Stages involved in app reconciliation with kapp

Products

• VMware Tanzu Platform - Kubernetes
• VMware Tanzu Platform - TAP

Issue/Introduction

kapp is a CLI tool (part of Carvel tools https://carvel.dev/kapp/) used to deploy, manage, and track applications.

As part of its features kapp is used for app reconciliation. Kapp performs a reconciliation loop between desired state (your YAML manifests) and the live state (what’s already running).

 

Environment

Tanzu Platform

Resolution

The following list described each stage of an app reconciliation process:

1. Collects current state
   • Kapp queries the cluster for all resources that belong to the app (my-app). It uses labels and ownership metadata to track them.

     2. Diff calculation

• • Kapp compares the desired config (manifests) against the live objects. It produces a clear diff view, showing what will be created, updated, or deleted.

     3. Apply changes

• • Kapp applies changes in a safe, ordered way:
    • Deletes resources in reverse dependency order.
    • Creates/updates in dependency order (e.g., Namespaces first, Deployments after).
    • It avoids unnecessary updates (if nothing changed, nothing gets touched).

      4. Wait for reconciliation

• • After applying, Kapp waits until resources reach their healthy state:
    • Pods must become Ready.
    • Deployments must match desired replicas.
    • Services must have endpoints.
    • If something doesn’t reconcile, Kapp reports errors instead of just exiting.