Cassandra is a free and open-source, distributed, wide column store, NoSQL database management system designed to handle large amounts of data across many commodity servers, providing high availability with no single point of failure. Cassandra offers robust support for clusters spanning multiple datacenters, with asynchronous masterless replication allowing low latency operations for all clients.

For other Clear Linux* OS based container images, see: https://hub.docker.com/u/clearlinux

Why use a clearlinux based image?

Clear Linux* OS is an open source, rolling release Linux distribution optimized for performance and security, from the Cloud to the Edge, designed for customization, and manageability.

Clear Linux* OS based container images use:

Optimized libraries that are compiled with latest compiler versions and flags.
Software packages that follow upstream source closely and update frequently.
An aggressive security model and best practices for CVE patching.
A multi-staged build approach to keep a reduced container image size.
The same container syntax as the official images to make getting started easy.

To learn more about Clear Linux* OS, visit: https://clearlinux.org.

Deployment:

Deploy with Docker

The easiest way to get started with this image is by simply pulling it from Docker Hub.

*Note: This container uses the same syntax as the official cassandra image.

Pull the image from Docker Hub:
```
docker pull clearlinux/cassandra
```

Start a container using the examples below:

docker run --name some-cassandra --network some-network -d clearlinux/cassandra:tag

connect to cassandra from cqlsh

docker run -it --network some-network --rm clearlinux/cassandra cqlsh -h some-cassandra

Deploy with Kubernetes

This image can also be deployed on a Kubernetes cluster.The following example YAML files are provided in the repository as reference for deploying Cassandra with Stateful Sets on a single node cluster:

pv-local.yaml: local persistent volumes for cassandra database.
storageclass.yaml: create a StorageClass with the volumeBindingMode set to “WaitForFirstConsumer”
cassandra-deployment.yaml: example using default configuration to create a basic cassandra service.
cassandra-deployment-conf.yaml: example using your own custom configuration to create a cassandra service.
cassandra-statefulset.yaml: create a Headless Service and a Statefulset for Cassandra with three replicas.

In this tutorial, we proposed 2 different kinds of method to deploy cassandra: stateless and stateful

If you want to deploy Cassandra in stateful manner, the example uses official clearlinux cassandra container, to deploy this container on a Kubernetes cluster, please follow with below steps:

Create /mnt/disks directory on local test cluster

$ mkdir /mnt/disks
$ for vol in vol1 vol2 vol3; do
      mkdir /mnt/disks/$vol
      chmod 777 /mnt/disks/$vol
done

Create a StorageClass
```
kubectl apply -f storageclass.yaml
```
Create local persistent volumes
```
kubectl apply -f pv-local.yaml
```
Create a Headless Service and a Statefulset for Cassandra with three replicas
```
kubectl apply -f cassandra-statefulset.yaml 
```

Validate the Cassandra StatefulSet

*Get the Cassandra StatefulSet:

kubectl get statefulset cassandra

The response should be:

NAME        READY   AGE
cassandra   4/4     19h

*Get the Pods to see the ordered creation status:

kubectl get pods -l="app=cassandra"

The response should be:

NAME          READY   STATUS    RESTARTS   AGE
cassandra-0   1/1     Running   0          19h
cassandra-1   1/1     Running   0          19h
cassandra-2   1/1     Running   1          19h
cassandra-3   1/1     Running   1          19h

*Run the Cassandra nodetool to display the status of the ring

kubectl exec -it cassandra-0 -- nodetool status

The response should be:

Datacenter: datacenter1
=======================
Status=Up/Down
|/ State=Normal/Leaving/Joining/Moving
--  Address      Load       Tokens   Owns (effective)  Host ID  Rack
UN  10.244.0.64  227.89 KiB  256     24.4%      d0bf15be-ce18-40be-b3c2-f6f80e307e31  rack1
UN  10.244.0.61  189.28 KiB  256     23.2%      2aa68c9c-99b7-4a70-803a-5886019391ac  rack1
UN  10.244.0.62  195.16 KiB  256     28.1%      ecb0fe92-2b28-4be5-921d-a7d6b3367b5f  rack1
UN  10.244.0.63  228.66 KiB  256     24.3%      9720efad-a434-4b81-9434-9b7cafd72a9b  rack1

If you want to deploy Cassandra in stateless manner, please follow with below steps:

If you want to deploy cassandra-deployment.yaml
```
kubectl create -f cassandra-deployment.yaml
```
Or if you want to deploy cassandra-deployment-conf.yaml
```
kubectl create -f cassandra-deployment-conf.yaml
```
Install Cassandra bundle and add environmental variable.
```
source cassandra-setup.sh
```
Connect to the service, where 30001 is the port number defined in your service.
```
cqlsh <nodeIP> 30001
```

Build and modify:

The Dockerfiles for all Clear Linux* OS based container images are available at https://github.com/clearlinux/dockerfiles. These can be used to build and modify the container images.

Clone the clearlinux/dockerfiles repository.

git clone https://github.com/clearlinux/dockerfiles.git

Change to the directory of the application:
```
cd cassandra/
```
Build the container image:
```
docker build -t clearlinux/cassandra .
```
Refer to the Docker documentation for default build arguments. Additionally:
- swupd_args - specifies arguments to pass to the Clear Linux* OS software manager. See the swupd man pages for more information.

Licenses

All licenses for the Clear Linux* Project and distributed software can be found at https://clearlinux.org/terms-and-policies

README.md

Clear Linux* OS cassandra container image

What is this image?