arizz96/freegeoip repository overview

⁠VGEOIP

This service is based on the original Apilayer's Freegeoip project⁠, with a little modifications.

⁠VGEOIP

VGEOIP service primary function is to do geolocation based on IP. It could help detect the city, the country, and so on and so forth.

⁠Technical overview

There are 3 separate, inter-related parts of VGEOIP:

• apiserver package (located at freegreoip/apiserver)
• main package (located at freegeoip/cmd/freegeoip)
• freegeoip package (located at the root folder)

The main package is the point of entry. This is definitely the package that gets compiled. This package however, is just a gate into apiserver, so the actual workload is basically not in the main package but in apiserver.Run().

Things that apiserver package does:

The core component of the apiserver package is the NewConfig and NewHandler functions that both create a Config and apiHandler struct respectively. apiHandler is a struct that consist the following structure:

type apiHandler struct {
  db    *freegeoip.DB
  conf  *Config
  cors  *cors.Cors
  nrapp newrelic.Application
}

However, NewHandler does not just create apiHandler struct, it actually also create the multiplexer from which all requests come in contact with. So, every single web request is handled by this multiplexer.

However, before it can serve any request, NewHandler turns out will also attempt to download a database using the openDB function of the same package (apiserver). When the system unable to setup the handler (for a host of reasons, one of which being unable to download the database), the system will fatally exit.

openDB basically will download a databse if it doesn't have a copy yet in the local filesystem. And, if we have the license and user ID, it will setup a special configuration that will help us later on to download the paid version of the database.

openDB eventually is calling OpenURL function of the freegeoip package (only associated with db.go). This package contains routines that help with:

• Downloading the database
• Opening the database, and setting up the reader/data-access object
• Watching the file when it's created/modified and notify it through appropriate channel back up
• Automatically update the database upon a due time/backoff period (default: 1 day)
• Performing Lookup of an IP

Once OpenURL is called, an autoUpdate function will kick in automatically in the background using a goroutine (similar to a Ruby's thread but lightweight). It will check if a newer database exist by checking the X-Database-MD5 and the file's size.

As we might already guess, there are two kinds of database: the paid version and the free version. If we run the service without the paid license, it will never send a request to download the paid version of the database.

⁠Deployment: Fargate

In the AWS world, there are many kind of deployment services that one can use to deploy app into it:

• EC2⁠: the bare metal
• AWS Elastic Beanstalk⁠: easy to use code deployment service somewhat trying to replicate Heroku, with 'but'
• EKS Elastic Container Service for Kubernetes⁠: Kube-style container-orchestrated deployment. Pretty expensive.
• ECS Elastic Container Service⁠: AWS own's answer of container-orchestrated deployment. Not expensive.
• Fargate⁠: Disregarding the concept of region and zone, this container-based deployment only ask us about what kind of CPU and Memory do we want, and deploy it to either ECS or EKS-manner (EKS not yet supported as of August 2018). Far so easy to deploy at.

Here is the step by step of deployment to AWS Fargate:

• Install Python
• Install awscli

$ pip install awscli

• Configure awscli⁠: require ACCESS KEY ID of your user account for it to be usable.
• Login to ECR:

$ $(aws ecr get-login --no-include-email --region ap-northeast-1)

• Obtain the Maxmind license key by signing up with a free account: https://www.maxmind.com/en/geolite2/signup⁠

• Build the docker image: Replace LICENSE_KEY with the license key you have from your Maxmind account

$ docker build . -t vgeoip:latest --build-arg INITIAL_DATABASE_URL="https://download.maxmind.com/app/geoip_download?edition_id=GeoLite2-City&suffix=tar.gz&license_key=LICENSE_KEY"

To see list of available images:

$ docker images

• Construct the docker registry address for AWS:

  • Find out your account ID⁠ eg: 607558961840
  • Determine the region ID⁠, eg: ap-northeast-1 for Tokyo

  Your constructed registry address: 607558961840.dkr.ecr. ap-northeast-1.amazonaws.com

• Tag the image with ECR repository tag:

$ docker tag vgeoip:latest 607558961840.dkr.ecr.ap-northeast-1.amazonaws.com/vgeoip:latest

• Push the tagged image to ECR

  • Ensure the repository (eg: vgeoip) is already created beforehand⁠. Click create repository on that page if haven't. Ensure Repository URI matches your ID and your region properly.
  • Push:

  $ docker push 607558961840.dkr.ecr.ap-northeast-1.amazonaws.com/vgeoip:latest
  

  Copy

⁠Deployment: Heroku

Add ENV INITIAL_DATABASE_URL with "https://download.maxmind.com/app/geoip_download?edition_id=GeoLite2-City&suffix=tar.gz&license_key=LICENSE_KEY⁠" where LICENSE_KEY is the Maxmind license key after signing up a free account: https://www.maxmind.com/en/geolite2/signup⁠