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Overview

This template provides a production‑ready Apache Cassandra instance as a Monk runnable. You can:
  • Run it directly to get a managed Cassandra container with sensible defaults
  • Inherit it in your own runnable to seamlessly add a distributed wide-column NoSQL database to your stack
Apache Cassandra is a highly scalable, distributed NoSQL database designed to handle large amounts of data across many commodity servers, providing high availability with no single point of failure.

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What this template manages

  • Cassandra container (cassandra image, configurable tag)
  • Network service on port 9042 (CQL native transport)
  • Persistent volumes for data storage
  • Authentication configuration

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Quick start (run directly)

  1. Load templates
monk load MANIFEST
  1. Run Cassandra with defaults
monk run cassandra/cassandra
  1. Customize credentials (recommended via inheritance)
Running directly uses the defaults defined in this template’s variables. Secrets added with monk secrets add will not affect this runnable unless you inherit it and reference those secrets.
  • Preferred: inherit and replace variables with secret("...") as shown below.
  • Alternative: fork/clone and edit the variables in cassandra/cassandra.yml, then monk load MANIFEST and run.
Once started, connect to localhost:9042 (or the runnable hostname inside Monk networks) using CQL.

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Configuration

Key variables you can customize in this template: 
variables:
  cassandra-image: "latest"              # container image tag
  cassandra-password: "monk"             # Cassandra password (env: CASSANDRA_PASSWORD)
Data is persisted under ${monk-volume-path}/cassandra on the host. Inherit the Cassandra runnable in your application and declare a connection. Example: 
namespace: myapp
db:
  defines: runnable
  inherits: cassandra/cassandra
api:
  defines: runnable
  containers:
    api:
      image: myorg/api
  connections:
    database:
      runnable: db
      service: cassandra
  variables:
    database-host:
      value: <- connection-hostname("database")
    database-password:
      value: <- secret("cassandra-password")
Then set the secrets once and run your app group: 
monk secrets add -g cassandra-password="STRONG_PASSWORD"
monk run myapp/api

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Ports and connectivity

  • Service: cassandra on TCP port 9042 (CQL native transport)
  • From other runnables in the same process group, use connection-hostname("\<connection-name>") to resolve the DB host.

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Persistence and configuration

  • Data path: ${monk-volume-path}/cassandra:/var/lib/cassandra
  • Cassandra stores all keyspaces, tables, and data in this directory
  • Cassandra cluster: see the cassandra-cluster/ template in this repository for a multi-node cluster setup with seed nodes
  • Combine with spark/ for analytics workloads
  • Use with prometheus-grafana/ for monitoring and metrics

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Troubleshooting

  • Cassandra may take several minutes to start, especially on first launch
  • If you changed cassandra-password but the container has existing data, authentication may fail. Either reset the data volume or update the password inside Cassandra to match.
  • Ensure the host volumes are writable by the container user.
  • Check logs:
monk logs -l 500 -f local/cassandra/cassandra