I have a lambda function that calls the parameter store to retrieve a credential. The code is as follows:
import boto3
ssm = boto3.client('ssm')
parameter = ssm.get_parameter(Name='credentials', WithDecryption=True)
print(parameter['Parameter']['Value'])
I have given AmazonSSMFullAccess to the lambda role. The lambda has a VPC which later I'll use it to connect to a Redshift database without public access. The inbound and outbound rules are as follows:
There is a post AWS Lambda cannot connect to Parameter Store which mentions that if the lambda requires VPC, then add a NAT gateway.
In the lambda subnet route table: , there seems to be already a route that goes to the internet?
But I am still getting lambda time-out errors :(
there seems to be already a route that goes to the internet?
Sadly, it does not. It seems you placed your lambda in a public subnet with route to internet gateway (IGW). However, you have to use private subnet with a route to NAT gateway. IGW and NAT are two different things. Have a look at this AWS guide how to make it work:
How do I give internet access to a Lambda function that's connected to an Amazon VPC?
Alternatively, you can setup VPC interface endpoint for Paramter store. Then you don't need internet access for your Lambda function.
Related
I have a Lambda function deployed into a public subnet in a VPC and I’m trying to connect to a Lambda function outside of a VPC and I’m running into connectivity issues.
I believe the security group settings and IAM policies will permit the connection, but I'm not sure if there's an issue with connecting to an out-of-VPC Lambda from an in-VPC one.
Is there a tool in AWS Console, AWS CLI or anywhere else that I can use to troubleshoot where the connection is failing? I’ve used the Reachability Analyzer before but it only works on a handful of resource types like EC2 instances.
I've tried invoking the out-of-VPC Lambda from inside my in-VPC Lambda, but the request doesn't work and I don't see any helpful information about what happened. I tried running the Reachability Analyzer, but it doesn't allow you to test if Lambda functions are reachable.
I was expecting the request to work, but I'm not sure if I need to configure a VPC interface endpoint because I'm connecting from an in-VPC Lambda to an out-of-VPC Lambda.
I’m new to networking and would appreciate any help.
I have a Lambda function deployed into a public subnet in a VPC and I’m trying to connect to a Lambda function outside of a VPC and I’m running into connectivity issues.
The Lambda function in the VPC never gets a public IP assigned to it. So it can't connect to anything outside of the VPC. It can't use the Internet Gateway attached to the public subnet because it doesn't have a public IP.
By "connect to a Lambda function outside of a VPC" what you are really doing is connecting to the AWS API outside of the VPC. You never "connect" to a Lambda function, because Lambda functions aren't running and just sitting around idle waiting for your request. Lambda functions don't really exist until a request comes in to the AWS Lambda Invoke API, at which point AWS spins up an instance of the Lambda function and passes it the invocation payload.
To fix this connectivity issue, you either need to create an AWS Lambda VPC Endpoint in your VPC, to handle requests to the Lambda API originating in your VPC. Or you need to move the VPC Lambda function to a private subnet, with a route to a NAT Gateway. Lambda functions in private subnets can access things outside the VPC by having their requests routed through the NAT Gateway.
I was expecting the request to work, but I'm not sure if I need to configure a VPC interface endpoint because I'm connecting from an in-VPC Lambda to an out-of-VPC Lambda.
That's not how VPC Interface Endpoints work. The entire purpose of VPC Interface Endpoints is to allow a resource inside your VPC to access part of the AWS API that exists outside the VPC. A VPC Interface Endpoint will absolutely allow your Lambda function running in the VPC to access the Lambda Invoke API, in order to trigger an execution of your out-of-VPC Lambda function.
I am connecting to AWS DocumentDB from a Lambda function. In order to be able to do this I had to attach lambda to the default VPC (that's where DocumentDB cluster is running) and the default (public) subnets. But, this has caused my Lambda to timeout whenever trying make an outbound request, e.g. push message to SQS. This, I want to avoid.
So what is the recommended way of connecting to DocumentDB without loosing functionality that occurs when putting Lambda in the VPC? There's gotta be a simple solution.
Lambda functions in a VPC never get a public IP address. So if the function needs to access both VPC resources and other resources outside of the VPC the function has to be deployed only to private subnets with routes to a NAT Gateway.
Alternatively, if the only external resources you need to access are other AWS services, then you could add VPC Endpoints for those services to the VPC.
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 am working on a AWS lambda in which i want to use DynamoDB and a VPC(Amazon elasticcache for redis). But I was getting time out error when trigger lambda
You either need to create a DyanmoDB VPC Endpoint in the VPC, or add a NAT Gateway to the VPC, and only deploy the Lambda function in subnets that have a route to the NAT Gateway.
Depending on the VPC configuration subnet/Security Group of your lambda,
If your lambda is in a private subnet :
If you want a secure internal way, you can pass with VPC endpoint
Else if you want to pass with internet, you must have a NAT Gateway.
Check also the security groups/NACLS....
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.