

Let me know how you go. Cheers!