Argo CD

Argo CD is a declarative, GitOps continuous delivery tool for **Kubernetes. It allows application definitions, configurations, and environments should be declarative and version controlled. Application deployment and lifecycle management should be automated, auditable, and easy to understand.

Documentation & Project Homepage: Argo CD Docs

Installation

Install Argo CD on a Kubernetes Cluster, using kubectl.

kubectl create namespace argocd

kubectl apply -n argocd -f https://raw.githubusercontent.com/argoproj/argo-cd/stable/manifests/install.yaml

Add **Traefik IngressRoute.

apiVersion: traefik.containo.us/v1alpha1
kind: IngressRoute
metadata:
  name: argocd-server
  namespace: argocd
spec:
  entryPoints:
    - websecure
  routes:
    - kind: Rule
      match: Host(`argocd.example.com`)
      priority: 10
      services:
        - name: argocd-server
          port: 80
    - kind: Rule
      match: Host(`argocd.example.com`) && Headers(`Content-Type`, `application/grpc`)
      priority: 11
      services:
        - name: argocd-server
          port: 80
          scheme: h2c
  tls:
    certResolver: default

Disable internal TLS

Edit the --insecure flag in the argocd-server command of the argocd-server deployment, or simply set server.insecure: "true" in the argocd-cmd-params-cm ConfigMap.

Get the admin password

For Argo CD v1.8 and earlier, the initial password is set to the name of the server pod, for Argo CD v1.9 and later, the initial password is available from a secret named argocd-initial-admin-secret.

kubectl -n argocd get secret argocd-initial-admin-secret -o jsonpath="{.data.password}" | base64 -d

Configuration

Add private GitHub Repositories

Create a github token: https://github.com/settings/tokens
Add new repository in ArgoCD via **kubectl or the GUI

apiVersion: v1  
kind: Secret  
metadata:  
  name: repo-private-1
  labels:  
    argocd.argoproj.io/secret-type: repository  
stringData:  
  url: https://github.com/xcad2k/private-repo 
  password: <github-token> 
  username: not-used

Verify new repository is connected

Declarative Application and ApplicationSet

Apart from using the WebUI to add managed apps to ArgoCD, you can configure Application and ApplicationSet resources. This enables you to define not only ArgoCD and your apps as code, but also the definition which application you want to manage. With apps defined as YAML via an Application, you can e.g. deploy the app within a CI/CD pipeline that deploys your Argo instance.

There are two types of resources. Application and ApplicationSet. The main difference is, that you can specify so called inline generators which allow you to template your Application definition. If you manage multiple clusters with ArgoCD and you want to get an Application deployed with cluster specific parameters you want to use an ApplicationSet.

Below, you find an example for an Application and an ApplicationSet.

Application:

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: guestbook
  namespace: argocd
spec:
  destination:
    namespace: default
    server: 'https://kubernetes.default.svc'
  source:
    path: kustomize-guestbook
    repoURL: 'https://github.com/argoproj/argocd-example-apps'
    targetRevision: HEAD
  project: default
  syncPolicy:
    automated:
      prune: false
      selfHeal: false

ApplicationSet:

apiVersion: argoproj.io/v1alpha1
kind: ApplicationSet
metadata:
  name: guestbook
  namespace: argocd
spec:
  generators:
  - clusters: {} # This is a generator, specifically, a cluster generator.
  template: 
    # This is a template Argo CD Application, but with support for parameter substitution.
    metadata:
      name: '{{name}}-guestbook'
    spec:
      project: "default"
      source:
        repoURL: https://github.com/argoproj/argocd-example-apps/
        targetRevision: HEAD
        path: kustomize-guestbook
      destination:
        server: '{{server}}'
        namespace: default

Further information

More examples and tutorials regarding ArgoCD can be found in the link list below:

Basic tutorial for installation and configuration: Let loose the squid - Deploy ArgoCD the declarative way
Writing ArgoCD Plugins: ArgoCD Custom Plugins

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