API Platform example

There are two API implementations under scr: student and experience.

They are a basic nodejs applicacion serving a dummy API with CRUD operations over an in-memory array.

The concept is to create to virtual machines with those implementations and merge them with an API Gateway.

Use API Manager to show features of API Platform.

TODOs

Improve systemd service script: user, permissions, etc
Create dev script on package.json with nodemon and leave start for production
Add service name on health response

Requirements

You need nodejs >10.x installed on each machine. From a clean Oracle Linux:

sudo yum install -y gcc-c++ make

curl -sL https://rpm.nodesource.com/setup_12.x | sudo -E bash -

sudo yum install -y nodejs

If you have Node already installed on the machine, it would be a good idea to clean up first:

sudo yum remove -y nodejs npm

Check the version of your Node JS installation:

node -v

Run services locally

Go to src/students, it will be the same steps for experience:

Install dependencies

npm install

Run the service

npm start

You can change the port (3000 by default) with a environment variable PORT like this:

PORT=4000 npm start

To detach the execution from the console in our student service:

nohup npm start &> student.log&

Test the health of the service with:

curl -s http://localhost:3000/health | jq .

Test with cURL

GET /student

curl -s http://<IP>:<PORT>/student

POST /student

curl -s -XPOST --header "Content-Type: application/json" --data '{"name": "Student 1"}' http://<IP>:<PORT>/student

PUT /student

curl -s -XPUT --header "Content-Type: application/json" --data '{"name": "Student 1 mod"}' http://<IP>:<PORT>/student/<id>

DELETE /student

curl -s -XDELETE http://<IP>:<PORT>/student/<id>

Deploy services

You can move src/student and src/experience to the remote machines with scp:

Remove node_modules first or it will take a while to send hundreds of files ;)

For student app

scp -r src/student opc@<PUBLIC_IP>:/home/opc/

For experience app

scp -r src/experience opc@<PUBLIC_IP>:/home/opc/

Remember to install the libraries for both services:

npm install

Open firewall port

You must open the port you are going to use at Subnet level with Security list.

Create a Security list from your Virtual Cloud Network
Add Ingress and Egress rules

Type	CIDR	Proto	src port	dest port	Allows
Ingress	src: 0.0.0.0/0	TCP	All	3000	TCP traffic for ports: 3000
Egress	dest: 0.0.0.0/0	TCP	3000	All	TCP traffic for ports: All

Add Security list to your subnet

You must add a local firewall rule in each machine like this to open the port 3000 for ingress and egress:

sudo iptables -I INPUT -p tcp --dport 3000 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT

sudo iptables -I OUTPUT -p tcp --sport 3000 -m conntrack --ctstate ESTABLISHED -j ACCEPT

Run services as deamons

Copy service file in /etc/systemd/system:

sudo cp student.service /etc/systemd/system

Reload daemon service to pick up the new service

sudo systemctl daemon-reload

Start the service

sudo systemctl start student

Check the status, it has to be active by now:

sudo systemctl status student

In order to see logs

journalctl -u student

The same for experience

sudo cp experience.service /etc/systemd/system

sudo systemctl daemon-reload

sudo systemctl start experience

sudo systemctl status experience

journalctl -u experience

When you are happy with the services running, don't forget to enable them so it will restart the service when reboot.

sudo systemctl enable experience

vmleon/api-gateway-example