Certificate Controller: Assignment 2 and 3

[jshiwamV]

This PR introduces the following methods and functionalities in the CertificateReconciler for managing certificates in Kubernetes:

1. Reconcile Method:

• The Reconcile method is responsible for checking the state of the Certificate resource and performing necessary actions such as:
  • Creating a New Certificate: If the Certificate resource does not have an expiry date (i.e., it is being created for the first time), the method:
    • Parses the ValidFor field from the CertificateSpec.
    • Generates a self-signed certificate based on the provided domain and validity period.
    • Updates the status of the Certificate with appropriate conditions (e.g., Pending, Issued).
  • Renewing a Certificate: If the certificate is close to expiry (within 5 minutes), it:
    • Initiates the certificate renewal process.
    • Updates the status conditions to reflect the renewal (e.g., Renewing, Renewed).
• Requeue Mechanism: The reconciler automatically requeues itself to check certificate expiration every minute.

2. createOrUpdateCertificate Method:

• This method is responsible for creating or updating the Secret resource that stores the certificate's PEM-encoded public and private keys.
• The method ensures that the secret is created with the appropriate owner reference (Certificate resource), allowing Kubernetes to clean up the secret automatically if the Certificate resource is deleted.
• If the secret already exists, it performs a patch update.

3. updateStatus Method:

• This method is used to update the status of the Certificate resource.
• It takes inputs such as the condition (metav1.Condition) and optionally, expiredAt and renewedAt timestamps.
• The status conditions (ConditionIssued, ConditionRenewed, etc.) are updated using this method along with the certificate's expiry and renewal times.
• The method fetches the current Certificate resource, updates its conditions, and persists the changes.

Key Functionalities:

• Certificate Creation: Generates a self-signed certificate when the Certificate resource is created and stores it in a Kubernetes Secret.
• Certificate Renewal: Automatically renews the certificate before it expires, ensuring that the system always has a valid certificate.
• Status Management: Continuously updates the status of the Certificate resource with relevant conditions, expiry dates, and renewal dates.
• Requeuing Logic: Ensures continuous monitoring of certificate expiration by requeuing the reconciliation process every minute.