Start simple

  • Massively powerful tools
  • Simple to use
  • Complex use cases
  • Focus on the key activities

This piece is about a massively powerful set of tools that collectively manage container-based applications. Each of these tools is vast in its power and scope. As such, each can be used in a plethora of different ways. By means of an introduction to each, my goal is to focus on a few functions of each tool, how they work and what they do.


Docker

  • Docker runtime
  • Running containers
  • Concurrent but isolated
  • Installation options
    • Dev
    • UAT and Production

Docker is not a hypervisor, but it behaves a little bit like one. It allows different workloads to be run side-by-side without interfering with each other. Containers ensure standardisation for distribution and isolation for execution. Docker can be installed for a variety of platforms. In production, or Production-like environments, that’s typically as a package for Linux.


Docker interactions

  • Runs containers
    • Entry point
    • Run as 1000:1000
  • Read-only file system
  • Volumes
  • Port mapping

Docker command-line

docker run -d --restart=unless-stopped \
  -p 80:80 -p 443:443 \
  rancher/rancher:latest

A single container running on a Docker host

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Docker compose

  • Run up multiple containers
  • File-based, YAML
  • Simple to start up docker-compose up
  • Simple to stop them docker-compose down

Docker compose

version: "3"
services:
    elasticsearch:
        image: docker.elastic.co/elasticsearch/elasticsearch:7.5.1
        environment:
            - discovery.type=single-node
        ports:
            - 9200:9200

    logstash:
        image: docker.elastic.co/logstash/logstash:7.5.1
        ports:
            - 5044:5044

    kibana:
        image: docker.elastic.co/kibana/kibana:7.5.1
        ports:
            - 5601:5601
        depends_on:
            - elasticsearch

A single Docker host running multiple containers side-by-side

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Kubernetes

  • Container orchestration
  • Networking
  • Services
    • Load balancing
    • High availability
  • Ingress
  • Secret management

Kubernetes entities

  • Pod
    • wraps a container
  • Deployment
    • defines pod and how it’s deployed to cluster
    • multiple instances of a pod
    • multiple different pods

A Kubernetes pod wrapping a single container

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A single Kubernetes pod wrapping multiple containers (sidecar pattern)

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Kubernetes entities

  • Services
    • routed across multiple pods
    • hides underlying implementation
  • Route to service
    • ClusterIP
    • NodePort
    • Ingress

Services broker requests to an orchestrated set of pods

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Pods may be replicates across multiple worker nodes

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Kubernetes cluster

  • Master nodes
  • Worker nodes

Help

If you’d like help organising and preparing your digital strategy, working with your team to foster a data-driven culture, or just hands-on-keyboard training in infrastructure-as-code, please get in touch.

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