I have a Lambda function (NodeJS) which consume an API that need to be accesed from certains IP, so team under the API ask me "please, provide us your IP to add it to the white list", but I'm not sure where or how to configure that static IP on AWS, where should I look?
Since #maurice show you the way, I will try to add some insight though I had to build a similar infrastructure like yours:
Third party provider requests us a static IP to connect to their API and our code was in a Lambda function (NodeJS).
In this case we did not want the lambdas to be reachable from outside, so we built two Subnets, one private and another one public. Lambdas go inside the private, which route Table 0.0.0.0/0 uses a NAT attached to the public subnet to manage the traffic that needs to connect to the Internet. Let me show you a few screenshots:
The Lambda must be in a VPC subnet with a NAT-Gateway.
The private subnet route table, which shows a NAT attachment:
The NAT belongs to the public subnet, and has an elastic IP attached (this is the key):
The public subnet has the following route table (everything is managed by the IGW):
This is something that is currently running in production environment and works flawless
You can't provide a static IP in a Lambda function directly.
You could deploy the Lambda function in a private subnet of a VPC that uses a NAT-Gateway for internet connectivity.
This NAT-Gateway will have an Elastic-IP, which you can tell your provider
(For high-availability you should have one NAT gateway per region).
Related
I've followed the tutorial here to create a VPC with public and private subnets.
Then I set up an AWS lambda function inside the public subnet to test if it could connect to the outside internet.
Here's my lambda function written in python3
import requests
def lambda_handler(event, context):
r = requests.get('http://www.google.com')
print(r)
The function above failed to fetch the content of http://www.google.com when I set it inside the public subnet in a VPC.
Here's the error message:
"errorMessage": "HTTPConnectionPool(host='www.google.com', port=80):
Max retries exceeded with url: / (Caused by
NewConnectionError(': Failed to establish a new connection: [Errno 110]
Connection timed out',))", "errorType": "ConnectionError",
I don't understand why.
The route table of the public subnet looks like this:
The GET request to http://www.google.com should match igw-XXXXXXXXX target. Why can't the internet-gateway(igw) deliver the request to http://www.google.com and get back the website content?
This article says that I must set the lambda function inside the private subnet in order to have internet access.
If your Lambda function needs to access private VPC resources (for
example, an Amazon RDS DB instance or Amazon EC2 instance), you must
associate the function with a VPC. 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.
But it doesn't explain why I can't set the lambda function inside the public subnet.
Lambda functions connected to a VPC public subnet cannot typically access the internet.
To access the internet from a public subnet you need a public IP or you need to route via a NAT that itself has a public IP. You also need an Internet Gateway (IGW). However:
Lambda functions do not, and cannot, have public IP addresses, and
the default route target in a VPC public subnet is the IGW, not a NAT
So, because the Lambda function only has a private IP and its traffic is routed to the IGW rather than to a NAT, all packets to the internet from the Lambda function will be dropped at the IGW.
Should I Configure my Lambda Function for VPC Access?
If your Lambda function does not need to reach private resources inside your VPC (e.g. an RDS database or Elasticsearch cluster) then do not configure the Lambda function to connect to the VPC.
If your Lambda function does need to reach private resources inside your VPC, then configure the Lambda function to connect to private subnets (and only private subnets).
NAT or Not?
If the Lambda function only needs access to resources in the VPC (e.g. an RDS database in a private subnet) then you don't need to route through NAT.
If the Lambda function only needs access to resources in the VPC and access to AWS services that are all available via private VPC Endpoint then you don't need to route through NAT. Use VPC Endpoints.
If your Lambda function needs to reach endpoints on the internet then ensure a default route from the Lambda function's private subnets to a NAT instance or NAT Gateway in a public subnet. And configure an IGW, if needed, without which internet access is not possible.
Be aware that NAT gateway charges per hour and per GB processed so it's worth understanding how to reduce data transfer costs for NAT gateway.
Best Practices
When configuring Lambda functions for VPC access, it is an HA best practice to configure multiple (private) subnets across different Availability Zones (AZs).
Intermittent Connectivity
Be sure that all the subnets you configure for your Lambda function are private subnets. It is a common mistake to configure, for example, 1 private subnet and 1 public subnet. This will result in your Lambda function working OK sometimes and failing at other times without any obvious cause.
For example, the Lambda function may succeed 5 times in a row, and then fail with a timeout (being unable to access some internet resource or AWS service). This happens because the first launch was in a private subnet, launches 2-5 reused the same Lambda function execution environment in the same private subnet (the so-called "warm start"), and then launch 6 was a "cold start" where the AWS Lambda service deployed the Lambda function in a public subnet where the Lambda function has no route to the internet.
You can make a lambda function access the public internet from within your VPC, you just need to make sure you really need it.
For accessing resources external to AWS such as Google API (like OP's example) you do need a Public IP. For other cases like RDS or S3 you don't need Public IP, you can use a VPC Endpoint, so communication between your Lambda and the desired AWS Service doesn't leave AWS network.
By default some AWS Services are indeed reached via public internet, but it doesn't have to be.
[EDIT]
Someone was concerned about scalability in the comments, but they missed this from AWS Docs:
"Multiple Lambda functions can share a network interface, if the functions share the same subnet and security group"
Also, you must have a Public IP for reaching Public Internet, whether you're using Lambda, EC2, ECS, even if you use a NAT Gateway it needs an Elastic Public IP if you want to reach the public internet through it.
Solution
To do that, you need to assign Elastic Public IPs to the Network Interfaces for each subnet linked to your lambda. First let's figure which subnets and security groups are linked to your lambda:
Next, go to EC2 Service, find the Public IPs menu under Network & Security. Allocate one IP for each subnet (in the example above there are two subnets).
Go to Network Interfaces menu, find the network interfaces attached to your lambda (same subnet and security group).
Associate the Public IPs in the actions menu for each one:
That's it, now your Lambda can reach out to public internet.
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 AWS Lambda function which:
checks a Redis Elasticache instance,
if the item is not found in the cache, goes to Google Places API service.
The Redis instance is in a private subnet; so, to fetch it, I added the VPC and the subnet in which the instance resides. I also specified the security group which allows all the outbound traffic. The Network ACL is the default one which is supposed to all the inbound and the outbound traffic.
When adding VPC to Lambda function like that via the console, it prompts:
When you enable VPC, your Lambda function will lose default internet access. If you require external internet access for your function, ensure that your security group allows outbound connections and that your VPC has a NAT gateway.
So, in the Route Table of the private subnet, I added a NAT gateway too. However, at the point where the Google Places API service call is made from the Lambda function it is always doomed to result in timeout.
In short, I doubt that the NAT gateway properly allows internet access of the Lambda function. How can I check what goes wrong with it?
Do NAT Gateways log the calls or the call attempts being tried through it somehow in CloudWatch etc.?
I want to elaborate on the answer from #vahdet. I was losing my mind trying to reconcile how the NAT Gateway was supposed to be in the public and private subnets simultaneously. It seemed like the official AWS documentation here was wrong, but of course it's not. There is a very subtle detail that myself and others have missed.
The NAT Gateway has to be "hot-wired" across two different subnets simultaneously in order to bridge private addresses to a public one that is internet facing.
First, I tried to put the NAT Gateway in the same route table as the IGW, but of course that doesn't work because you can't have two identical routes (0.0.0.0/0) with different targets.
The guide was saying to put the NAT Gateway in the route table for the Private Network, which I did, but that didn't seem to work.
The critical detail I was missing was that the NAT Gateway has to be created in a public subnet. The documentation actually says this, but it seems confusing because we are later told to put the route for NAT Gateway in the private table.
Both things are true. Create the NAT Gateway in the public subnet and then only add a route table entry in the private route table.
The documentation tells you to create the following network resources in the VPC:
two new subnets
two new route tables
one new NAT Gateway
I already had a route table and some subnets, so I tried to only add one new subnet and one new route table and this is where I got into trouble. It really was better to create two of each as documented.
Here's what it the subnets look like for me:
subnet-public 10.8.9.0/24 us-east-1a
subnet-private 10.8.8.0/24 us-east-1a
Then create the NAT Gateway in subnet-public.
It will be pending for a couple of minutes, which is important, because it must go to available status before it can be referenced in a route table entry.
Here are the route tables:
route-table-public
10.8.0.0/16 local
0.0.0.0/0 igw-xyz
subnet-association: subnet-public
route-table-private
10.8.0.0/16 local
0.0.0.0/0 nat-abc
subnet-association: subnet-private
Do you see what happened there? It's really subtle. The NAT Gateway is cross-wired. It "lives" in the public subnet it was created in, but all traffic in the private subnet gets routed to it.
If you create the NAT Gateway in the private subnet like I did at first, then the NAT Gateway is just as isolated as everything else in the private subnet, and has no way to route traffic out to the internet. It must be created in the public subnet to have internet access, because it must have an IP address inside the public subnet. My NAT Gateway got an internal IP of 10.8.9.127 and an external IP in the 54.X.X.X range.
By making the NAT Gateway the 0.0.0.0/0 route in the private routing table, we are telling all non-10.8.0.0/16 traffic to go straight to the NAT Gateway, even though it isn't actually inside the private subnet.
The VPC itself knows how to bridge traffic across its own subnets, and is able to send the 10.8.8.X traffic to the NAT Gateway's 10.8.9.X IP. It then acts as a bridge, and translates all of that traffic across it's internal IP to its external IP. Because it is in a public subnet that is in a route table with an internet gateway, the external IP has a clear path to the internet.
Now my private VPC lambda in subnet-private has verified internet access through the NAT Gateway.
The following steps are required
An IAM role with full VPC permission assigned to your lambda function.
VPC with public and private subnet
while creating a NAT Gateway
a)the subnet has to be public subnet
b)Elastic IP creat a new one or allocate one
Create the route table and add another route with target as our NAT gateway we created above.
And your lambda should be happy now
The problem for my case turned out to the fact that, I had created the NAT Gateway in the private subnet.
Make sure you place the NAT Gateways in the public subnet.
By the way, there are metrics but no direct logging records available in CloudWatch for NAT Gateway.
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I am trying to make an outbound API request to a third-party service from within a Lambda function, but the function always times out without any error.
This previously happened when trying to perform a s3.putObject operation within a different function (still within the same VPC / subnets), and I managed to get around that by adding an Endpoint with a service name com.amazonaws.us-east-1.s3 and connecting it to the route table that is associated with the VPC that this Lambda function resides in.
Within the Lambda dashboard inside Network box -> Security Groups section, I see this warning:
When you enable VPC, your Lambda function will lose default internet
access. If you require external internet access for your function,
ensure that your security group allows outbound connections and that
your VPC has a NAT gateway.
I believe that this security group allows outbound connections, based off of the Outbound rules table right underneath:
For that second requirement, I can confirm this VPC has a NAT gateway, because on the VPC Dashboard, within NAT Gateways tab, the one that appears there has a VCP associated with it, and that VPC is the same one hosting the Lambda function.
I followed a guide to create a Flow Log to monitor traffic in and out of the VPC, hoping to see that those outbound requests are indeed rejected. However, after doing so and inspecting the CloudWatch logs, all of the records end in either ACCEPT OK or NODATA.
How can I grant internet access to my VPC Lambda function? is the guide I originally tried to follow, but I got stuck on step 4 under To create a public or private subnet:
From the Change to: drop-down menu, choose an appropriate route table:
For a private subnet, the default route should point to a NAT gateway
or NAT instance:
Destination: 0.0.0.0/0
Target: nat-… (or eni-…)
For a public subnet,
the default route should point to an internet gateway:
Destination: 0.0.0.0/0
Target: igw-…
For all four of the subnets within this VPC, clicking the drop-down to the right of Change to: only showed one option, the one already selected, rtb-xxxxxxxx. After clicking on the link to that route table, and clicking the Routes tab next to Summary, I see this:
What might I be doing wrong that is blocking the Lambda function's access to the Internet?
For Lambda to have access to the internet via VPC it should be in the Private Subnet with NAT Gateway attached.
As per your screenshots, route table attached to subnet has igw-xxxxxxx attached making your current subnet a public subnet.
So to make things work, you can do following:
Attach NAT Gateway instead of igw-xxxxxx in route table of your current subnet
OR
Find ENI attached to your Lambda and attach Elastic IP if you want to have internet access.
OR
As per #John Rotenstein if your Lambda doesnt need VPC recources you can move Lambda out of VPC
I developed a step by step tutorial with explicit screenshots about it:
Part I
Create a lambda function in AWS
Create an API Gateway to redirect all the requests to your AWS Lambda Function
https://medium.com/#shontauro/how-can-i-turn-my-restful-api-into-a-serverless-application-and-deploy-it-to-aws-lambda-step-by-ec7ce38e18be
Part II
Configure a VPC for your lambda function
Grant internet access to the lambda function in a safety way
Deploy the Node.js Restful API into your Lambda Function
https://medium.com/#shontauro/how-can-i-turn-my-restful-api-into-a-serverless-application-and-deploy-it-to-aws-lambda-step-by-8ff6cc97780f
One thing you may be doing wrong (which is exactly what I did wrong but got a hint about from #Ramratan Gupta above) is to put the NAT gateway in the private subnet and not in the public.
The NAT gateway provides your private IP Lambda function with internet connectivity and so it sort of stands to reason the NAT gateway needs to have internet access itself and be in the Public network.
To summarise:
You have to create at least two subnets: one public and one private. Put both in the same VPC.
What makes a subnet public or private is the 0.0.0.0/0 route.
You need to have both an internet gateway (igw) and a NAT gateway (ngw).
To create the NAT gateway, you need an Elastic IP.
Also, and here's what I did wrong, you need to create the NAT gateway in the PUBLIC network.
The igw goes in the same subnet that the NAT gateway is: the public one.
You need to have two routes: one with the 0.0.0.0/0 route referencing the igw and the other referencing the ngw.
You then need to associate the NAT-route containing route table with the private subnet and the igw-route containing route table with the public subnet. Please note that until you do this association, there is no difference between the subnet that would make one public and one private. You make one private and the other public by how you associate the subnets with the route tables.
Finally, you need to connect your Lambda function to the VPC and also to the private subnet only. This way, when your lambda tries to reach the internet, it goes to the private subnet, looks for the 0.0.0.0/0 route, which directs it to the NAT gateway that is in the public subnet. The NAT gateway then contacts the internet using the igw (because they are in the same subnet) and upon receiving a response, returns it to your Lambda function.
Please also note that there are some permissions your Lambda function needs (that AWS will warn you about) in order to connect to a VPC.
Setting up AWS Lambda Internet access in VPC mode is tricky as no proper AWS documentation is provaded on AWS side, I did read this aritical many times https://aws.amazon.com/premiumsupport/knowledge-center/internet-access-lambda-function/ but did not wached YouTube Video. After so much of R&D I can summrise as below steps are need for set up AWS Lambda in VPC mode
- Route Tables two router
- One for EC2 - EC2_ROUTER
- Another for AWS Lambda - AWS_Lambda_ROUTER
- Create an Internet Gateway
- Add 0.0.0.0/0 rule in EC2_ROUTER for target igw-xxxxx
- This will create public subnet and give INTERNET access for EC2
- Create a NATGateway with public subnet which has igw-xxxxx as target
- Create a private subnet which and attach to AWS_Lambda_ROUTER, with target 0.0.0.0/0 as nat-xxxxxxx
- Select VPC for AWS Lambda
- Select a/all private subnet which is private having NAT Gateway for all traffic 0.0.0.0/0
all done, go ahead and enjoy
Note
NATGateway is required when access to public API other than AWS
There is AWS Endpoints for internal AWS services, and one can attach AWS endpoints in AWS_Lambda_ROUTER by creating
Internet access in AWS Lambda -> Private Subnet with NATGateway -> NATGateway is in public subnet with Internet Gateway which access to AWS Lambda.
PS
I have no Idea why AWS Lambda can not have INTERNET access via InternetGateway why it needs NATGateway