Book Image

Argo CD in Practice

By : Liviu Costea, Spiros Economakis
Book Image

Argo CD in Practice

By: Liviu Costea, Spiros Economakis

Overview of this book

GitOps follows the practices of infrastructure as code (IaC), allowing developers to use their day-to-day tools and practices such as source control and pull requests to manage apps. With this book, you’ll understand how to apply GitOps bootstrap clusters in a repeatable manner, build CD pipelines for cloud-native apps running on Kubernetes, and minimize the failure of deployments. You’ll start by installing Argo CD in a cluster, setting up user access using single sign-on, performing declarative configuration changes, and enabling observability and disaster recovery. Once you have a production-ready setup of Argo CD, you’ll explore how CD pipelines can be built using the pull method, how that increases security, and how the reconciliation process occurs when multi-cluster scenarios are involved. Next, you’ll go through the common troubleshooting scenarios, from installation to day-to-day operations, and learn how performance can be improved. Later, you’ll explore the tools that can be used to parse the YAML you write for deploying apps. You can then check if it is valid for new versions of Kubernetes, verify if it has any security or compliance misconfigurations, and that it follows the best practices for cloud-native apps running on Kubernetes. By the end of this book, you’ll be able to build a real-world CD pipeline using Argo CD.
Table of Contents (15 chapters)
1
Part 1: The Fundamentals of GitOps and Argo CD
4
Part 2: Argo CD as a Site Reliability Engineer
7
Part 3: Argo CD in Production

Core concepts and vocabulary

In this section, we will describe some of the core components of Argo CD like reconciliation and describe in detail the core objects CRDs of Argo CD. In parallel, we will set up a vocabulary so we can have a common language for Argo CD operations. Lastly, we will observe the reconciliation loop and how Argo CD works.

Argo CD reconciliation

Argo CD as we described previously has a duty to match the desired state described in a Git repository with the live state in the cluster and deliver it in the environment of our preference. This is called reconciliation and Argo CD is in a reconciling loop from Git repository to Kubernetes as the following image shows, assuming we use Helm:

Figure 2.1 – Reconciling loop

As we see in Figure 2.1, Argo CD watches the Git repository and runs first a Helm template to generate the Kubernetes manifest YAML and compare them with the desired state in the cluster and it is called Sync status. If Argo CD identifies any differences...