gitops-linkerd

Progressive Delivery workshop with Linkerd, Flagger, Flux and Weave GitOps.

Introduction

What is GitOps?

GitOps is a way to do Continuous Delivery, it works by using Git as a source of truth for declarative infrastructure and workloads. For Kubernetes this means using git push instead of kubectl apply/delete or helm install/upgrade.

In this workshop you'll be using GitHub to host the config repository and Flux as the GitOps delivery solution.

What is Progressive Delivery?

Progressive delivery is an umbrella term for advanced deployment patterns like canaries, feature flags and A/B testing. Progressive delivery techniques are used to reduce the risk of introducing a new software version in production by giving app developers and SRE teams a fine-grained control over the blast radius.

In this workshop you'll be using Flagger, Linkerd and Prometheus to automate Canary Releases and A/B Testing for your applications.

Prerequisites

For this workshop you will need a GitHub account and a Kubernetes cluster version 1.21 or newer with Load Balancer support.

In order to follow the guide you'll need a GitHub account and a personal access token that can create repositories (check all permissions under repo).

Fork the repository

Start by forking the gitops-linkerd repository on your own GitHub account. Then generate a GitHub personal access token that can create repositories (check all permissions under repo), and export your GitHub token, username and repo name as environment variables:

export GITHUB_TOKEN=<your-token>
export GITHUB_USER=<your-username>
export GITHUB_REPO="gitops-linkerd"

Next clone your repository locally with:

git clone https://github.com/${GITHUB_USER}/${GITHUB_REPO}.git
cd ${GITHUB_REPO}

Install CLI tools

Install flux, kubectl, linkerd, step and other CLI tools with Homebrew:

brew bundle

The complete list of tools can be found in the Brewfile.

Cluster bootstrap

With the flux bootstrap command you can install Flux on a Kubernetes cluster and configure it to manage itself from a Git repository. If the Flux components are present on the cluster, the bootstrap command will perform an upgrade if needed.

flux bootstrap github \
  --owner=${GITHUB_USER} \
  --repository=${GITHUB_REPO} \
  --branch=main \
  --path=./clusters/my-cluster \
  --personal

When Flux has access to your repository it will do the following:

• installs the Flux UI (Weave GitOps OSS)
• installs cert-manager and generates the Linkerd trust anchor certificate
• installs Linkerd using the linkerd-crds, linkerd-control-plane, linkerd-viz and linkerd-smi Helm charts
• waits for the Linkerd control plane to be ready
• installs the Kubernetes NGINX ingress in the ingress-nginx namespace
• installs Flagger and configures its load testing service inside the flagger-system namespace
• waits for NGINX and Flagger to be ready
• creates the frontend deployment and configures it for A/B testing
• creates the backend deployment and configures it for progressive traffic shifting

Watch Flux installing Linkerd first, then the demo apps:

flux get kustomizations --watch

When bootstrapping a cluster with Linkerd, it is important to control the installation order. For the applications pods to be injected with Linkerd proxy, the Linkerd control plane must be up and running before the apps. For the ingress controller to forward traffic to the apps, NGINX must be injected with the Linker sidecar.

Access the dashboards

To access the Flux dashboard, start port forwarding with:

kubectl -n flux-system port-forward svc/weave-gitops 9001:9001 &

Navigate to http://localhost:9001 and login using the username admin and the password flux.

To access the Linkerd dashboard, start port forwarding with:

kubectl -n linkerd-viz port-forward svc/web 8084:8084 &

Navigate to http://localhost:8084 to access the dashboard.