ceafive / streams-count

an API to count concurrent number of streams

streams-count-api

Count concurrent number of streams

A service in Node.js that exposes an API which can be consumed from any client. This service checks how many video streams a given user is watching and prevent a user from watching more than 3 video streams concurrently. Uses services like API Gateway, Lambda, DynamoDB etc

🤔 How do I use this?

Hey- before you actually use this, make sure you've [Docker](https://www.docker.com/) installed and running. Expand to read more

### 🚨 AWS CREDENTIALS

This project uses AWS credentials that have been provided separately to help you run this project. This have been set to ENV variables with the keys below:

1. ACCESS_KEY_ID
2. SECRET_ACCESS_KEY
3. DEFAULT_REGION

Once you have each of these: access key id, secret access key, region, you're all set!

Step 1: Build Image

In your project directory, run

docker build --build-arg ACCESS_KEY_ID=<ACCESS_KEY_ID> --build-arg SECRET_ACCESS_KEY=<SECRET_ACCESS_KEY> --build-arg DEFAULT_REGION=<DEFAULT_REGION> -t streams-count-api . 

Step 2: Verify Image

When build is complete you can verify your image with:

docker images

Then run your image with (make sure port 8080 is free on your local machine):

docker run -p 8080:8080 -d --name streams-count-api streams-count-api 

Step 3: Follow Logs

Run following commands to follow logs

docker ps
docker logs streams-count-api

If you need to go inside the container you can use the exec command:

docker exec -it streams-count-api /bin/bash

Step 4: Open Postman and try out the api

First do a curl

curl -i localhost:8080

You should get a ITS WORKING response. You can open Postman (to make it easier) and test your the api

The endpoint for getting the streams for current user is localhost:8080/streams

Please note there are some users currently in database. The localhost:8080/streams endpoint requires a X-ID header in other to identify the current user

You can user the following ids to test out the endpoint:

1. 123
2. 1234
3. 12345
4. 123456

You can skip all the above setup and test the deploy prod endpoints at:

curl -i https://l788umca3c.execute-api.us-west-2.amazonaws.com/prod/

Please note, you require a X-ID header in other to identify the current user. Possible values are listed above

curl https://l788umca3c.execute-api.us-west-2.amazonaws.com/prod/streams -H "X-ID: 123"

Scaling strategy

This api uses AWS Lambda, Lambda automatically scales out for incoming requests, if all existing execution contexts (lambda instances) are busy. Also we can use AWS Lambda with an Application Load Balancer,

We can also use Application Auto Scaling. Application Auto Scaling allows us to configure automatic scaling for different resources, including Provisioned Concurrency for Lambda. We can scale resources based on a specific CloudWatch metric or at a specific date and time.

Logging & monitoring

This api implements CloudWatch logs to help in logging and monitoring at scale. The api uses winston-cloudwatch to send specific logs to CloudWatch under a log group name.

The Log Group Name is unique and the Log Streams Name is also unique to aid in filtering and setting metrics.

Every other stdout goes to to a different Log Group