nix expression for a custom ruby app with various custom gem dependencies

default.nix

{ pkgs, stdenv, ruby, rubygems, rubyLibs, ... }:

let
  myGems = pkgs.recurseIntoAttrs (pkgs.callPackage ./rubylibs.nix { });
  synapse_requirements = [
    rubyLibs.aws_sdk
    myGems.zk
    myGems.docker_api
  ];
in
  stdenv.mkDerivation rec {
    name = "synapse-aurora-${version}";
    version = "0.11.2.1";

    src = pkgs.fetchgit {
      url = "https://github.com/benley/synapse.git";
      rev = "70008ef0431d907991195a207135e86cbcb0387c";
      sha256 = "a44e11d361a5d2d3fe71710a78571471609a23a82d8ac80f327f77fac6d46369";
    };

    meta = {
      description = "Synapse with Aurora support";
      homepage = "https://github.com/benley/synapse";
    };

    buildInputs = with pkgs; [ ruby rubygems git makeWrapper ];
    propagatedBuildInputs = synapse_requirements;

    buildPhase = "gem build synapse.gemspec";

    installPhase = ''
      set -x
      export HOME=$TMP/home; mkdir -pv "$HOME"

      gem install \
        --ignore-dependencies \
        --install-dir "$out/${ruby.gemPath}" \
        --bindir "$out/bin" \
        "${name}.gem" $gemFlags -- $buildFlags

      # Don't keep the .gem file in the finished package
      rm -frv "$out/${ruby.gemPath}/cache"

      addToSearchPath GEM_PATH "$out/${ruby.gemPath}"

      for prog in $out/bin/*; do
        wrapProgram "$prog" \
          --prefix GEM_PATH : "$GEM_PATH" \
          --prefix RUBYLIB : "${rubygems}/lib" \
          --set RUBYOPT rubygems \
          $extraWrapperFlags ''${extraWrapperFlagsArray[@]}
      done

      # Make sure all the executables are actually in the package
      for prog in $out/gems/*/bin/*; do
        [[ -e "$out/bin/$(basename $prog)" ]]
      done

      # looks like useless files which break build repeatability and consume space
      rm $out/${ruby.gemPath}/doc/*/*/created.rid \
         $out/${ruby.gemPath}/gems/*/ext/*/mkmf.log || true

      runHook postInstall
    '';

    propagatedUserEnvPkgs = synapse_requirements;

    passthru.isRubyGem = true;
  }

Gemfile.nix

# WARNING: automatically generated file
# Generated by 'gem nix' command that comes from 'nix' gem
g: # Get dependencies from patched gems
{
  aliases = {
    archive_tar_minitar = g.archive_tar_minitar_0_5_2;
    aws_sdk = g.aws_sdk_1_60_2;
    aws_sdk_v1 = g.aws_sdk_v1_1_60_2;
    docker_api = g.docker_api_1_17_0;
    excon = g.excon_0_42_1;
    json = g.json_1_8_1;
    little_plugger = g.little_plugger_1_1_3;
    logging = g.logging_1_8_2;
    mini_portile = g.mini_portile_0_6_2;
    multi_json = g.multi_json_1_10_1;
    nokogiri = g.nokogiri_1_6_5;
    synapse_aurora = g.synapse_aurora_0_11_2_1;
    zk = g.zk_1_9_4;
    zookeeper = g.zookeeper_1_4_9;
  };
  gem_nix_args = [ ''synapse-aurora'' ];
  gems = {
    archive_tar_minitar_0_5_2 = {
      basename = ''archive_tar_minitar'';
      meta = {
        description = ''Provides POSIX tarchive management from Ruby programs.'';
        homepage = ''http://rubyforge.org/projects/ruwiki/'';
        longDescription = ''Archive::Tar::Minitar is a pure-Ruby library and command-line utility that provides the ability to deal with POSIX tar(1) archive files. The implementation is based heavily on Mauricio Ferna'ndez's implementation in rpa-base, but has been reorganised to promote reuse in other projects.'';
      };
      name = ''archive-tar-minitar-0.5.2'';
      requiredGems = [  ];
      sha256 = ''1j666713r3cc3wb0042x0wcmq2v11vwwy5pcaayy5f0lnd26iqig'';
    };
    aws_sdk_1_60_2 = {
      basename = ''aws_sdk'';
      meta = {
        description = ''AWS SDK for Ruby V1'';
        homepage = ''http://aws.amazon.com/sdkforruby'';
        longDescription = ''Version 1 of the AWS SDK for Ruby. Available as both `aws-sdk` and `aws-sdk-v1`.
Use `aws-sdk-v1` if you want to load v1 and v2 of the Ruby SDK in the same
application.'';
      };
      name = ''aws-sdk-1.60.2'';
      requiredGems = [ g.aws_sdk_v1_1_60_2 ];
      sha256 = ''027d3c5sxh7d7528hsvmqlix0lja1f7kdpr9sn7130pqdd4mcmah'';
    };
    aws_sdk_v1_1_60_2 = {
      basename = ''aws_sdk_v1'';
      meta = {
        description = ''AWS SDK for Ruby V1'';
        homepage = ''http://aws.amazon.com/sdkforruby'';
        longDescription = ''Version 1 of the AWS SDK for Ruby. Available as both `aws-sdk` and `aws-sdk-v1`.
Use `aws-sdk-v1` if you want to load v1 and v2 of the Ruby SDK in the same
application.'';
      };
      name = ''aws-sdk-v1-1.60.2'';
      requiredGems = [ g.nokogiri_1_6_5 g.json_1_8_1 ];
      sha256 = ''0124zc4p4bcxa07npbf2ychbqlavfm923vsmm1cjz51k8zl49n9c'';
    };
    docker_api_1_17_0 = {
      basename = ''docker_api'';
      meta = {
        description = ''A simple REST client for the Docker Remote API'';
        homepage = ''https://github.com/swipely/docker-api'';
        longDescription = ''A simple REST client for the Docker Remote API'';
      };
      name = ''docker-api-1.17.0'';
      requiredGems = [ g.excon_0_42_1 g.json_1_8_1 g.archive_tar_minitar_0_5_2 ];
      sha256 = ''0ifc0hgssr6x2650wxn8i2mpmc8girb6vihbr1xlr6jb7j7l8r4v'';
    };
    excon_0_42_1 = {
      basename = ''excon'';
      meta = {
        description = ''speed, persistence, http(s)'';
        homepage = ''https://github.com/excon/excon'';
        longDescription = ''EXtended http(s) CONnections'';
      };
      name = ''excon-0.42.1'';
      requiredGems = [  ];
      sha256 = ''1za1jmp83149qmykih2bfgxlwyyz3hrpaq4kxww7467fvgwh58xj'';
    };
    json_1_8_1 = {
      basename = ''json'';
      meta = {
        description = ''JSON Implementation for Ruby'';
        homepage = ''http://flori.github.com/json'';
        longDescription = ''This is a JSON implementation as a Ruby extension in C.'';
      };
      name = ''json-1.8.1'';
      requiredGems = [  ];
      sha256 = ''0002bsycvizvkmk1jyv8px1hskk6wrjfk4f7x5byi8gxm6zzn6wn'';
    };
    little_plugger_1_1_3 = {
      basename = ''little_plugger'';
      meta = {
        description = ''LittlePlugger is a module that provides Gem based plugin management.'';
        homepage = ''http://gemcutter.org/gems/little-plugger'';
        longDescription = ''LittlePlugger is a module that provides Gem based plugin management.
By extending your own class or module with LittlePlugger you can easily
manage the loading and initializing of plugins provided by other gems.'';
      };
      name = ''little-plugger-1.1.3'';
      requiredGems = [  ];
      sha256 = ''0crxv0yl5iwmqzj2y7hh9s7qbwr7s7305vgdbsanbzq059ca98yp'';
    };
    logging_1_8_2 = {
      basename = ''logging'';
      meta = {
        description = ''A flexible and extendable logging library for Ruby'';
        homepage = ''http://rubygems.org/gems/logging'';
        longDescription = ''Logging is a flexible logging library for use in Ruby programs based on the
design of Java's log4j library. It features a hierarchical logging system,
custom level names, multiple output destinations per log event, custom
formatting, and more.'';
      };
      name = ''logging-1.8.2'';
      requiredGems = [ g.little_plugger_1_1_3 g.multi_json_1_10_1 ];
      sha256 = ''0vcckpk3sffhz9phpzkbbqzzcffsg2n292rmq5b4gx6dp9g4n86p'';
    };
    mini_portile_0_6_2 = {
      basename = ''mini_portile'';
      meta = {
        description = ''Simplistic port-like solution for developers'';
        homepage = ''http://github.com/flavorjones/mini_portile'';
        longDescription = ''Simplistic port-like solution for developers. It provides a standard and simplified way to compile against dependency libraries without messing up your system.'';
      };
      name = ''mini_portile-0.6.2'';
      requiredGems = [  ];
      sha256 = ''0h3xinmacscrnkczq44s6pnhrp4nqma7k056x5wv5xixvf2wsq2w'';
    };
    multi_json_1_10_1 = {
      basename = ''multi_json'';
      meta = {
        description = ''A common interface to multiple JSON libraries.'';
        homepage = ''http://github.com/intridea/multi_json'';
        longDescription = ''A common interface to multiple JSON libraries, including Oj, Yajl, the JSON gem (with C-extensions), the pure-Ruby JSON gem, NSJSONSerialization, gson.rb, JrJackson, and OkJson.'';
      };
      name = ''multi_json-1.10.1'';
      requiredGems = [  ];
      sha256 = ''1ll21dz01jjiplr846n1c8yzb45kj5hcixgb72rz0zg8fyc9g61c'';
    };
    nokogiri_1_6_5 = {
      basename = ''nokogiri'';
      meta = {
        description = ''Nokogiri (鋸) is an HTML, XML, SAX, and Reader parser'';
        homepage = ''http://nokogiri.org'';
        longDescription = ''Nokogiri (鋸) is an HTML, XML, SAX, and Reader parser.  Among Nokogiri's
many features is the ability to search documents via XPath or CSS3 selectors.

XML is like violence - if it doesn’t solve your problems, you are not using
enough of it.'';
      };
      name = ''nokogiri-1.6.5'';
      requiredGems = [ g.mini_portile_0_6_2 ];
      sha256 = ''1xmxz6fa0m4p7c7ngpgz6gjgv65lzz63dsf0b6vh7gs2fkiw8j7l'';
    };
    synapse_aurora_0_11_2_1 = {
      basename = ''synapse_aurora'';
      meta = {
        description = ''Fork of Airbnb Synapse with support for Apache Aurora'';
        homepage = ''https://github.com/benley/synapse'';
        longDescription = ''Synapse is Airbnb's new system for service discovery.  Synapse solves the
problem of automated fail-over in the cloud, where failover via network
re-configuration is impossible.  The end result is the ability to connect
internal services together in a scalable, fault-tolerant way.

This is a forked version which adds support for Apache Aurora service
announcements.
'';
      };
      name = ''synapse-aurora-0.11.2.1'';
      requiredGems = [ g.aws_sdk_1_60_2 g.docker_api_1_17_0 g.zk_1_9_4 ];
      sha256 = ''0yhqxcczc6wycaqj8q36nmwv5f6vfhyjisiiasfd2zc5qqvi9jgr'';
    };
    zk_1_9_4 = {
      basename = ''zk'';
      meta = {
        description = ''A high-level wrapper around the zookeeper driver'';
        homepage = ''https://github.com/slyphon/zk'';
        longDescription = ''A high-level wrapper around the zookeeper driver
'';
      };
      name = ''zk-1.9.4'';
      requiredGems = [ g.zookeeper_1_4_9 g.logging_1_8_2 ];
      sha256 = ''1rgghyhnbqp7lcn0vik3rn93msv51igsh5cwag88rp6hhnvd141j'';
    };
    zookeeper_1_4_9 = {
      basename = ''zookeeper'';
      meta = {
        description = ''Apache ZooKeeper driver for Rubies'';
        homepage = ''https://github.com/slyphon/zookeeper'';
        longDescription = ''A low-level multi-Ruby wrapper around the ZooKeeper API bindings. For a
friendlier interface, see http://github.com/slyphon/zk. Currently supported:
MRI: {1.8.7, 1.9.2, 1.9.3}, JRuby: ~> 1.6.7, Rubinius: 2.0.testing, REE 1.8.7.

This library uses version 3.4.5 of zookeeper bindings.

'';
      };
      name = ''zookeeper-1.4.9'';
      requiredGems = [  ];
      sha256 = ''1zjb8sri15nqyqv1w9v34dv2d7q1lf3phr126mcfrj8v6vawhzcc'';
    };
  };
}

rubylibs.nix

{ stdenv, config, fetchurl, callPackage
, gemfile ? ./Gemfile.nix
, patches ? null
, overrides ? null
}:

let
  inherit (stdenv.lib) fold optional;
  gemsMergeableFun = { generatedFuns ? [], patchFuns ? [], overrideFuns ? [] }:
  let
    generatedAttrs = map (f: f customGems) generatedFuns;
    generatedGems = map (a: a.gems) generatedAttrs;
    gem = callPackage <nixpkgs/pkgs/development/interpreters/ruby/gem.nix> {
      patches = map (f: callPackage f { inherit gems; }) patchFuns;
      overrides = map (f: callPackage f { }) overrideFuns;
    };
    customGems = stdenv.lib.mapAttrs gem (fold (x: y: x // y) { } generatedGems);
    gems = fold (x: y: x // y) customGems (map (a: a.aliases) generatedAttrs);
  in
  gems // {
    merge = { generated ? null, patches ? null, overrides ? null }:
      gemsMergeableFun {
        generatedFuns = generatedFuns ++ optional (generated != null) generated;
        patchFuns = patchFuns ++ optional (patches != null) patches;
        overrideFuns = overrideFuns ++ optional (overrides != null) overrides;
      };
  };
in
  ((gemsMergeableFun { }).merge {
    generated = import gemfile;
    inherit patches;
    inherit overrides;
  }).merge (
    let
      getLocalGemFun = name: stdenv.lib.attrByPath [ "gems" name ] null config;
    in
    {
      generated = getLocalGemFun "generated";
      patches = getLocalGemFun "patches";
      overrides = getLocalGemFun "overrides";
    }
  )