From f6dc30c8b54379deefd64ccc4de5bc758d69f64f Mon Sep 17 00:00:00 2001
From: Timofei Larkin <lllamnyp@gmail.com>
Date: Tue, 30 Jul 2024 00:06:24 +0300
Subject: [PATCH] supplement observables with desired replicas calculation,
 decouple configmap templating from reconciliation logic

---
 internal/controller/etcdcluster_controller.go | 33 ++++++++--
 internal/controller/factory/configmap.go      | 31 +++++++++
 internal/controller/observables.go            | 66 +++++++++++++++----
 site/content/en/docs/v0.4/reference/api.md    |  4 +-
 4 files changed, 115 insertions(+), 19 deletions(-)

diff --git a/internal/controller/etcdcluster_controller.go b/internal/controller/etcdcluster_controller.go
index 8efafbce..2cb13a80 100644
--- a/internal/controller/etcdcluster_controller.go
+++ b/internal/controller/etcdcluster_controller.go
@@ -91,6 +91,7 @@ func (r *EtcdClusterReconciler) Reconcile(ctx context.Context, req ctrl.Request)
 	}
 
 	state := observables{}
+	state.instance = instance
 
 	// create two services and the pdb
 	err = r.ensureUnconditionalObjects(ctx, instance)
@@ -112,11 +113,8 @@ func (r *EtcdClusterReconciler) Reconcile(ctx context.Context, req ctrl.Request)
 	}
 	state.endpointsFound = clusterClient != nil && singleClients != nil
 
-	if !state.endpointsFound {
-		if !state.stsExists {
-			// TODO: happy path for new cluster creation
-			log.Debug(ctx, "happy path for new cluster creation (not yet implemented)")
-		}
+	if clusterClient != nil {
+		state.endpoints = clusterClient.Endpoints()
 	}
 
 	// fetch PVCs
@@ -125,6 +123,20 @@ func (r *EtcdClusterReconciler) Reconcile(ctx context.Context, req ctrl.Request)
 		return ctrl.Result{}, err
 	}
 
+	if !state.endpointsFound {
+		if !state.stsExists {
+			cm := factory.TemplateClusterStateConfigMap(instance, "new", state.desiredReplicas())
+			err := ctrl.SetControllerReference(instance, cm, r.Scheme)
+			if err != nil {
+				return ctrl.Result{}, err
+			}
+			err = r.patchOrCreateObject(ctx, cm)
+			if err != nil {
+				return ctrl.Result{}, err
+			}
+		}
+	}
+
 	// get status of every endpoint and member list from every endpoint
 	state.etcdStatuses = make([]etcdStatus, len(singleClients))
 	{
@@ -667,3 +679,14 @@ func (r *EtcdClusterReconciler) ensureUnconditionalObjects(ctx context.Context,
 	}
 	return nil
 }
+
+func (r *EtcdClusterReconciler) patchOrCreateObject(ctx context.Context, obj client.Object) error {
+	err := r.Patch(ctx, obj, client.Apply, &client.PatchOptions{FieldManager: "etcd-operator"}, client.ForceOwnership)
+	if err == nil {
+		return nil
+	}
+	if client.IgnoreNotFound(err) == nil {
+		err = r.Create(ctx, obj)
+	}
+	return err
+}
diff --git a/internal/controller/factory/configmap.go b/internal/controller/factory/configmap.go
index a2d282ca..7a06e477 100644
--- a/internal/controller/factory/configmap.go
+++ b/internal/controller/factory/configmap.go
@@ -19,6 +19,7 @@ package factory
 import (
 	"context"
 	"fmt"
+	"strings"
 
 	etcdaenixiov1alpha1 "github.com/aenix-io/etcd-operator/api/v1alpha1"
 	"github.com/aenix-io/etcd-operator/internal/log"
@@ -29,6 +30,36 @@ import (
 	"sigs.k8s.io/controller-runtime/pkg/client"
 )
 
+func TemplateClusterStateConfigMap(cluster *etcdaenixiov1alpha1.EtcdCluster, state string, replicas int) *corev1.ConfigMap {
+
+	initialClusterMembers := make([]string, replicas)
+	clusterService := fmt.Sprintf("%s.%s.svc:2380", GetHeadlessServiceName(cluster), cluster.Namespace)
+	for i := 0; i < replicas; i++ {
+		podName := fmt.Sprintf("%s-%d", cluster.Name, i)
+		initialClusterMembers[i] = fmt.Sprintf("%s=https://%s.%s",
+			podName, podName, clusterService,
+		)
+	}
+	initialCluster := strings.Join(initialClusterMembers, ",")
+
+	configMap := &corev1.ConfigMap{
+		TypeMeta: metav1.TypeMeta{
+			APIVersion: "v1",
+			Kind:       "ConfigMap",
+		},
+		ObjectMeta: metav1.ObjectMeta{
+			Name:      fmt.Sprintf("%s-cluster-state", cluster.Name),
+			Namespace: cluster.Namespace,
+		},
+		Data: map[string]string{
+			"ETCD_INITIAL_CLUSTER_STATE": state,
+			"ETCD_INITIAL_CLUSTER":       initialCluster,
+			"ETCD_INITIAL_CLUSTER_TOKEN": fmt.Sprintf("%s-%s", cluster.Name, cluster.Namespace),
+		},
+	}
+	return configMap
+}
+
 func GetClusterStateConfigMapName(cluster *etcdaenixiov1alpha1.EtcdCluster) string {
 	return cluster.Name + "-cluster-state"
 }
diff --git a/internal/controller/observables.go b/internal/controller/observables.go
index 38c5fd8e..f1af8e18 100644
--- a/internal/controller/observables.go
+++ b/internal/controller/observables.go
@@ -6,6 +6,7 @@ import (
 	"strings"
 	"sync"
 
+	"github.com/aenix-io/etcd-operator/api/v1alpha1"
 	"github.com/aenix-io/etcd-operator/pkg/set"
 	clientv3 "go.etcd.io/etcd/client/v3"
 	appsv1 "k8s.io/api/apps/v1"
@@ -25,13 +26,13 @@ type etcdStatus struct {
 // observables stores observations that the operator can make about
 // states of objects in kubernetes
 type observables struct {
+	instance       *v1alpha1.EtcdCluster
 	statefulSet    appsv1.StatefulSet
 	stsExists      bool
-	endpoints      corev1.Endpoints
+	endpoints      []string
 	endpointsFound bool
 	etcdStatuses   []etcdStatus
 	clusterID      uint64
-	_              int
 	pvcs           []corev1.PersistentVolumeClaim
 }
 
@@ -99,19 +100,37 @@ func (s *etcdStatus) fill(ctx context.Context, c *clientv3.Client) {
 	wg.Wait()
 }
 
-func (o *observables) pvcMaxIndex() int {
-	idx := -1
+func (o *observables) pvcMaxIndex() (max int) {
+	max = -1
 	for i := range o.pvcs {
-		subs := strings.Split(o.pvcs[i].Name, "-")
-		index, err := strconv.Atoi(subs[len(subs)-1])
+		tokens := strings.Split(o.pvcs[i].Name, "-")
+		index, err := strconv.Atoi(tokens[len(tokens)-1])
 		if err != nil {
 			continue
 		}
-		if index > idx {
-			idx = index
+		if index > max {
+			max = index
 		}
 	}
-	return idx
+	return max
+}
+
+func (o *observables) endpointMaxIndex() (max int) {
+	for i := range o.endpoints {
+		tokens := strings.Split(o.endpoints[i], ":")
+		if len(tokens) < 2 {
+			continue
+		}
+		tokens = strings.Split(tokens[len(tokens)-2], "-")
+		index, err := strconv.Atoi(tokens[len(tokens)-1])
+		if err != nil {
+			continue
+		}
+		if index > max {
+			max = index
+		}
+	}
+	return max
 }
 
 // TODO: make a real function to determine the right number of replicas.
@@ -119,13 +138,36 @@ func (o *observables) pvcMaxIndex() int {
 // started, but if the name field is populated, this is a member of the
 // initial cluster. If the name field is empty, this member has just been
 // added with etcdctl member add (or equivalent API call).
-func (o *observables) _() int {
+func (o *observables) desiredReplicas() (max int) {
+	max = -1
 	if o.etcdStatuses != nil {
 		for i := range o.etcdStatuses {
 			if o.etcdStatuses[i].memberList != nil {
-				return len(o.etcdStatuses[i].memberList.Members)
+				for j := range o.etcdStatuses[i].memberList.Members {
+					tokens := strings.Split(o.etcdStatuses[i].memberList.Members[j].Name, "-")
+					index, err := strconv.Atoi(tokens[len(tokens)-1])
+					if err != nil {
+						continue
+					}
+					if index > max {
+						max = index
+					}
+				}
 			}
 		}
 	}
-	return 0
+	if max > -1 {
+		return max + 1
+	}
+
+	if epMax := o.endpointMaxIndex(); epMax > max {
+		max = epMax
+	}
+	if pvcMax := o.pvcMaxIndex(); pvcMax > max {
+		max = pvcMax
+	}
+	if max == -1 {
+		return int(*o.instance.Spec.Replicas)
+	}
+	return max + 1
 }
diff --git a/site/content/en/docs/v0.4/reference/api.md b/site/content/en/docs/v0.4/reference/api.md
index 7c972d28..4ce45aa5 100644
--- a/site/content/en/docs/v0.4/reference/api.md
+++ b/site/content/en/docs/v0.4/reference/api.md
@@ -167,8 +167,8 @@ _Appears in:_
 
 | Field | Description | Default | Validation |
 | --- | --- | --- | --- |
-| `minAvailable` _[IntOrString](#intorstring)_ | MinAvailable describes minimum ready replicas. If both are empty, controller will implicitly<br />calculate MaxUnavailable based on number of replicas<br />Mutually exclusive with MaxUnavailable. |  |  |
-| `maxUnavailable` _[IntOrString](#intorstring)_ | MinAvailable describes maximum not ready replicas. If both are empty, controller will implicitly<br />calculate MaxUnavailable based on number of replicas<br />Mutually exclusive with MinAvailable |  |  |
+| `minAvailable` _[IntOrString](https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.30.0/#intorstring-intstr-util)_ | MinAvailable describes minimum ready replicas. If both are empty, controller will implicitly<br />calculate MaxUnavailable based on number of replicas<br />Mutually exclusive with MaxUnavailable. |  |  |
+| `maxUnavailable` _[IntOrString](https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.30.0/#intorstring-intstr-util)_ | MinAvailable describes maximum not ready replicas. If both are empty, controller will implicitly<br />calculate MaxUnavailable based on number of replicas<br />Mutually exclusive with MinAvailable |  |  |
 
 
 #### PodTemplate