README.md

# Geolix

MaxMind GeoIP2 database reader/decoder.


## Installation

Fetch both the Geolix repository and a distribution of the
[MaxMind GeoIP2](http://dev.maxmind.com/geoip/geoip2/downloadable/)
databases (or the free [GeoLite2](http://dev.maxmind.com/geoip/geoip2/geolite2/)
variant).


## Setup

### Dependency

To use Geolix with your projects, edit your `mix.exs` file and add the project
as a dependency:

```elixir
defp deps do
  [ { :geolix, "~> 0.10" } ]
end
```

You should also update your applications to include all necessary projects:

```elixir
def application do
  [ applications: [ :geolix ] ]
end
```

### Configuration

Add the paths of the MaxMind databases you want to use to your project
configuration:

```elixir
use Mix.Config

# static configuration
config :geolix,
  databases: [
    { :city,       "/absolute/path/to/cities/db"    },
    { :country,    "/absolute/path/to/countries/db" },
    { :enterprise, "http://my.internal.server/database.mmdb" }
  ]

# system environment configuration
config :geolix,
  databases: [
    { :city, { :system, "SOME_SYSTEM_ENV_VARIABLE" }}
  ]
```

_Note_: if you do not want to use absolute paths or system variables please
be aware that any code in the config file is evaluated at compile time.


An appropriate filename will be automatically appended to the path. If the
filename ends in ".gz" it will be loaded as a compressed file.

It is also possible to (re-) configure the loaded databases during runtime:

```elixir
iex(1)> Geolix.set_database(:city, "/absolute/path/to/cities/db.mmdb")
:ok
iex(2)> Geolix.set_database(:country, { :system, "SOME_SYSTEM_ENV_VARIABLE" })
:ok
```

If Geolix cannot find the database it will return `{ :error, message }`,
otherwise the return value will be `:ok`. Running `set_database/2` on an
already configured database will reload it.


#### Configuration (remote files)

If you configure a database with a filename starting with "http" (yep, also
matches "https"), the application will request it from that location.

Returning a status of `200` and the actual contents of the database then
results in the regular loading process. Using this configuration you can
load a database during startup from basically any location you can reach.

_Note_: Please be aware of the drawbacks of remote files! You should take into
account the startup times as the file will be requested during
`GenServer.init/1`. Unstable or slow networks could result in nasty timeouts.

_Note_: Be responsible with the source you configure! Having a public download
mirror (or the official MaxMind location) set might flag you as a
"not so nice person". Ideally use your own server or online storage.


## Usage

Lookups are done using `Geolix.lookup/1,2`:

```elixir
iex(1)> Geolix.lookup("127.0.0.1")
%{ city:    %Geolix.Result.City{ ... },
   country: %Geolix.Result.Country{ ... }}
iex(2)> Geolix.lookup({ 127, 0, 0, 1 }, [ as: :raw, where: :city ])
%{ ... }
```

Using `Geolix.lookup/2` with only one parameter (the IP) will lookup the
information on all registered databases, returning `nil` if the IP was not
found.

Lookup options:

* `:as` - Return the result as a `:struct` or `:raw` (plain map)
* `:locale` - Language (atom) to fetch information for.
  Only affects "top level" struct values.
* `:where` - Lookup information in a single registered database

Every non-nil result will include the IP as a tuple either directly in the
result field `:ip_address` or inside `%{ traits: %{ ip_address: ... }}` if
a city or country database is used.

### Floating point precision

Please be aware that all values of the type `float` are rounded to 4 decimal
digits and `double` values to 8 decimal digits.

This might be changed in the future if there are datasets known to return
values with a higher precision.

### Benchmarking

If you are curious on how long a lookup of an IP takes, you can simply measure
it using the erlang `:timer` module:

```elixir
iex(1)> :timer.tc(fn -> Geolix.lookup({ 108, 168, 255, 243 }) end)
{ 1337,
  %{ city:    ... ,
     country: ... } }
```

The time returned are the `microseconds` of the complete lookup including
every overhead by for example the process pool. For more details refer to the
[official erlang documentation](http://www.erlang.org/doc/man/timer.html#tc-1).

### Result Verification

For (ongoing) verification of the result accuracy a special test environment
is configured for each travis run.

This environment performs the following 4 steps:

- generate a set of random IPs
- lookup using geolix
- lookup using python ([geoip2](https://github.com/maxmind/GeoIP2-python))
- compare the results

To run these tests on a local machine please refer to the travis scripts
executed on each run
(i.e. `./travis/verify_install.sh` and `./travis/verify_script.sh`).


## License

[Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0)

License information about the supported
[MaxMind GeoIP2 Country](http://www.maxmind.com/en/country),
[MaxMind GeoIP2 City](http://www.maxmind.com/en/city) and
[MaxMind GeoLite2](http://dev.maxmind.com/geoip/geoip2/geolite2/) databases
can be found on their respective sites.