diff --git a/.circleci/config.yml b/.circleci/config.yml
new file mode 100644
index 0000000..33a2481
--- /dev/null
+++ b/.circleci/config.yml
@@ -0,0 +1,41 @@
+# Ruby CircleCI 2.0 configuration file
+#
+# Check https://circleci.com/docs/2.0/language-ruby/ for more details
+#
+version: 2
+jobs:
+  build:
+    docker:
+      # Specify the Ruby version you desire here
+      - image: circleci/ruby:2.3.5
+
+    working_directory: ~/identity-hostdata
+    steps:
+      - checkout
+
+      - restore-cache:
+          key: identity-hostdata-{{ checksum "Gemfile.lock" }}
+
+      - run:
+          name: Install dependencies
+          command: |
+            gem install bundler
+            bundle install --deployment --jobs=4 --retry=3 --without deploy development doc production --path vendor/bundle
+
+      # Store bundle cache
+      - save-cache:
+          key: identity-hostdata-{{ checksum "Gemfile.lock" }}
+          paths:
+            - vendor/bundle
+
+      - run:
+          name: Run Tests
+          command: |
+            make test
+
+      # collect reports
+      - store_test_results:
+          path: /tmp/test-results
+      - store_artifacts:
+          path: /tmp/test-results
+          destination: test-results
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..8eb3b06
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,12 @@
+/.bundle/
+/.yardoc
+/Gemfile.lock
+/_yardoc/
+/coverage/
+/doc/
+/pkg/
+/spec/reports/
+/tmp/
+
+# rspec failure tracking
+.rspec_status
diff --git a/.rspec b/.rspec
new file mode 100644
index 0000000..8c18f1a
--- /dev/null
+++ b/.rspec
@@ -0,0 +1,2 @@
+--format documentation
+--color
diff --git a/.travis.yml b/.travis.yml
new file mode 100644
index 0000000..a3c82e9
--- /dev/null
+++ b/.travis.yml
@@ -0,0 +1,5 @@
+sudo: false
+language: ruby
+rvm:
+  - 2.3.5
+before_install: gem install bundler -v 1.15.4
diff --git a/CHANGELOG.md b/CHANGELOG.md
new file mode 100644
index 0000000..e429041
--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,4 @@
+# 0.1.0 (2017-09-21)
+
+- Added `Identity::Hostdata.domain`
+- Added `Identity::Hostdata.env`
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
new file mode 100644
index 0000000..e71175f
--- /dev/null
+++ b/CONTRIBUTING.md
@@ -0,0 +1,90 @@
+## Welcome!
+
+We're so glad you're thinking about contributing to an 18F open source project!
+If you're unsure about anything, just ask — or submit the issue or pull request
+anyway. The worst that can happen is you'll be politely asked to change
+something. We love all friendly contributions.
+
+We want to ensure a welcoming environment for all of our projects. Our staff
+follow the [18F Code of Conduct][code] and all contributors should do the same.
+
+We encourage you to read this project's CONTRIBUTING policy (you are here), its
+[LICENSE](LICENSE.md), and its [README](README.md).
+
+If you have any questions or want to read more, check out the
+[18F Open Source Policy GitHub repository][os-policy], or just
+[shoot us an email](mailto:18f@gsa.gov).
+
+[code]: https://github.com/18F/code-of-conduct/blob/master/code-of-conduct.md
+[os-policy]: https://github.com/18f/open-source-policy
+
+## Pull request guidelines
+
+Please follow our [Git Protocol][git] and [Code Review][review] guidelines.
+[Glen Sanford's thoughts on code reviews][thoughts] are also well worth
+reading.
+
+[git]: https://github.com/18F/development-guide/tree/master/git_protocol
+[review]: https://github.com/18F/development-guide/tree/master/code_review
+[thoughts]: http://glen.nu/ramblings/oncodereview.php
+
+### Commit message style guide:
+
+- Write your commit message summary in the imperative: "Fix bug" and not
+"Fixed bug" or "Fixes bug."  This convention matches up with commit messages
+generated by commands like `git merge` and `git revert`.
+
+- Under the summary, start by explaining why this change is necessary, and
+add details to help the person reviewing your code understand what your
+pull request is about.
+
+- If the pull request fixes a GitHub issue, mention it at the bottom using
+GitHub's syntax, such as `Fixes #123`.
+
+Example:
+
+```
+Load seed using before(:suite) in RSpec config
+
+**Why**:
+- Loading the seed in a `before(:each)` block results in an unnecessary
+database call before every single test, slowing down the test suite,
+and making development less efficient.
+
+**How**:
+- Use `before(:suite)` instead, since the data that is loaded is not
+meant to change, and so that only one database call is made.
+- To prevent the data from being wiped out after each spec, configure
+Database Cleaner to ignore those static tables.
+
+Fixes #123
+```
+
+Note that we use [Overcommit] to enforce some of the commit message rules.
+If this is your first time contributing to this repo, you will need to
+sign your Overcommit configuration by running `overcommit --sign` before
+being able to run `git commit`. See the [Security] section in the Overcommit
+README for more details.
+
+[Overcommit]: https://github.com/brigade/overcommit
+[Security]: https://github.com/brigade/overcommit#security
+
+### Additional notes on pull requests and code reviews
+
+- Prioritize code reviews above your other work
+- Review pull requests within 24 hours of being opened
+- Keep pull requests as small as possible, and focused on a single topic
+- Once a pull request is good to go, the code reviewer is the one who merges
+  it, then deletes the branch.
+
+## Public domain
+
+This project is in the public domain within the United States, and
+copyright and related rights in the work worldwide are waived through
+the [CC0 1.0 Universal public domain dedication][CC0].
+
+All contributions to this project will be released under the CC0
+dedication. By submitting a pull request, you are agreeing to comply
+with this waiver of copyright interest.
+
+[CC0]: https://creativecommons.org/publicdomain/zero/1.0/
diff --git a/Gemfile b/Gemfile
new file mode 100644
index 0000000..87d7942
--- /dev/null
+++ b/Gemfile
@@ -0,0 +1,6 @@
+source "https://rubygems.org"
+
+git_source(:github) {|repo_name| "https://github.com/#{repo_name}" }
+
+# Specify your gem's dependencies in identity-hostdata.gemspec
+gemspec
diff --git a/LICENSE.md b/LICENSE.md
new file mode 100644
index 0000000..19fa33d
--- /dev/null
+++ b/LICENSE.md
@@ -0,0 +1,31 @@
+As a work of the United States Government, this project is in the
+public domain within the United States.
+
+Additionally, we waive copyright and related rights in the work
+worldwide through the CC0 1.0 Universal public domain dedication.
+
+## CC0 1.0 Universal Summary
+
+This is a human-readable summary of the [Legal Code (read the full text)](https://creativecommons.org/publicdomain/zero/1.0/legalcode).
+
+### No Copyright
+
+The person who associated a work with this deed has dedicated the work to
+the public domain by waiving all of his or her rights to the work worldwide
+under copyright law, including all related and neighboring rights, to the
+extent allowed by law.
+
+You can copy, modify, distribute and perform the work, even for commercial
+purposes, all without asking permission.
+
+### Other Information
+
+In no way are the patent or trademark rights of any person affected by CC0,
+nor are the rights that other persons may have in the work or in how the
+work is used, such as publicity or privacy rights.
+
+Unless expressly stated otherwise, the person who associated a work with
+this deed makes no warranties about the work, and disclaims liability for
+all uses of the work, to the fullest extent permitted by applicable law.
+When using or citing the work, you should not imply endorsement by the
+author or the affirmer.
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..6da396f
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,5 @@
+setup:
+	bin/setup
+
+test: setup
+	bundle exec rake spec
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..fabc450
--- /dev/null
+++ b/README.md
@@ -0,0 +1,43 @@
+# Identity::Hostdata
+
+A gem to help read configuration from login.gov infrastructure
+
+## Installation
+
+Add this line to your application's Gemfile:
+
+```ruby
+gem 'identity-hostdata', github: '18F/identity-hostdata'
+```
+
+## Usage
+
+Use this gem to access config data on a per-host basis
+
+```
+require 'identity/hostdata'
+
+Identity::Hostdata.domain
+# => "login.gov"
+```
+
+## Development
+
+Run tests:
+
+```
+make test
+```
+
+## Contributing
+
+See [CONTRIBUTING](CONTRIBUTING.md) for additional information.
+
+## Public domain
+
+This project is in the worldwide [public domain](LICENSE.md). As stated in [CONTRIBUTING](CONTRIBUTING.md):
+
+> This project is in the public domain within the United States, and copyright and related rights in the work worldwide are waived through the [CC0 1.0 Universal public domain dedication](https://creativecommons.org/publicdomain/zero/1.0/).
+>
+> All contributions to this project will be released under the CC0 dedication. By submitting a pull request, you are agreeing to comply with this waiver of copyright interest.
+
diff --git a/Rakefile b/Rakefile
new file mode 100644
index 0000000..b7e9ed5
--- /dev/null
+++ b/Rakefile
@@ -0,0 +1,6 @@
+require "bundler/gem_tasks"
+require "rspec/core/rake_task"
+
+RSpec::Core::RakeTask.new(:spec)
+
+task :default => :spec
diff --git a/bin/console b/bin/console
new file mode 100755
index 0000000..098b927
--- /dev/null
+++ b/bin/console
@@ -0,0 +1,14 @@
+#!/usr/bin/env ruby
+
+require "bundler/setup"
+require "identity/hostdata"
+
+# You can add fixtures and/or initialization code here to make experimenting
+# with your gem easier. You can also use a different console, if you like.
+
+# (If you use this, don't forget to add pry to your Gemfile!)
+# require "pry"
+# Pry.start
+
+require "irb"
+IRB.start(__FILE__)
diff --git a/bin/setup b/bin/setup
new file mode 100755
index 0000000..dce67d8
--- /dev/null
+++ b/bin/setup
@@ -0,0 +1,8 @@
+#!/usr/bin/env bash
+set -euo pipefail
+IFS=$'\n\t'
+set -vx
+
+bundle install
+
+# Do any other automated setup that you need to do here
diff --git a/identity-hostdata.gemspec b/identity-hostdata.gemspec
new file mode 100644
index 0000000..a155bf2
--- /dev/null
+++ b/identity-hostdata.gemspec
@@ -0,0 +1,38 @@
+# coding: utf-8
+lib = File.expand_path("../lib", __FILE__)
+$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
+require "identity/hostdata/version"
+
+Gem::Specification.new do |spec|
+  spec.name          = "identity-hostdata"
+  spec.version       = Identity::Hostdata::VERSION
+  spec.authors       = ["Zach Margolis"]
+  spec.email         = ["zachary.margolis@gsa.gov"]
+
+  spec.summary       = %q{Library to help read host data for login.gov}
+  spec.description   = %q{Common helpers across login.gov infrastructure}
+  spec.homepage      = "https://github.com/18F/identity-hostdata"
+  spec.license       = "LICENSE.md"
+
+  # Prevent pushing this gem to RubyGems.org. To allow pushes either set the 'allowed_push_host'
+  # to allow pushing to a single host or delete this section to allow pushing to any host.
+  if spec.respond_to?(:metadata)
+    spec.metadata["allowed_push_host"] = "TODO: Set to 'http://mygemserver.com'"
+  else
+    raise "RubyGems 2.0 or newer is required to protect against " \
+      "public gem pushes."
+  end
+
+  spec.files         = `git ls-files -z`.split("\x0").reject do |f|
+    f.match(%r{^(test|spec|features)/})
+  end
+  spec.bindir        = "exe"
+  spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
+  spec.require_paths = ["lib"]
+
+  spec.add_development_dependency "bundler", "~> 1.15"
+  spec.add_development_dependency "rake", "~> 10.0"
+  spec.add_development_dependency "rspec", "~> 3.0"
+
+  spec.add_development_dependency "fakefs", "~> 0.11"
+end
diff --git a/lib/identity/hostdata.rb b/lib/identity/hostdata.rb
new file mode 100644
index 0000000..d004b59
--- /dev/null
+++ b/lib/identity/hostdata.rb
@@ -0,0 +1,39 @@
+require "identity/hostdata/version"
+
+module Identity
+  module Hostdata
+    class MissingConfigError < StandardError; end
+
+    CONFIG_DIR = '/etc/login.gov'
+    DOMAIN_PATH = File.join(CONFIG_DIR, 'info/domain')
+    ENV_PATH = File.join(CONFIG_DIR, 'info/env')
+
+    def self.domain
+      @domain ||= begin
+        File.read(DOMAIN_PATH).chomp
+      rescue Errno::ENOENT => err
+        raise MissingConfigError, err.message if in_datacenter?
+      end
+    end
+
+    def self.env
+      @env ||= begin
+        File.read(ENV_PATH).chomp
+      rescue Errno::ENOENT => err
+        raise MissingConfigError, err.message if in_datacenter?
+      end
+    end
+
+    def self.in_datacenter?
+      File.directory?(CONFIG_DIR)
+    end
+
+    # @api private
+    # Used to clear memoized values (intended for specs)
+    def self.reset!
+      instance_variables.each do |variable|
+        remove_instance_variable(variable)
+      end
+    end
+  end
+end
diff --git a/lib/identity/hostdata/version.rb b/lib/identity/hostdata/version.rb
new file mode 100644
index 0000000..d222064
--- /dev/null
+++ b/lib/identity/hostdata/version.rb
@@ -0,0 +1,5 @@
+module Identity
+  module Hostdata
+    VERSION = "0.1.0"
+  end
+end
diff --git a/spec/identity/hostdata_spec.rb b/spec/identity/hostdata_spec.rb
new file mode 100644
index 0000000..03d5375
--- /dev/null
+++ b/spec/identity/hostdata_spec.rb
@@ -0,0 +1,89 @@
+require "spec_helper"
+
+RSpec.describe Identity::Hostdata do
+  it "has a version number" do
+    expect(Identity::Hostdata::VERSION).not_to be nil
+  end
+
+  context 'reading config from the filesystem' do
+    around(:each) do |ex|
+      Identity::Hostdata.reset!
+
+      FakeFS.with_fresh do
+        ex.run
+      end
+    end
+
+    describe '.domain' do
+      context 'when /etc/login.gov exists (in a datacenter environment)' do
+        before { FileUtils.mkdir_p('/etc/login.gov') }
+
+        context 'when the info/domain file exists' do
+          before do
+            FileUtils.mkdir_p('/etc/login.gov/info')
+            File.open('/etc/login.gov/info/domain', 'w') { |f| f.puts 'identitysandbox.gov' }
+          end
+
+          it 'reads the contents of the file' do
+            expect(Identity::Hostdata.domain).to eq('identitysandbox.gov')
+          end
+        end
+
+        context 'when the info/domain file does not exist' do
+          it 'blows up' do
+            expect { Identity::Hostdata.domain }.
+              to raise_error(Identity::Hostdata::MissingConfigError)
+          end
+        end
+      end
+
+      context 'when /etc/login.gov does not exist (development environment)' do
+        it 'is nil' do
+          expect(Identity::Hostdata.domain).to eq(nil)
+        end
+      end
+    end
+
+    describe '.env' do
+      context 'when /etc/login.gov exists (in a datacenter environment)' do
+        before { FileUtils.mkdir_p('/etc/login.gov') }
+
+        context 'when the info/env file exists' do
+          before do
+            FileUtils.mkdir_p('/etc/login.gov/info')
+            File.open('/etc/login.gov/info/env', 'w') { |f| f.puts 'staging' }
+          end
+
+          it 'reads the contents of the file' do
+            expect(Identity::Hostdata.env).to eq('staging')
+          end
+        end
+
+        context 'when the info/env file does not exist' do
+          it 'blows up' do
+            expect { Identity::Hostdata.env }.
+              to raise_error(Identity::Hostdata::MissingConfigError)
+          end
+        end
+      end
+
+      context 'when /etc/login.gov does not exist (development environment)' do
+        it 'is nil' do
+          expect(Identity::Hostdata.env).to eq(nil)
+        end
+      end
+    end
+
+    describe '.in_datacenter?' do
+      it 'is true when the /etc/login.gov directory exists' do
+        FileUtils.mkdir_p('/etc/login.gov')
+
+        expect(Identity::Hostdata.in_datacenter?).to eq(true)
+      end
+
+      it 'is false when the /etc/login.gov does note exist' do
+        expect(Identity::Hostdata.in_datacenter?).to eq(false)
+      end
+    end
+  end
+end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
new file mode 100644
index 0000000..57d1382
--- /dev/null
+++ b/spec/spec_helper.rb
@@ -0,0 +1,19 @@
+require "bundler/setup"
+require "identity/hostdata"
+require "pp"
+require "fakefs/safe"
+require "fakefs/spec_helpers"
+
+RSpec.configure do |config|
+  # Enable flags like --only-failures and --next-failure
+  config.example_status_persistence_file_path = ".rspec_status"
+
+  # Disable RSpec exposing methods globally on `Module` and `main`
+  config.disable_monkey_patching!
+
+  config.expect_with :rspec do |c|
+    c.syntax = :expect
+  end
+
+  config.include FakeFS::SpecHelpers, fakefs: true
+end