Flux Infrastructure

Highly opinionated template for deploying a single k3s cluster with Ansible and Terraform backed by Flux and SOPS.

The purpose here is to showcase how you can deploy an entire Kubernetes cluster and show it off to the world using the GitOps tool Flux. When completed, your Git repository will be driving the state of your Kubernetes cluster. In addition with the help of the Ansible, Terraform and Flux SOPS integrations you'll be able to commit Age encrypted secrets to your public repo.

Overview

• Introduction
• Prerequisites
• Repository structure
• Lets go!
• Thanks

👋 Introduction

The following components will be installed in your k3s cluster by default. They are only included to get a minimum viable cluster up and running. You are free to add / remove components to your liking but anything outside the scope of the below components are not supported by this template.

Feel free to read up on any of these technologies before you get started to be more familiar with them.

• cert-manager - SSL certificates - with Cloudflare DNS challenge
• calico - CNI (container network interface)
• echo-server - REST Server Tests (Echo-Server) API (useful for debugging HTTP issues)
• flux - GitOps tool for deploying manifests from the cluster directory
• hajimari - start page with ingress discovery
• kube-vip - layer 2 load balancer for the Kubernetes control plane
• local-path-provisioner - default storage class provided by k3s
• metallb - bare metal load balancer
• reloader - restart pods when Kubernetes configmap or secret changes
• reflector - mirror configmaps or secrets to other Kubernetes namespaces
• system-upgrade-controller - automate upgrading k3s
• traefik - ingress controller

For provisioning the following tools will be used:

• Ubuntu - this is a pretty universal operating system that supports running all kinds of home related workloads in Kubernetes
• Ansible - this will be used to provision the Ubuntu operating system to be ready for Kubernetes and also to install k3s
• Terraform - in order to help with the DNS settings this will be used to provision an already existing Cloudflare domain and DNS settings

📝 Prerequisites

💻 Systems

• One or more nodes with a fresh install of Ubuntu Server 20.04. These nodes can be bare metal or VMs.
• A Cloudflare account with a domain, this will be managed by Terraform.
• Some experience in debugging problems and a positive attitude ;)

🔧 Tools

📍 You should install the below CLI tools on your workstation. Make sure you pull in the latest versions.

Required

Tool	Purpose
ansible	Preparing Ubuntu for Kubernetes and installing k3s
direnv	Exports env vars based on present working directory
flux	Operator that manages your k8s cluster based on your Git repository
age	A simple, modern and secure encryption tool (and Go library) with small explicit keys, no config options, and UNIX-style composability.
go-task	A task runner / simpler Make alternative written in Go
ipcalc	Used to verify settings in the configure script
jq	Used to verify settings in the configure script
kubectl	Allows you to run commands against Kubernetes clusters
sops	Encrypts k8s secrets with Age
terraform	Prepare a Cloudflare domain to be used with the cluster

Optional

Tool	Purpose
helm	Manage Kubernetes applications
kustomize	Template-free way to customize application configuration
pre-commit	Runs checks pre git commit
gitleaks	Scan git repos (or files) for secrets
prettier	Prettier is an opinionated code formatter.

⚠️ pre-commit

It is advisable to install pre-commit and the pre-commit hooks that come with this repository. sops-pre-commit and gitleaks will check to make sure you are not by accident committing your secrets un-encrypted.

After pre-commit is installed on your machine run:

task pre-commit:init

Remember to run this on each new clone of the repository for it to have effect.

Commands are of interest, for learning purposes:

This command makes it so pre-commit runs on git commit, and also installs environments per the config file.

pre-commit install --install-hooks

This command checks for new versions of hooks, though it will occasionally make mistakes, so verify its results.

pre-commit autoupdate

📂 Repository structure

The Git repository contains the following directories under cluster and are ordered below by how Flux will apply them.

• base directory is the entrypoint to Flux
• crds directory contains custom resource definitions (CRDs) that need to exist globally in your cluster before anything else exists
• core directory (depends on crds) are important infrastructure applications (grouped by namespace) that should never be pruned by Flux
• apps directory (depends on core) is where your common applications (grouped by namespace) could be placed, Flux will prune resources here if they are not tracked by Git anymore

cluster
├── apps
│   ├── default
│   ├── networking
│   └── system-upgrade
├── base
│   └── flux-system
├── core
│   ├── cert-manager
│   ├── metallb-system
│   ├── namespaces
│   └── system-upgrade
└── crds
    └── cert-manager

🚀 Lets go!

Very first step will be to create a new repository by clicking the Use this template button on this page.

Clone the repo to you local workstation and cd into it.

📍 All of the below commands are run on your local workstation, not on any of your cluster nodes.

🔐 Setting up Age

📍 Here we will create a Age Private and Public key. Using SOPS with Age allows us to encrypt and decrypt secrets.

1. Create a Age Private / Public Key

age-keygen -o age.agekey

2. Set up the directory for the Age key and move the Age file to it

mkdir -p ~/.config/sops/age
mv age.agekey ~/.config/sops/age/keys.txt

3. Export the SOPS_AGE_KEY_FILE variable in your bashrc, zshrc or config.fish and source it, e.g.

export SOPS_AGE_KEY_FILE=~/.config/sops/age/keys.txt
source ~/.bashrc

4. Fill out the Age public key in the .config.env under BOOTSTRAP_AGE_PUBLIC_KEY, note the public key should start with age...

☁️ Global Cloudflare API Key

In order to use Terraform and cert-manager with the Cloudflare DNS challenge you will need to create a API key.

1. Head over to Cloudflare and create a API key by going here.

2. Under the API Keys section, create a global API Key.

3. Use the API Key in the configuration section below.

📍 You may wish to update this later on to a Cloudflare API Token which can be scoped to certain resources. I do not recommend using a Cloudflare API Key, but for the purposes of this template it is easier getting started without having to define which scopes and resources are needed. For more information see the Cloudflare docs on API Keys and Tokens.

📄 Configuration

📍 The .config.env file contains necessary configuration that is needed by Ansible, Terraform and Flux.

📍 It is suggested to use three control plane nodes. If you only need a single control plane node, make sure you update ./provision/ansible/inventory/group_vars/kubernetes/k3s.yml and set k3s_use_unsupported_config to true

1. Copy the .config.sample.env to .config.env and start filling out all the environment variables. All are required and read the comments they will explain further what is required.

2. Once that is done, verify the configuration is correct by running ./configure.sh --verify

3. If you do not encounter any errors run ./configure.sh to start having the script wire up the templated files and place them where they need to be.

⚡ Preparing Ubuntu with Ansible

📍 Here we will be running a Ansible Playbook to prepare Ubuntu for running a Kubernetes cluster.

📍 Nodes are not security hardened by default, you can do this with dev-sec/ansible-collection-hardening or something similar.

1. Ensure you are able to SSH into you nodes from your workstation with using your private ssh key. This is how Ansible is able to connect to your remote nodes.

2. Install the deps by running task ansible:deps

3. Verify Ansible can view your config by running task ansible:list

4. Verify Ansible can ping your nodes by running task ansible:adhoc:ping

5. Finally, run the Ubuntu Prepare playbook by running task ansible:playbook:ubuntu-prepare

6. If everything goes as planned you should see Ansible running the Ubuntu Prepare Playbook against your nodes.

⛵ Installing k3s with Ansible

📍 Here we will be running a Ansible Playbook to install k3s with this wonderful k3s Ansible galaxy role. After completion, Ansible will drop a kubeconfig in ./provision/kubeconfig for use with interacting with your cluster with kubectl.

📍 Once more over, it is suggested to use three control plane nodes. If you only need a single control plane node, make sure you update ./provision/ansible/inventory/group_vars/kubernetes/k3s.yml and set k3s_use_unsupported_config to true

1. Verify Ansible can view your config by running task ansible:list

2. Verify Ansible can ping your nodes by running task ansible:adhoc:ping

3. Run the k3s install playbook by running task ansible:playbook:k3s-install

4. If everything goes as planned you should see Ansible running the k3s install Playbook against your nodes.

5. Verify the nodes are online

kubectl --kubeconfig=./provision/kubeconfig get nodes
# NAME           STATUS   ROLES                       AGE     VERSION
# k8s-0          Ready    control-plane,master      4d20h   v1.21.5+k3s1
# k8s-1          Ready    worker                    4d20h   v1.21.5+k3s1

🔹 GitOps with Flux

📍 Here we will be installing flux after some quick bootstrap steps.

1. Verify Flux can be installed

flux --kubeconfig=./provision/kubeconfig check --pre
# ► checking prerequisites
# ✔ kubectl 1.21.5 >=1.18.0-0
# ✔ Kubernetes 1.21.5+k3s1 >=1.16.0-0
# ✔ prerequisites checks passed

2. Pre-create the flux-system namespace

kubectl --kubeconfig=./provision/kubeconfig create namespace flux-system --dry-run=client -o yaml | kubectl --kubeconfig=./provision/kubeconfig apply -f -

3. Add the Age key in-order for Flux to decrypt SOPS secrets

cat ~/.config/sops/age/keys.txt |
    kubectl --kubeconfig=./provision/kubeconfig \
    -n flux-system create secret generic sops-age \
    --from-file=age.agekey=/dev/stdin

📍 Variables defined in ./cluster/base/cluster-secrets.sops.yaml and ./cluster/base/cluster-settings.yaml will be usable anywhere in your YAML manifests under ./cluster

4. Verify the ./cluster/base/cluster-secrets.sops.yaml and ./cluster/core/cert-manager/secret.sops.yaml files are encrypted with SOPS

5. If you verified all the secrets are encrypted, you can delete the tmpl directory now

6. Push you changes to git

git add -A
git commit -m "initial commit"
git push

7. Add a Github SSH key for Flux

   1. Create a new ssh key for Flux to use exclusively.

   ssh-keygen -t ed25519 -C "<computername>@hello@iwrite.software"

   2. Add the key to your Github SSH Keystore

   3. Provide flux with the SSH key.

   flux -n flux-system create secret git flux-system \
       --url=ssh://git@github.com/sparksd2145/flux-infra \
       ---ssh-key-algorithm=ed25519 \
       --private-key-file=./private.key

8. Install Flux

📍 Due to race conditions with the Flux CRDs you will have to run the below command twice. There should be no errors on this second run.

kubectl --kubeconfig=./provision/kubeconfig apply --kustomize=./cluster/base/flux-system
# namespace/flux-system configured
# customresourcedefinition.apiextensions.k8s.io/alerts.notification.toolkit.fluxcd.io created
# ...
# unable to recognize "./cluster/base/flux-system": no matches for kind "Kustomization" in version "kustomize.toolkit.fluxcd.io/v1beta1"
# unable to recognize "./cluster/base/flux-system": no matches for kind "GitRepository" in version "source.toolkit.fluxcd.io/v1beta1"
# unable to recognize "./cluster/base/flux-system": no matches for kind "HelmRepository" in version "source.toolkit.fluxcd.io/v1beta1"
# unable to recognize "./cluster/base/flux-system": no matches for kind "HelmRepository" in version "source.toolkit.fluxcd.io/v1beta1"
# unable to recognize "./cluster/base/flux-system": no matches for kind "HelmRepository" in version "source.toolkit.fluxcd.io/v1beta1"
# unable to recognize "./cluster/base/flux-system": no matches for kind "HelmRepository" in version "source.toolkit.fluxcd.io/v1beta1"

8. Verify Flux components are running in the cluster

kubectl --kubeconfig=./provision/kubeconfig get pods -n flux-system
# NAME                                       READY   STATUS    RESTARTS   AGE
# helm-controller-5bbd94c75-89sb4            1/1     Running   0          1h
# kustomize-controller-7b67b6b77d-nqc67      1/1     Running   0          1h
# notification-controller-7c46575844-k4bvr   1/1     Running   0          1h
# source-controller-7d6875bcb4-zqw9f         1/1     Running   0          1h

🤝 Thanks

Big shout out to all the authors and contributors to the projects that we are using in this repository.