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publisher.go
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publisher.go
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// Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License"). You may
// not use this file except in compliance with the License. A copy of the
// License is located at
//
// http://aws.amazon.com/apache2.0/
//
// or in the "license" file accompanying this file. This file 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.
// Package publisher is used to batch and send metric data to CloudWatch
package publisher
import (
"context"
"sync"
"time"
"github.com/aws/amazon-vpc-cni-k8s/pkg/awsutils/awssession"
"github.com/aws/amazon-vpc-cni-k8s/pkg/ec2metadatawrapper"
"github.com/aws/amazon-vpc-cni-k8s/pkg/ec2wrapper"
"github.com/aws/amazon-vpc-cni-k8s/pkg/utils/logger"
"github.com/aws/aws-sdk-go/aws"
"github.com/aws/aws-sdk-go/service/cloudwatch"
"github.com/aws/aws-sdk-go/service/cloudwatch/cloudwatchiface"
"github.com/pkg/errors"
)
const (
// defaultInterval for monitoring the watch list
defaultInterval = time.Second * 60
// cloudwatchMetricNamespace for custom metrics
cloudwatchMetricNamespace = "Kubernetes"
// Metric dimension constants
clusterIDDimension = "CLUSTER_ID"
// localMetricData is the default size for the local queue(slice)
localMetricDataSize = 100
// maxDataPoints is the maximum number of data points per PutMetricData API request
maxDataPoints = 20
// Default cluster id if unable to detect something more suitable
defaultClusterID = "k8s-cluster"
)
var (
// List of EC2 tags (in priority order) to use as the CLUSTER_ID metric dimension
clusterIDTags = []string{
"eks:cluster-name",
"CLUSTER_ID",
"Name",
}
)
// Publisher defines the interface to publish one or more data points
type Publisher interface {
// Publish publishes one or more metric data points
Publish(metricDataPoints ...*cloudwatch.MetricDatum)
// Start is to initiate the batch and publish operation
Start()
// Stop is to terminate the batch and publish operation
Stop()
}
// cloudWatchPublisher implements the `Publisher` interface for batching and publishing
// metric data to the CloudWatch metrics backend
type cloudWatchPublisher struct {
ctx context.Context
cancel context.CancelFunc
updateIntervalTicker *time.Ticker
clusterID string
cloudwatchClient cloudwatchiface.CloudWatchAPI
localMetricData []*cloudwatch.MetricDatum
lock sync.RWMutex
log logger.Logger
}
// Logic to fetch Region and CLUSTER_ID
// Case 1: Cx not using IRSA, we need to get region and clusterID using IMDS
// Case 2: Cx using IRSA but not specified clusterID, we can still get this info if IMDS is not blocked
// Case 3: Cx blocked IMDS access and not using IRSA (which means region == "") AND
// not specified clusterID then its a Cx error
// New returns a new instance of `Publisher`
func New(ctx context.Context, region string, clusterID string, log logger.Logger) (Publisher, error) {
sess := awssession.New()
// If Customers have explicitly specified clusterID then skip generating it
if clusterID == "" {
ec2Client, err := ec2wrapper.NewMetricsClient()
if err != nil {
return nil, errors.Wrap(err, "publisher: unable to obtain EC2 service client")
}
clusterID = getClusterID(ec2Client, log)
}
// Try to fetch region if not available
if region == "" {
// Get ec2metadata client
ec2MetadataClient := ec2metadatawrapper.New(sess)
val, err := ec2MetadataClient.Region()
if err != nil {
return nil, errors.Wrap(err, "publisher: Unable to obtain region")
}
region = val
}
log.Infof("Using REGION=%s and CLUSTER_ID=%s", region, clusterID)
// Get AWS session
awsCfg := aws.Config{
Region: aws.String(region),
}
sess = sess.Copy(&awsCfg)
// Get CloudWatch client
cloudwatchClient := cloudwatch.New(sess)
// Build derived context
derivedContext, cancel := context.WithCancel(ctx)
return &cloudWatchPublisher{
ctx: derivedContext,
cancel: cancel,
cloudwatchClient: cloudwatchClient,
clusterID: clusterID,
localMetricData: make([]*cloudwatch.MetricDatum, 0, localMetricDataSize),
log: log,
}, nil
}
// Start is used to setup the monitor loop
func (p *cloudWatchPublisher) Start() {
p.log.Info("Starting monitor loop for CloudWatch publisher")
p.monitor(defaultInterval)
}
// Stop is used to cancel the monitor loop
func (p *cloudWatchPublisher) Stop() {
p.log.Info("Stopping monitor loop for CloudWatch publisher")
p.cancel()
}
// Publish is a variadic function to publish one or more metric data points
func (p *cloudWatchPublisher) Publish(metricDataPoints ...*cloudwatch.MetricDatum) {
// Fetch dimensions for override
p.log.Info("Fetching CloudWatch dimensions")
dimensions := p.getCloudWatchMetricDatumDimensions()
// Grab lock
p.lock.Lock()
defer p.lock.Unlock()
// NOTE: Iteration is used to override the metric dimensions
for _, metricDatum := range metricDataPoints {
metricDatum.Dimensions = dimensions
p.localMetricData = append(p.localMetricData, metricDatum)
}
}
func (p *cloudWatchPublisher) pushLocal() {
p.lock.Lock()
data := p.localMetricData[:]
p.localMetricData = make([]*cloudwatch.MetricDatum, 0, localMetricDataSize)
p.lock.Unlock()
p.push(data)
}
func (p *cloudWatchPublisher) push(metricData []*cloudwatch.MetricDatum) {
if len(metricData) == 0 {
p.log.Info("Missing data for publishing CloudWatch metrics")
return
}
// Setup input
input := cloudwatch.PutMetricDataInput{}
input.Namespace = p.getCloudWatchMetricNamespace()
// NOTE: Ensure cap of 40K per request and enforce rate limiting
for len(metricData) > 0 {
input.MetricData = metricData[:maxDataPoints]
// Publish data
err := p.send(input)
if err != nil {
p.log.Warnf("Unable to publish CloudWatch metrics: %v", err)
}
// Mutate slice
index := min(maxDataPoints, len(metricData))
metricData = metricData[index:]
// Reset Input
input = cloudwatch.PutMetricDataInput{}
input.Namespace = p.getCloudWatchMetricNamespace()
}
}
func (p *cloudWatchPublisher) send(input cloudwatch.PutMetricDataInput) error {
p.log.Info("Sending data to CloudWatch metrics")
_, err := p.cloudwatchClient.PutMetricData(&input)
return err
}
func (p *cloudWatchPublisher) monitor(interval time.Duration) {
p.updateIntervalTicker = time.NewTicker(interval)
for {
select {
case <-p.updateIntervalTicker.C:
p.pushLocal()
case <-p.ctx.Done():
p.Stop()
return
}
}
}
func (p *cloudWatchPublisher) getCloudWatchMetricNamespace() *string {
return aws.String(cloudwatchMetricNamespace)
}
func getClusterID(ec2Client *ec2wrapper.EC2Wrapper, log logger.Logger) string {
var clusterID string
var err error
for _, tag := range clusterIDTags {
clusterID, err = ec2Client.GetClusterTag(tag)
if err == nil && clusterID != "" {
break
}
}
if clusterID == "" {
clusterID = defaultClusterID
}
log.Infof("Using cluster ID ", clusterID)
return clusterID
}
func (p *cloudWatchPublisher) getCloudWatchMetricDatumDimensions() []*cloudwatch.Dimension {
return []*cloudwatch.Dimension{
{
Name: aws.String(clusterIDDimension),
Value: aws.String(p.clusterID),
},
}
}
// min is a helper to compute the min of two integers
func min(x, y int) int {
if x < y {
return x
}
return y
}