Fetch cluster health in go-routine

pkg/deployment/deployment.go

@@ -141,6 +141,7 @@ func New(config Config, deps Dependencies, apiObject *api.ArangoDeployment) (*De
 		ci := newClusterScalingIntegration(d)
 		d.clusterScalingIntegration = ci
 		go ci.ListenForClusterEvents(d.stopCh)
+		go d.resources.RunDeploymentHealthLoop(d.stopCh)
 	}
 	if config.AllowChaos {
 		d.chaosMonkey = chaos.NewMonkey(deps.Log, d)

pkg/deployment/resources/deployment_health.go

@@ -0,0 +1,89 @@
+//
+// DISCLAIMER
+//
+// Copyright 2018 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
+//
+// Author Ewout Prangsma
+//
+
+package resources
+
+import (
+	"context"
+	"time"
+
+	api "github.com/arangodb/kube-arangodb/pkg/apis/deployment/v1alpha"
+	"github.com/arangodb/kube-arangodb/pkg/metrics"
+)
+
+var (
+	fetchDeploymentHealthCounters = metrics.MustRegisterCounterVec("deployment_resources", "fetchDeploymentHealth", "Number of times the health of the deployment was fetched", "deployment", "result")
+)
+
+// RunDeploymentHealthLoop creates a loop to fetch the health of the deployment.
+// The loop ends when the given channel is closed.
+func (r *Resources) RunDeploymentHealthLoop(stopCh <-chan struct{}) {
+	log := r.log
+	deploymentName := r.context.GetAPIObject().GetName()
+
+	if r.context.GetSpec().GetMode() != api.DeploymentModeCluster {
+		// Deployment health is currently only applicable for clusters
+		return
+	}
+
+	for {
+		if err := r.fetchDeploymentHealth(); err != nil {
+			log.Debug().Err(err).Msg("Failed to fetch deployment health")
+			fetchDeploymentHealthCounters.WithLabelValues(deploymentName, "failed").Inc()
+		} else {
+			fetchDeploymentHealthCounters.WithLabelValues(deploymentName, "success").Inc()
+		}
+		select {
+		case <-time.After(time.Second * 5):
+			// Continue
+		case <-stopCh:
+			// We're done
+			return
+		}
+	}
+}
+
+// cleanupRemovedClusterMembers removes all arangod members that are no longer part of the cluster.
+func (r *Resources) fetchDeploymentHealth() error {
+	// Ask cluster for its health
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second*15)
+	defer cancel()
+	client, err := r.context.GetDatabaseClient(ctx)
+	if err != nil {
+		return maskAny(err)
+	}
+	c, err := client.Cluster(ctx)
+	if err != nil {
+		return maskAny(err)
+	}
+	h, err := c.Health(ctx)
+	if err != nil {
+		return maskAny(err)
+	}
+
+	// Save cluster health
+	r.health.mutex.Lock()
+	defer r.health.mutex.Unlock()
+	r.health.clusterHealth = h
+	r.health.timestamp = time.Now()
+	return nil
+}

pkg/deployment/resources/member_cleanup.go

@@ -23,11 +23,11 @@
 package resources
 
 import (
-	"context"
 	"time"
 
 	driver "github.com/arangodb/go-driver"
 	api "github.com/arangodb/kube-arangodb/pkg/apis/deployment/v1alpha"
+	"github.com/arangodb/kube-arangodb/pkg/metrics"
 	"github.com/arangodb/kube-arangodb/pkg/util/k8sutil"
 )
 
@@ -35,6 +35,11 @@ const (
 	// minMemberAge is the minimum duration we expect a member to be created before we remove it because
 	// it is not part of a deployment.
 	minMemberAge        = time.Minute * 10
+	maxClusterHealthAge = time.Second * 20
+)
+
+var (
+	cleanupRemovedMembersCounters = metrics.MustRegisterCounterVec("deployment_resources", "cleanupRemovedMembers", "Number of cleanup-removed-members actions", "deployment", "result")
 )
 
 // CleanupRemovedMembers removes all arangod members that are no longer part of ArangoDB deployment.
@@ -43,8 +48,10 @@ func (r *Resources) CleanupRemovedMembers() error {
 	switch r.context.GetSpec().GetMode() {
 	case api.DeploymentModeCluster:
 		if err := r.cleanupRemovedClusterMembers(); err != nil {
+			cleanupRemovedMembersCounters.WithLabelValues(r.context.GetAPIObject().GetName(), "failed").Inc()
 			return maskAny(err)
 		}
+		cleanupRemovedMembersCounters.WithLabelValues(r.context.GetAPIObject().GetName(), "success").Inc()
 		return nil
 	default:
 		// Other mode have no concept of cluster in which members can be removed
@@ -55,20 +62,16 @@ func (r *Resources) CleanupRemovedMembers() error {
 // cleanupRemovedClusterMembers removes all arangod members that are no longer part of the cluster.
 func (r *Resources) cleanupRemovedClusterMembers() error {
 	log := r.log
-	ctx := context.Background()
 
-	// Ask cluster for its health
-	client, err := r.context.GetDatabaseClient(ctx)
-	if err != nil {
-		return maskAny(err)
-	}
-	c, err := client.Cluster(ctx)
-	if err != nil {
-		return maskAny(err)
-	}
-	h, err := c.Health(ctx)
-	if err != nil {
-		return maskAny(err)
+	// Fetch recent cluster health
+	r.health.mutex.Lock()
+	h := r.health.clusterHealth
+	ts := r.health.timestamp
+	r.health.mutex.Unlock()
+
+	// Only accept recent cluster health values
+	if time.Since(ts) > maxClusterHealthAge {
+		return nil
 	}
 
 	serverFound := func(id string) bool {

pkg/deployment/resources/resources.go

@@ -22,13 +22,24 @@
 
 package resources
 
-import "github.com/rs/zerolog"
+import (
+	"sync"
+	"time"
+
+	driver "github.com/arangodb/go-driver"
+	"github.com/rs/zerolog"
+)
 
 // Resources is a service that creates low level resources for members
 // and inspects low level resources, put the inspection result in members.
 type Resources struct {
 	log     zerolog.Logger
 	context Context
+	health  struct {
+		clusterHealth driver.ClusterHealth // Last fetched cluster health
+		timestamp     time.Time            // Timestamp of last fetch of cluster health
+		mutex         sync.Mutex           // Mutex guarding fields in this struct
+	}
 }
 
 // NewResources creates a new Resources service, used to

pkg/util/errors/errors.go

@@ -0,0 +1,203 @@
+//
+// DISCLAIMER
+//
+// Copyright 2018 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
+//
+// Author Ewout Prangsma
+//
+
+package errors
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net"
+	"net/url"
+	"os"
+	"syscall"
+
+	driver "github.com/arangodb/go-driver"
+	errs "github.com/pkg/errors"
+)
+
+var (
+	Cause     = errs.Cause
+	New       = errs.New
+	WithStack = errs.WithStack
+	Wrap      = errs.Wrap
+	Wrapf     = errs.Wrapf
+)
+
+// WithMessage annotates err with a new message.
+// The messages of given error is hidden.
+// If err is nil, WithMessage returns nil.
+func WithMessage(err error, message string) error {
+	if err == nil {
+		return nil
+	}
+	return &withMessage{
+		cause: err,
+		msg:   message,
+	}
+}
+
+type withMessage struct {
+	cause error
+	msg   string
+}
+
+func (w *withMessage) Error() string { return w.msg }
+func (w *withMessage) Cause() error  { return w.cause }
+
+func (w *withMessage) Format(s fmt.State, verb rune) {
+	switch verb {
+	case 'v':
+		if s.Flag('+') {
+			fmt.Fprintf(s, "%+v\n", w.Cause())
+			io.WriteString(s, w.msg)
+			return
+		}
+		fallthrough
+	case 's', 'q':
+		io.WriteString(s, w.Error())
+	}
+}
+
+type timeout interface {
+	Timeout() bool
+}
+
+// IsTimeout returns true if the given error is caused by a timeout error.
+func IsTimeout(err error) bool {
+	if err == nil {
+		return false
+	}
+	if t, ok := errs.Cause(err).(timeout); ok {
+		return t.Timeout()
+	}
+	return false
+}
+
+type temporary interface {
+	Temporary() bool
+}
+
+// IsTemporary returns true if the given error is caused by a temporary error.
+func IsTemporary(err error) bool {
+	if err == nil {
+		return false
+	}
+	if t, ok := errs.Cause(err).(temporary); ok {
+		return t.Temporary()
+	}
+	return false
+}
+
+// IsEOF returns true if the given error is caused by an EOF error.
+func IsEOF(err error) bool {
+	err = errs.Cause(err)
+	if err == io.EOF {
+		return true
+	}
+	if ok, err := libCause(err); ok {
+		return IsEOF(err)
+	}
+	return false
+}
+
+// IsConnectionRefused returns true if the given error is caused by an "connection refused" error.
+func IsConnectionRefused(err error) bool {
+	err = errs.Cause(err)
+	if err, ok := err.(syscall.Errno); ok {
+		return err == syscall.ECONNREFUSED
+	}
+	if ok, err := libCause(err); ok {
+		return IsConnectionRefused(err)
+	}
+	return false
+}
+
+// IsConnectionReset returns true if the given error is caused by an "connection reset by peer" error.
+func IsConnectionReset(err error) bool {
+	err = errs.Cause(err)
+	if err, ok := err.(syscall.Errno); ok {
+		return err == syscall.ECONNRESET
+	}
+	if ok, err := libCause(err); ok {
+		return IsConnectionReset(err)
+	}
+	return false
+}
+
+// IsContextCanceled returns true if the given error is caused by a context cancelation.
+func IsContextCanceled(err error) bool {
+	err = errs.Cause(err)
+	if err == context.Canceled {
+		return true
+	}
+	if ok, err := libCause(err); ok {
+		return IsContextCanceled(err)
+	}
+	return false
+}
+
+// IsContextDeadlineExpired returns true if the given error is caused by a context deadline expiration.
+func IsContextDeadlineExpired(err error) bool {
+	err = errs.Cause(err)
+	if err == context.DeadlineExceeded {
+		return true
+	}
+	if ok, err := libCause(err); ok {
+		return IsContextDeadlineExpired(err)
+	}
+	return false
+}
+
+// IsContextCanceledOrExpired returns true if the given error is caused by a context cancelation
+// or deadline expiration.
+func IsContextCanceledOrExpired(err error) bool {
+	err = errs.Cause(err)
+	if err == context.Canceled || err == context.DeadlineExceeded {
+		return true
+	}
+	if ok, err := libCause(err); ok {
+		return IsContextCanceledOrExpired(err)
+	}
+	return false
+}
+
+// libCause returns the Cause of well known go library errors.
+func libCause(err error) (bool, error) {
+	original := err
+	for {
+		switch e := err.(type) {
+		case *driver.ResponseError:
+			err = e.Err
+		case *net.DNSConfigError:
+			err = e.Err
+		case *net.OpError:
+			err = e.Err
+		case *os.SyscallError:
+			err = e.Err
+		case *url.Error:
+			err = e.Err
+		default:
+			return err != original, err
+		}
+	}
+}