EC2

Summary

• Setting up
  • Instances
  • Subnets
• Running a web application
  • Installation (Rails example)
  • Deployment

Setting up

Instances

The EC2 setting up is pretty straight forward as you set up a standard virtual machine. Just follow the wizard and you will have a brand new VM on your hands.

Focus should be on

• SSH key pair (to be able to connect to it)
• Assigned security group should allow HTTP from anywhere and SSH from your IP address only

Key pairs are region-dependent. If the same key pair has to be shared betweem multiple regions, it must be uploaded manually regions by regions

Subnets

Instances must be attached to be subnet. As a primary network, the subnet cannot be changed. IP settings (dynamic IP assignments) can be changed by re-assigning a new IP. An instance is connected to a subnet thanks to an ENI: Elastic Network Interface

Sources:

• AWS docs: Elastic Network Interfaces
• Move EC2 to another subnet

Load balancer

New load balancers are:

• application load balancer: https://docs.aws.amazon.com/elasticloadbalancing/latest/application/introduction.html
• network load balancer: https://docs.aws.amazon.com/elasticloadbalancing/latest/network/introduction.html

Comparison: https://aws.amazon.com/elasticloadbalancing/features/#Product_comparisons

Application load balancer

An application load balancer:

• a service, no instance to handle
• has a A record DNS name
• can be dual stack or IPv4 only

The balancing is done by adding listeners. A listener listens to a specific port and an action must be specified. Such actions can be forwarding to a target group or redirect.

A target group is a set of instances on one or multiple availability zones on a specific port.

Running a web application

Installation

Rails example:

• Start with the first of all:

  sudo apt-get update
  

• Install Ruby. I was going the RVM route
  • https://gorails.com/setup/ubuntu/18.04
  • https://www.howtoforge.com/tutorial/ubuntu-ruby-on-rails/
• Install Rails via a simple gem install rails
• PostgreSQL pg gem is a bit tricky:

  sudo apt-get install postgresql-client libpq5 libpq-dev
  sudo gem install pg
  

• As a non-root user, we cannot use the 80 port (any port below 1024 actually). Trick is to use port forward from 80 to 3000
  1. sudo ufw enable => enable firewall
  2. sudo ufw allow http
  3. sudo ufw allow https
  4. sudo ufw allow ssh do not forget this one
  5. Proceed to port forwarding
• Run the Rails application with puma as usual to check if it works

Deployment and long server run

That’s the good two cents question as-of January 2019

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Sources: