Introduction

Red Hat OpenShift GitOps is an operator that provides a workflow that integrates git repositories, continuous integration/continuous delivery (CI/CD) tools, and Kubernetes to realize faster, more secure, scalable software development, without compromising quality.

OpenShift GitOps enables customers to build and integrate declarative git driven CD workflows directly into their application development platform.

There’s no single tool that converts a development pipeline to "DevOps". By implementing a GitOps framework, updates and changes are pushed through declarative code, automating infrastructure and deployment requirements, and CI/CD.

OpenShift GitOps takes advantage of Argo CD and integrates it into Red Hat OpenShift to deliver a consistent, fully supported, declarative Kubernetes platform to configure and use with GitOps principles.

OpenShift and OpenShift GitOps:

Apply consistency across cluster and deployment lifecycles
Consolidate administration and management of applications across on-premises and cloud environments
Check the state of clusters making application constraints known early
Rollback code changes across clusters
Roll out new changes submitted via Git

Deploying your Application with OpenShift GitOps

From the OpenShift Console Administrator view click through HOME -> Operators -> Operator Hub, search for "Red Hat OpenShift GitOps" and hit Install. Make sure to select the Channel gitops-1.15.1. Accept all other defaults and click on Install.

Create a new project

oc new-project bgd

Sample Output

Now using project "bgd" on server "https://api.c90qz1cy.eastus.aroapp.io:6443".

You can add applications to this project with the 'new-app' command. For example, try:

    oc new-app rails-postgresql-example

to build a new example application in Ruby. Or use kubectl to deploy a simple Kubernetes application:

    kubectl create deployment hello-node --image=k8s.gcr.io/e2e-test-images/agnhost:2.33 -- /agnhost serve-hostname

Deploy ArgoCD into your project

cat <<EOF | oc apply -f -
---
apiVersion: argoproj.io/v1beta1
kind: ArgoCD
metadata:
  name: argocd
  namespace: bgd
spec:
  sso:
    dex:
      openShiftOAuth: true
      resources:
        limits:
          cpu: 500m
          memory: 256Mi
        requests:
          cpu: 250m
          memory: 128Mi
    provider: dex
  rbac:
    defaultPolicy: "role:readonly"
    policy: "g, system:authenticated, role:admin"
    scopes: "[groups]"
  server:
    route:
      enabled: true
      tls:
        insecureEdgeTerminationPolicy: Redirect
        termination: reencrypt
EOF

Sample Output

argocd.argoproj.io/argocd created

ArgoCD deployment will require additional Worker nodes. The MachineAutoscalers will create the Worker machines and nodes automatically. Watch progress of the MachineAutoscaler as follows: oc get pods -A | grep Pending; oc -n openshift-machine-api get machines; oc get nodes This process will take about six minutes.

Wait for ArgoCD to be ready

oc rollout status deploy/argocd-server

Sample Output

deployment "argocd-server" successfully rolled out

Apply the gitops configuration

cat <<EOF | oc apply -f -
---
apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: bgd-app
  namespace: bgd
spec:
  destination:
    namespace: bgd
    server: https://kubernetes.default.svc
  project: default
  source:
    path: apps/bgd/base
    repoURL: https://github.com/rh-mobb/gitops-bgd-app
    targetRevision: main
  syncPolicy:
    automated:
      prune: true
      selfHeal: false
    syncOptions:
    - CreateNamespace=false
EOF

Sample Output

application.argoproj.io/bgd-app created

Find the URL for your Argo CD dashboard and log in using your OpenShift credentials

oc get route argocd-server -n bgd -o jsonpath='{"https://"}{.spec.host}{"\n"}'

Sample Output

https://argocd-server-bgd.apps.c90qz1cy.eastus.aroapp.io

Click on the Application bgd-app to show its topology

Verify that OpenShift sees the Deployment as rolled out

oc rollout status deploy/bgd -n bgd

Sample Output

deployment "bgd" successfully rolled out

Get the route and browse to it in your browser

oc get route bgd -n bgd -o jsonpath='{"https://"}{.spec.host}{"\n"}'

Sample Output

https://bgd-bgd.apps.c90qz1cy.eastus.aroapp.io

You should see a green box in the website like so

Patch the OpenShift resource to force it to be out of sync with git

oc patch deploy/bgd --type='json' \
   -p='[{"op": "replace", "path":
   "/spec/template/spec/containers/0/env/0/value", "value":"blue"}]'

Sample Output

deployment.apps/bgd patched

Refresh your browser and you should see a blue box in the website like so
Meanwhile check ArgoCD it should show the application as out of sync. Click the Sync button and then click on Synchronize to have it revert the change you made in OpenShift
Check again, you should see a green box in the website like so

Patch the ArgoCD application to automatically self heal

oc patch application bgd-app --type merge \
   -p='{"spec":{"syncPolicy":{"automated":{"selfHeal": true}}}}'

Sample Output

application.argoproj.io/bgd-app patched

Change the Application again and watch the ArgoCD web gui, you should see the change made in the cluster get quickly reverted back to match what is in github.
```
oc patch deploy/bgd --type='json' \
   -p='[{"op": "replace", "path":
   "/spec/template/spec/containers/0/env/0/value", "value":"blue"}]'
```
Sample Output
```
deployment.apps/bgd patched
```
The self healing may happen so fast you don’t even see it happen. If you missed just run the command again and be sure to have the Argo CD view up and ready!

Summary

Here you learned how to:

Install OpenShift GitOps
Deploy an application using GitOps
Synchronize application configuration and configure self-healing with GitOps