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pubsub.go
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pubsub.go
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package cloud_pubsub
import (
"context"
"encoding/base64"
"fmt"
"sync"
"time"
"cloud.google.com/go/pubsub"
"github.com/influxdata/telegraf"
"github.com/influxdata/telegraf/config"
"github.com/influxdata/telegraf/internal"
"github.com/influxdata/telegraf/plugins/outputs"
"github.com/influxdata/telegraf/plugins/serializers"
"golang.org/x/oauth2/google"
"google.golang.org/api/option"
)
const sampleConfig = `
## Required. Name of Google Cloud Platform (GCP) Project that owns
## the given PubSub topic.
project = "my-project"
## Required. Name of PubSub topic to publish metrics to.
topic = "my-topic"
## Required. Data format to consume.
## Each data format has its own unique set of configuration options.
## Read more about them here:
## https://github.com/influxdata/telegraf/blob/master/docs/DATA_FORMATS_INPUT.md
data_format = "influx"
## Optional. Filepath for GCP credentials JSON file to authorize calls to
## PubSub APIs. If not set explicitly, Telegraf will attempt to use
## Application Default Credentials, which is preferred.
# credentials_file = "path/to/my/creds.json"
## Optional. If true, will send all metrics per write in one PubSub message.
# send_batched = true
## The following publish_* parameters specifically configures batching
## requests made to the GCP Cloud PubSub API via the PubSub Golang library. Read
## more here: https://godoc.org/cloud.google.com/go/pubsub#PublishSettings
## Optional. Send a request to PubSub (i.e. actually publish a batch)
## when it has this many PubSub messages. If send_batched is true,
## this is ignored and treated as if it were 1.
# publish_count_threshold = 1000
## Optional. Send a request to PubSub (i.e. actually publish a batch)
## when it has this many PubSub messages. If send_batched is true,
## this is ignored and treated as if it were 1
# publish_byte_threshold = 1000000
## Optional. Specifically configures requests made to the PubSub API.
# publish_num_go_routines = 2
## Optional. Specifies a timeout for requests to the PubSub API.
# publish_timeout = "30s"
## Optional. If true, published PubSub message data will be base64-encoded.
# base64_data = false
## Optional. PubSub attributes to add to metrics.
# [outputs.cloud_pubsub.attributes]
# my_attr = "tag_value"
`
type PubSub struct {
CredentialsFile string `toml:"credentials_file"`
Project string `toml:"project"`
Topic string `toml:"topic"`
Attributes map[string]string `toml:"attributes"`
SendBatched bool `toml:"send_batched"`
PublishCountThreshold int `toml:"publish_count_threshold"`
PublishByteThreshold int `toml:"publish_byte_threshold"`
PublishNumGoroutines int `toml:"publish_num_go_routines"`
PublishTimeout config.Duration `toml:"publish_timeout"`
Base64Data bool `toml:"base64_data"`
Log telegraf.Logger `toml:"-"`
t topic
c *pubsub.Client
stubTopic func(id string) topic
serializer serializers.Serializer
publishResults []publishResult
}
func (ps *PubSub) Description() string {
return "Publish Telegraf metrics to a Google Cloud PubSub topic"
}
func (ps *PubSub) SampleConfig() string {
return sampleConfig
}
func (ps *PubSub) SetSerializer(serializer serializers.Serializer) {
ps.serializer = serializer
}
func (ps *PubSub) Connect() error {
if ps.Topic == "" {
return fmt.Errorf(`"topic" is required`)
}
if ps.Project == "" {
return fmt.Errorf(`"project" is required`)
}
if ps.stubTopic == nil {
return ps.initPubSubClient()
}
return nil
}
func (ps *PubSub) Close() error {
if ps.t != nil {
ps.t.Stop()
}
return nil
}
func (ps *PubSub) Write(metrics []telegraf.Metric) error {
ps.refreshTopic()
// Serialize metrics and package into appropriate PubSub messages
msgs, err := ps.toMessages(metrics)
if err != nil {
return err
}
cctx, cancel := context.WithCancel(context.Background())
// Publish all messages - each call to Publish returns a future.
ps.publishResults = make([]publishResult, len(msgs))
for i, m := range msgs {
ps.publishResults[i] = ps.t.Publish(cctx, m)
}
// topic.Stop() forces all published messages to be sent, even
// if PubSub batch limits have not been reached.
go ps.t.Stop()
return ps.waitForResults(cctx, cancel)
}
func (ps *PubSub) initPubSubClient() error {
var credsOpt option.ClientOption
if ps.CredentialsFile != "" {
credsOpt = option.WithCredentialsFile(ps.CredentialsFile)
} else {
creds, err := google.FindDefaultCredentials(context.Background(), pubsub.ScopeCloudPlatform)
if err != nil {
return fmt.Errorf(
"unable to find GCP Application Default Credentials: %v."+
"Either set ADC or provide CredentialsFile config", err)
}
credsOpt = option.WithCredentials(creds)
}
client, err := pubsub.NewClient(
context.Background(),
ps.Project,
credsOpt,
option.WithScopes(pubsub.ScopeCloudPlatform),
option.WithUserAgent(internal.ProductToken()),
)
if err != nil {
return fmt.Errorf("unable to generate PubSub client: %v", err)
}
ps.c = client
return nil
}
func (ps *PubSub) refreshTopic() {
if ps.stubTopic != nil {
ps.t = ps.stubTopic(ps.Topic)
} else {
t := ps.c.Topic(ps.Topic)
ps.t = &topicWrapper{t}
}
ps.t.SetPublishSettings(ps.publishSettings())
}
func (ps *PubSub) publishSettings() pubsub.PublishSettings {
settings := pubsub.PublishSettings{}
if ps.PublishNumGoroutines > 0 {
settings.NumGoroutines = ps.PublishNumGoroutines
}
if time.Duration(ps.PublishTimeout) > 0 {
settings.CountThreshold = 1
}
if ps.SendBatched {
settings.CountThreshold = 1
} else if ps.PublishCountThreshold > 0 {
settings.CountThreshold = ps.PublishCountThreshold
}
if ps.PublishByteThreshold > 0 {
settings.ByteThreshold = ps.PublishByteThreshold
}
return settings
}
func (ps *PubSub) toMessages(metrics []telegraf.Metric) ([]*pubsub.Message, error) {
if ps.SendBatched {
b, err := ps.serializer.SerializeBatch(metrics)
if err != nil {
return nil, err
}
if ps.Base64Data {
encoded := base64.StdEncoding.EncodeToString(b)
b = []byte(encoded)
}
msg := &pubsub.Message{Data: b}
if ps.Attributes != nil {
msg.Attributes = ps.Attributes
}
return []*pubsub.Message{msg}, nil
}
msgs := make([]*pubsub.Message, len(metrics))
for i, m := range metrics {
b, err := ps.serializer.Serialize(m)
if err != nil {
ps.Log.Debugf("Could not serialize metric: %v", err)
continue
}
if ps.Base64Data {
encoded := base64.StdEncoding.EncodeToString(b)
b = []byte(encoded)
}
msgs[i] = &pubsub.Message{
Data: b,
}
if ps.Attributes != nil {
msgs[i].Attributes = ps.Attributes
}
}
return msgs, nil
}
func (ps *PubSub) waitForResults(ctx context.Context, cancel context.CancelFunc) error {
var pErr error
var setErr sync.Once
var wg sync.WaitGroup
for _, pr := range ps.publishResults {
wg.Add(1)
go func(r publishResult) {
defer wg.Done()
// Wait on each future
_, err := r.Get(ctx)
if err != nil {
setErr.Do(func() {
pErr = err
cancel()
})
}
}(pr)
}
wg.Wait()
return pErr
}
func init() {
outputs.Add("cloud_pubsub", func() telegraf.Output {
return &PubSub{}
})
}