docker image tagging best practices feature

Docker image tagging: best practices in a CI pipeline

This article explains why you should not tag your own Docker images with only the “latest” tag. I discuss alternative best practices, categorizing them into stable vs. unstable version tags. I also fully deconstruct a Docker image tag into its basic components to improve your understanding of Docker image names and tags. Introduction When you … Read more

self-hosted gitlab runner

Operating a self-hosted GitLab runner with Docker

In this article I explain how (and why) you install and use a Linux-based self-hosted GitLab CI/CD runner that executes jobs of your GitLab pipelines. I go into a few caveats and how you can reduce maintenance efforts for the runner to a minimum. Introduction GitLab CI/CD has a distributed architecture that consists of a … Read more

clean code summary feature

Book recommendation: Clean Code (Robert C. Martin)

In this book recommendation, I review the book Clean Code by Robert C. Martin, released in 2008. I offer my 13 page summary of the book as free download, and provide links to further reading material. Introduction to clean code In 2008, Robert C. Martin (a.k.a. “Uncle Bob”) released the book Clean code. It was … Read more

continuous deployment docker

Automatic Continuous Deployment of Docker containers

This article explains how to achieve Continuous Deployment of Docker-based software, using either pull-based approaches (external tools such as watchtower and harbormaster), or push-based techniques (deployment from the CI/CD pipeline). I explain the advantages and disadvantages of each approach, and also illustrate how automated testing greatly reduces the risk of unnoticed failed deployments. Introduction When … Read more

operating docker tips

Tips for operating Docker – the best tools and commands

This article presents useful tips for operating Docker engine on a Linux server. I explain how you can improve the server’s security via automatic updates and scanning the images of your running containers, how to reduce the maintenance efforts by making sure your disks don’t run out of space, and how to set up a … Read more

optimize Docker image size feature

Docker optimization guide: 8 tricks to optimize your Docker image size

This article introduces several tricks that you can apply at build-time, to reduce the size of your Docker images, including the use of a small base image, multi-stage builds, consolidation of RUN statements, avoiding separate chown commands, or using the tool docker-slim. Introduction Docker has become a commodity to package and distribute (backend) software. So … Read more

optimize Docker build speed in CI

Docker optimization guide: optimize build speed in CI pipelines

This article offers several tips for tweaking the build speed of Docker images in CI pipelines. I explain multiple caching-tricks offered by BuildKit, which is an alternative image build engine. I also elaborate on how the .dockerignore file and extra arguments to package managers such as apt can speed up your image builds. Introduction As … Read more

optimize Dockre development speed

Docker optimization guide: the 5 best tips to optimize Docker development speed

This article presents 5 tips that improve the speed of building Docker images locally. It focuses on two problems: iterating on your unfinished Dockerfile (where you still figure out configuration options and which packages to install), and iterating on your code (assuming a finished Dockerfile). I discuss tricks such as using BuildKit, the .dockerignore file, … Read more

GitOps with GitLab ArgoCD and Renovate Bot

GitOps for managing cluster software using GitLab, ArgoCD and Renovate Bot

This article demonstrates how to use the ArgoCD GitOps controller to deploy applications to a Kubernetes cluster. The definitions/manifests of these applications, such as an Ingress controller, monitoring stack, etc., are stored in GitLab. They are automatically updated by Renovate Bot, which regularly scans your GitLab project for outdated dependencies. A demo project illustrates how … Read more