Try to deploy multiple Usergrid containers on different machines, and make them point to a Cassandra cluster. But I cannot find documents about running multiple Usergrid nodes, and I only found instructions about Cassandra cluster.
Is this the right way to scale up my Usergrid services ? Or, what is the best practice to run multiple Usergrid nodes ?
My understanding is this is the correct way to go about it. You just need to to deploy the ROOT.war file to a new Tomcat instance.
Docs for configuring the usergrid-deployment.properties file so that UG knows where Cass and ES instances are, then deploying to Tomcat are steps 4 and 5 here: https://usergrid.apache.org/docs/installation/deployment-guide.html#deploying-the-usergrid-stack
You can also use the AWS cloudformation scripts in the repo to have AWS handle this for you (https://github.com/apache/usergrid/tree/master/deployment/aws)