Chapter 1. Deploying a Spring Boot application with Argo CD

Procedure

1. In the Argo CD dashboard, click NEW APP to add a new Argo CD application.

2. For this workflow, create a spring-petclinic application with the following configurations:

   Application Name

   spring-petclinic

   Project

   default

   Sync Policy

   Automatic

   Repository URL

   https://github.com/redhat-developer/openshift-gitops-getting-started

   Revision

   HEAD

   Path

   app

   Destination

   https://kubernetes.default.svc

   Namespace

   spring-petclinic

3. Click CREATE to create your application.
4. Open the Administrator perspective of the web console and expand Administration Namespaces.
5. Search for and select the namespace, then enter argocd.argoproj.io/managed-by=openshift-gitops in the Label field so that the Argo CD instance in the openshift-gitops namespace can manage your namespace.

Procedure

1. Download the sample application:

   $ git clone git@github.com:redhat-developer/openshift-gitops-getting-started.git

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2. Create the application:

   $ oc create -f openshift-gitops-getting-started/argo/app.yaml

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3. Run the oc get command to review the created application:

   $ oc get application -n openshift-gitops

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4. Add a label to the namespace your application is deployed in so that the Argo CD instance in the openshift-gitops namespace can manage it:

   $ oc label namespace spring-petclinic argocd.argoproj.io/managed-by=openshift-gitops

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Procedure

1. In the Argo CD dashboard, verify that your application has the Synced status.
2. Click the app-spring-petclinic tile in the Argo CD dashboard to view the application resources that are deployed to the cluster.
3. In the OpenShift Container Platform web console, navigate to the Developer perspective.

4. Modify the Spring PetClinic deployment and commit the changes to the app/ directory of the Git repository. Argo CD will automatically deploy the changes to the cluster.

   1. Fork the OpenShift GitOps getting started repository.
   2. In the deployment.yaml file, change the failureThreshold value to 5.

   3. In the deployment cluster, run the following command to verify the changed value of the failureThreshold field:

      $ oc edit deployment spring-petclinic -n spring-petclinic

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5. Test the self-healing behavior by modifying the deployment on the cluster and scaling it up to two pods while watching the application in the OpenShift Container Platform web console.

   1. Run the following command to modify the deployment:

      $ oc scale deployment spring-petclinic --replicas 2  -n spring-petclinic

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   2. In the OpenShift Container Platform web console, notice that the deployment scales up to two pods and immediately scales down again to one pod. Argo CD detected a difference from the Git repository and auto-healed the application on the OpenShift Container Platform cluster.
6. In the Argo CD dashboard, click the app-spring-petclinic tile APP DETAILS EVENTS. The EVENTS tab displays the following events: Argo CD detecting out of sync deployment resources on the cluster and then resyncing the Git repository to correct it.