Add sns notification support back

[ecasti-gmail-com]

Hi all,
i'm trying to send notification to a SNS topic from alertmanager for trigger autoscaling of ECS,
i tried successfully slack notification,
but when i try to enable SNS notification the alertmanager panic with this error :
time="2015-11-18T15:20:11Z" level=info msg="Sent 1 notifications" file=manager.go line=353
panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xb code=0x1 addr=0x20 pc=0x6b51d2]

goroutine 1 [running]:
github.com/aws/aws-sdk-go/service/sns.New(0x0, 0x0, 0x0, 0x0, 0x0, 0x0)
/app/.build/gopath/src/github.com/aws/aws-sdk-go/service/sns/service.go:53 +0x72
github.com/prometheus/alertmanager/manager.(_notifier).sendAmazonSnsNotification(0xc820194ae0, 0x1, 0xc820195560, 0xc82017c580, 0x0, 0x0)
/app/.build/gopath/src/github.com/prometheus/alertmanager/manager/notifier.go:464 +0x55
github.com/prometheus/alertmanager/manager.(_notifier).handleNotification(0xc820194ae0, 0xc82017c580, 0x1, 0xc8200d9500)
/app/.build/gopath/src/github.com/prometheus/alertmanager/manager/notifier.go:809 +0x853
github.com/prometheus/alertmanager/manager.(*notifier).Dispatch(0xc820194ae0)
/app/.build/gopath/src/github.com/prometheus/alertmanager/manager/notifier.go:817 +0x86
main.main()
/app/main.go:159 +0x1280

goroutine 17 [syscall, 1 minutes, locked to thread]:
runtime.goexit()
/usr/local/go/src/runtime/asm_amd64.s:1696 +0x1

i"m using Docker images with this release:

branch master
date 20151109-20:48:36
go_version 1.5.1
revision 86f5f80
user @afbbf75ae75d
version 0.0.4

and alertmanager.conf is this:

notification_config {
name: "alertmanager_test"
amazon_sns_config {
topic_arn: "arn:aws:sns:us-east-1:1234567890X:MyTopicName"
send_resolved: true
}
}

aggregation_rule {
repeat_rate_seconds: 300
notification_config_name: "alertmanager_test"
}

My goal is authenticate to AWS using Instance-role, so i created one that permit action to AWS SNS, ( it's supported by AWS-SDK ) , but i also tried using credentials and environment variable but i had same issue

Best,
Enrico Casti

[juliusv]

/cc @GiantToast This nil-pointer crash probably got introduced due to this upstream change in the Go AWS library: aws/aws-sdk-go@1a69d06. Would you be up for looking into it since you added the SNS support?

[GiantToast]

Sorry just seeing this. After a quick glance at that Go AWS library change and the code I added, looks like a one line change. I don't have time right now to test it out, but I should be able to get that fixed tomorrow afternoon.

[juliusv]

@GiantToast Any news on this?

[GiantToast]

Went to make the needed change, and everything has changed! All that was needed was to change
sns.New(nil) to sns.New(session.New())
but it looks like the SNS stuff got lost in the rewrite.

[crhuber]

Is anyone working on this? I think this is a pretty key feature to have

[lhoss]

any update on this ?
we need SNS support soon in one of our prometheus deployments .

is there anything missing to make a PR with @GiantToast 's suggestion above ? ( #157 (comment) )

[stuartnelson3]

The recommendation is to create a webhook notifer, as we are not currently adding new notifiers.