Yes, you should write logic inside the Reconcile() function to decide what actions to take when the Controller Manager triggers it after detecting a change in a Kubernetes resource.

1. What Happens in the Reconcile() Function?

When a resource (like your Macroservice CR) changes, the Controller Manager calls your Reconcile() function. Inside Reconcile(), you implement the logic to ensure that the actual state matches the desired state.

This includes:

• Fetching the resource from the Kubernetes API.
• Checking its current state.
• Deciding what to do next (create, update, delete related resources).
• Returning a result to indicate whether reconciliation is complete or needs requeueing.

2. Basic Structure of a Reconcile() Function

Here’s a simple example of what happens inside Reconcile():

go
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func (r *MacroserviceReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
    // 1. Fetch the Macroservice resource from Kubernetes
    var macroservice senseyv1.Macroservice
    if err := r.Get(ctx, req.NamespacedName, &macroservice); err != nil {
        if client.IgnoreNotFound(err) == nil {
            // The resource was deleted, no need to reconcile further
            return ctrl.Result{}, nil
        }
        return ctrl.Result{}, err // Other errors should be reported
    }

    // 2. Check the desired state (e.g., does a Deployment exist for this Macroservice?)
    var deployment appsv1.Deployment
    err := r.Get(ctx, types.NamespacedName{Name: macroservice.Name, Namespace: macroservice.Namespace}, &deployment)
    if err != nil && errors.IsNotFound(err) {
        // 3. If the Deployment does not exist, create it
        newDeployment := createNewDeployment(macroservice)
        if err := r.Create(ctx, newDeployment); err != nil {
            return ctrl.Result{}, err
        }
    } else if err != nil {
        return ctrl.Result{}, err
    }

    // 4. If needed, update the Deployment
    // (Check if it needs updates and apply changes)

    // 5. Return successfully (no need to requeue)
    return ctrl.Result{}, nil
}

3. What Should You Write in Reconcile()?

✅ Yes, You Should Handle These Cases

• Check if the resource exists.
• Create necessary sub-resources (e.g., Deployments, Services).
• Update resources if needed.
• Delete orphaned resources if they shouldn’t exist anymore.