Merge branch '22864-add-clean-environment-name' into 'master'

Add a slug to environments

## What does this MR do?

Adds a `slug` field to the `environments` table, populating existing rows and ensuring that new rows will get an entry.

Cleaning examples:

* `review/foo`  => `review-foo-5gghdf`
* `review-foo` => `review-foo`
* `1-foo` => `env-1-foo-e2hx12`
* `production` => `production`
* `Production` => `production-f8ddlz`

## Are there points in the code the reviewer needs to double check?

This migration requires downtime. I don't see a way to avoid it.

## Why was this MR needed?

External services often have more restrictive rules on naming than those enforced for `environments.name`. In particular, forward slashes and names longer than 24 characters causes problems on OpenShift. `slug` is designed to be an acceptable alternative to `name` in these situations. Since forward slashes are a documented part of environment names, to set environment types, we need an envionmnent slug, not just a slug for the branch name.

## Does this MR meet the acceptance criteria?

- [x] [Changelog entry](https://docs.gitlab.com/ce/development/changelog.html) added
- [x] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [X] API support added
- Tests
  - [X] Added for this feature/bug
  - [x] All builds are passing
- [X] Conform by the [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [X] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [X] Branch has no merge conflicts with `master` (if it does - rebase it please)
- [X] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?

Part of #22864

See merge request !7983

4 files changed, 27 insertions, 1 deletions

diff --git a/lib/api/entities.rb b/lib/api/entities.rb
index 01c0f5072ba..dfbb3ab86dd 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 80bbd9bb6e4..1a7e68f0528 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 00000000000..0a8f3073a50
--- /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 7c711d581e8..9e0b0e5ea98 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