从 Lagom 连接到 AWS Managed Cassandra 服务

Question

I'm having problems connecting to AWS Managed Cassandra Service from my Lagom environment. Here's what I have tried, with what results.

(1) Amazon provides instructions for connecting to AWS MCS from Java code:

https://docs.aws.amazon.com/fr_fr/mcs/latest/devguide/cqlsh.html#using_java_driver

The gist of the instructions is that you need to install a certificate and then pass it to the JVM as follows:

-Djavax.net.ssl.trustStore=path_to_file/cassandra_truststore.jks 
-Djavax.net.ssl.trustStorePassword=amazon

Then, you can use any Cassandra Java drivers of your choice. And my choice is the DataStax drivers provided with the Lagom framework.

This I did by adding the following to build.sbt :

javaOptions ++= Seq(
  "-Djavax.net.ssl.trustStore=project/cassandra_truststore.jks",
  "-Djavax.net.ssl.trustStorePassword=amazon"
)

// Must enable JVM forking to use javaOptions with runAll.
fork := true

(2) Before deploying my Lagom application to AWS, I want to work with it in Dev mode but connecting it to AWS MCS instead of the embedded Cassandra server. Lagom provides instructions for doing this in Dev mode:

https://www.lagomframework.com/documentation/1.6.x/scala/CassandraServer.html#Connecting-to-a-locally-running-Cassandra-instance

The gist of the instructions is to add the following lines to build.sbt :

lagomCassandraEnabled in ThisBuild := false
lagomUnmanagedServices in ThisBuild := Map("cas_native" -> "tcp://localhost:9042")

The URI in this example assumes a Cassandra server running on localhost:9042 . In my case, I substituted that with cassandra.us-east-1.amazonaws.com:9142 .

(3) Nevertheless, when I run sbt runAll , I'm getting timeouts when trying to reach AWS MCS:

Caused by: com.datastax.driver.core.exceptions.NoHostAvailableException: All host(s) tried for query failed (tried: cassandra.us-east-1.amazonaws.com/3.83.168.143:9142 (com.datastax.driver.core.exceptions.OperationTimedOutException: [cassandra.us-east-1.amazonaws.com/3.83.168.143:9142] Operation timed out))

(4) I have isolated the problem by bypassing Lagom entirely and just writing a very simple piece of code, like this:

  System.setProperty("javax.net.ssl.trustStore", "redacted_absolute_file_path/cassandra_truststore.jks")
  System.setProperty("javax.net.ssl.trustStorePassword", "amazon")

  val cluster = Cluster.builder.addContactPoint("cassandra.us-east-1.amazonaws.com").withPort(9142).build()
  val session = cluster.connect()
  session.close()
  cluster.close()

This is as simple as it gets. But the same timeout occurs. What am I doing wrong?

Answer 1

Found a solution by looking at the AWS MCS Python documentation (the Java documentation is conspicuously silent on the matter). Turns out I do need to configure MCS service-specific credentials and then provide them in the Lagom's application.conf file as follows:

cassandra.default {
  port = 9142

  ssl.truststore {
    path = "path/cassandra_truststore.jks"
    password = "amazon"
  }

  authentication {
    username = "service-specific username"
    password = "service-specific password"
  }
}

cassandra-journal {
  port = ${cassandra.default.port}

  ssl.truststore {
    path = ${cassandra.default.ssl.truststore.path}
    password = ${cassandra.default.ssl.truststore.password}
  }

  authentication {
    username = ${cassandra.default.authentication.username}
    password = ${cassandra.default.authentication.password}
  }
}

cassandra-snapshot-store {
  port = ${cassandra.default.port}

  ssl.truststore {
    path = ${cassandra.default.ssl.truststore.path}
    password = ${cassandra.default.ssl.truststore.password}
  }

  authentication {
    username = ${cassandra.default.authentication.username}
    password = ${cassandra.default.authentication.password}
  }
}

lagom.persistence.read-side.cassandra {
  port = ${cassandra.default.port}

  ssl.truststore {
    path = ${cassandra.default.ssl.truststore.path}
    password = ${cassandra.default.ssl.truststore.password}
  }

  authentication {
    username = ${cassandra.default.authentication.username}
    password = ${cassandra.default.authentication.password}
  }
}