diff --git a/app/models/environment.rb b/app/models/environment.rb
index 96700143ddd9893eb4d930eb4f5e4a8e59670e65..0abbf674b9d070e00d30967fe113fcd38e1ec49d 100644
--- a/app/models/environment.rb
+++ b/app/models/environment.rb
@@ -1,9 +1,15 @@
 class Environment < ActiveRecord::Base
+  # Used to generate random suffixes for the slug
+  NUMBERS = '0'..'9'
+  SUFFIX_CHARS = ('a'..'z').to_a + NUMBERS.to_a
+
   belongs_to :project, required: true, validate: true
 
   has_many :deployments
 
   before_validation :nullify_external_url
+  before_validation :generate_slug, if: ->(env) { env.slug.blank? }
+
   before_save :set_environment_type
 
   validates :name,
@@ -13,6 +19,13 @@ class Environment < ActiveRecord::Base
             format: { with: Gitlab::Regex.environment_name_regex,
                       message: Gitlab::Regex.environment_name_regex_message }
 
+  validates :slug,
+            presence: true,
+            uniqueness: { scope: :project_id },
+            length: { maximum: 24 },
+            format: { with: Gitlab::Regex.environment_slug_regex,
+                      message: Gitlab::Regex.environment_slug_regex_message }
+
   validates :external_url,
             uniqueness: { scope: :project_id },
             length: { maximum: 255 },
@@ -107,4 +120,41 @@ class Environment < ActiveRecord::Base
       action.expanded_environment_name == environment
     end
   end
+
+  # An environment name is not necessarily suitable for use in URLs, DNS
+  # or other third-party contexts, so provide a slugified version. A slug has
+  # the following properties:
+  #   * contains only lowercase letters (a-z), numbers (0-9), and '-'
+  #   * begins with a letter
+  #   * has a maximum length of 24 bytes (OpenShift limitation)
+  #   * cannot end with `-`
+  def generate_slug
+    # Lowercase letters and numbers only
+    slugified = name.to_s.downcase.gsub(/[^a-z0-9]/, '-')
+
+    # Must start with a letter
+    slugified = "env-" + slugified if NUMBERS.cover?(slugified[0])
+
+    # Maximum length: 24 characters (OpenShift limitation)
+    slugified = slugified[0..23]
+
+    # Cannot end with a "-" character (Kubernetes label limitation)
+    slugified = slugified[0..-2] if slugified[-1] == "-"
+
+    # Add a random suffix, shortening the current string if necessary, if it
+    # has been slugified. This ensures uniqueness.
+    slugified = slugified[0..16] + "-" + random_suffix if slugified != name
+
+    self.slug = slugified
+  end
+
+  private
+
+  # Slugifying a name may remove the uniqueness guarantee afforded by it being
+  # based on name (which must be unique). To compensate, we add a random
+  # 6-byte suffix in those circumstances. This is not *guaranteed* uniqueness,
+  # but the chance of collisions is vanishingly small
+  def random_suffix
+    (0..5).map { SUFFIX_CHARS.sample }.join
+  end
 end
diff --git a/changelogs/unreleased/22864-add-environment-slug.yml b/changelogs/unreleased/22864-add-environment-slug.yml
new file mode 100644
index 0000000000000000000000000000000000000000..f90f79337d5c73137947d76701617d3fcfdaa7d5
--- /dev/null
+++ b/changelogs/unreleased/22864-add-environment-slug.yml
@@ -0,0 +1,4 @@
+---
+title: Add a slug to environments
+merge_request: 7983
+author:
diff --git a/db/migrate/20161207231626_add_environment_slug.rb b/db/migrate/20161207231626_add_environment_slug.rb
new file mode 100644
index 0000000000000000000000000000000000000000..7153e6a32b1cdc93088899852d3c17824cefa8ba
--- /dev/null
+++ b/db/migrate/20161207231626_add_environment_slug.rb
@@ -0,0 +1,60 @@
+# See http://doc.gitlab.com/ce/development/migration_style_guide.html
+# for more information on how to write migrations for GitLab.
+
+class AddEnvironmentSlug < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = true
+  DOWNTIME_REASON = 'Adding NOT NULL column environments.slug with dependent data'
+
+  # Used to generate random suffixes for the slug
+  NUMBERS = '0'..'9'
+  SUFFIX_CHARS = ('a'..'z').to_a + NUMBERS.to_a
+
+  def up
+    environments = Arel::Table.new(:environments)
+
+    add_column :environments, :slug, :string
+    finder = environments.project(:id, :name)
+
+    connection.exec_query(finder.to_sql).rows.each do |id, name|
+      updater = Arel::UpdateManager.new(ActiveRecord::Base).
+        table(environments).
+        set(environments[:slug] => generate_slug(name)).
+        where(environments[:id].eq(id))
+
+      connection.exec_update(updater.to_sql, self.class.name, [])
+    end
+
+    change_column_null :environments, :slug, false
+  end
+
+  def down
+    remove_column :environments, :slug
+  end
+
+  # Copy of the Environment#generate_slug implementation
+  def generate_slug(name)
+    # Lowercase letters and numbers only
+    slugified = name.to_s.downcase.gsub(/[^a-z0-9]/, '-')
+
+    # Must start with a letter
+    slugified = "env-" + slugified if NUMBERS.cover?(slugified[0])
+
+    # Maximum length: 24 characters (OpenShift limitation)
+    slugified = slugified[0..23]
+
+    # Cannot end with a "-" character (Kubernetes label limitation)
+    slugified = slugified[0..-2] if slugified[-1] == "-"
+
+    # Add a random suffix, shortening the current string if necessary, if it
+    # has been slugified. This ensures uniqueness.
+    slugified = slugified[0..16] + "-" + random_suffix if slugified != name
+
+    slugified
+  end
+
+  def random_suffix
+    (0..5).map { SUFFIX_CHARS.sample }.join
+  end
+end
diff --git a/db/migrate/20161209153400_add_unique_index_for_environment_slug.rb b/db/migrate/20161209153400_add_unique_index_for_environment_slug.rb
new file mode 100644
index 0000000000000000000000000000000000000000..e9fcef1cd45601d53f132d211c7a743a3d2cdbcd
--- /dev/null
+++ b/db/migrate/20161209153400_add_unique_index_for_environment_slug.rb
@@ -0,0 +1,15 @@
+# See http://doc.gitlab.com/ce/development/migration_style_guide.html
+# for more information on how to write migrations for GitLab.
+
+class AddUniqueIndexForEnvironmentSlug < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = true
+  DOWNTIME_REASON = 'Adding a *unique* index to environments.slug'
+
+  disable_ddl_transaction!
+
+  def change
+    add_concurrent_index :environments, [:project_id, :slug], unique: true
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 83c8ad485378cd5f77ab974d569815b97e270082..67ff83d96d9128867ad141edaf8443f88dcde67d 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20161207231621) do
+ActiveRecord::Schema.define(version: 20161212142807) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -98,14 +98,14 @@ ActiveRecord::Schema.define(version: 20161207231621) do
     t.text "help_page_text_html"
     t.text "shared_runners_text_html"
     t.text "after_sign_up_text_html"
+    t.boolean "sidekiq_throttling_enabled", default: false
+    t.string "sidekiq_throttling_queues"
+    t.decimal "sidekiq_throttling_factor"
     t.boolean "housekeeping_enabled", default: true, null: false
     t.boolean "housekeeping_bitmaps_enabled", default: true, null: false
     t.integer "housekeeping_incremental_repack_period", default: 10, null: false
     t.integer "housekeeping_full_repack_period", default: 50, null: false
     t.integer "housekeeping_gc_period", default: 200, null: false
-    t.boolean "sidekiq_throttling_enabled", default: false
-    t.string "sidekiq_throttling_queues"
-    t.decimal "sidekiq_throttling_factor"
     t.boolean "html_emails_enabled", default: true
   end
 
@@ -428,9 +428,11 @@ ActiveRecord::Schema.define(version: 20161207231621) do
     t.string "external_url"
     t.string "environment_type"
     t.string "state", default: "available", null: false
+    t.string "slug", null: false
   end
 
   add_index "environments", ["project_id", "name"], name: "index_environments_on_project_id_and_name", unique: true, using: :btree
+  add_index "environments", ["project_id", "slug"], name: "index_environments_on_project_id_and_slug", unique: true, using: :btree
 
   create_table "events", force: :cascade do |t|
     t.string "target_type"
@@ -737,8 +739,8 @@ ActiveRecord::Schema.define(version: 20161207231621) do
     t.integer "visibility_level", default: 20, null: false
     t.boolean "request_access_enabled", default: false, null: false
     t.datetime "deleted_at"
-    t.text "description_html"
     t.boolean "lfs_enabled"
+    t.text "description_html"
     t.integer "parent_id"
   end
 
@@ -1219,8 +1221,8 @@ ActiveRecord::Schema.define(version: 20161207231621) do
     t.datetime "otp_grace_period_started_at"
     t.boolean "ldap_email", default: false, null: false
     t.boolean "external", default: false
-    t.string "incoming_email_token"
     t.string "organization"
+    t.string "incoming_email_token"
     t.boolean "authorized_projects_populated"
   end
 
diff --git a/doc/api/enviroments.md b/doc/api/enviroments.md
index 87a5fa67124996dcf9e80d93800ecb6d581b7353..1299aca8c45c7f499930034ec5578c106f188d7e 100644
--- a/doc/api/enviroments.md
+++ b/doc/api/enviroments.md
@@ -22,8 +22,9 @@ Example response:
 [
   {
     "id": 1,
-    "name": "Env1",
-    "external_url": "https://env1.example.gitlab.com"
+    "name": "review/fix-foo",
+    "slug": "review-fix-foo-dfjre3",
+    "external_url": "https://review-fix-foo-dfjre3.example.gitlab.com"
   }
 ]
 ```
@@ -54,6 +55,7 @@ Example response:
 {
   "id": 1,
   "name": "deploy",
+  "slug": "deploy",
   "external_url": "https://deploy.example.gitlab.com"
 }
 ```
@@ -85,6 +87,7 @@ Example response:
 {
   "id": 1,
   "name": "staging",
+  "slug": "staging",
   "external_url": "https://staging.example.gitlab.com"
 }
 ```
@@ -112,6 +115,7 @@ Example response:
 {
   "id": 1,
   "name": "deploy",
+  "slug": "deploy",
   "external_url": "https://deploy.example.gitlab.com"
 }
 ```
diff --git a/lib/api/entities.rb b/lib/api/entities.rb
index 01c0f5072ba40dc1b29fc4b5996989e5a9ecdc03..dfbb3ab86dd23c00f55c84a9e978290862068808 100644
--- a/lib/api/entities.rb
+++ b/lib/api/entities.rb
@@ -629,7 +629,7 @@ module API
     end
 
     class EnvironmentBasic < Grape::Entity
-      expose :id, :name, :external_url
+      expose :id, :name, :slug, :external_url
     end
 
     class Environment < EnvironmentBasic
diff --git a/lib/api/environments.rb b/lib/api/environments.rb
index 80bbd9bb6e4d4fb963ba61f3186cb4edf439581d..1a7e68f0528f3d15f628d48fb3a47c824ce3c2e5 100644
--- a/lib/api/environments.rb
+++ b/lib/api/environments.rb
@@ -1,6 +1,7 @@
 module API
   # Environments RESTfull API endpoints
   class Environments < Grape::API
+    include ::API::Helpers::CustomValidators
     include PaginationParams
 
     before { authenticate! }
@@ -29,6 +30,7 @@ module API
       params do
         requires :name,           type: String,   desc: 'The name of the environment to be created'
         optional :external_url,   type: String,   desc: 'URL on which this deployment is viewable'
+        optional :slug, absence: { message: "is automatically generated and cannot be changed" }
       end
       post ':id/environments' do
         authorize! :create_environment, user_project
@@ -50,6 +52,7 @@ module API
         requires :environment_id, type: Integer,  desc: 'The environment ID'
         optional :name,           type: String,   desc: 'The new environment name'
         optional :external_url,   type: String,   desc: 'The new URL on which this deployment is viewable'
+        optional :slug, absence: { message: "is automatically generated and cannot be changed" }
       end
       put ':id/environments/:environment_id' do
         authorize! :update_environment, user_project
diff --git a/lib/api/helpers/custom_validators.rb b/lib/api/helpers/custom_validators.rb
new file mode 100644
index 0000000000000000000000000000000000000000..0a8f3073a50e1fc191e6eeee21ea9314d2b93f32
--- /dev/null
+++ b/lib/api/helpers/custom_validators.rb
@@ -0,0 +1,14 @@
+module API
+  module Helpers
+    module CustomValidators
+      class Absence < Grape::Validations::Base
+        def validate_param!(attr_name, params)
+          return if params.respond_to?(:key?) && !params.key?(attr_name)
+          raise Grape::Exceptions::Validation, params: [@scope.full_name(attr_name)], message: message(:absence)
+        end
+      end
+    end
+  end
+end
+
+Grape::Validations.register_validator(:absence, ::API::Helpers::CustomValidators::Absence)
diff --git a/lib/gitlab/regex.rb b/lib/gitlab/regex.rb
index 7c711d581e8bdaeab91f03c0f8a5768e84898b5f..9e0b0e5ea98ea9c831f5b2efbb4ea3a3235af933 100644
--- a/lib/gitlab/regex.rb
+++ b/lib/gitlab/regex.rb
@@ -131,5 +131,14 @@ module Gitlab
     def kubernetes_namespace_regex_message
       "can contain only letters, digits or '-', and cannot start or end with '-'"
     end
+
+    def environment_slug_regex
+      @environment_slug_regex ||= /\A[a-z]([a-z0-9-]*[a-z0-9])?\z/.freeze
+    end
+
+    def environment_slug_regex_message
+      "can contain only lowercase letters, digits, and '-'. " \
+      "Must start with a letter, and cannot end with '-'"
+    end
   end
 end
diff --git a/spec/lib/gitlab/regex_spec.rb b/spec/lib/gitlab/regex_spec.rb
index c51b10bdc69b5870673b06cd998938dc6149ea6a..c78cd30157e5e8ed3264bf351a9965520c1d905d 100644
--- a/spec/lib/gitlab/regex_spec.rb
+++ b/spec/lib/gitlab/regex_spec.rb
@@ -29,4 +29,20 @@ describe Gitlab::Regex, lib: true do
   describe 'file path regex' do
     it { expect('foo@/bar').to match(Gitlab::Regex.file_path_regex) }
   end
+
+  describe 'environment slug regex' do
+    def be_matched
+      match(Gitlab::Regex.environment_slug_regex)
+    end
+
+    it { expect('foo').to be_matched }
+    it { expect('foo-1').to be_matched }
+
+    it { expect('FOO').not_to be_matched }
+    it { expect('foo/1').not_to be_matched }
+    it { expect('foo.1').not_to be_matched }
+    it { expect('foo*1').not_to be_matched }
+    it { expect('9foo').not_to be_matched }
+    it { expect('foo-').not_to be_matched }
+  end
 end
diff --git a/spec/models/environment_spec.rb b/spec/models/environment_spec.rb
index c8170164898640e2a49bc42729580745f1168bc8..706f1a5cd1c1c12843b73067a164f187fe967489 100644
--- a/spec/models/environment_spec.rb
+++ b/spec/models/environment_spec.rb
@@ -1,7 +1,7 @@
 require 'spec_helper'
 
 describe Environment, models: true do
-  let(:environment) { create(:environment) }
+  subject(:environment) { create(:environment) }
 
   it { is_expected.to belong_to(:project) }
   it { is_expected.to have_many(:deployments) }
@@ -15,15 +15,11 @@ describe Environment, models: true do
   it { is_expected.to validate_uniqueness_of(:name).scoped_to(:project_id) }
   it { is_expected.to validate_length_of(:name).is_at_most(255) }
 
-  it { is_expected.to validate_length_of(:external_url).is_at_most(255) }
-
-  # To circumvent a not null violation of the name column:
-  # https://github.com/thoughtbot/shoulda-matchers/issues/336
-  it 'validates uniqueness of :external_url' do
-    create(:environment)
+  it { is_expected.to validate_uniqueness_of(:slug).scoped_to(:project_id) }
+  it { is_expected.to validate_length_of(:slug).is_at_most(24) }
 
-    is_expected.to validate_uniqueness_of(:external_url).scoped_to(:project_id)
-  end
+  it { is_expected.to validate_length_of(:external_url).is_at_most(255) }
+  it { is_expected.to validate_uniqueness_of(:external_url).scoped_to(:project_id) }
 
   describe '#nullify_external_url' do
     it 'replaces a blank url with nil' do
@@ -199,4 +195,38 @@ describe Environment, models: true do
       expect(environment.actions_for('review/master')).to contain_exactly(review_action)
     end
   end
+
+  describe '#slug' do
+    it "is automatically generated" do
+      expect(environment.slug).not_to be_nil
+    end
+
+    it "is not regenerated if name changes" do
+      original_slug = environment.slug
+      environment.update_attributes!(name: environment.name.reverse)
+
+      expect(environment.slug).to eq(original_slug)
+    end
+  end
+
+  describe '#generate_slug' do
+    SUFFIX = "-[a-z0-9]{6}"
+    {
+      "staging-12345678901234567" => "staging-123456789" + SUFFIX,
+      "9-staging-123456789012345" => "env-9-staging-123" + SUFFIX,
+      "staging-1234567890123456"  => "staging-1234567890123456",
+      "production"                => "production",
+      "PRODUCTION"                => "production" + SUFFIX,
+      "review/1-foo"              => "review-1-foo" + SUFFIX,
+      "1-foo"                     => "env-1-foo" + SUFFIX,
+      "1/foo"                     => "env-1-foo" + SUFFIX,
+      "foo-"                      => "foo" + SUFFIX,
+    }.each do |name, matcher|
+      it "returns a slug matching #{matcher}, given #{name}" do
+        slug = described_class.new(name: name).generate_clean_name
+
+        expect(slug).to match(/\A#{matcher}\z/)
+      end
+    end
+  end
 end
diff --git a/spec/requests/api/environments_spec.rb b/spec/requests/api/environments_spec.rb
index 126496c43a5bbf5656859447372d6c274de20b54..b9d535bc314c7b33fb52399102d58078245135e7 100644
--- a/spec/requests/api/environments_spec.rb
+++ b/spec/requests/api/environments_spec.rb
@@ -46,6 +46,7 @@ describe API::Environments, api: true  do
 
         expect(response).to have_http_status(201)
         expect(json_response['name']).to eq('mepmep')
+        expect(json_response['slug']).to eq('mepmep')
         expect(json_response['external']).to be nil
       end
 
@@ -60,6 +61,13 @@ describe API::Environments, api: true  do
 
         expect(response).to have_http_status(400)
       end
+
+      it 'returns a 400 if slug is specified' do
+        post api("/projects/#{project.id}/environments", user), name: "foo", slug: "foo"
+
+        expect(response).to have_http_status(400)
+        expect(json_response["error"]).to eq("slug is automatically generated and cannot be changed")
+      end
     end
 
     context 'a non member' do
@@ -86,6 +94,15 @@ describe API::Environments, api: true  do
       expect(json_response['external_url']).to eq(url)
     end
 
+    it "won't allow slug to be changed" do
+      slug = environment.slug
+      api_url = api("/projects/#{project.id}/environments/#{environment.id}", user)
+      put api_url, slug: slug + "-foo"
+
+      expect(response).to have_http_status(400)
+      expect(json_response["error"]).to eq("slug is automatically generated and cannot be changed")
+    end
+
     it "won't update the external_url if only the name is passed" do
       url = environment.external_url
       put api("/projects/#{project.id}/environments/#{environment.id}", user),