Chapter 1. GitOps overview

See the following prerequisites and requirements:

When you search for an Argo CD application, you are directed to the Applications page. Complete the following steps to access the Argo CD application from the Search page:

For more information about search, see Search in the console.

Complete the following steps to register managed clusters to OpenShift GitOps:

You can now use the Red Hat Advanced Cluster Management GitOpsCluster resource to register a non-OpenShift Container Platform cluster to a OpenShift GitOps cluster. With this capability, you can deploy application resources to the non-OpenShift Container Platform cluster by using the OpenShift GitOps console. To register a non-OpenShift Container Platform cluster to a OpenShift GitOps cluster, complete the following steps:

When you integrate with the OpenShift GitOps operator, for every managed cluster that is bound to the OpenShift GitOps namespace through the placement and ManagedClusterSetBinding custom resources, a secret with a token to access the ManagedCluster is created in the OpenShift GitOps instance server namespace.

The OpenShift GitOps controller needs this secret to sync resources to the managed cluster. By default, the service account application manager works with the cluster administrator permissions on the managed cluster to generate the OpenShift GitOps cluster secret in the OpenShift GitOps instance server namespace. The default namespace is openshift-gitops.

If you do not want this default, create a service account with customized permissions on the managed cluster for generating the OpenShift GitOps cluster secret in the OpenShift GitOps instance server namespace. The default namespace is still, openshift-gitops. For more information, see Creating a customized service account for Argo CD push model.

For more information, see the following resources and examples:

View the following prerequisites for the Argo CD Pull model:

Important:

cannot create resource "services" in API group "" in the namespace
"mortgage",deployments.apps is forbidden: User
"system:serviceaccount:openshift-gitops:openshift-gitops-Argo CD-application-controller"

See the following requirements to use the Argo CD Pull model:

For both Push and Pull model, the Argo CD ApplicationSet controller on the hub cluster reconciles to create application resources for each target managed cluster. See the following information about architecture for both models:

The Argo CD ApplicationSet resource is used to deploy applications on the managed clusters by using the Push or Pull model with a placement resource in the generator field that is used to get a list of managed clusters.

The following is an example MulticlusterApplicationSetReport YAML file for the guestbook application:

apiVersion: apps.open-cluster-management.io/v1alpha1
kind: MulticlusterApplicationSetReport
metadata:
  labels:
    apps.open-cluster-management.io/hosting-applicationset: openshift-gitops.guestbook-allclusters-app-set
  name: guestbook-allclusters-app-set
  namespace: openshift-gitops
statuses:
  clusterConditions:
  - cluster: cluster1
    conditions:
    - message: 'Failed sync attempt: one or more objects failed to apply, reason: services is forbidden: User "system:serviceaccount:openshift-gitops:openshift-gitops-Argo CD-application-controller" cannot create resource "services" in API group "" in the namespace "guestbook",deployments.apps is forbidden: User <name> cannot create resource "deployments" in API group "apps" in the namespace "guestboo...'
      type: SyncError
    healthStatus: Missing
    syncStatus: OutOfSync
  - cluster: pcluster1
    healthStatus: Progressing
    syncStatus: Synced
  - cluster: pcluster2
    healthStatus: Progressing
    syncStatus: Synced
  summary:
    clusters: "3"
    healthy: "0"
    inProgress: "2"
    notHealthy: "3"
    notSynced: "1"
    synced: "2"

Note: If a resource fails to deploy, the resource is not included in the resource list. See error messages for information.

You must log in to your hub cluster.

Required access: Cluster administrator

Deprecated: PlacementRule

To create a ClusterRole resource for OpenShift GitOps, with access to create, read, update, and delete policies and placements:

You can use OpenShift GitOps to generate policies by using the Policy Generator through GitOps. Since the Policy Generator does not come preinstalled in the OpenShift GitOps container image, you must complete customizations.

With the ArgoCD resoure, use OpenShift GitOps for you to define custom logic that determines the current health of specific resource based on the resource state. Define custom health checks to report the policy as healthy only when your policy is compliant. When you add a health check for a resource, you must add it as a group in the resourceHealthChecks field.

Important: To verify that you did not download something malicious from the Internet, review every policy before you apply it.

To define health checks for your resource kinds complete the following steps:

You can generate a policy that installs OpenShift Container Platform GitOps by using the Policy Generator. The OpenShift Container Platform GitOps operator offers the all namespaces installation mode, which you can view in the following example. Create a Subscription manifest file called openshift-gitops-subscription.yaml, similar to the following example:

apiVersion: operators.coreos.com/v1alpha1
kind: Subscription
metadata:
  name: openshift-gitops-operator
  namespace: openshift-operators
spec:
  channel: stable
  name: openshift-gitops-operator
  source: redhat-operators
  sourceNamespace: openshift-marketplace

To pin to a specific version of the operator, add the following parameter and value: spec.startingCSV: openshift-gitops-operator.v<version>. Replace <version> with your preferred version.

A PolicyGenerator configuration file is required. Use the configuration file named policy-generator-config.yaml to generate a policy to install OpenShift Container Platform GitOps on all OpenShift Container Platform managed clusters. See the following example:

apiVersion: policy.open-cluster-management.io/v1
kind: PolicyGenerator
metadata:
  name: install-openshift-gitops
policyDefaults:
  namespace: policies
  placement:
    clusterSelectors:
      vendor: "OpenShift"
  remediationAction: enforce
policies:
  - name: install-openshift-gitops
    manifests:
      - path: openshift-gitops-subscription.yaml

The last required file is kustomization.yaml, which requires the following configuration:

generators:
  - policy-generator-config.yaml

The generated policy might resemble the following file with PlacementRule(Deprecated):

apiVersion: apps.open-cluster-management.io/v1
kind: PlacementRule
metadata:
  name: placement-install-openshift-gitops
  namespace: policies
spec:
  clusterConditions:
    - status: "True"
      type: ManagedClusterConditionAvailable
  clusterSelector:
    matchExpressions:
      - key: vendor
        operator: In
        values:
          - OpenShift
---
apiVersion: policy.open-cluster-management.io/v1
kind: PlacementBinding
metadata:
  name: binding-install-openshift-gitops
  namespace: policies
placementRef:
  apiGroup: apps.open-cluster-management.io
  kind: PlacementRule
  name: placement-install-openshift-gitops
subjects:
  - apiGroup: policy.open-cluster-management.io
    kind: Policy
    name: install-openshift-gitops
---
apiVersion: policy.open-cluster-management.io/v1
kind: Policy
metadata:
  annotations:
    policy.open-cluster-management.io/categories: CM Configuration Management
    policy.open-cluster-management.io/controls: CM-2 Baseline Configuration
    policy.open-cluster-management.io/standards: NIST SP 800-53
    policy.open-cluster-management.io/description:
  name: install-openshift-gitops
  namespace: policies
spec:
  disabled: false
  policy-templates:
    - objectDefinition:
        apiVersion: policy.open-cluster-management.io/v1
        kind: ConfigurationPolicy
        metadata:
          name: install-openshift-gitops
        spec:
          object-templates:
            - complianceType: musthave
              objectDefinition:
                apiVersion: operators.coreos.com/v1alpha1
                kind: Subscription
                metadata:
                  name: openshift-gitops-operator
                  namespace: openshift-operators
                spec:
                  channel: stable
                  name: openshift-gitops-operator
                  source: redhat-operators
                  sourceNamespace: openshift-marketplace
          remediationAction: enforce
          severity: low

Generated policies from manifests in the OpenShift Container Platform documentation is supported. Any configuration guidance from the OpenShift Container Platform documentation can be applied using the Policy Generator.

When you install an operator with an OperatorGroup manifest, the OperatorGroup must exist on the cluster before the Subscription is created. Use the policy dependency feature along with the Policy Generator to ensure that the OperatorGroup policy is compliant before you enforce the Subscription policy.

Set up policy dependencies by listing the manifests in the order that you want. For example, you might want to create the namespace policy first, create the OperatorGroup next, and create the Subscription last.

Enable the policyDefaults.orderManifests parameter and disable policyDefaults.consolidateManifests in the Policy Generator configuration manifest to automatically set up dependencies between the manifests.

The managedserviceaccount custom resource on the hub provides a convenient way to create serviceaccounts on the managed clusters. When a managedserviceccount custom resource is created in the <managed_cluster> namespace on the hub cluster, a serviceccount is created on the managed cluster.

To create a managed service account, see Enabling managedserviceaccount add-ons.

When the service account is created, it does not have any permission associated to it. To grant permissions to the new service account, use the clusterpermission resource. The clusterpermission resource is created in the managed cluster namespace on the hub. It provides a convenient way to create roles, cluster roles resources on the managed clusters, and bind them to a service account through a rolebinding or clusterrolebinding resource.

After you create the sample, <clusterpermission>, the following resources are created in the sample managed cluster:

The GitOpsCluster resource uses placement to import selected managed clusters into the Argo CD, including the creation of the Argo CD cluster secrets which contains information used to access the clusters. By default, the Argo CD cluster secret uses the application manager service account to access the managed clusters.

Deploy an Argo CD application from the Argo CD console by using the pushing model. The Argo CD application is deployed with the managed service account, <managed-sa-sample>.

When the GitOpsCluster resource is updated with the `managedServiceAccountRef`, each managed cluster in the placement of this GitOpsCluster needs to have the service account. If you have several managed clusters, it becomes tedious for you to create the managed service account and cluster permission for each managed cluster. You can simply this process by using a policy to create the managed service account and cluster permission for all your managed clusters

When you apply the managedServiceAccount and clusterPermission resources to the hub cluster, the placement of this policy is bound to the local cluster. Replicate those resources to the managed cluster namespace for all of the managed clusters in the placement of the GitOpsCluster resource.

Using a policy to create the managedServiceAccount and clusterPermission resources include the following attributes: