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sns.go
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sns.go
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// Copyright 2021 Prometheus Team
// 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.
package sns
import (
"context"
"fmt"
"net/http"
"strings"
"unicode/utf8"
"github.com/aws/aws-sdk-go/aws"
"github.com/aws/aws-sdk-go/aws/awserr"
"github.com/aws/aws-sdk-go/aws/credentials"
"github.com/aws/aws-sdk-go/aws/credentials/stscreds"
"github.com/aws/aws-sdk-go/aws/session"
"github.com/aws/aws-sdk-go/service/sns"
"github.com/go-kit/kit/log"
"github.com/go-kit/kit/log/level"
"github.com/prometheus/alertmanager/config"
"github.com/prometheus/alertmanager/notify"
"github.com/prometheus/alertmanager/template"
"github.com/prometheus/alertmanager/types"
commoncfg "github.com/prometheus/common/config"
)
// Notifier implements a Notifier for SNS notifications.
type Notifier struct {
conf *config.SNSConfig
tmpl *template.Template
logger log.Logger
client *http.Client
retrier *notify.Retrier
isFifo *bool
}
// New returns a new SNS notification handler.
func New(c *config.SNSConfig, t *template.Template, l log.Logger, httpOpts ...commoncfg.HTTPClientOption) (*Notifier, error) {
client, err := commoncfg.NewClientFromConfig(*c.HTTPConfig, "sns", append(httpOpts, commoncfg.WithHTTP2Disabled())...)
if err != nil {
return nil, err
}
return &Notifier{
conf: c,
tmpl: t,
logger: l,
client: client,
retrier: ¬ify.Retrier{},
}, nil
}
func (n *Notifier) Notify(ctx context.Context, alert ...*types.Alert) (bool, error) {
var (
err error
data = notify.GetTemplateData(ctx, n.tmpl, alert, n.logger)
tmpl = notify.TmplText(n.tmpl, data, &err)
)
client, err := createSNSClient(n, tmpl)
if err != nil {
if e, ok := err.(awserr.RequestFailure); ok {
return n.retrier.Check(e.StatusCode(), strings.NewReader(e.Message()))
} else {
return true, err
}
}
publishInput, err := createPublishInput(ctx, n, tmpl)
if err != nil {
return true, err
}
publishOutput, err := client.Publish(publishInput)
if err != nil {
if e, ok := err.(awserr.RequestFailure); ok {
return n.retrier.Check(e.StatusCode(), strings.NewReader(e.Message()))
} else {
return true, err
}
}
level.Debug(n.logger).Log("msg", "SNS message successfully published", "message_id", publishOutput.MessageId, "sequence number", publishOutput.SequenceNumber)
return false, nil
}
func createSNSClient(n *Notifier, tmpl func(string) string) (*sns.SNS, error) {
var creds *credentials.Credentials = nil
// If there are provided sigV4 credentials we want to use those to create a session.
if n.conf.Sigv4.AccessKey != "" && n.conf.Sigv4.SecretKey != "" {
creds = credentials.NewStaticCredentials(n.conf.Sigv4.AccessKey, string(n.conf.Sigv4.SecretKey), "")
}
sess, err := session.NewSessionWithOptions(session.Options{
Config: aws.Config{
Region: aws.String(n.conf.Sigv4.Region),
Endpoint: aws.String(tmpl(n.conf.APIUrl)),
},
Profile: n.conf.Sigv4.Profile,
})
if err != nil {
return nil, err
}
if n.conf.Sigv4.RoleARN != "" {
var stsSess *session.Session
if n.conf.APIUrl == "" {
stsSess = sess
} else {
// If we have set the API URL we need to create a new session to get the STS Credentials.
stsSess, err = session.NewSessionWithOptions(session.Options{
Config: aws.Config{
Region: aws.String(n.conf.Sigv4.Region),
Credentials: creds,
},
Profile: n.conf.Sigv4.Profile,
})
if err != nil {
return nil, err
}
}
creds = stscreds.NewCredentials(stsSess, n.conf.Sigv4.RoleARN)
}
// Use our generated session with credentials to create the SNS Client.
client := sns.New(sess, &aws.Config{Credentials: creds})
// We will always need a region to be set by either the local config or the environment.
if aws.StringValue(sess.Config.Region) == "" {
return nil, fmt.Errorf("region not configured in sns.sigv4.region or in default credentials chain")
}
return client, nil
}
func createPublishInput(ctx context.Context, n *Notifier, tmpl func(string) string) (*sns.PublishInput, error) {
publishInput := &sns.PublishInput{}
messageAttributes := createMessageAttributes(n, tmpl)
// Max message size for a message in a SNS publish request is 256KB, except for SMS messages where the limit is 1600 characters/runes.
messageSizeLimit := 256 * 1024
if n.conf.TopicARN != "" {
topicTmpl := tmpl(n.conf.TopicARN)
publishInput.SetTopicArn(topicTmpl)
if n.isFifo == nil {
// If we are using a topic ARN it could be a FIFO topic specified by the topic postfix .fifo.
n.isFifo = aws.Bool(n.conf.TopicARN[len(n.conf.TopicARN)-5:] == ".fifo")
}
if *n.isFifo {
// Deduplication key and Message Group ID are only added if it's a FIFO SNS Topic.
key, err := notify.ExtractGroupKey(ctx)
if err != nil {
return nil, err
}
publishInput.SetMessageDeduplicationId(key.Hash())
publishInput.SetMessageGroupId(key.Hash())
}
}
if n.conf.PhoneNumber != "" {
publishInput.SetPhoneNumber(tmpl(n.conf.PhoneNumber))
// If we have an SMS message, we need to truncate to 1600 characters/runes.
messageSizeLimit = 1600
}
if n.conf.TargetARN != "" {
publishInput.SetTargetArn(tmpl(n.conf.TargetARN))
}
messageToSend, isTrunc, err := validateAndTruncateMessage(tmpl(n.conf.Message), messageSizeLimit)
if err != nil {
return nil, err
}
if isTrunc {
// If we truncated the message we need to add a message attribute showing that it was truncated.
messageAttributes["truncated"] = &sns.MessageAttributeValue{DataType: aws.String("String"), StringValue: aws.String("true")}
}
publishInput.SetMessage(messageToSend)
publishInput.SetMessageAttributes(messageAttributes)
if n.conf.Subject != "" {
publishInput.SetSubject(tmpl(n.conf.Subject))
}
return publishInput, nil
}
func validateAndTruncateMessage(message string, maxMessageSizeInBytes int) (string, bool, error) {
if !utf8.ValidString(message) {
return "", false, fmt.Errorf("non utf8 encoded message string")
}
if len(message) <= maxMessageSizeInBytes {
return message, false, nil
}
// if the message is larger than our specified size we have to truncate.
truncated := make([]byte, maxMessageSizeInBytes)
copy(truncated, message)
return string(truncated), true, nil
}
func createMessageAttributes(n *Notifier, tmpl func(string) string) map[string]*sns.MessageAttributeValue {
// Convert the given attributes map into the AWS Message Attributes Format
attributes := make(map[string]*sns.MessageAttributeValue, len(n.conf.Attributes))
for k, v := range n.conf.Attributes {
attributes[tmpl(k)] = &sns.MessageAttributeValue{DataType: aws.String("String"), StringValue: aws.String(tmpl(v))}
}
return attributes
}