Apache Cassandra

Configuration loading is designed for containerization in mind. The container engine and orchestrator can mount volumes (secret or regular) as well as set the environment variables as outlined below.

You may set configurations through both files and environment variables. Please note that environment variables will override the settings in the configuration files. The configuration files are all expected to be in YAML format.

Table of contents

• File Location(s)
• Configuration File
  • Example Configuration File
  • Example Environment Variables
• Design Documentation

File Location(s)

The configuration loader will search for the configurations in the following order:

Location	Details
/etc/MCQPlatform.conf/	The etc directory is the canonical location for configurations.
$HOME/.MCQPlatform/	Configurations can be located in the user's home directory.
./configs/	The config folder in the root directory where the application is located.
Environment variables	Finally, the configurations will be loaded from environment variables and override configuration files

Configuration File

The expected file name is CassandraConfig.yaml. All the configuration items below are required.

Name	Environment Variable Key	Type	Description
Authentication	CASSANDRA_AUTHENTICATION		Parent key for authentication information.
↳ username	↳ .USERNAME	string	Username for Cassandra session login.
↳ password	↳ .PASSWORD	string	Password for Cassandra session login.
Keyspace	CASSANDRA_KEYSPACE		Parent key for Keyspace configuration.
↳ name	↳ .NAME	string	Keyspace name.
↳ replication_class	↳ .REPLICATION_CLASS	string	Data replication strategy.
↳ replication_factor	↳ .REPLICATION_FACTOR	int	Data replication factor.
Connection	CASSANDRA_CONNECTION		Parent key for connection configuration.
↳ consistency	↳ .CONSISTENCY	string	Keyspace name.
↳ cluster_ip	↳ .CLUSTER_IP	string array	An array of cluster IPs to bootstrap the connection. May optionally contain the port numbers.
↳ proto_version	↳ .PROTO_VERSION	int	Connection protocol version.
↳ timeout	↳ .TIMEOUT	int	Connection timeout in seconds.
↳ max_connection_attempts	↳ .MAX_CONNECTION_ATTEMPTS	int	The maximum number of initial connection attempts to Cassandra before failing.

:warning: Consistency :warning:

It is highly advised that the consistency level be set to Quorum. Quorum provides a good balance between read and write performance thereby providing an appropriate balance between consistency and availability. Setting the level to All can negatively impact read and write performance.

A balance between consistency and availability is vital to mitigate data inconsistencies with user account credentials.

Example Configuration File

authentication:
  username: admin
  password: root
keyspace:
  name: mcq_platform
  replication_class: SimpleStrategy
  replication_factor: 3
connection:
  consistency: quorum
  cluster_ip: [127.0.0.1]
  proto_version: 4
  timeout: 10
  max_connection_attempts: 5

Example Environment Variables

export CASSANDRA_AUTHENTICATION.USERNAME=admin
export CASSANDRA_AUTHENTICATION.PASSWORD=root

Design Documentation

The technology selection case study and table schema design documentation can be found here.