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/
notifier.go
127 lines (109 loc) · 2.96 KB
/
notifier.go
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/*
Package notifier provides clients for sending messages to SNS and SQS.
*/
package notifier
import (
"crypto/md5"
"errors"
"fmt"
"github.com/aws/aws-sdk-go/aws"
"github.com/aws/aws-sdk-go/service/sns"
"github.com/aws/aws-sdk-go/service/sns/snsiface"
"github.com/aws/aws-sdk-go/service/sqs"
"github.com/aws/aws-sdk-go/service/sqs/sqsiface"
"github.com/twitchscience/aws_utils/common"
)
var (
Retrier = &common.Retrier{
Times: 3,
BackoffFactor: 2,
}
)
type MessageCreator map[string]func(...interface{}) (string, error)
type SQSClient struct {
Signer *MessageCreator
sqsClient sqsiface.SQSAPI
}
func BuildSQSClient(client sqsiface.SQSAPI) *SQSClient {
m := make(MessageCreator)
m.RegisterMessageType("error", func(args ...interface{}) (string, error) {
return fmt.Sprintf("%v", args...), nil
})
return &SQSClient{
Signer: &m,
sqsClient: client,
}
}
func (s *SQSClient) SendMessage(messageType, qName string, args ...interface{}) error {
out, err := s.sqsClient.GetQueueUrl(&sqs.GetQueueUrlInput{
QueueName: aws.String(qName),
})
if err != nil {
return fmt.Errorf("Error getting URL for SQS queue %s: %v", qName, err)
}
message, err := s.Signer.SignBody(messageType, args...)
if err != nil {
return err
}
return s.handle(message, aws.StringValue(out.QueueUrl))
}
func (s *SQSClient) handle(message, qURL string) error {
var res *sqs.SendMessageOutput
err := Retrier.Retry(func() error {
var e error
res, e = s.sqsClient.SendMessage(&sqs.SendMessageInput{
QueueUrl: aws.String(qURL),
MessageBody: aws.String(message),
})
return e
})
if err != nil {
return err
}
// check md5
expectedHash := md5.New()
expectedHash.Write([]byte(message))
expected := fmt.Sprintf("%x", expectedHash.Sum(nil))
if expected != aws.StringValue(res.MD5OfMessageBody) {
return fmt.Errorf("message %s did not match expected %s", res.MD5OfMessageBody, expected)
}
return nil
}
type SNSClient struct {
Signer *MessageCreator
snsClient snsiface.SNSAPI
}
func BuildSNSClient(client snsiface.SNSAPI) *SNSClient {
m := make(MessageCreator)
m.RegisterMessageType("error", func(args ...interface{}) (string, error) {
return fmt.Sprintf("%v", args...), nil
})
return &SNSClient{
Signer: &m,
snsClient: client,
}
}
func (s *SNSClient) SendMessage(messageType, topicARN string, args ...interface{}) error {
message, err := s.Signer.SignBody(messageType, args...)
if err != nil {
return err
}
err = Retrier.Retry(func() error {
_, err := s.snsClient.Publish(&sns.PublishInput{
Message: &message,
TopicArn: &topicARN,
})
return err
})
return err
}
func (m *MessageCreator) RegisterMessageType(name string, messageType func(...interface{}) (string, error)) {
(*m)[name] = messageType
}
func (m *MessageCreator) SignBody(messageType string, args ...interface{}) (string, error) {
if fn, ok := (*m)[messageType]; ok {
return fn(args...)
} else {
return "", errors.New("message" + messageType + "does not exists")
}
}