Installation

There are a number of ways to install Elassandra: from the tarball, with the deb or rpm package, with a docker image, or even from source.

Elassandra is based on Cassandra and ElasticSearch, thus it will be easier if you’re already familiar with one on these technologies.

Tarball

Elassandra requires at least Java 8. Oracle JDK is the recommended version, but OpenJDK should work as well. You can check which version is installed on your computer:

$ java -version
java version "1.8.0_121"
Java(TM) SE Runtime Environment (build 1.8.0_121-b13)
Java HotSpot(TM) 64-Bit Server VM (build 25.121-b13, mixed mode)

Once java is correctly installed, download the Elassandra tarball:

wget https://github.com/strapdata/elassandra/releases/download/v6.2.3.1/elassandra-6.2.3.1.tar.gz

Then extract its content:

tar -xzf elassandra-6.2.3.1.tar.gz

Go to the extracted directory:

cd elassandra-6.2.3.1

Configure conf/cassandra.yaml if necessary, then run:

bin/cassandra -e

This has started cassandra with elasticsearch enabled (according to the -e option).

Get the node status:

bin/nodetool status

Now connect to the node with cqlsh:

bin/cqlsh

You’re now able to type CQL commands. See the CQL reference.

Check the elasticsearch API:

curl -X GET http://localhost:9200/

You should get something like:

{
  "name" : "127.0.0.1",
  "cluster_name" : "Test Cluster",
  "cluster_uuid" : "7cb65cea-09c1-4d6a-a17a-24efb9eb7d2b",
  "version" : {
    "number" : "6.2.3",
    "build_hash" : "b0b4cb025cb8aa74538124a30a00b137419983a3",
    "build_timestamp" : "2017-04-19T13:11:11Z",
    "build_snapshot" : true,
    "lucene_version" : "5.5.2"
  },
  "tagline" : "You Know, for Search"
}

You’re done !

On a production environment, it’s better to modify some system settings like disabling swap. This guide shows you how to. On linux, consider installing jemalloc.

deb

Download the last deb package from github relases page

wget -O elassandra.deb https://github.com/strapdata/elassandra/releases/download/v6.2.3.1/elassandra-6.2.3.1.deb

Install it with dpkg tool:

sudo dpkg -i elassandra.deb

To start elassandra, just run:

sudo systemctl start cassandra

or:

sudo service cassandra start

Files locations:

  • /usr/bin: startup script, cqlsh, nodetool, elasticsearch-plugin
  • /etc/cassandra and /etc/default/cassandra: configurations
  • /var/lib/cassandra: data
  • /var/log/cassandra: logs
  • /usr/share/cassandra: plugins, modules, libs, …
  • /usr/lib/python2.7/dist-packages/cqlshlib/: python library for cqlsh

rpm

Download the last rpm package from github relases page

wget -O elassandra.rpm https://github.com/strapdata/elassandra/releases/download/v6.2.3.1/elassandra-6.2.3.1.rpm

Install it with yum:

sudo yum install elassandra.rpm

To start elassandra, just run:

sudo systemctl start cassandra

or:

sudo service cassandra start

Files locations:

  • /usr/bin: startup script, cqlsh, nodetool, elasticsearch-plugin
  • /etc/cassandra and /etc/sysconfig/cassandra: configurations
  • /var/lib/cassandra: data
  • /var/log/cassandra: logs
  • /usr/share/cassandra: plugins, modules, libs, …
  • /usr/lib/python2.7/site-packages/cqlshlib/: python library for cqlsh

Docker image

We provide an image on docker hub:

docker pull strapdata/elassandra

This image is based on the official Cassandra image whose the documentation is valid as well for Elassandra.

The source code is on github at strapdata/docker-elassandra.

Start an elassandra server instance

Starting an Elassandra instance is simple:

docker run --name some-elassandra -d strapdata/elassandra:tag

…where some-cassandra is the name you want to assign to your container and tag is the tag specifying the Elassandra version you want. Default is latest.

Run nodetool and cqlsh:

docker exec -it some-elassandra nodetool status
docker exec -it some-elassandra cqlsh

Connect to Cassandra from an application in another Docker container

This image exposes the standard Cassandra and ElasticSearch ports, so container linking makes the Elassandra instance available to other application containers. Start your application container like this in order to link it to the Elassandra container:

docker run --name some-app --link some-elassandra:elassandra -d app-that-uses-elassandra

For instance, consuming the elasticsearch API from another container can be done like this:

docker run --link some-elassandra:elassandra -it strapdata/elassandra curl http//elassandra:9200

… where strapdata/elassandra could be any image with curl installed.

Environment Variables

When you start the Elassandra image, you can adjust the configuration of the Elassandra instance by passing one or more environment variables on the docker run command line.

Variable Name Description
CASSANDRA_LISTEN_ADDRESS This variable is for controlling which IP address to listen for incoming connections on. The default value is auto, which will set the listen_address option in cassandra.yaml to the IP address of the container as it starts. This default should work in most use cases.
CASSANDRA_BROADCAST_ADDRESS This variable is for controlling which IP address to advertise to other nodes. The default value is the value of CASSANDRA_LISTEN_ADDRESS. It will set the broadcast_address and broadcast_rpc_address options in cassandra.yaml.
CASSANDRA_RPC_ADDRESS This variable is for controlling which address to bind the thrift rpc server to. If you do not specify an address, the wildcard address (0.0.0.0) will be used. It will set the rpc_address option in cassandra.yaml.
CASSANDRA_START_RPC This variable is for controlling if the thrift rpc server is started. It will set the start_rpc option in cassandra.yaml. As Elastic search used this port in Elassandra, it will be set ON by default.
CASSANDRA_SEEDS This variable is the comma-separated list of IP addresses used by gossip for bootstrapping new nodes joining a cluster. It will set the seeds value of the seed_provider option in cassandra.yaml. The CASSANDRA_BROADCAST_ADDRESS will be added the the seeds passed in so that the sever will talk to itself as well.
CASSANDRA_CLUSTER_NAME This variable sets the name of the cluster and must be the same for all nodes in the cluster. It will set the cluster_name option of cassandra.yaml.
CASSANDRA_NUM_TOKENS This variable sets number of tokens for this node. It will set the num_tokens option of cassandra.yaml.
CASSANDRA_DC This variable sets the datacenter name of this node. It will set the dc option of cassandra-rackdc.properties.
CASSANDRA_RACK This variable sets the rack name of this node. It will set the rack option of cassandra-rackdc.properties.
CASSANDRA_ENDPOINT_SNITCH This variable sets the snitch implementation this node will use. It will set the endpoint_snitch option of cassandra.yml.
CASSANDRA_DAEMON The Cassandra entry-point class: org.apache.cassandra.service.ElassandraDaemon to start with ElasticSearch enabled (default), org.apache.cassandra.service.ElassandraDaemon otherwise.

Files locations

  • /opt/elassandra-|release|: elassandra installation
  • /var/lib/cassandra: data (sstables, lucene segment, commitlogs, …)
  • var/log/cassandra: logs files.

/var/lib/cassandra is automatically managed as a docker volume. But it’s a good target to bind mount from the host filesystem.

Exposed ports

  • 7000: intra-node communication
  • 7001: TLS intra-node communication
  • 7199: JMX
  • 9042: CQL
  • 9160: thrift service
  • 9200: ElasticSearch HTTP
  • 9300: ElasticSearch transport

Make a cluster

In case there is only one elassandra instance per docker host, the easiest way is to start the container with --net=host.

When using the host network is not an option, you could just map the necessary ports with -p 9042:9042, -p 9200:9200 and so on… but you should be aware that docker default network will considerably slow down performances.

Also, elassandra cluster can be fully managed over a swarm cluster. But this will basically require some more customization. Feel free to open an issue on our github repository to discuss about this.

Build from source

Requirements:
  • Oracle JDK 1.8 or OpenJDK 8
  • gradle >= 3.5

Clone Elassandra repository and Cassandra sub-module:

git clone --recursive git@github.com:strapdata/elassandra.git
cd elassandra

Elassandra 5.5+ uses Gradle for its build system. Simply run:

gradle assemble

or to build only the tgz tarball for a release version :

gradle assemble distribution:tar:assemble -Dbuild.snapshot=false

It’s gonna take a while, you might go for a cup of tea. If everything succeed, tarballs will be built in:

distribution/(tar|zip|rpm|deb)/build/distributions/

Then follow the instructions for tarball installation.