How to Install Apache Cassandra on Rocky Linux 9/8

Apache Cassandra is a highly scalable, high-performance distributed database designed to handle large amounts of data across many commodity servers, providing high availability with no single point of failure. It is renowned for its robust support for clusters spanning multiple data centers, with asynchronous masterless replication allowing low latency and operational simplicity. Cassandra is ideal for applications requiring high write throughput, fault tolerance, and linear scalability.

The following guide will demonstrate the steps to install Apache Cassandra on Rocky Linux 9 or 8 using command-line commands. This process involves setting up the appropriate repository and configuring your system to ensure optimal performance and reliability for your distributed database environment.

Update Rocky Linux System Before Apache Cassandra Installation

First, before installing Apache Cassandra, it is a good idea to ensure all system packages are up-to-date to avoid any potential issues when installing the NoSQL database.

In your terminal, run the following command and upgrade any outstanding packages.

sudo dnf upgrade --refresh

Import Apache Cassandra Repository

The first step involves importing the repository for Apache Cassandra. Fortunately, you can accomplish this with a single command. The tutorial will show how to import the 5.0, 4.0, or 4.1 branches. Since the 3.xx branch is nearing its end, the tutorial will not include instructions for adding these.

4.0 Apache Cassandra RPM Import

sudo tee /etc/yum.repos.d/cassandra-4.0.repo<<EOF
[cassandra]
name=Apache Cassandra 4.0
baseurl=https://redhat.cassandra.apache.org/41x/
gpgcheck=1
repo_gpgcheck=1
gpgkey=https://downloads.apache.org/cassandra/KEYS
EOF

4.1 Apache Cassandra RPM Import

sudo tee /etc/yum.repos.d/cassandra-4.1.repo<<EOF
[cassandra]
name=Apache Cassandra 4.1
baseurl=https://redhat.cassandra.apache.org/41x/
gpgcheck=1
repo_gpgcheck=1
gpgkey=https://downloads.apache.org/cassandra/KEYS
EOF

5.0 Apache Cassandra RPM Import

sudo tee /etc/yum.repos.d/cassandra-5.0.alpha.repo<<EOF
[cassandra]
name=Apache Cassandra 5.0
baseurl=https://redhat.cassandra.apache.org/50x/
gpgcheck=1
repo_gpgcheck=1
gpgkey=https://downloads.apache.org/cassandra/KEYS
EOF

Install Apache Cassandra via DNF Command

You can install Cassandra with the following command; the repository has been imported.

sudo dnf install cassandra -y

Confirm the version installed by running the following command.

cassandra -v

Note if you see the following error importing GPG keys.

Key import failed (code 2). Failing package is: cassandra-4.1~alpha1-1.noarch
 GPG Keys are configured as: https://www.apache.org/dist/cassandra/KEYS
The downloaded packages were saved in cache until the next successful transaction.
You can remove cached packages by executing 'dnf clean packages'.

Change the crypto policies and set the policy to LEGACY.

sudo update-crypto-policies --set LEGACY

Sometimes, you may need to reboot for this change to occur successfully. I found you did not need to, but it is advised.

reboot

Create Apache Cassandra Systemd Service

After the installation is complete, you need to create the systemd service. Again, this is a simple task; copy and paste the following command to create the file.

sudo tee /etc/systemd/system/cassandra.service<<EOF
[Unit]
Description=Apache Cassandra
After=network.target

[Service]
Type=simple
PIDFile=/var/run/cassandra/cassandra.pid
User=cassandra
Group=cassandra

ExecStart=/usr/sbin/cassandra -f -p /var/run/cassandra/cassandra.pid
Restart=always

[Install]
WantedBy=multi-user.target
EOF

You must reload the daemon to start using the Cassandra service, and you cannot skip this step.

sudo systemctl daemon-reload

Now, start the Cassandra service.

sudo systemctl start cassandra

Next, check the systemctl status of Cassandra to ensure there are no errors.

systemctl status cassandra

Optionally, you can enable the Cassandra service on automatic start when you start your computer or server using the following command.

sudo systemctl enable cassandra

Install Apache Cassandra Client (cqlsh) on Rocky Linux

Install Python

Before installing the Cassandra client, ensure Python is available on your system. Apache Cassandra’s client, cqlsh, is Python-based, making Python a prerequisite. Install Python on Rocky Linux by executing:

sudo dnf install python3 -y

Install PIP

Next, install PIP, Python’s package manager, for managing Python packages. PIP is essential for installing the Cassandra Python driver. If PIP is not already installed on your system, add it by running:

sudo dnf install python3-pip -y

Install Cassandra Python Driver

The Cassandra Python driver is necessary for cqlsh to connect to the Cassandra database. This driver enables communication between the client and the database. Install the driver using PIP with the command:

pip install cassandra-driver

Installing cqlsh

With the prerequisites in place, you’re now ready to install cqlsh. This command-line interface allows for interaction with Apache Cassandra, enabling you to execute queries and manage your database. Install cqlsh by executing:

pip install cqlsh

Lastly, connect with cqlsh using the following command.

cqlsh

Example output of your successful connection:

[cqlsh 6.1.0 | Cassandra 4.1-alpha1 | CQL spec 3.4.5 | Native protocol v5]
Use HELP for help.
cqlsh> 

Configure Apache Cassandra

Setting up and personalizing Cassandra requires alterations in its configuration files and utilizing certain command line utilities.

Setting Up Basic Configuration

The principal configuration files for Cassandra are located in /etc/cassandra. Meanwhile, logs and data directories are typically situated at /var/log/cassandra and /var/lib/cassandra respectively.

For adjustments at the JVM level, such as heap size, you’d look towards the /etc/cassandra/conf/cassandra-env.sh file. Within this file, you can add supplementary JVM command-line arguments to the JVM_OPTS variable which Cassandra reads upon startup.

Enabling User Authentication with Apache Cassandra

Before activating user authentication, it’s wise to create a backup of the /etc/cassandra/conf/cassandra.yaml file:

sudo cp /etc/cassandra/conf/cassandra.yaml /etc/cassandra/conf/cassandra.yaml.backup

Subsequently, open the cassandra.yaml file:

sudo nano /etc/cassandra/conf/cassandra.yaml

Within the file, you’d want to search for and modify these parameters:

authenticator: org.apache.cassandra.auth.PasswordAuthenticator
authorizer: org.apache.cassandra.auth.CassandraAuthorizer
roles_validity_in_ms: 0
permissions_validity_in_ms: 0

Tweak other settings per your needs, and if they appear commented out, ensure you uncomment them. Complete the editing process by saving the file.

Afterward, reboot Cassandra to apply your modifications:

sudo systemctl restart cassandra

Adding an Administrative Superuser For Apache Cassandra

With authentication now activated, it’s essential to configure a user. Using the Cassandra Command shell utility, log in using the default user credentials:

cqlsh -u cassandra -p cassandra

Initiate a new superuser by replacing [username] and [yourpassword] with your specifics:

CREATE ROLE [username] WITH PASSWORD = '[yourpassword]' AND SUPERUSER = true AND LOGIN = true;

After that, exit and re-login with your new superuser details:

cqlsh -u username -p yourpassword

Diminish the default Cassandra account’s elevated permissions:

ALTER ROLE cassandra WITH PASSWORD = 'cassandra' AND SUPERUSER = false AND LOGIN = false;
REVOKE ALL PERMISSIONS ON ALL KEYSPACES FROM cassandra;

And, grant full permissions to your superuser:

GRANT ALL PERMISSIONS ON ALL KEYSPACES TO '[username]';

Conclude this section by logging out.

Customizing the Console Configuration

The Cassandra Shell can be tailored to your needs. It reads its configuration from the cqlshrc file found in the ~/.cassandra directory. A sample file providing insights into possible settings lies at /etc/cassandra/conf/cqlshrc.sample.

Begin by copying this sample file:

sudo cp /etc/cassandra/conf/cqlshrc.sample ~/.cassandra/cqlshrc

Adjust the cqlshrc file’s permissions:

sudo chmod 600 ~/.cassandra/cqlshrc
sudo chown $USER:$USER ~/.cassandra/cqlshrc

Open it for editing:

nano ~/.cassandra/cqlshrc

To automate login with superuser credentials, locate and edit the following section:

[authentication]
username = [superuser]
password = [password]

Remember to save after completing your edits. Now, when you log in to the Cassandra shell, it will reflect your changes:

cqlsh

Renaming the Cluster

You might want to rename the cluster to make the system more identifiable. Initiate by logging into the cqlsh terminal:

cqlsh

Replace [new_name] with your desired cluster name:

UPDATE system.local SET cluster_name = '[new_name]' WHERE KEY = 'local';

Exit the terminal and open /etc/cassandra/conf/cassandra.yaml for further editing:

sudo nano /etc/cassandra/conf/cassandra.yaml

Locate the cluster_name variable and replace its value with your chosen name. Save your changes.

Lastly, clear Cassandra’s system cache:

nodetool flush system

Restart Cassandra:

sudo systemctl restart cassandra

When you log in to the shell, it will display your chosen cluster name.

Verifying Configuration Changes

After making configuration alterations, it’s always a good practice to ensure they’ve taken effect and check the Cassandra cluster’s overall health.

Cluster Name Verification: Post the renaming process when you log back into the cqlsh shell:

cqlsh

The prompt should now display the newly set cluster name.

Conclusion

In this guide, we’ve walked through the steps to install Apache Cassandra on Rocky Linux, covering both versions 9 and 8. These instructions provide you with a robust, scalable database solution for big data needs. Regularly check for updates to keep Cassandra performing well and secure. Practice using Cassandra to fully master its features. Dive in, experiment, and see how it can transform your data management.