How To Install Cassandra on CentOS 7

Apache Cassandra was initially released in 2008 by the Apache Software Foundation. It is a free, open-source, NoSQL type database management system that is designed to address large amounts of information that can be shared across multiple servers and, it provides high availability, so it eliminates the single point of failure issues! It has excellent fault tolerances when operating on basic hardware or in a larger cloud infrastructure. It is used by high-profile companies like Constant Contact, CERN, Comcast, eBay, GitHub, GoDaddy, Hulu, Instagram, Intuit, Netflix, Reddit, The Weather Channel and a multitude of other business concerns. They selected to use Cassandra as it’s a wise choice to host your decentralized, NoSQL database solution.

Let’s get started with the installation. In this article, we’ll be installing Apache Cassandra on a CentOS 7 VPS server.

Prerequisites

We need to verify a few items and then install Java as Cassandra was developed using the Java programming language.

First, let’s verify our version of CentOS

[root@test yum.repos.d]# cat /etc/redhat-release
CentOS Linux release 7.6.1810 (Core)

Next, make sure your server is up to date with the latest software

yum -y update

Step 1: Install Java

Now that we have those prerequisites out of the way let’s install Java. We’re going to use the newer OpenJDK install (Open Java Development Kit) because, the earlier Oracle JDK is EOL (end of life) as of Jan. 2019 and will no longer provide any updates unless you purchase a business license. As Oracle announced, “Public updates for Oracle Java SE 8 released after January 2019 will not be available for business, commercial, or production use without a commercial license”. However, the OpenJDK is completely open source and can be used freely.

There are no radical technical differences between the two software titles since the builds for the Oracle JDK is based on OpenJDK. All the major Linux distributions (Fedora, Ubuntu, Red Hat) provide OpenJDK as the default Java SE implementation, so we’ll trust their judgment in choosing that platform as well.

yum -y install java

Now, let’s quickly check the version of java we just installed

java -version
 openjdk version "1.8.0_201"
 OpenJDK Runtime Environment (build 1.8.0_201-b09)
 OpenJDK 64-Bit Server VM (build 25.201-b09, mixed mode)

Step 2: Adding the Cassandra Repo

Ok, time to add the Cassandra repo to the server. We’ll be using VIM (because what other awesome editor is there?)

vim /etc/yum.repos.d/cassandra.repo
(click insert on your keyboard and then 
copy/paste the info below into the repo file)

[cassandra]
name=Apache Cassandra
baseurl=https://www.apache.org/dist/cassandra/redhat/311x/
gpgcheck=1
repo_gpgcheck=1
gpgkey=https://www.apache.org/dist/cassandra/KEYS

(after that, click on the escape key to end editing the file)

Once complete, use ‘:wq’ to save the file.
Ok, let’s update our system again, so all the changes are picked up.

[root@new ~]# yum -y update
 Loaded plugins: fastestmirror, priorities
 Loading mirror speeds from cached hostfile
 * base: mirrors.liquidweb.com
 * extras: mirrors.liquidweb.com
 * updates: mirrors.liquidweb.com
 cassandra/signature | 833 B 00:00:00
 Retrieving key from https://www.apache.org/dist/cassandra/KEYS
 Importing GPG key 0xF2833C93:
 Userid     : "Eric Evans <eevans@sym-link.com>"
 Fingerprint: cec8 6bb4 a0ba 9d0f 9039 7cae f835 8fa2 f283 3c93
 From       : https://www.apache.org/dist/cassandra/KEYS
 cassandra/signature  | 2.9 kB 00:00:00 !!!
 cassandra/primary_db | 4.2 kB 00:00:00
 No packages marked for update

Step 3: Install Cassandra

Now, time to install Cassandra!

[root@new ~]# yum install cassandra
 Dependencies Resolved
 Package  Arch Version Repository Size

 Installing:
 cassandra noarch 3.11.4-1 cassandra 28 M
 Transaction Summary

 Install  1 Package
 Total download size: 28 M
 Installed size: 38 M
 Is this ok [y/d/N]: y
 Downloading packages:
 warning: /var/cache/yum/x86_64/7/cassandra/packages/cassandra-3.11.4-1.noarch.rpm: Header V4 RSA/SHA256 Signature, key ID fe4b2bda: NOKEY
 Public key for cassandra-3.11.4-1.noarch.rpm is not installed
 cassandra-3.11.4-1.noarch.rpm  | 28 MB 00:00:00
 Retrieving key from https://www.apache.org/dist/cassandra/KEYS
 Importing GPG key 0xF2833C93:
 Userid     : "Eric Evans <eevans@sym-link.com>"
 Fingerprint: cec8 6bb4 a0ba 9d0f 9039 7cae f835 8fa2 f283 3c93
 From       : https://www.apache.org/dist/cassandra/KEYS
 Is this ok [y/N]: y
 Importing GPG key 0x8D77295D:
 Userid     : "Eric Evans <eevans@sym-link.com>"
 Fingerprint: c496 5ee9 e301 5d19 2ccc f2b6 f758 ce31 8d77 295d
 From       : https://www.apache.org/dist/cassandra/KEYS
 Is this ok [y/N]: y
 Importing GPG key 0x2B5C1B00:
 Userid     : "Sylvain Lebresne (pcmanus) <sylvain@datastax.com>"
 Fingerprint: 5aed 1bf3 78e9 a19d ade1 bcb3 4bd7 36a8 2b5c 1b00
 From       : https://www.apache.org/dist/cassandra/KEYS
 Is this ok [y/N]: y
 Importing GPG key 0x0353B12C:
 Userid     : "T Jake Luciani <jake@apache.org>"
 Fingerprint: 514a 2ad6 31a5 7a16 dd00 47ec 749d 6eec 0353 b12c
 From       : https://www.apache.org/dist/cassandra/KEYS
 Is this ok [y/N]: y
 Importing GPG key 0xFE4B2BDA:
 Userid     : "Michael Shuler <michael@pbandjelly.org>"
 Fingerprint: a26e 528b 271f 19b9 e5d8 e19e a278 b781 fe4b 2bda
 From       : https://www.apache.org/dist/cassandra/KEYS
 Is this ok [y/N]: y
 Running transaction check
 Running transaction test
 Transaction test succeeded
 Running transaction
 Installing : cassandra-3.11.4-1.noarch  1/1
 Verifying  : cassandra-3.11.4-1.noarch  1/1
 Installed:
 cassandra.noarch 0:3.11.4-1
 Complete!

Step 4: Start Cassandra

Now, let's start/enable the Cassandra service:

[root@new ~]# systemctl enable cassandra
 cassandra.service is not a native service, redirecting to /sbin/chkconfig.
 Executing /sbin/chkconfig cassandra on[root@new ~]# systemctl start cassandra

Next, we’ll check to see if Cassandra is running.

[root@new ~]# nodetool status
 Datacenter: datacenter1
 =======================
 Status=Up/Down
 |/ State=Normal/Leaving/Joining/Moving
 --  Address    Load Tokens       Owns (effective) Host ID   Rack

[root@new ~]# nodetool status
 Datacenter: datacenter1
 =======================
 Status=Up/Down
 |/ State=Normal/Leaving/Joining/Moving
 --  Address  Load Tokens  Owns (effective) Host ID Rack
 UN  127.0.0.1  103.67 KiB 256 100.0% cda3cdf2-e210-4736-a36c-4bad87eadf7b  rack1

Perfect! Cassandra is now installed.

(As an aside, Cassandra's data is kept in the /var/lib/cassandra folder)

[root@new ~]# cd /var/lib/cassandra
 [root@new cassandra]# ll
 total 16
 drwxr-xr-x 2 cassandra cassandra 4096 Mar 28 15:30 commitlog
 drwxr-xr-x 7 cassandra cassandra 4096 Mar 28 15:30 data
 drwxr-xr-x 2 cassandra cassandra 4096 Feb  2 18:48 hints
 drwxr-xr-x 2 cassandra cassandra 4096 Feb  2 18:48 saved_caches

The configuration files are kept in the /etc/cassandra folder.

[root@new cassandra]# vim [root@new ~]# nodetool status
 Datacenter: datacenter1
 =======================
 Status=Up/Down
 |/ State=Normal/Leaving/Joining/Moving
 --  Address  Load Tokens  Owns (effective) Host ID Rack
 UN  127.0.0.1  103.67 KiB 256 100.0% cda3cdf2-e210-4736-a36c-4bad87eadf7b  rack1/etc/cassandra/
 conf/  default.conf/[root@new cassandra]# vim /etc/cassandra/conf/
 cassandra-env.sh  cassandra.yaml.orig logback.xml
 cassandra-env.sh.orig  commitlog_archiving.properties metrics-reporter-config-sample.yaml
 cassandra-jaas.config cqlshrc.sample README.txt
 cassandra-rackdc.properties hotspot_compiler triggers/
 cassandra-topology.properties jvm.options
 cassandra.yaml logback-tools.xml

Lastly, the java configs can be found in the /etc/default/cassandra file

[root@new cassandra]# cat /etc/default/cassandra
 # NOTICE: See also /etc/cassandra/cassandra-env.sh# EXTRA_CLASSPATH provides the means to extend Cassandra's classpath with
 # additional libraries.  It is formatted as a colon-delimited list of
 # class directories and/or jar files.  For example, to enable the
 # JMX-to-web bridge install libmx4j-java and uncomment the following.
 #EXTRA_CLASSPATH="/usr/share/java/mx4j-tools.jar"

Cassandra starts off listening on localhost by default so the configurations will need to be modified by a dev or a system's admin to suit your needs.

If you get an error such as:

‘Failed to connect to ’127.0.0.1:7199′: Connection refused’

Then check the following tutorial to resolve that issue:
Error: Failed to connect to ’127.0.0.1:7199′: Connection refused (Cassandra) [SOLVED]

To restart Cassandra

[root@new cassandra]# systemctl restart cassandra

To shut down Cassandra

[root@new cassandra]# service cassandra stop