[Bugfix] Extend Agency HealthCheck for replace (#1030)

CHANGELOG.md

@@ -25,6 +25,7 @@
 - (Feature) Set Logger format
 - (Bugfix) Ensure Wait actions to be present after AddMember
 - (Documentation) Refactor metrics (Part 1)
+- (Bugfix) Extend Agency HealthCheck for replace
 
 ## [1.2.13](https://github.com/arangodb/kube-arangodb/tree/1.2.13) (2022-06-07)
 - (Bugfix) Fix arangosync members state inspection

docs/generated/metrics/README.md

@@ -3,7 +3,14 @@
 ## List
 
 |                                                      Name                                                       |     Namespace     |    Group     | Type  | Description                                        |
-|:-------------------------------------------------------------------------:|:-----------------:|:------:|:-----:|:-------------------------------------------|
+|:---------------------------------------------------------------------------------------------------------------:|:-----------------:|:------------:|:-----:|:---------------------------------------------------|
 |                     [arangodb_operator_agency_errors](./arangodb_operator_agency_errors.md)                     | arangodb_operator |    agency    | Count | Current count of agency cache fetch errors         |
 |                    [arangodb_operator_agency_fetches](./arangodb_operator_agency_fetches.md)                    | arangodb_operator |    agency    | Count | Current count of agency cache fetches              |
 |                      [arangodb_operator_agency_index](./arangodb_operator_agency_index.md)                      | arangodb_operator |    agency    | Gauge | Current index of the agency cache                  |
+|       [arangodb_operator_agency_cache_health_present](./arangodb_operator_agency_cache_health_present.md)       | arangodb_operator | agency_cache | Gauge | Determines if local agency cache health is present |
+|              [arangodb_operator_agency_cache_healthy](./arangodb_operator_agency_cache_healthy.md)              | arangodb_operator | agency_cache | Gauge | Determines if agency is healthy                    |
+|              [arangodb_operator_agency_cache_leaders](./arangodb_operator_agency_cache_leaders.md)              | arangodb_operator | agency_cache | Gauge | Determines agency leader vote count                |
+| [arangodb_operator_agency_cache_member_commit_offset](./arangodb_operator_agency_cache_member_commit_offset.md) | arangodb_operator | agency_cache | Gauge | Determines agency member commit offset             |
+|       [arangodb_operator_agency_cache_member_serving](./arangodb_operator_agency_cache_member_serving.md)       | arangodb_operator | agency_cache | Gauge | Determines if agency member is reachable           |
+|              [arangodb_operator_agency_cache_present](./arangodb_operator_agency_cache_present.md)              | arangodb_operator | agency_cache | Gauge | Determines if local agency cache is present        |
+|              [arangodb_operator_agency_cache_serving](./arangodb_operator_agency_cache_serving.md)              | arangodb_operator | agency_cache | Gauge | Determines if agency is serving                    |

docs/generated/metrics/arangodb_operator_agency_cache_health_present.md

@@ -0,0 +1,12 @@
+# arangodb_operator_agency_cache_health_present (Gauge)
+
+## Description
+
+Determines if local agency cache health is present
+
+## Labels
+
+|   Label   | Description          |
+|:---------:|:---------------------|
+| namespace | Deployment Namespace |
+|   name    | Deployment Name      |

docs/generated/metrics/arangodb_operator_agency_cache_healthy.md

@@ -0,0 +1,12 @@
+# arangodb_operator_agency_cache_healthy (Gauge)
+
+## Description
+
+Determines if agency is healthy
+
+## Labels
+
+|   Label   | Description          |
+|:---------:|:---------------------|
+| namespace | Deployment Namespace |
+|   name    | Deployment Name      |

docs/generated/metrics/arangodb_operator_agency_cache_leaders.md

@@ -0,0 +1,13 @@
+# arangodb_operator_agency_cache_leaders (Gauge)
+
+## Description
+
+Determines agency leader vote count. Should be always one
+
+## Labels
+
+|   Label   | Description          |
+|:---------:|:---------------------|
+| namespace | Deployment Namespace |
+|   name    | Deployment Name      |
+|   agent   | Agent ID             |

docs/generated/metrics/arangodb_operator_agency_cache_member_commit_offset.md

@@ -0,0 +1,13 @@
+# arangodb_operator_agency_cache_member_commit_offset (Gauge)
+
+## Description
+
+Determines agency member commit offset. Set to -1 if Agent is not reachable
+
+## Labels
+
+|   Label   | Description          |
+|:---------:|:---------------------|
+| namespace | Deployment Namespace |
+|   name    | Deployment Name      |
+|   agent   | Agent ID             |

docs/generated/metrics/arangodb_operator_agency_cache_member_serving.md

@@ -0,0 +1,13 @@
+# arangodb_operator_agency_cache_member_serving (Gauge)
+
+## Description
+
+Determines if agency member is reachable
+
+## Labels
+
+|   Label   | Description          |
+|:---------:|:---------------------|
+| namespace | Deployment Namespace |
+|   name    | Deployment Name      |
+|   agent   | Agent ID             |

docs/generated/metrics/arangodb_operator_agency_cache_present.md

@@ -0,0 +1,12 @@
+# arangodb_operator_agency_cache_present (Gauge)
+
+## Description
+
+Determines if local agency cache is present
+
+## Labels
+
+|   Label   | Description          |
+|:---------:|:---------------------|
+| namespace | Deployment Namespace |
+|   name    | Deployment Name      |

docs/generated/metrics/arangodb_operator_agency_cache_serving.md

@@ -0,0 +1,12 @@
+# arangodb_operator_agency_cache_serving (Gauge)
+
+## Description
+
+Determines if agency is serving
+
+## Labels
+
+|   Label   | Description          |
+|:---------:|:---------------------|
+| namespace | Deployment Namespace |
+|   name    | Deployment Name      |

go.mod

@@ -28,6 +28,7 @@ require (
 	github.com/arangodb/go-driver v1.2.1
 	github.com/arangodb/go-driver/v2 v2.0.0-20211021031401-d92dcd5a4c83
 	github.com/arangodb/go-upgrade-rules v0.0.0-20180809110947-031b4774ff21
+	github.com/arangodb/rebalancer v0.1.1
 	github.com/cenkalti/backoff v2.2.1+incompatible
 	github.com/dchest/uniuri v0.0.0-20160212164326-8902c56451e9
 	github.com/gin-gonic/gin v1.7.2

internal/metrics.yaml

@@ -5,6 +5,76 @@ destination: pkg/generated/metric_descriptions
 
 namespaces:
   arangodb_operator:
+    agency_cache:
+      present:
+        shortDescription: "Determines if local agency cache is present"
+        description: "Determines if local agency cache is present"
+        type: "Gauge"
+        labels:
+          - key: namespace
+            description: "Deployment Namespace"
+          - key: name
+            description: "Deployment Name"
+      health_present:
+        shortDescription: "Determines if local agency cache health is present"
+        description: "Determines if local agency cache health is present"
+        type: "Gauge"
+        labels:
+          - key: namespace
+            description: "Deployment Namespace"
+          - key: name
+            description: "Deployment Name"
+      serving:
+        shortDescription: "Determines if agency is serving"
+        description: "Determines if agency is serving"
+        type: "Gauge"
+        labels:
+          - key: namespace
+            description: "Deployment Namespace"
+          - key: name
+            description: "Deployment Name"
+      healthy:
+        shortDescription: "Determines if agency is healthy"
+        description: "Determines if agency is healthy"
+        type: "Gauge"
+        labels:
+          - key: namespace
+            description: "Deployment Namespace"
+          - key: name
+            description: "Deployment Name"
+      member_serving:
+        shortDescription: "Determines if agency member is reachable"
+        description: "Determines if agency member is reachable"
+        type: "Gauge"
+        labels:
+          - key: namespace
+            description: "Deployment Namespace"
+          - key: name
+            description: "Deployment Name"
+          - key: agent
+            description: "Agent ID"
+      member_commit_offset:
+        shortDescription: "Determines agency member commit offset"
+        description: "Determines agency member commit offset. Set to -1 if Agent is not reachable"
+        type: "Gauge"
+        labels:
+          - key: namespace
+            description: "Deployment Namespace"
+          - key: name
+            description: "Deployment Name"
+          - key: agent
+            description: "Agent ID"
+      leaders:
+        shortDescription: "Determines agency leader vote count"
+        description: "Determines agency leader vote count. Should be always one"
+        type: "Gauge"
+        labels:
+          - key: namespace
+            description: "Deployment Namespace"
+          - key: name
+            description: "Deployment Name"
+          - key: agent
+            description: "Agent ID"
     agency:
       index:
         shortDescription: "Current index of the agency cache"

pkg/deployment/agency/cache.go

@@ -24,14 +24,20 @@ import (
 	"context"
 	"sync"
 
+	"github.com/arangodb/go-driver"
 	"github.com/arangodb/go-driver/agency"
 	api "github.com/arangodb/kube-arangodb/pkg/apis/deployment/v1"
+	"github.com/arangodb/kube-arangodb/pkg/generated/metric_descriptions"
 	"github.com/arangodb/kube-arangodb/pkg/util/errors"
 	"github.com/arangodb/kube-arangodb/pkg/util/globals"
+	"github.com/arangodb/kube-arangodb/pkg/util/metrics"
 )
 
 type health struct {
+	namespace, name string
+
 	leaderID string
+	leader   driver.Connection
 
 	agencySize int
 
@@ -41,6 +47,42 @@ type health struct {
 	election      map[string]int
 }
 
+func (h health) Leader() (driver.Connection, bool) {
+	if l := h.leader; l != nil {
+		return l, true
+	}
+
+	return nil, false
+}
+
+func (h health) CollectMetrics(m metrics.PushMetric) {
+	if err := h.Serving(); err == nil {
+		m.Push(metric_descriptions.ArangodbOperatorAgencyCacheServing().Gauge(1, h.namespace, h.name))
+	} else {
+		m.Push(metric_descriptions.ArangodbOperatorAgencyCacheServing().Gauge(0, h.namespace, h.name))
+	}
+
+	if err := h.Healthy(); err == nil {
+		m.Push(metric_descriptions.ArangodbOperatorAgencyCacheHealthy().Gauge(1, h.namespace, h.name))
+	} else {
+		m.Push(metric_descriptions.ArangodbOperatorAgencyCacheHealthy().Gauge(0, h.namespace, h.name))
+	}
+
+	for _, name := range h.names {
+		if i, ok := h.commitIndexes[name]; ok {
+			m.Push(metric_descriptions.ArangodbOperatorAgencyCacheMemberServing().Gauge(1, h.namespace, h.name, name),
+				metric_descriptions.ArangodbOperatorAgencyCacheMemberCommitOffset().Gauge(float64(i), h.namespace, h.name, name))
+		} else {
+			m.Push(metric_descriptions.ArangodbOperatorAgencyCacheMemberServing().Gauge(0, h.namespace, h.name, name),
+				metric_descriptions.ArangodbOperatorAgencyCacheMemberCommitOffset().Gauge(-1, h.namespace, h.name, name))
+		}
+	}
+
+	for k, l := range h.election {
+		m.Push(metric_descriptions.ArangodbOperatorAgencyCacheLeaders().Gauge(float64(l), h.namespace, h.name, k))
+	}
+}
+
 func (h health) LeaderID() string {
 	return h.leaderID
 }
@@ -97,26 +139,34 @@ type Health interface {
 
 	// LeaderID returns a leader ID or empty string if a leader is not known.
 	LeaderID() string
+
+	// Leader returns connection to the Agency leader
+	Leader() (driver.Connection, bool)
+
+	CollectMetrics(m metrics.PushMetric)
 }
 
 type Cache interface {
-	Reload(ctx context.Context, size int, clients []agency.Agency) (uint64, error)
+	Reload(ctx context.Context, size int, clients map[string]agency.Agency) (uint64, error)
 	Data() (State, bool)
 	CommitIndex() uint64
 	// Health returns true when healthy object is available.
 	Health() (Health, bool)
 }
 
-func NewCache(mode *api.DeploymentMode) Cache {
+func NewCache(namespace, name string, mode *api.DeploymentMode) Cache {
 	if mode.Get() == api.DeploymentModeSingle {
 		return NewSingleCache()
 	}
 
-	return NewAgencyCache()
+	return NewAgencyCache(namespace, name)
 }
 
-func NewAgencyCache() Cache {
-	return &cache{}
+func NewAgencyCache(namespace, name string) Cache {
+	return &cache{
+		namespace: namespace,
+		name:      name,
+	}
 }
 
 func NewSingleCache() Cache {
@@ -135,7 +185,7 @@ func (c cacheSingle) Health() (Health, bool) {
 	return nil, false
 }
 
-func (c cacheSingle) Reload(_ context.Context, _ int, _ []agency.Agency) (uint64, error) {
+func (c cacheSingle) Reload(_ context.Context, _ int, _ map[string]agency.Agency) (uint64, error) {
 	return 0, nil
 }
 
@@ -144,6 +194,8 @@ func (c cacheSingle) Data() (State, bool) {
 }
 
 type cache struct {
+	namespace, name string
+
 	lock sync.RWMutex
 
 	valid bool
@@ -181,7 +233,7 @@ func (c *cache) Health() (Health, bool) {
 	return nil, false
 }
 
-func (c *cache) Reload(ctx context.Context, size int, clients []agency.Agency) (uint64, error) {
+func (c *cache) Reload(ctx context.Context, size int, clients map[string]agency.Agency) (uint64, error) {
 	c.lock.Lock()
 	defer c.lock.Unlock()
 
@@ -195,6 +247,9 @@ func (c *cache) Reload(ctx context.Context, size int, clients []agency.Agency) (
 		return 0, err
 	}
 
+	health.namespace = c.namespace
+	health.name = c.name
+
 	c.health = health
 	if leaderConfig.CommitIndex == c.commitIndex && c.valid {
 		// We are on same index, nothing to do
@@ -215,21 +270,25 @@ func (c *cache) Reload(ctx context.Context, size int, clients []agency.Agency) (
 
 // getLeader returns config and client to a leader agency, and health to check if agencies are on the same page.
 // If there is no quorum for the leader then error is returned.
-func getLeader(ctx context.Context, size int, clients []agency.Agency) (agency.Agency, *Config, Health, error) {
+func getLeader(ctx context.Context, size int, clients map[string]agency.Agency) (agency.Agency, *Config, health, error) {
 	configs := make([]*Config, len(clients))
 	errs := make([]error, len(clients))
+	names := make([]string, 0, len(clients))
+	for k := range clients {
+		names = append(names, k)
+	}
 
 	var wg sync.WaitGroup
 
 	// Fetch Agency config
-	for i := range clients {
+	for i := range names {
 		wg.Add(1)
 		go func(id int) {
 			defer wg.Done()
 
 			ctxLocal, cancel := globals.GetGlobals().Timeouts().Agency().WithTimeout(ctx)
 			defer cancel()
-			config, err := GetAgencyConfig(ctxLocal, clients[id])
+			config, err := GetAgencyConfig(ctxLocal, clients[names[id]])
 
 			if err != nil {
 				errs[id] = err
@@ -243,8 +302,9 @@ func getLeader(ctx context.Context, size int, clients []agency.Agency) (agency.A
 	wg.Wait()
 
 	var h health
+
 	h.agencySize = size
-	h.names = make([]string, len(clients))
+	h.names = names
 	h.commitIndexes = make(map[string]uint64, len(clients))
 	h.leaders = make(map[string]string, len(clients))
 	h.election = make(map[string]int, len(clients))
@@ -252,7 +312,7 @@ func getLeader(ctx context.Context, size int, clients []agency.Agency) (agency.A
 	for id := range configs {
 		if config := configs[id]; config != nil {
 			name := config.Configuration.ID
-			h.names[id] = name
+			if name == h.names[id] {
 				h.commitIndexes[name] = config.CommitIndex
 				if config.LeaderId != "" {
 					h.leaders[name] = config.LeaderId
@@ -261,16 +321,21 @@ func getLeader(ctx context.Context, size int, clients []agency.Agency) (agency.A
 				}
 			}
 		}
-
+	}
 	if err := h.Serving(); err != nil {
-		return nil, nil, nil, err
+		logger.Err(err).Warn("Agency Not serving")
+		return nil, nil, h, err
+	}
+	if err := h.Healthy(); err != nil {
+		logger.Err(err).Warn("Agency Not healthy")
 	}
 
-	for id := range clients {
+	for id := range names {
 		if h.leaderID == h.names[id] {
-			return clients[id], configs[id], h, nil
+			h.leader = clients[names[id]].Connection()
+			return clients[names[id]], configs[id], h, nil
 		}
 	}
 
-	return nil, nil, nil, errors.Newf("Unable to find agent")
+	return nil, nil, h, errors.Newf("Unable to find agent")
 }

pkg/deployment/agency/logger.go

@@ -0,0 +1,25 @@
+//
+// DISCLAIMER
+//
+// Copyright 2016-2022 ArangoDB GmbH, Cologne, Germany
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Copyright holder is ArangoDB GmbH, Cologne, Germany
+//
+
+package agency
+
+import "github.com/arangodb/kube-arangodb/pkg/logging"
+
+var logger = logging.Global().RegisterAndGetLogger("agency", logging.Info)

pkg/deployment/deployment.go

@@ -176,17 +176,19 @@ func (d *Deployment) RefreshAgencyCache(ctx context.Context) (uint64, error) {
 			lCtx, c := globals.GetGlobalTimeouts().Agency().WithTimeout(ctx)
 			defer c()
 
-			var clients []agencydriver.Agency
+			rsize := int(*size)
+
+			clients := make(map[string]agencydriver.Agency)
 			for _, m := range d.GetStatusSnapshot().Members.Agents {
 				a, err := d.GetAgency(lCtx, m.ID)
 				if err != nil {
 					return 0, err
 				}
 
-				clients = append(clients, a)
+				clients[m.ID] = a
 			}
 
-			return d.agencyCache.Reload(lCtx, int(*size), clients)
+			return d.agencyCache.Reload(lCtx, rsize, clients)
 		}
 	}
 
@@ -248,7 +250,7 @@ func New(config Config, deps Dependencies, apiObject *api.ArangoDeployment) (*De
 		deps:        deps,
 		eventCh:     make(chan *deploymentEvent, deploymentEventQueueSize),
 		stopCh:      make(chan struct{}),
-		agencyCache: agency.NewCache(apiObject.Spec.Mode),
+		agencyCache: agency.NewCache(apiObject.GetNamespace(), apiObject.GetName(), apiObject.Spec.Mode),
 		acs:         acs.NewACS(apiObject.GetUID(), i),
 	}
 

pkg/deployment/metrics.go

@@ -70,7 +70,7 @@ func (i *inventory) Describe(descs chan<- *prometheus.Desc) {
 	pd := metrics.NewPushDescription(descs)
 	pd.Push(i.deploymentsMetric, i.deploymentMetricsMembersMetric, i.deploymentAgencyStateMetric, i.deploymentShardLeadersMetric, i.deploymentShardsMetric, i.operatorStateRefreshMetric)
 
-	pd.Push(metric_descriptions.ArangodbOperatorAgencyErrors(), metric_descriptions.ArangodbOperatorAgencyFetches(), metric_descriptions.ArangodbOperatorAgencyIndex())
+	metric_descriptions.Descriptions(pd)
 }
 
 func (i *inventory) Collect(m chan<- prometheus.Metric) {
@@ -160,4 +160,17 @@ func (d *Deployment) CollectMetrics(m metrics.PushMetric) {
 	m.Push(metric_descriptions.ArangodbOperatorAgencyErrors().Gauge(float64(d.metrics.agency.errors), d.namespace, d.name))
 	m.Push(metric_descriptions.ArangodbOperatorAgencyFetches().Gauge(float64(d.metrics.agency.fetches), d.namespace, d.name))
 	m.Push(metric_descriptions.ArangodbOperatorAgencyIndex().Gauge(float64(d.metrics.agency.index), d.namespace, d.name))
+
+	if c := d.agencyCache; c != nil {
+		m.Push(metric_descriptions.ArangodbOperatorAgencyCachePresent().Gauge(1, d.namespace, d.name))
+		if h, ok := c.Health(); ok {
+			m.Push(metric_descriptions.ArangodbOperatorAgencyCacheHealthPresent().Gauge(1, d.namespace, d.name))
+
+			h.CollectMetrics(m)
+		} else {
+			m.Push(metric_descriptions.ArangodbOperatorAgencyCacheHealthPresent().Gauge(0, d.namespace, d.name))
+		}
+	} else {
+		m.Push(metric_descriptions.ArangodbOperatorAgencyCachePresent().Gauge(0, d.namespace, d.name))
+	}
 }

pkg/deployment/reconcile/action_wait_for_member_in_sync.go

@@ -106,6 +106,16 @@ func (a *actionWaitForMemberInSync) checkCluster() (bool, error) {
 			a.log.Str("mode", "cluster").Str("member", a.MemberID()).Int("shard", len(notInSyncShards)).Info("DBServer contains not in sync shards")
 			return false, nil
 		}
+	case api.ServerGroupAgents:
+		agencyHealth, ok := a.actionCtx.GetAgencyHealth()
+		if !ok {
+			a.log.Str("mode", "cluster").Str("member", a.MemberID()).Info("AgencyHealth is missing")
+			return false, nil
+		}
+		if err := agencyHealth.Healthy(); err != nil {
+			a.log.Str("mode", "cluster").Str("member", a.MemberID()).Err(err).Info("Agency is not yet synchronized")
+			return false, nil
+		}
 	}
 	return true, nil
 }

pkg/deployment/reconcile/plan_builder_rotate_upgrade.go

@@ -477,6 +477,16 @@ func groupReadyForRestart(context PlanBuilderContext, status api.DeploymentStatu
 		if s := len(blockingRestartShards); s > 0 {
 			return false, fmt.Sprintf("There are %d shards which are blocking restart", s)
 		}
+	case api.ServerGroupAgents:
+		agencyHealth, ok := context.GetAgencyHealth()
+		if !ok {
+			// Unable to get agency state, do not restart
+			return false, "Unable to get agency cache"
+		}
+
+		if err := agencyHealth.Healthy(); err != nil {
+			return false, fmt.Sprintf("Restart of agent is not allowed due to: %s", err.Error())
+		}
 	}
 
 	return true, "Restart allowed"

pkg/deployment/reconcile/plan_builder_scale.go

@@ -43,32 +43,32 @@ func (r *Reconciler) createScaleMemberPlan(ctx context.Context, apiObject k8suti
 	switch spec.GetMode() {
 	case api.DeploymentModeSingle:
 		// Never scale down
-		plan = append(plan, r.createScalePlan(status, status.Members.Single, api.ServerGroupSingle, 1).Filter(filterScaleUP)...)
+		plan = append(plan, r.createScalePlan(status, status.Members.Single, api.ServerGroupSingle, 1, context).Filter(filterScaleUP)...)
 	case api.DeploymentModeActiveFailover:
 		// Only scale agents & singles
 		if a := status.Agency; a != nil && a.Size != nil {
-			plan = append(plan, r.createScalePlan(status, status.Members.Agents, api.ServerGroupAgents, int(*a.Size)).Filter(filterScaleUP)...)
+			plan = append(plan, r.createScalePlan(status, status.Members.Agents, api.ServerGroupAgents, int(*a.Size), context).Filter(filterScaleUP)...)
 		}
-		plan = append(plan, r.createScalePlan(status, status.Members.Single, api.ServerGroupSingle, spec.Single.GetCount())...)
+		plan = append(plan, r.createScalePlan(status, status.Members.Single, api.ServerGroupSingle, spec.Single.GetCount(), context)...)
 	case api.DeploymentModeCluster:
 		// Scale agents, dbservers, coordinators
 		if a := status.Agency; a != nil && a.Size != nil {
-			plan = append(plan, r.createScalePlan(status, status.Members.Agents, api.ServerGroupAgents, int(*a.Size)).Filter(filterScaleUP)...)
+			plan = append(plan, r.createScalePlan(status, status.Members.Agents, api.ServerGroupAgents, int(*a.Size), context).Filter(filterScaleUP)...)
 		}
-		plan = append(plan, r.createScalePlan(status, status.Members.DBServers, api.ServerGroupDBServers, spec.DBServers.GetCount())...)
-		plan = append(plan, r.createScalePlan(status, status.Members.Coordinators, api.ServerGroupCoordinators, spec.Coordinators.GetCount())...)
+		plan = append(plan, r.createScalePlan(status, status.Members.DBServers, api.ServerGroupDBServers, spec.DBServers.GetCount(), context)...)
+		plan = append(plan, r.createScalePlan(status, status.Members.Coordinators, api.ServerGroupCoordinators, spec.Coordinators.GetCount(), context)...)
 	}
 	if spec.GetMode().SupportsSync() {
 		// Scale syncmasters & syncworkers
-		plan = append(plan, r.createScalePlan(status, status.Members.SyncMasters, api.ServerGroupSyncMasters, spec.SyncMasters.GetCount())...)
-		plan = append(plan, r.createScalePlan(status, status.Members.SyncWorkers, api.ServerGroupSyncWorkers, spec.SyncWorkers.GetCount())...)
+		plan = append(plan, r.createScalePlan(status, status.Members.SyncMasters, api.ServerGroupSyncMasters, spec.SyncMasters.GetCount(), context)...)
+		plan = append(plan, r.createScalePlan(status, status.Members.SyncWorkers, api.ServerGroupSyncWorkers, spec.SyncWorkers.GetCount(), context)...)
 	}
 
 	return plan
 }
 
 // createScalePlan creates a scaling plan for a single server group
-func (r *Reconciler) createScalePlan(status api.DeploymentStatus, members api.MemberStatusList, group api.ServerGroup, count int) api.Plan {
+func (r *Reconciler) createScalePlan(status api.DeploymentStatus, members api.MemberStatusList, group api.ServerGroup, count int, context PlanBuilderContext) api.Plan {
 	var plan api.Plan
 	if len(members) < count {
 		// Scale up
@@ -87,6 +87,11 @@ func (r *Reconciler) createScalePlan(status api.DeploymentStatus, members api.Me
 		if m, err := members.SelectMemberToRemove(topologyMissingMemberToRemoveSelector(status.Topology), topologyAwarenessMemberToRemoveSelector(group, status.Topology)); err != nil {
 			r.planLogger.Err(err).Str("role", group.AsRole()).Warn("Failed to select member to remove")
 		} else {
+			ready, message := groupReadyForRestart(context, status, m, group)
+			if !ready {
+				r.planLogger.Str("member", m.ID).Str("role", group.AsRole()).Str("message", message).Warn("Unable to ScaleDown member")
+				return nil
+			}
 
 			r.planLogger.
 				Str("member-id", m.ID).
@@ -117,6 +122,12 @@ func (r *Reconciler) createReplaceMemberPlan(ctx context.Context, apiObject k8su
 				return nil
 			}
 			if member.Conditions.IsTrue(api.ConditionTypeMarkedToRemove) {
+				ready, message := groupReadyForRestart(context, status, member, group)
+				if !ready {
+					r.planLogger.Str("member", member.ID).Str("role", group.AsRole()).Str("message", message).Warn("Unable to recreate member")
+					continue
+				}
+
 				switch group {
 				case api.ServerGroupDBServers:
 					plan = append(plan, actions.NewAction(api.ActionTypeAddMember, group, withPredefinedMember("")))

pkg/deployment/reconcile/plan_executor.go

@@ -239,7 +239,6 @@ func (d *Reconciler) executePlan(ctx context.Context, statusPlan api.Plan, pg pl
 
 			if newPlan, changed := getActionPlanAppender(action, plan); changed {
 				// Our actions have been added to the end of plan
-				d.planLogger.Info("Appending new plan items")
 				return newPlan, true, nil
 			}
 
@@ -265,35 +264,45 @@ func (d *Reconciler) executePlan(ctx context.Context, statusPlan api.Plan, pg pl
 }
 
 func (d *Reconciler) executeAction(ctx context.Context, planAction api.Action, action Action) (done, abort, callAgain, retry bool, err error) {
+	log := d.planLogger.Str("action", string(planAction.Type)).Str("member", planAction.MemberID)
+
 	if !planAction.IsStarted() {
 		// Not started yet
 		ready, err := action.Start(ctx)
 		if err != nil {
 			if g := getStartFailureGracePeriod(action); g > 0 && !planAction.CreationTime.IsZero() {
 				if time.Since(planAction.CreationTime.Time) < g {
-					d.planLogger.Err(err).Error("Failed to start action, but still in grace period")
+					log.Err(err).Error("Failed to start action, but still in grace period")
 					return false, false, false, true, errors.WithStack(err)
 				}
 			}
-			d.planLogger.Err(err).Error("Failed to start action")
+			log.Err(err).Error("Failed to start action")
 			return false, false, false, false, errors.WithStack(err)
 		}
 
 		if ready {
-			d.planLogger.Bool("ready", ready).Debug("Action Start completed")
+			log.Bool("ready", ready).Info("Action Start completed")
 			return true, false, false, false, nil
 		}
+		log.Bool("ready", ready).Info("Action Started")
 
 		return false, false, true, false, nil
 	}
+
+	if t := planAction.StartTime; t != nil {
+		if tm := t.Time; !tm.IsZero() {
+			log = log.SinceStart("duration", tm)
+		}
+	}
+
 	// First action of plan has been started, check its progress
 	ready, abort, err := action.CheckProgress(ctx)
 	if err != nil {
-		d.planLogger.Err(err).Debug("Failed to check action progress")
+		log.Err(err).Debug("Failed to check action progress")
 		return false, false, false, false, errors.WithStack(err)
 	}
 
-	d.planLogger.
+	log.
 		Bool("abort", abort).
 		Bool("ready", ready).
 		Debug("Action CheckProgress completed")
@@ -303,11 +312,11 @@ func (d *Reconciler) executeAction(ctx context.Context, planAction api.Action, a
 	}
 
 	if abort {
-		d.planLogger.Warn("Action aborted. Removing the entire plan")
+		log.Warn("Action aborted. Removing the entire plan")
 		d.context.CreateEvent(k8sutil.NewPlanAbortedEvent(d.context.GetAPIObject(), string(planAction.Type), planAction.MemberID, planAction.Group.AsRole()))
 		return false, true, false, false, nil
 	} else if time.Now().After(planAction.CreationTime.Add(GetActionTimeout(d.context.GetSpec(), planAction.Type))) {
-		d.planLogger.Warn("Action not finished in time. Removing the entire plan")
+		log.Warn("Action not finished in time. Removing the entire plan")
 		d.context.CreateEvent(k8sutil.NewPlanTimeoutEvent(d.context.GetAPIObject(), string(planAction.Type), planAction.MemberID, planAction.Group.AsRole()))
 		return false, true, false, false, nil
 	}

pkg/generated/metric_descriptions/arangodb_operator_agency_cache_health_present.go

@@ -0,0 +1,35 @@
+//
+// DISCLAIMER
+//
+// Copyright 2016-2022 ArangoDB GmbH, Cologne, Germany
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Copyright holder is ArangoDB GmbH, Cologne, Germany
+//
+
+package metric_descriptions
+
+import "github.com/arangodb/kube-arangodb/pkg/util/metrics"
+
+var (
+	arangodbOperatorAgencyCacheHealthPresent = metrics.NewDescription("arangodb_operator_agency_cache_health_present", "Determines if local agency cache health is present", []string{`namespace`, `name`}, nil)
+)
+
+func init() {
+	registerDescription(arangodbOperatorAgencyCacheHealthPresent)
+}
+
+func ArangodbOperatorAgencyCacheHealthPresent() metrics.Description {
+	return arangodbOperatorAgencyCacheHealthPresent
+}

pkg/generated/metric_descriptions/arangodb_operator_agency_cache_healthy.go

@@ -0,0 +1,35 @@
+//
+// DISCLAIMER
+//
+// Copyright 2016-2022 ArangoDB GmbH, Cologne, Germany
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Copyright holder is ArangoDB GmbH, Cologne, Germany
+//
+
+package metric_descriptions
+
+import "github.com/arangodb/kube-arangodb/pkg/util/metrics"
+
+var (
+	arangodbOperatorAgencyCacheHealthy = metrics.NewDescription("arangodb_operator_agency_cache_healthy", "Determines if agency is healthy", []string{`namespace`, `name`}, nil)
+)
+
+func init() {
+	registerDescription(arangodbOperatorAgencyCacheHealthy)
+}
+
+func ArangodbOperatorAgencyCacheHealthy() metrics.Description {
+	return arangodbOperatorAgencyCacheHealthy
+}

pkg/generated/metric_descriptions/arangodb_operator_agency_cache_leaders.go

@@ -0,0 +1,35 @@
+//
+// DISCLAIMER
+//
+// Copyright 2016-2022 ArangoDB GmbH, Cologne, Germany
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Copyright holder is ArangoDB GmbH, Cologne, Germany
+//
+
+package metric_descriptions
+
+import "github.com/arangodb/kube-arangodb/pkg/util/metrics"
+
+var (
+	arangodbOperatorAgencyCacheLeaders = metrics.NewDescription("arangodb_operator_agency_cache_leaders", "Determines agency leader vote count", []string{`namespace`, `name`, `agent`}, nil)
+)
+
+func init() {
+	registerDescription(arangodbOperatorAgencyCacheLeaders)
+}
+
+func ArangodbOperatorAgencyCacheLeaders() metrics.Description {
+	return arangodbOperatorAgencyCacheLeaders
+}

pkg/generated/metric_descriptions/arangodb_operator_agency_cache_member_commit_offset.go

@@ -0,0 +1,35 @@
+//
+// DISCLAIMER
+//
+// Copyright 2016-2022 ArangoDB GmbH, Cologne, Germany
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Copyright holder is ArangoDB GmbH, Cologne, Germany
+//
+
+package metric_descriptions
+
+import "github.com/arangodb/kube-arangodb/pkg/util/metrics"
+
+var (
+	arangodbOperatorAgencyCacheMemberCommitOffset = metrics.NewDescription("arangodb_operator_agency_cache_member_commit_offset", "Determines agency member commit offset", []string{`namespace`, `name`, `agent`}, nil)
+)
+
+func init() {
+	registerDescription(arangodbOperatorAgencyCacheMemberCommitOffset)
+}
+
+func ArangodbOperatorAgencyCacheMemberCommitOffset() metrics.Description {
+	return arangodbOperatorAgencyCacheMemberCommitOffset
+}

pkg/generated/metric_descriptions/arangodb_operator_agency_cache_member_serving.go

@@ -0,0 +1,35 @@
+//
+// DISCLAIMER
+//
+// Copyright 2016-2022 ArangoDB GmbH, Cologne, Germany
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Copyright holder is ArangoDB GmbH, Cologne, Germany
+//
+
+package metric_descriptions
+
+import "github.com/arangodb/kube-arangodb/pkg/util/metrics"
+
+var (
+	arangodbOperatorAgencyCacheMemberServing = metrics.NewDescription("arangodb_operator_agency_cache_member_serving", "Determines if agency member is reachable", []string{`namespace`, `name`, `agent`}, nil)
+)
+
+func init() {
+	registerDescription(arangodbOperatorAgencyCacheMemberServing)
+}
+
+func ArangodbOperatorAgencyCacheMemberServing() metrics.Description {
+	return arangodbOperatorAgencyCacheMemberServing
+}

pkg/generated/metric_descriptions/arangodb_operator_agency_cache_present.go

@@ -0,0 +1,35 @@
+//
+// DISCLAIMER
+//
+// Copyright 2016-2022 ArangoDB GmbH, Cologne, Germany
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Copyright holder is ArangoDB GmbH, Cologne, Germany
+//
+
+package metric_descriptions
+
+import "github.com/arangodb/kube-arangodb/pkg/util/metrics"
+
+var (
+	arangodbOperatorAgencyCachePresent = metrics.NewDescription("arangodb_operator_agency_cache_present", "Determines if local agency cache is present", []string{`namespace`, `name`}, nil)
+)
+
+func init() {
+	registerDescription(arangodbOperatorAgencyCachePresent)
+}
+
+func ArangodbOperatorAgencyCachePresent() metrics.Description {
+	return arangodbOperatorAgencyCachePresent
+}

pkg/generated/metric_descriptions/arangodb_operator_agency_cache_serving.go

@@ -0,0 +1,35 @@
+//
+// DISCLAIMER
+//
+// Copyright 2016-2022 ArangoDB GmbH, Cologne, Germany
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Copyright holder is ArangoDB GmbH, Cologne, Germany
+//
+
+package metric_descriptions
+
+import "github.com/arangodb/kube-arangodb/pkg/util/metrics"
+
+var (
+	arangodbOperatorAgencyCacheServing = metrics.NewDescription("arangodb_operator_agency_cache_serving", "Determines if agency is serving", []string{`namespace`, `name`}, nil)
+)
+
+func init() {
+	registerDescription(arangodbOperatorAgencyCacheServing)
+}
+
+func ArangodbOperatorAgencyCacheServing() metrics.Description {
+	return arangodbOperatorAgencyCacheServing
+}