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https://github.com/pchol22/sls-natgateway
A "free" serverless alternative to AWS NAT Gateways. Still WIP ⚙️, help welcome!
https://github.com/pchol22/sls-natgateway
aws cdk free nat-gateway serverless typescript
Last synced: 14 days ago
JSON representation
A "free" serverless alternative to AWS NAT Gateways. Still WIP ⚙️, help welcome!
- Host: GitHub
- URL: https://github.com/pchol22/sls-natgateway
- Owner: PChol22
- Created: 2023-07-14T23:37:27.000Z (over 1 year ago)
- Default Branch: main
- Last Pushed: 2023-07-14T23:40:02.000Z (over 1 year ago)
- Last Synced: 2024-10-04T21:08:59.228Z (about 1 month ago)
- Topics: aws, cdk, free, nat-gateway, serverless, typescript
- Language: JavaScript
- Homepage:
- Size: 319 KB
- Stars: 5
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
# sls-natgateway
## Why and what?
### The problem with NAT Gateways
I am software engineer and I love doing serverless on AWS 🌸.
One day I had to access a resource residing inside a private VPC subnet from a Lambda function. The plan was simple: place the Lambda function inside the same subnet. 💪
_PROBLEM:_ the subnet was private, so the Lambda function could not access the internet anymore. 😭
_SOLUTION:_ I placed a NAT Gateway inside the subnet. 💪
**BIG PROBLEM:** NAT gateways are f\*cking expensive, and are not serverless at all. 💀
At this point, I started thinking, and found a loophole: VPC Gateway Endpoints! These are FREE and SERVERLESS endpoints that allow resources inside private VPCs to access S3 and DynamoDB without going through a NAT Gateway. 🎉
This only solves issues when trying to access S3 or DynamoDB, but you see me coming, with a little tweaking, you can use execute any HTTP request from the private subnet. 🧠
### The serverless alternative
Meet my "genius solution": sls-natgateway. 🤪
sls-natgateway is a set of 2 npm packages:
- 1️⃣ `@sls-natgateway/construct`: a CDK construct that provisions a S3 Bucket and a Lambda function able to execute HTTP requests. Everytime an object `{id}/request.json` is created in the bucket, the Lambda function will execute the HTTP request described in the JSON file and store the response in `{id}/response.json`.
- 2️⃣ `@sls-natgateway/sdk`: a single TS function that replaces `fetch`. It's simple: it creates a `{id}/request.json` file in the S3 bucket, waits for the `{id}/response.json` file to be created, and returns the response.
## How to use?
### 1️⃣ Add a S3 Gateway Endpoint to your VPC
First, you need to add a S3 Gateway Endpoint to your VPC. This lib does not do it for you. Here is a code example using AWS CDK:
```typescript
const SUBNET_GROUP_NAME = 'private-subnet-group';
const vpc = new cdk.aws_ec2.Vpc(this, 'Vpc', {
subnetConfiguration: [
{
name: SUBNET_GROUP_NAME,
subnetType: cdk.aws_ec2.SubnetType.PRIVATE_ISOLATED,
},
],
gatewayEndpoints: {
S3: {
service: cdk.aws_ec2.GatewayVpcEndpointAwsService.S3,
subnets: [
{
subnetGroupName: SUBNET_GROUP_NAME,
},
],
},
},
});
```
### 2️⃣ Add the sls-natgateway construct to your CDK stack
Very simple:
```typescript
import { SlsNatGatewayConstruct } from '@sls-natgateway/construct';
const { bucket } = new SlsNatGatewayConstruct(this, 'SlsNatConstruct');
```
Do not forget to grant access to the bucket to the Lambda living in your private subnet, and to pass it the bucket name as an environment variable.
```typescript
const privateLambda = new cdk.aws_lambda_nodejs.NodejsFunction(
this,
'PrivateLambda',
{
entry: path.join(__dirname, 'private-lambda', 'handler.ts'),
handler: 'handler',
vpc,
vpcSubnets: {
subnetGroupName: SUBNET_GROUP_NAME,
},
securityGroups: [
new cdk.aws_ec2.SecurityGroup(this, 'PrivateLambdaSecurityGroup', {
vpc,
allowAllOutbound: true,
}),
],
environment: {
BUCKET_NAME: bucket.bucketName,
},
timeout: cdk.Duration.seconds(15),
},
);
bucket.grantReadWrite(privateLambda);
```
### 3️⃣ Use the sls-natgateway SDK in your private Lambda
The code speaks for itself:
```typescript
import { S3Client } from '@aws-sdk/client-s3';
import { getNatFetchRequest } from '@sls-natgateway/sdk';
const client = new S3Client({});
const bucketName = process.env.BUCKET_NAME;
if (bucketName === undefined) {
throw new Error('BUCKET_NAME is not defined');
}
const natFetch = getNatFetchRequest(bucketName, client);
export const handler = async (event: { pokemon: string }): Promise => {
const { body, status } = await natFetch(
`https://pokeapi.co/api/v2/pokemon/${event.pokemon}`,
{
method: 'GET',
},
);
console.log(status, body);
};
```
## Caveats
- This library only supports requests to HTTP endpoints.
- This library only supports JSON payloads for now (contributions welcome!)
- Usual response delay is increased by around 2 seconds, which can increase compute costs.
_I am not sure this is a good idea, but I had fun doing it. 🤷♂️ **It's 100% not production ready**, but I would love to hear your feedback, and get your help to make it better!_
## Thanks
The project template was generated using [Swarmion](https://github.com/swarmion/swarmion). Go check them out they are great!