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locus

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locus is library for Erlang/OTP and Elixir that allows you to pinpoint the country, city or ASN of IP addresses using MaxMind GeoIP2 and other providers.

The databases will be loaded on-demand and, when retrieved from the network, cached on the filesystem and updated automatically.

⚠️ For instructions on how to upgrade to 2.x, check MIGRATION.md

Usage

1. Configure your license key

Skip this step if you're not loading databases directly from MaxMind.

Get a free license key from MaxMind if you haven't one already. Once logged in, you'll find the page to generate it on the left menu, under "Manage License Keys".

Then clone the repository, run make shell and declare your key:

application:set_env(locus, license_key, "YOUR_LICENSE_KEY").

If you're using Elixir, add locus as a dependency to your mix project:

defp deps do
    [
      ...
      {:locus, "~> 2.3"}
    ]
  end

Then, configure your license key in config.exs:

config :locus,
  license_key: <MAXMIND_API_KEY>

2. Start the database loader

ok = locus:start_loader(country, {maxmind, "GeoLite2-Country"}).
% You can also use:
% * an HTTP(S) URL,
% * or a local path, e.g. "/usr/share/GeoIP/GeoLite2-City.mmdb"
% * or a {custom_fetcher, Module, Args} tuple, with Module
%   implementing the locus_custom_fetcher behaviour.

Or, in Elixir, start the database loaders that you'll be using in application.ex:

  def start(_type, _args) do
    # :locus.start_loader(:asn, {:maxmind, "GeoLite2-ASN"})
    # :locus.start_loader(:country, {:maxmind, "GeoLite2-Country"})
    :locus.start_loader(:city, {:maxmind, "GeoLite2-City"})

    ...

3. Wait for the database to load (optional)

{ok, _DatabaseVersion} = locus:await_loader(country). % or `{error, Reason}'

4. Look up IP addresses

% > locus:lookup(country, "93.184.216.34").
% > locus:lookup(country, "2606:2800:220:1:248:1893:25c8:1946").

% * '{ok, Entry}' in case of success;
% * 'not_found' if no entry was found
% * '{error, _}' if something bad happened

{ok,#{<<"continent">> =>
          #{<<"code">> => <<"NA">>,
            <<"geoname_id">> => 6255149,
            <<"names">> =>
                #{<<"de">> => <<"Nordamerika">>,
                  <<"en">> => <<"North America">>,
                  <<"es">> => <<"Norteamérica"/utf8>>,
                  <<"fr">> => <<"Amérique du Nord"/utf8>>,
                  <<"ja">> => <<"北アメリカ"/utf8>>,
                  <<"pt-BR">> => <<"América do Norte"/utf8>>,
                  <<"ru">> => <<"Северная Америка"/utf8>>,
                  <<"zh-CN">> => <<"北美洲"/utf8>>}},
      <<"country">> =>
          #{<<"geoname_id">> => 6252001,
            <<"iso_code">> => <<"US">>,
            <<"names">> =>
                #{<<"de">> => <<"USA">>,
                  <<"en">> => <<"United States">>,
                  <<"es">> => <<"Estados Unidos">>,
                  <<"fr">> => <<"États-Unis"/utf8>>,
                  <<"ja">> => <<"アメリカ合衆国"/utf8>>,
                  <<"pt-BR">> => <<"Estados Unidos">>,
                  <<"ru">> => <<"США"/utf8>>,
                  <<"zh-CN">> => <<"美国"/utf8>>}},
      <<"registered_country">> =>
          #{<<"geoname_id">> => 6252001,
            <<"iso_code">> => <<"US">>,
            <<"names">> =>
                #{<<"de">> => <<"USA">>,
                  <<"en">> => <<"United States">>,
                  <<"es">> => <<"Estados Unidos">>,
                  <<"fr">> => <<"États-Unis"/utf8>>,
                  <<"ja">> => <<"アメリカ合衆国"/utf8>>,
                  <<"pt-BR">> => <<"Estados Unidos">>,
                  <<"ru">> => <<"США"/utf8>>,
                  <<"zh-CN">> => <<"美国"/utf8>>}}}}

Or, in Elixir, call the erlang library from your Elixir application:

iex> :locus.lookup(:city, "93.184.216.34")
{:ok,
 %{
   "city" => %{"geoname_id" => 4945936, "names" => %{"en" => "Norwell"}},
   ...
 }}

Documentation

  1. Supported File Formats
  2. Database Types and Loading
  3. Database Validation
  4. Remote sources: Downloading and Updating
  5. Remote sources: Caching
  6. Local sources: Loading and Updating
  7. Logging
  8. Event Subscriptions
  9. API Reference
  10. Tested Setup
  11. License
  12. Alternative Providers
  13. Alternative Libraries (Erlang)
  14. Alternative Libraries (Elixir)

Supported File Formats

  • gzip-compressed tarballs (.tar.gz, .tgz)
  • plain tarballs (.tar)
  • MMDB files (.mmdb)
  • gzip-compressed MMDB files (.mmdb.gz)

For tarball files, the first file to be found within it with an .mmdb extension is the one that's chosen for loading.

The implementation of MaxMind DB format is complete except for the data cache container data type.

Database Types and Loading

  • The free GeoLite2 Country, City and ASN databases were all successfully tested; presumably locus can deal with any MMDB database that maps IP address prefixes to arbitrary data
  • The databases are loaded into memory (mostly) as is; reference counted binaries are shared with the application callers using persistent_term, and the original binary search tree is used to lookup addresses. The data for each entry is decoded on the fly upon successful lookups.

Database Validation

Databases, local or remote, can have their compatibility validated through the locus:check/1 function after they've been loaded (see function reference.)

Alternatively, they can also be checked from the command line by use of the locus CLI utility:

  1. Run make cli to build the script, named locus, which will be deployed to the current directory.

  2. Check the database:

    ./locus check GeoLite2-City.mmdb
# Loading database from "GeoLite2-City.mmdb"...
# Database version {{2019,11,6},{11,58,0}} successfully loaded
# Checking database for flaws...
# Database is wholesome.

The script will exit with code 1 in case of failure, and 0 otherwise.

Warnings can produce failure through the --warnings-as-errors flag.

Run ./locus check --help for a description of supported options and arguments.

Remote sources: Downloading and Updating

  • The downloaded database files, when compressed, are inflated in memory
  • For MaxMind and HTTP downloads, the last-modified response header, if present, is used to condition subsequent download attempts (using if-modified-since request headers) in order to save bandwidth
  • The downloaded databases are cached on the filesystem in order to more quickly achieve readiness on future launches of the database loader
  • Database download attempts are retried upon error according to an exponential backoff policy - quickly at first (every few seconds) but gradually slowing down to every 15 minutes. Successful and dismissed download attempts will be checked for update after 6 hours. Both of these behaviours can be tweaked through the error_retries and update_period loader settings (see function reference.)
  • When downloading from a MaxMind edition or an HTTP URL, the remote certificate will be authenticated against a list of known Certification Authorities and connection negotiation will fail in case of an expired certificate, mismatched hostname, self-signed certificate or unknown certification authority. These checks can be disabled by specifying the insecure loader option.

Remote sources: Caching

  • Caching is a best effort; the system falls back to relying exclusively on the network if needed
  • By default a caching directory named locus_erlang is created under the 'user_cache' basedir
  • A cached database is named after either:
    • the MaxMind database edition name (when explicitly downloading from MaxMind), or
    • the SHA256 hash of the HTTP(S) URL, or
    • for {custom_fetcher, Module, Args} sources, a filesystem-safe version of Module's name concatenated with the 32-bit erlang:phash2/2 value of the opaque database source as returned by the callbacks.
  • Modification time of the databases is retrieved from either:
    • the last-modified response header (when present, for MaxMind and HTTP(S) sources)
    • the modified_on metadata property for successful locus_custom_fetcher :fetch/1 and :conditionally_fetch/2 callbacks (for databases loaded with locus_custom_fetcher)
  • Caching can be disabled by specifying the no_cache option when running :start_loader
  • The cache database location can be customised by providing {database_cache_file, FilePath} option for locus_loader (FilePath must have a ".mmdb.gz" extension)

Local sources: Loading and Updating

  • The loaded database files, when compressed, are inflated in memory
  • The database modification timestamp is used to condition subsequent load attempts in order to lower I/O activity
  • Database load attempts are retried upon error according to an exponential backoff policy - quickly at first (every few seconds) but gradually slowing down to every 30 seconds. Successful and dismissed load attempts will be checked for update after 30 seconds. Both of these behaviours can be tweaked through the error_retries and update_period loader settings (see function reference.)

Logging

  • Five logging levels are supported: debug, info, warning, error and none
  • The chosen backend is logger if lager is either missing or it hasn't removed logger's default handler.
  • The default log level is error; it can be changed in the application's env config
  • To tweak the log level in runtime, use locus_logger:set_loglevel/1

Event Subscriptions

  • Any number of event subscribers can be attached to a database loader by specifying the {event_subscriber, Subscriber} option when starting the database
  • A Subscriber can be either a module implementing the locus_event_subscriber behaviour or an arbitrary pid()
  • The format and content of reported events can be consulted in detail on the locus_event_subscriber module documentation; most key steps in the loader pipeline are reported (download started, download succeeded, download failed, caching succeeded, loading failed, etc.)

API Reference

The API reference can be found on HexDocs.

Tested setup

  • Erlang/OTP 22 or newer
  • rebar3

License

MIT License

Copyright (c) 2017-2024 Guilherme Andrade

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

locus is an independent project and has not been authorized, sponsored, or otherwise approved by MaxMind.

Alternative Providers

  • IPinfo MMDB databases are compatible with locus since version 2.3.8
  • DB-IP.com: lite databases seem to work but setting up auto-update for them is not practical, as there's no "latest" official URL.

Alternative Libraries (Erlang)

  • egeoip: IP Geolocation module, currently supporting the MaxMind GeoLite City Database
  • geodata2: Application for working with MaxMind geoip2 (.mmdb) databases
  • geoip: Returns the location of an IP address; based on the ipinfodb.com web service
  • geolite2data: Periodically fetches the free MaxMind GeoLite2 databases
  • ip2location-erlang: Uses IP2Location geolocation database

Alternative Libraries (Elixir)

  • asn: IP-to-AS-to-ASname lookup
  • freegeoip: Simple wrapper for freegeoip.net HTTP API
  • freegeoipx: API Client for freegeoip.net
  • geoip: Lookup the geo location for a given IP address, hostname or Plug.Conn instance
  • geolix: MaxMind GeoIP2 database reader/decoder
  • plug_geoip2: Adds geo location to a Plug connection based upon the client IP address by using MaxMind's GeoIP2 database
  • tz_world: Resolve timezones rom a location efficiently using PostGIS and Ecto