How can I create this scenario:
- A private subnet-1
- Lambda in subnet-1
- RDS in subnet-1(same subnet with Lambda)
- Both inside the same VPC.
is the above feasible and is it a good architecture ?
I have tried implementing it only issue is, it's timing out. But, when the Lambda is out of the subnet-1 it's working fine.
My understanding is since both RDS and Lambda are in the same subnet they should easily communicate.
It is perfectly okay to have Amazon RDS and the AWS Lambda function connected to the same private subnet.
Some things to note:
If the Lambda function also requires access to the Internet (eg to make calls to Amazon S3), then the VPC will also require a NAT Gateway in a public subnet.
The Lambda function should refer to the RDS instance by DNS Name. This should resolve to a private IP address local to the VPC.
The Lambda function should be assigned a Security Group (eg Lambda-SG)
The security group associated with the RDS instance (RDS-SG) should permit inbound access on the appropriate port (eg 3306 for MySQL) from Lambda-SG.
That is, RDS-SG should permit inbound connections from Lambda-SG.
Related
RDS Database details:
I have an publicly accessible RDS database which is restricted to be accessible to only specific IP address.
The RDS have 2 security groups attached to the RDS:
1st security group allows a specific IP address to access it.
2nd security group allows multiple specific IP addresses to access
it.
Note: I know I can just keep a single security group for this purpose.
This RDS database have the default VPC and 3 public subnets. All these subnets have 2 routes in route tables:
Destination: default vpc's cidr range and Target: local
Destination: 0.0.0.0/0 and Target: internet gateway
Lambda function details:
I have a lambda function, which does not have any vpc configured.
I am trying to access the RDS database from code in the lambda function. Since lambda doesn't have any specific IP address, I couldn't add inbound rule in RDS's security group to allow it. When I simply add inbound rule in RDS's security group to allow access from all IPs then my lambda function code is able to connect to RDS database and work with it.
I wouldn't want my RDS database to be allowed access from anywhere on the internet, what configuration/settings do I need to make to be able to access RDS from lambda.
I also tried configuring the lambda function to be in same vpc and same subnets as that of for RDS instance; but I haven't been successful in making a connection to the RDS database.
Best in this case is to use the same VPC for your lambda as the RDS instance. This is cheaper and is more secure. You don't have to setup a internet gateway and elastic IP. And you can only access your RDS instance from within the VPC.
You can enable this using Lambda management console. Select Lambda function which need access to RDS instance and then go to Configuration -> Advanced settings and select the VPC (which is your RDS instance is in) you need it to access.
For instances attached to the same security group—make the security group the source for the inbound rule and the destination for the outbound rule.
For instances in different security groups—make sure that both security groups allow access to one another.
If this is still not working check the error message that is returned when setting up the connection with RDS. Timeout means issue with network.
find out more here https://aws.amazon.com/premiumsupport/knowledge-center/connect-lambda-to-an-rds-instance/
There are couple of questions around this, but none seem to solve my specific problem.
So i have a publicly accessible RDS instance in a VPC with two Security Groups : one the default SG for VPC & other to allow incoming connections from our developer machines. I am able to successfully connect to this RDS via my developer machines(personal laptops/PCs) as a result of the 2nd Security group.
Now, when i try to connect to this RDS via a Lambda running in same VPC, it fails with this error : "java.net.UnknownHostException: ****.rds.amazonaws.com: Name or service not known "
My lambda is getting launched in the same VPC as RDS and i have chosen all the RDS VPC subnets for the lambda. It also is tied to the default VPC security group.
Below is my understanding(obviously not right as connection is not working), what am i missing here?
The Default VPC SG(security group) associated to the lambda has outgoing rules set as 0.0.0.0/0 , hence it should allow lambda to access the whole world; so at least the RDS in VPC should be accessible.
The same default VPC SG should allow the RDS to accept incoming connections from any ip in the SG subnets(inbound rule mentions SG/default) ; hence lambda should be able to access it.
The error message is indicating that it cannot resolve the DNS Name of the RDS database (Name or service not known).
I suspect that this is due to the fact that the RDS instance has been configured as publicly accessible, which gives it a public DNS Name and IP address.
An AWS Lambda function connected to a VPC will send all network traffic via the VPC. It does not have access to the Internet unless there is a NAT in the VPC and the Lambda function is connected to a Private Subnet. Thus, the connection attempts from the Lambda function are possibly attempting to resolve a Public DNS Name, but is failing to do so.
This could likely be resolved by changing the RDS instance to be Publicly Available = No. This not only makes it safer, but it means that the DNS Name will resolve to a Private IP address, which should work correctly with a Lambda function connected to the VPC.
Alternatively, you could configure the Lambda function to not be connected to the VPC. This gives it Internet access, so it will connect to the RDS database just like any other computer on the Internet.
So the problem was that in my developer machine, I was using the db instance endpoint , but in lambda i was using the cluster endpoint. They look similar, hence i was not able to catch it earlier. On fixing the lambda to use the instance endpoint, both lambda & developer machines can successfully connect to the RDS.
However, I am now curious why the cluster url is not accessible, but i will create another question for that.
I have a lambda function that needs to access RDS and the internet. Everything out there points to having to set up a NAT gateway; the RDS in question is publicly accessible, the lambda is able to connect to it if I allow connections to the RDS from all IPs; however, I would like to avoid that. Is there a way to determine the possible range of IPs to be assigned to a lambda function and whitelist that range in the security group>?
Locate your Lambda into your VPC, private subnet and set the security group for Lambda. After that, add the Lambda security group to the inbound source of the RDS security group. Then, the Lambda will communicate with the RDS privately.
The private subnet should route the target 0.0.0.0/0 to the internet through a NAT gateway where the NAT should locate in the public subnet. Then, the private subnet can connect to the internet safely.
I've created an EC2 instance inside a public subnet (so that I can access it from my home network) and I have created some Lambda's inside the private subnets of my VPC.
My 1st lambda can freely access the internet (through a NAT Gateway) and do its job. Which is to fetch a file from the internet and upload it to S3, once per day.
My 2nd lambda is supposed to retrieve this file from S3 (which it does without issue) read the file & then upload the data to MySQL running on the EC2 instance. It is unable to connect to the Database (using either the EC2's public or private IP's) and the Cloudwatch logs show that the session times out, making me think this is a networking issue.
I have a 3rd lambda that will also need to interact with the EC2/DB instance.
My security group allows for all incoming traffic from my home network IP, the NAT gateway & the VPC IP range. All outbound traffic is allowed.
I appreciate its not usual to have an EC2/DB set up this way, in a public subnet, but its my preference to interact it with it this way from home using Sequel Pro.
However, is my set up even possible? Eg can my private subnet lambdas interact with a public subnet ec2 instance? if so, does anybody have any ideas how I can make this happen?
It appears that your situation is:
An Amazon EC2 instance running in a public subnet, with MySQL
The EC2 instance has a Security Group allowing all incoming traffic from your home network IP, the NAT gateway and the VPC IP range
An AWS Lambda function connected to a private subnet of the same VPC
A NAT Gateway allowing private subnets to connect to the Internet
The Lambda function is unable to connect with the MySQL database running on the EC2 instance
The normal security configuration for this scenario would be:
A Security Group on the Lambda function (Lambda-SG) that allows all Outbound access (no Inbound required)
A Security Group on the EC2 instance (EC2-SG) that allows inbound access from Lambda-SG on port 3306, plus whatever inbound permissions you want for accessing your instance via SSH, etc.
Given that your Security Group includes "the VPC IP range", this should be sufficient to permit inbound access.
The Lambda function should reference the EC2 instance via its private IP address to keep traffic within the VPC. By default, all subnets within a VPC can communicate with each other unless the Network ACLs have been modified (and they should generally be left at default values).
This means that the only remaining explanation would be that the MySQL database is not accepting traffic from the VPC IP range. (I'm not a MySQL person, but I know that PostgreSQL requires incoming IP ranges to be defined, so this might be true for MySQL too.)
To diagnose what might be happening in your network, I recommend:
Launch another Amazon EC2 instance in the public subnet
Connect to the new instance and try to connect to the MySQL database via the private IP address
If that works, repeat the process but from an EC2 instance in the private subnet. To use this you will need to connect to the 'public' EC2 instance, and from there connect to the 'private' EC2 instance. Then, try and connect to MySQL from that private instance.
These steps will progressively let you identify where the network problem might lie. Let us know what you find!
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.