I would like my lambda function to be able to access the internet. I have followed the following AWS tutorial: AWS Knowledge Center Videos: How do I give internet access to my Lambda function in a VPC?
I have created a NAT.
Then I created a public-lambda network and created a route table that forwards default traffic to the NAT
Then on my lambda function I have attached it to the public-lambda network
Inside my lambda function I make a request to a server out on the web. It just times out. I don't get logs on why it timed out but I'm assuming it wasn't able to reach the internet.
Why I'm not being able to access the internet from my lambda function?
if your subnet has outbound access to internet(NAT/IGW) then definitely you lambda will get access to the internet.
first check with the subnet, try to spin one ec2 instance into that subnet and check the outbound connectivity using ping or curl.
second check the attached SG with lambda function.
just give a try, best of luck.
After watching AWS: How to Place Your Lambda Functions in a VPC - YouTube I was able to fix my issue.
The fix was that I needed to create a private subnet and create a routing table to route all default traffic to the NAT.
Related
current situation:
I'm developing an AWS lambda that would launch an EC2 instance through a cloud formation stack.
I've deployed it inside a VPC, and thus had created endpoints to give it access to ressources such as S3/DynamoDB. However I cannot find any endpoints for the cloud formation, and as a result my function gets stucked at:
Starting new HTTPS connection (1): cloudformation.ap-south-1.amazonaws.com:443
update 1
Here is the snippet of code I'm using to connect to cloudformation:
self.cfn = session.resource('cloudformation')
stackdata = self.cfn.create_stack(
StackName="STACK-{}".format(instance_name),
DisableRollback=True,
TemplateURL=constants.TEMPLATE_TYPE[instance_type],
Parameters=params,
Capabilities=['CAPABILITY_IAM', 'CAPABILITY_AUTO_EXPAND','CAPABILITY_NAMED_IAM']
)
Please be noted that my code works just fine in a none-VPC setup (if I deploy my lambda outside of a VPC)
Could anyone help me try to figure out what I'm missing here?
Lambda function that is deployed to the VPC doesn't have access to the internet. That means that it's not able to access any of the AWS services endpoints unless you do one of two things:
create a VPC endpoint for that service
Add NAT Gateway so Lambda function can use it to access internet
You add NAT gateway to the public subnet.
After that, you need to edit route tables for private subnets to point to the NAT gateway. When you add a Lambda function to the VPC, you choose in which subnets it can be deployed. It's necessary to associate all of those subnets with the NAT gateway, so you're sure that the Lambda function will always have access to the NAT gateway.
If your Lambda function really needs to be in VPC (it needs access to some other resources inside of VPC), this is ok, but if it's not really necessary, I'd suggest you just move it outside of VPC (NAT gateway is $35/month + traffic).
You can see the details here as well: AWS Knowledgebase
I have a lambda job that works fine until I put it in a VPC, it seems to stop reading the kinesis stream as soon as that is done and works again when I put it in no VPC. Anyone have any advice on how to solve this?
For lambda to work properly in VPC, you need to add AWSLambdaVPCAccessExecutionRole managed policy to your function's execution role.
Also it needs to be remembered that lambda in your vpc does not have access to Internet:
When you connect a function to a VPC in your account, it does not have access to the internet unless your VPC provides access.
To enable access to public kinesis endpoints:
To give your function access to the internet, route outbound traffic to a NAT gateway in a public subnet. The NAT gateway has a public IP address and can connect to the internet through the VPC's internet gateway.
Alternatively, can setup VPC interface endpoints to access kinesis without going to the internet.
Hope this will be helpful.
So I have a very confusing issue that I don't know how to solve. My setup is API Gateway -> Lambda -> IoT Core. I setup the code and it works fine from my IDE. I deploy it to AWS, and my connection to AWS times out.
The Lambda is in a single subnet and the subnet does have a default route to an IGW. I did a test, and the Lambda function can resolve the IP of my IoT endpoint to a public IP (54.x.x.x). But the connect() method times out. My security group for the Lambda function is setup to allow all incoming / outgoing.
What am I missing? Why can't I get to IoT Core from inside a VPC with an IGW configured and seems to be working. Any direction would be greatly appreciated.
UPDATE
After playing around with many different things, I can't identify what exactly I had messed up with my configuration. But following the accepted answer I ended up with the following setup which appears to work for what I need.
subnet-1 10.14.10.0/24 (auto-assign-public=false)
local route ( 10.14.0.0/16 ) and default route=nat-gateway
subnet-2 10.14.20.0/24 (auto-assign-public=false)
local route ( 10.14.0.0/16 ) and default route=nat-gateway
subnet-3 10.14.30.0/24 (auto-assign-public=false)
local route ( 10.14.0.0/16 ) and default route=nat-gateway
subnet-4 10.14.40.0/24 (auto-assign-public=false)
local route ( 10.14.0.0/16 ) and default route=nat-gateway
subnet-5 10.14.200.0/24 (auto-assign-public=true)
local route ( 10.14.0.0/16 ) and default route=igw
nat-gateway
in subnet-5
I don't know if this is what I intended, but this is what I was looking for. A series of subnets that are not publicly accessible, but has an internet connection for access to other AWS services. So my Lambda resources, ECS, etc can sit privately and access what they need.
Thank you everyone for the information.
You should not deploy the Lambda function to a public subnet (that's the subnet with the default route to the IGW). It won't work the way you want it to work. The Lambda function doesn't have, and cannot have, a public IP so cannot route to the internet via the IGW.
If the Lambda needs to be in VPC, then move it to a private subnet and make sure that the private subnet has a default route to a NAT (or NAT gateway) in a public subnet. Or deploy the Lambda function outside of VPC completely, if that's viable.
More information at:
Why can't Lambda in public subnet reach the internet?
Why do we need private subnet in a VPC?
When you say "I did a test, and the Lambda function can resolve the IP of my IoT endpoint to a public IP (54.x.x.x)" Do you mean DNS resolution, or you've checked this with a actual network traffic.
In either case, you can turn VPC Flow Logs for your VPC, and try again. The flow log will identify whether SGs or NACLs are blocking your traffic.
Remember also that Lambda's cannot exists in a public subnet, they have to reside in private subnets, and use NAT GW on public subnets to connect to the internet.
I encountered the same issue. Thankfully, AWS has automated this process and it's only a few clicks but sadly an extra $$$/month (about $30 to start).
You need to create a VPC group that has both public and private subnets. For my case, I was accessing a RDS database to then build email templates and fire off these emails via SES.
What did not work:
When I deployed a default VPC on my lambda function, the RDS would work, but the SES would not. The reason being is the SES API has no access to the internet via default VPCs, you need to setup a private subnet to allow for this.
VPC wizard can do this all for you with a few simple clicks, but you're looking at spending about $30/month (CAD) to setup a NAT gateway + any potential data processing charges per GB (read the pricing). For my case, firing a few email templates off it outweighed deploying another ec2 instance and gave me flexibility for scaling without too much on-the-fly configuration.
This link is a good place to get started. How do I give internet access to a Lambda function that's connected to an Amazon VPC?
Follow the VPC wizard hyperlink within that article, and you just need to go to the VPC console and create a VPC, should look something like this (below)
Once AWS works its magic, you need to assign the VPC to your Lambda function, assign the right permissions to your lambda function AND don't forget to configure your security group with the correct inbound rules. In my case I need to add a PostGres rule to access my RDS.
Hope this helps!
I have a lambda function that simply does an http.get to http://www.google.com. If I don't have the function behind a VPC, it works fine. The trouble happens when I put it in my VPC.
I know you need to set up an Internet Gateway. I did this. My two subnets are attached to route tables that route 0.0.0.0/0 to this Internet Gateway. Shouldn't that be all I need?
The function still hangs regardless of the Internet Gateway's association. The subnet's security groups allows All Traffic out of 0.0.0.0/0".
According to Grant Internet Access to a VPC Lambda Function that is everything I should need to do.
Edit:
Adding full list of VPC components to be clear.
Created a new VPC (vpc-09*)
Created a new subnet (subnet-05*) point to my new:
route table, (rtb-0b). I see subnet-05* under Subnet Associations. Under Routes, I see Destination 0.0.0.0/0 linked to the Target of
a new NAT Gateway (nat-08*). This NAT Gateway has an Elastic IP Address and a Private IP Address. It resides in the correct Subnet. The status is Available.
Additionally, I created a new Security Group for the Lambda function. This contains one Outbound Rules for "All traffic" with Destination 0.0.0.0/0
As far as I can tell, I've done absolutely everything in that AWS Documentation link to provide my Lambda with internet access. Yet, it still hangs forever when trying to make a request to the outside internet.
You're almost there. The link that you've provided address your issue directly:
If your function also requires internet access (for example, to reach a public AWS service endpoint), your function must use a NAT gateway or instance
You're missing this:
Your VPC should contain a NAT gateway or instance in a public subnet.
This means that without a NAT, your Lambdas won't be able to access the internet - even though "they are" in a public subnet. This is how lambda fundamentally works in VPCs.
The exact same link that you provided instructs you on how to create this NAT Gateway alongside your VPCs and Lambdas.
Complementing the answer - on why you would need a NAT Gateway in this scenario - is due to:
... you can use a network address translation (NAT) gateway to enable instances in a private subnet to connect to the internet or other AWS services, but prevent the internet from initiating a connection with those instances...
Extracted from aws docs
Keep in mind: If you need your lambdas to access only the internet - and not any other resource in the same VPC - I recommend to make them non-VPC and then they'll have internet access out of the box - and you won't pay for the cost of NATs.
I have a target group which has two EC2 instances behind an application load balancer. I'm trying to build a lambda service to monitor EC2 instance healthy status outside of load balancer listener.
this lambda works as expected if VPC is not enabled. once I enabled VPC, then following code will fail:
client = boto3.client("elbv2", region_name=default_region_name)
tg_res = client.describe_target_groups(Names=[self.name])
API describe_target_groups will stuck there until timeout.
this VPC does have internet access and security group inbound/outbound temporary open for all IP.
any hit will be highly appreciated.
==========update==================
From lambda log, timeout happens at:
Starting new HTTPS connection (1): elasticloadbalancing.us-west-2.amazonaws.com
I checked network setting and I'm sure this VPC has NAT configuration.
this issue is solved by assigned another two internal access only subnets.
1) two EC2 instances are behind an ALB. EC2 instances are in subnet, let's say: west-2a-public, west-2b-public. These two subnets are internet facing and can assign public IP.
2) I assigned lambda service into same subnet: west-2a-public and west-2b-public but it doesn't work.
3) I then assigned lambda service into another two subnets: west-2a-private and west-2b-private. These two subnet does have NAT but doesn't have public IP assignment.
I guess the issue the router mapping but I need time to figure out exactly root cause. so far, it works.
You might need to edit your aws lambda function to add VPC support.
You can read more about here
I think the reason for this is the following: First, you need a NAT Gateway to access the Internet for Lambda functions as described here:
https://aws.amazon.com/de/blogs/aws/new-access-resources-in-a-vpc-from-your-lambda-functions/
Internet Access – As soon as you enable this functionality for a
particular function, the function no longer has access to the Internet
by default. If your function requires this type of access, you will
need to set up a Managed NAT Gateway in your VPC (see New – Managed
NAT (Network Address Translation) Gateway for AWS for more
information) or run your own NAT (see NAT Instances).
Second, if you have an EC2 instance or other Service such as a Load Balancer that need to be accessible inbound from the internet then you also need an Internet Gateway. However, it is not possible to assign an Internet Gateway and the NAT to one subnet. Therefore, you need to setup two subnets.
Here is an article describing the correct setup and configurations:
https://marcelog.github.io/articles/aws_lambda_internet_vpc.html