Kerberos Docker Compose Example

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Kerberos, a network authentication protocol, is designed to provide strong authentication for client/server applications using secret-key cryptography. Integrating Kerberos authentication can be essential for applications requiring secure network communication in modern development environments. Docker, a leading platform for developing, shipping, and running applications, can be configured to work with Kerberos authentication, allowing developers to create secure, isolated environments for their applications. This article provides a practical guide on integrating Kerberos authentication within a Docker Compose setup, complete with an example configuration.

Table of Contents

Prerequisites

Before diving into the Docker Compose configuration, ensure you have the following prerequisites covered:

Docker and Docker Compose installed on your machine.
Basic understanding of Docker, Docker Compose, and Kerberos authentication.
Access to a Kerberos server or the necessary permissions to set up one within your network.

Docker Compose with Kerberos: An Example Configuration

The following example demonstrates how to set up a Docker Compose environment that integrates with Kerberos for authentication. This setup includes a service that acts as a Kerberos client, communicating with a Kerberos server for authentication.

Step 1: Define Your Docker Compose File

Create a docker-compose.yml file in your project directory. This file will define two services: one for the Kerberos server and another for the client application that requires Kerberos authentication.

version: '3.8'

services:
  kerberos-server:
    image: krb5-server
    environment:
      KERBEROS_REALM: EXAMPLE.COM
      KERBEROS_ADMIN: admin/admin
      KERBEROS_ADMIN_PASSWORD: adminpassword
    ports:
      - "88:88"
      - "749:749"
    volumes:
      - kerberos_data:/var/lib/krb5kdc

  app-client:
    build: ./app
    environment:
      KERBEROS_REALM: EXAMPLE.COM
      KERBEROS_KDC: kerberos-server
    volumes:
      - app_data:/app/data

volumes:
  kerberos_data:
  app_data:

In this configuration:

kerberos-server uses a hypothetical krb5-server image should be replaced with the image you intend to use for your Kerberos server. The environment variables KERBEROS_REALM, KERBEROS_ADMIN, and KERBEROS_ADMIN_PASSWORD These are placeholders for your Kerberos realm, admin user, and password.
app-client represents the client application requiring Kerberos authentication. This service is built from a Dockerfile located in the ./app directory. The environment variables KERBEROS_REALM and KERBEROS_KDC are configured to match the Kerberos server settings.
volumes are used to persist data across container restarts for both the Kerberos server and the client application.

Step 2: Configure Your Client Application

Ensure your client application (represented by app-client in the Docker Compose file) is properly configured to use Kerberos for authentication. This typically involves setting up a Kerberos client library in your application and configuring it to use the correct realm and KDC (Key Distribution Center) address.

Step 3: Build and Run Your Docker Compose Environment

Navigate to your project directory, where the docker-compose.yml file is located and run the following command to build and start your services:

docker compose up --build

This command builds the app-client service from its Dockerfile and starts both the Kerberos server and the client application, establishing a network where they can communicate securely using Kerberos authentication.

Conclusion

Integrating Kerberos authentication within a Docker Compose environment adds a layer of security to your applications, ensuring that communications are authenticated and authorized securely. While the example provided is a basic illustration, it lays the groundwork for implementing more complex and secure application architectures. Always replace placeholder values with your actual configuration details and adjust the setup according to your specific requirements and infrastructure.

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Anastasios Antoniadis

Anastasios Antoniadis is the founder and editor-in-chief of BORDERPOLAR... He is a software engineer, blogger, and avid gamer covering tech, gaming, and coding guides for over 4 years. He is a 2014 graduate of the Department of Informatics and Telecommunications of the University of Athens, an M.Sc. holder in Computer Science, and a Ph.D. student in Program Analysis.