AWS SNS Creation times out

Question

I have Lambda function when invoked it creates SNS topic, adds subscribers to it and then publishes a message to it. After publishing the messages it deletes the topic. The name of the topic to be created and the subscribers are supplied to the lambda function as payload.

Sometimes it works and sometimes it fails with Task timed out after x seconds I have increased the lambda timeout and still same issue.

I dug a little and found out that

sns.createTopic(params, function(err, data) {
    if(err) {
        console.log('Error Creating SNS Topic:',err);
    } else {
        console.log('SNS Topic Created Successfully:',data);
    }
}

never returns, no error no data and I don't see result of console.log()

When it works, everything is good but when it fails I can't see to find the issue.

EDIT:

So I did a little more digging, I decreased the timeout of SNS topic creation it was 5 minutes by default now it is 5 seconds. When the failing happens I get this"

{ [TimeoutError: Connection timed out after 5000ms]
message: 'Connection timed out after 5000ms',
code: 'NetworkingError',
time: Thu Mar 30 2017 15:35:20 GMT+0000 (UTC),
region: 'us-east-1',
hostname: 'sns.us-east-1.amazonaws.com',
retryable: true }

well, it works one time not the other. I would think of this if it was happening all the times. — johnny, Mar 30 '17 at 19:17
Can you share the full code? If not, does the function do anything else besides the SNS work you mentioned? It could be that it really does need more than 5 minutes and that's why it's timing out but if all it's doing is really just need few SNS calls you mentioned then that shouldn't take anywhere near 5 minutes at all. There's nothing that sticks out as obvious from what you've mentioned so sharing the code could help or telling us more about what all your function does. — alanwill, Mar 31 '17 at 00:06

score 8 · Answer 1 · answered Apr 05 '17 at 14:43

8

I think I figured the issue out, my Lambada is in VPC and I had selected a couple of subnets under my Lambada configuration. Some of the selected subnets didn't have access to the internet and I think that was the reason when the lambda container was being created under these subnets(with no internet) it was not able to access SNS and timing out. After removing the violating subnets it starts working. I haven't see the issue since then.

answered Apr 05 '17 at 14:43

johnny

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Yep that would do it too. Glad you were able to figure it out – alanwill Apr 06 '17 at 01:39
2

We encountered the same thing, private VPC subnets had a NAT gateway enabled to talk to the public subnets, but the public subnets did not have one configured and where therefore not allowed to talk to the internet. Thank you! – luk2302 Jul 24 '17 at 10:09
See e.g. http://forum.serverless.com/t/solved-publishing-to-created-sns-topic/1426 for more details. – luk2302 Jul 24 '17 at 10:15
Thanks for this! Been searching for fecking ages for a solution :) – edzillion Dec 10 '18 at 14:38
Glad it helped. – johnny Dec 10 '18 at 16:23

score 8 · Answer 2 · answered Nov 11 '19 at 14:50

For a lambda function to have internet access (while also being attached to a VPC)

Select only private subnets for your lambda function
Security group can be default.
The private subnet should be attached to a route table which has a route 0.0.0.0/0 to a NAT gateway (X)
The tricky part is that NAT gateway X should be attached to a public subnet(AWS console asks for a subnet while creation)
The trickier part is that the public subnet we just used in step 4 should be attached to a route table which has a route 0.0.0.0/0 to a IGW. (The configuration of this route makes it a public subnet)

There is a great video by Amazon on this and it was very helpful for someone like me who had 0 knowledge on all the AWS jargon. https://www.youtube.com/watch?v=JcRKdEP94jM#action=share

AWS SNS Creation times out

2 Answers2

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