docker-development-youtube-series/kubernetes/fluxcd

Introduction to Flux CD v2

Create a kubernetes cluster

In this guide we we''ll need a Kubernetes cluster for testing. Let's create one using kind

kind create cluster --name fluxcd --image kindest/node:v1.23.5

See cluster up and running:

kubectl get nodes
NAME                  STATUS   ROLES                  AGE     VERSION
fluxcd-control-plane   Ready    control-plane,master   2m12s   v1.23.5

Run a container to work in

run Alpine Linux:

docker run -it --rm -v ${HOME}:/root/ -v ${PWD}:/work -w /work --net host alpine sh

install some tools

# install curl 
apk add --no-cache curl

# install kubectl 
curl -sLO https://storage.googleapis.com/kubernetes-release/release/`curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt`/bin/linux/amd64/kubectl
chmod +x ./kubectl
mv ./kubectl /usr/local/bin/kubectl

# install helm 

curl -o /tmp/helm.tar.gz -LO https://get.helm.sh/helm-v3.10.1-linux-amd64.tar.gz
tar -C /tmp/ -zxvf /tmp/helm.tar.gz
mv /tmp/linux-amd64/helm /usr/local/bin/helm
chmod +x /usr/local/bin/helm

test cluster access:

/work # kubectl get nodes
NAME                    STATUS   ROLES    AGE   VERSION
fluxcd-control-plane   Ready    control-plane,master   3m26s   v1.23.5

Flux CD

get flux command-line tool

Let's download the flux command-line utility.
We can get this utility from the GitHub Releases page

It's also worth noting that you want to ensure you get a compatible version of flux which supports your version of Kubernetes. Checkout the prerequisites page.

curl -o /tmp/flux.tar.gz -sLO https://github.com/fluxcd/flux2/releases/download/v0.41.1/flux_0.41.1_linux_amd64.tar.gz
tar -C /tmp/ -zxvf /tmp/flux.tar.gz
mv /tmp/flux /usr/local/bin/flux
chmod +x /usr/local/bin/flux

Now we can run flux --help to see its installed

Check our cluster

flux check --pre

Documentation

As with every guide, we start with the documentation
The Core Concepts is a good place to start.

We begin by following the steps under the bootstrap section for GitHub

We'll need to generate a personal access token (PAT) that can create repositories by checking all permissions under repo.

Once we have a token, we can set it:

export GITHUB_TOKEN=<your-token>

Then we can bootstrap it using the GitHub bootstrap method

flux bootstrap github \
  --owner=marcel-dempers \
  --repository=docker-development-youtube-series \
  --path=kubernetes/fluxcd/repositories/config/clusters/dev-cluster \
  --personal \
  --branch fluxcd-2022

flux check

# flux manages itself using GitOps objects:
kubectl -n flux-system get GitRepository
kubectl -n flux-system get Kustomization

Check the source code that flux bootstrap created

git pull origin <branch-name>

Repository structure

https://fluxcd.io/flux/guides/repository-structure/

• Mono Repo
• Repo per team
• Repo per app

- apps
  - example-app-1
  - example-app-2
- infrastructure
  - ingress-nginx
  - monitoring
- clusters
  -dev-cluster
  -prod-cluster

build our app

cd kubernetes/fluxcd/repositories/example-app-1/src

docker build . -t example-app-1:0.0.1

#load the image to our test cluster so we dont need to push to a registry
kind load docker-image example-app-1:0.0.1 --name fluxcd 

deploy our app

kubectl -n default apply -f repositories/config/apps/example-app-1/gitrepository.yaml
kubectl -n default apply -f repositories/config/apps/example-app-1/kustomization.yaml

# check our flux resources 
kubectl -n default describe gitrepository example-app-1
kubectl -n default describe kustomization example-app-1

# check deployed resources
kubectl get all

kubectl port-forward svc/example-app-1 80:80

changes to our app

Once we make changes to our app.py we can build a new image with a new tag

cd kubernetes/fluxcd/repositories/example-app-1/src

docker build . -t example-app-1:0.0.2

#load the image to our test cluster so we dont need to push to a registry
kind load docker-image example-app-1:0.0.2 --name fluxcd 

# git commit & git push to branch!

deploy by updating manifest

To update our app, we simply have to update the image tag in our kubernetes YAML file and flux will sync it.
This is generally the role of CI, where flux concern is mainly CD.

Here is an example on how to automate that

deploy by image scanning

An alternative method is to use your CI to build and push a newly tagged image to your registry (same as first option) and use Flux image scanner to trigger the rollout instead of automating a commit to your config repo.

We firstly need to enable image scanning as its not enabled by default.
To do this we just need to re-bootstrap flux with an addition flag

flux bootstrap github \
  --owner=marcel-dempers \
  --repository=docker-development-youtube-series \
  --path=kubernetes/fluxcd/repositories/config/clusters/dev-cluster \
  --components-extra=image-reflector-controller,image-automation-controller \
  --personal \
  --branch fluxcd-2022

We need to create a image reigsitry credential where we will push our image:

kubectl -n default create secret docker-registry dockerhub-credential --docker-username "" --docker-password "" --docker-email test@test.com

kubectl -n default apply -f repositories/config/apps/example-app-1/imagerepository.yaml

Build and push our app

docker build . -t aimvector/example-app-1:0.0.2
docker push aimvector/example-app-1:0.0.2

#see changes
kubectl describe imagerepository