From ca1423400963878e1446550ef74401447b343de1 Mon Sep 17 00:00:00 2001
From: Benjamin Wang <benjamin.ahrtr@gmail.com>
Date: Tue, 28 Jan 2025 16:32:32 +0000
Subject: [PATCH] Add the initial scaffold of certificate management

Signed-off-by: Benjamin Wang <benjamin.ahrtr@gmail.com>
---
 pkg/certificate/auto/doc.go         |   8 ++
 pkg/certificate/cert-manager/doc.go |   6 ++
 pkg/certificate/interface.go        | 112 ++++++++++++++++++++++++++++
 3 files changed, 126 insertions(+)
 create mode 100644 pkg/certificate/auto/doc.go
 create mode 100644 pkg/certificate/cert-manager/doc.go
 create mode 100644 pkg/certificate/interface.go

diff --git a/pkg/certificate/auto/doc.go b/pkg/certificate/auto/doc.go
new file mode 100644
index 0000000..961bb66
--- /dev/null
+++ b/pkg/certificate/auto/doc.go
@@ -0,0 +1,8 @@
+package auto
+
+/*
+AutoProvider generates self-signed certificates.
+
+It isn't recommended for production use. It's only designed for
+test purpose only.
+*/
diff --git a/pkg/certificate/cert-manager/doc.go b/pkg/certificate/cert-manager/doc.go
new file mode 100644
index 0000000..6deff6e
--- /dev/null
+++ b/pkg/certificate/cert-manager/doc.go
@@ -0,0 +1,6 @@
+package cert_manager
+
+/*
+CertManagerProvider enables users to integrate their existing
+cert-manager deployments with etcd-operator.
+*/
diff --git a/pkg/certificate/interface.go b/pkg/certificate/interface.go
new file mode 100644
index 0000000..5215bd6
--- /dev/null
+++ b/pkg/certificate/interface.go
@@ -0,0 +1,112 @@
+package certificate
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"time"
+)
+
+type ProviderType string
+
+const (
+	Auto        ProviderType = "auto"
+	CertManager ProviderType = "cert-manager"
+	// add more ...
+)
+
+func NewProvider(pt ProviderType) (Provider, error) {
+	switch pt {
+	case Auto:
+		return nil, nil // change me later
+	case CertManager:
+		return nil, nil // change me later
+	}
+
+	return nil, fmt.Errorf("unknown provider type: %s", pt)
+}
+
+// AltNames contains the domain names and IP addresses that will be added
+// to the x509 certificate SubAltNames fields. The values will be passed
+// directly to the x509.Certificate object.
+type AltNames struct {
+	DNSNames []string
+	IPs      []net.IP
+}
+
+// Config contains the basic fields required for creating a certificate
+type Config struct {
+	CommonName       string
+	Organization     []string
+	AltNames         AltNames
+	ValidityDuration time.Duration
+	CABundle         []byte
+
+	// ExtraConfig contains provider specific configurations.
+	ExtraConfig map[string]any
+}
+
+type Provider interface {
+	// EnsureCertificateSecret ensures the specified certificate is
+	// available as a Secret in Kubernetes. If the Secret does not
+	// exist, it will be created.
+	//
+	// Parameters:
+	// - ctx: Context for cancellation and deadlines.
+	// - secretName: Name of the Secret to ensure.
+	// - namespace: Namespace where the Secret should reside.
+	// - cfg: Configuration for the certificate.
+	//
+	// Returns:
+	// - nil if the operation succeeds, or an error otherwise.
+	EnsureCertificateSecret(ctx context.Context, secretName string, namespace string, cfg *Config) error
+
+	// ValidateCertificateSecret validates the certificate stored
+	// in the specified Secret. This checks if the certificate is
+	// valid (e.g., not expired, matches configuration).
+	//
+	// Parameters:
+	// - ctx: Context for cancellation and deadlines.
+	// - secretName: Name of the Secret to validate.
+	// - namespace: Namespace where the Secret resides.
+	// - cfg: Configuration to validate against.
+	//
+	// Returns:
+	// - true if the Secret is valid, false otherwise, along with
+	//   an error if validation fails.
+	ValidateCertificateSecret(ctx context.Context, secretName string, namespace string, cfg *Config) (bool, error)
+
+	// DeleteCertificateSecret explicitly deletes the Secret containing
+	// the certificate. This should only be used if the certificate
+	// is no longer needed.
+	//
+	// Parameters:
+	// - ctx: Context for cancellation and deadlines.
+	// - secretName: Name of the Secret to delete.
+	// - namespace: Namespace where the Secret resides.
+	//
+	// Returns:
+	// - nil if the operation succeeds, or an error otherwise.
+	DeleteCertificateSecret(ctx context.Context, secretName string, namespace string) error
+
+	// RevokeCertificate revokes a certificate if supported by the provider.
+	//
+	// Parameters:
+	// - ctx: Context for cancellation and deadlines.
+	// - secretName: Name of the Secret containing the certificate to revoke.
+	// - namespace: Namespace where the Secret resides.
+	//
+	// Returns:
+	// - nil if the revocation succeeds, or an error otherwise.
+	RevokeCertificate(ctx context.Context, secretName string, namespace string) error
+
+	// GetCertificateConfig returns the certificate configuration from the provider.
+	//
+	// Parameters:
+	// - secretName: Name of the Secret containing the certificate.
+	// - namespace: Namespace where the Secret resides.
+	//
+	// Returns:
+	// - Config if the Secret exists and is valid, or an error otherwise.
+	GetCertificateConfig(ctx context.Context, secretName string, namespace string) (*Config, error)
+}