I have an AWS lambda function that makes a request to the internet. When it makes the request with NO VPC, it's ok, but when I add it to the VPC, it stops working. I've attached an Internet Gateway to the VPC and created a NAT Gateway with RT to use outbound 0.0.0.0/0, but it stills not working.
With the 15seconds timeout, it's always throwing TO.
Could you please help me?
I've already followed these sites:
https://gist.github.com/reggi/dc5f2620b7b4f515e68e46255ac042a7
http://derpturkey.com/lambda-vpc-and-internet-access-configuration/
Everything seems to be well configured.
Lambda configuration
Route Table configuration
IGW attached to VPC
There are three ways to grant Internet access to an AWS Lambda function:
Do not assign it a VPC, or
Assign it to a VPC and attach an Elastic IP Address to the ENI (Elastic Network Interface) that is created in the VPC, or
Assign it to a private subnet in a VPC and use a NAT Gateway to grant the private subnet access to the Internet
If you have already verified the network configurtions like VPC setup, Subnets, Route Table, IG/NAG gate way. And associated the Lambda with current subnet and security groups.
Then the last thing to verify would be:
For Lambda functions to work into custom or User Defined VPC, Adding Lambda to the VPC would require AWSLambdaVPCAccessExecutionRole in addition to AWSLambdaBasicExecutionRole.
Ensure that the associated role has the above permissions.
Source:
https://docs.aws.amazon.com/lambda/latest/dg/vpc-rds-create-iam-role.html
Related
As the title suggests, I placed my Lambda function in a private subnet and now It cannot access or timeout when scanning the DB. Prior to this, it could access and scan the DB. What should I do?
Your DynamoDB resources are not in your VPC. Since you've configured your Lambda functions to connect to your VPC, you need to setup a NAT Gateway or NAT Instance to allow your private resources to access the internet. As the docs state:
AWS Lambda uses the VPC information you provide to set up ENIs that
allow your Lambda function to access VPC resources. Each ENI is
assigned a private IP address from the IP address range within the
Subnets you specify, but is not assigned any public IP addresses.
Therefore, if your Lambda function requires Internet access (for
example, to access AWS services that don't have VPC endpoints), you
can configure a NAT instance inside your VPC or you can use the Amazon
VPC NAT gateway. You cannot use an Internet gateway attached to your
VPC, since that requires the ENI to have public IP addresses.
AWS Lambda Doc
Validate the following:
The route table for the Lambda has a NAT Gateway for internet traffic that resides in public subnet.
DynamoDB Gateway endpoint exists? Check its policy to ensure that it is not limited to specific sources
Outbound access is allowed via the security group and NACL
I have a lambda function that makes a REST call. While developing, I had tagged it to "No VPC" and it was working. Since, the function needed to talk to RDS, I had to tag to VPC that hosted RDS. Since then REST call is not working.
I followed the article -
https://aws.amazon.com/premiumsupport/knowledge-center/internet-access-lambda-function/
The VPC is tagged to default security group. The security group has both inbound and outbound allowed
The VPC has 6 subnets. 5 are named as private subnet and 1 is named as public subnet
The public subnet is linked to public router which is linked to internet gateway
All the 5 subnets are linked to private router that is linked to NAT Gateway
ACLs have both inbound and outbound allowed
The lambda function was linked to two private subnets
When I try my lambda function, it still doesnt work.
Further analysis revealed that NAT gateway is linked to ENI-XXXXX through elastic IP. When I check the inbound and outbound rule for ENI-XXX, there is nothing listed. When I tried to change the security group, I received - You do not have permission to access the specified resource. Please note, I was trying to change it through root account
I tried creating a Elastic IP, and tagged it to existing eni-xxx that has inbound and outbound rule. However I am not able to link it to new NAT(the new NAT fails with message that EIP is already associated). If I again create a new NAT Gateway, it creates a new ENI-XXXX which has no inbound or outbound and I dont find option of linking new NAT to an ENI that has inbound and outbound rule.
Has anyone faced this issue? Please let me know where am I going wrong?
I was struggled this too and resolved by this:
Create a NAT gateway into the public subnet, then it will be linked to public IP.
Now, go to the Routing table in the VPC service and create it.
Linked subnets should be the private subnets of lambda.
destination to your VPC as local
destination to 0.0.0.0/0 as NAT gateway what you created a bit ago.
Test your lambda.
I didn't touch any ENI things.
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.
My setup is:
S3 (website) -> API Gateway -> Lambda -> RDS
-> S3 (configuration)
-> Shopify
-> Transactional Mail
I have an Internet Gateway set up to allow access to my S3 configurations and I need to hook up a NAT to allow me to make my calls out to 3rd parties. I've attempted to only use the NAT (per this question) by changing my Routing Table entry for 0.0.0.0/0 -> {my NAT}, but that just results in not being able to access my S3 configuration bucket.
Any help would be greatly appreciated!
Edit: To be clear I've read the documentation, what I'm having issues understanding is the relationships between the Security Group my Lambdas and RDS share, and the Subnets they're associated with.
When I configure my lambda to be part of the security group my RDS instances is in, I need to associate it with at least 2 subnets... Should those be new subnets, and not the ones associated with my RDS instances? AKA does a lambda need to share a subnet with an RDS in order to access it?
If the Lambda function only needs to access VPC resources and S3, then the easiest way to configure this is to add an S3 Endpoint to your VPC. If your Lambda function needs to access VPC resources plus other resources besides S3 and DynamoDB (the only 2 services that currently support VPC endpoints) then your Lambda function has to be in a private subnet with a NAT Gateway.
Instances in a public subnet have the option of having a public IP address, but it isn't a requirement. Lambda functions in a VPC do not ever get public IP addresses, which is why Lambda functions inside a VPC have to be in a private subnet with NAT gateway in order to have Internet access.
The only time Lambda functions get a public IP is when they are not in a VPC at all. In that instance they can access anything except resources in your VPC.
A note about your "same security group" comment: Being in the same security group does not allow resources to access each other. The Lambda function needs to be in a security group that the RDS security group has granted access to. Regarding subnets, the Lambda simply needs to be in any subnet in the same VPC, it does not need to be in the same subnet as the RDS instance.
I am trying to have an architecture with:
Route53 <-> API gateway <-> Lambda <-> RDS and DynamoDB.
I am confused about some networking aspects here!
From most of the documentation, what I understand is that Lambda is by default launched in default VPC and can access internet from there but no resources inside a "VPC". And this 2nd VPC (in quotes) refers to non-default VPCs in most discussions. But what is not clear is what if I placed the Lambda and RDS both in default VPC, lambda in a public subnet with --vpc-config info and RDS in a private subnet, will my Lambda have the internet connection?
Even when everything is in default subnet, should I put my lambda function in to a private subnet with Internet access through an Amazon VPC NAT gateway?
I know it is a theoretical question - documents are confusing me by not explicitly mentioning what cannot be done!
From most of the documentation, what I understand is that Lambda is by
default launched in default VPC and can access internet from there but
no resources inside a "VPC".
That is incorrect. By default Lambda is not launched in a VPC at all. Or if it is in a VPC it is in one that you cannot see because it doesn't exist in your AWS account.
what if I placed the Lambda and RDS both in default VPC, lambda in a
public subnet with --vpc-config info and RDS in a private subnet, will
my Lambda have the internet connection?
No, your Lambda function will not have internet access, even in a public subnet. This is because it is never assigned a public IP address. Once you place a Lambda function inside a VPC you have to have a NAT gateway in order to for the Lambda function to access anything outside the VPC.
Even when everything is in default subnet, should I put my lambda
function in to a private subnet with Internet access through an Amazon
VPC NAT gateway?
Yes, that is the correct way to provide a Lambda function with access to both a VPC and resources that exist outside the VPC.
Also note that DynamoDB (and the AWS API) does not run in your VPC. So if you place a Lambda function inside your VPC that needs to access DynamoDB, or anything else that is accessed via the AWS API, you will have to add a NAT gateway to the VPC.
Note that the "Default VPC" is the term for a the VPC that is setup for you when you first create your AWS account. You can see this VPC in your account in the VPC service console. Aside from it being created for you with default settings, you should just think of this as another VPC in your account. The Default VPC is not used by Lambda when you don't specify a VPC, and it is not used by other services like DynamoDB that exist outside your VPC network.