Pass external_url from environment if job doesn't have one

Also update the document and add a changelog entry

app/models/ci/build.rb

@@ -501,9 +501,15 @@ module Ci
     def persisted_environment_variables
       variables = persisted_environment.predefined_variables
 
+      if environment_url
         variables << { key: 'CI_ENVIRONMENT_URL',
                        value: expanded_environment_url,
-                     public: true } if environment_url
+                       public: true }
+      elsif persisted_environment.external_url.present?
+        variables << { key: 'CI_ENVIRONMENT_URL',
+                       value: persisted_environment.external_url,
+                       public: true }
+      end
 
       variables
     end

changelogs/unreleased/25680-CI_ENVIRONMENT_URL.yml

+---
+title: Add $CI_ENVIRONMENT_URL to predefined variables for pipelines
+merge_request: 11695
+author:

doc/ci/environments.md

@@ -94,6 +94,12 @@ the name given in `.gitlab-ci.yml` (with any variables expanded), while the
 second is a "cleaned-up" version of the name, suitable for use in URLs, DNS,
 etc.
 
+>**Note:**
+Starting with GitLab 9.3, the environment URL is exposed to the Runner via
+`$CI_ENVIRONMENT_URL`. The URL would be expanded from `.gitlab-ci.yml`, or if
+the URL was not defined there, the external URL from the environment would be
+used.
+
 To sum up, with the above `.gitlab-ci.yml` we have achieved that:
 
 - All branches will run the `test` and `build` jobs.

doc/ci/variables/README.md

@@ -43,6 +43,7 @@ future GitLab releases.**
 | **CI_DEBUG_TRACE**              | all    | 1.7    | Whether [debug tracing](#debug-tracing) is enabled |
 | **CI_ENVIRONMENT_NAME**         | 8.15   | all    | The name of the environment for this job |
 | **CI_ENVIRONMENT_SLUG**         | 8.15   | all    | A simplified version of the environment name, suitable for inclusion in DNS, URLs, Kubernetes labels, etc. |
+| **CI_ENVIRONMENT_URL**          | 9.3    | all    | The URL of the environment for this job |
 | **CI_JOB_ID**                   | 9.0    | all    | The unique id of the current job that GitLab CI uses internally |
 | **CI_JOB_MANUAL**               | 8.12   | all    | The flag to indicate that job was manually started |
 | **CI_JOB_NAME**                 | 9.0    | 0.5    | The name of the job as defined in `.gitlab-ci.yml` |

spec/models/ci/build_spec.rb

@@ -20,7 +20,7 @@ describe Ci::Build, :models do
   it { is_expected.to validate_presence_of(:ref) }
   it { is_expected.to respond_to(:has_trace?) }
   it { is_expected.to respond_to(:trace) }
-  it { is_expected.to validate_length_of(:external_url).is_at_most(255) }
+  it { is_expected.to validate_length_of(:environment_url).is_at_most(255) }
 
   describe '#actionize' do
     context 'when build is a created' do
@@ -1208,33 +1208,55 @@ describe Ci::Build, :models do
         ]
       end
 
+      let!(:environment) do
+        create(:environment,
+          project: build.project,
+          name: 'production',
+          slug: 'prod-slug',
+          external_url: '')
+      end
+
       before do
         build.update(environment: 'production')
-        create(:environment, project: build.project, name: 'production', slug: 'prod-slug')
       end
 
-      context 'when no URL was set' do
+      shared_examples 'containing environment variables' do
         it { environment_variables.each { |v| is_expected.to include(v) } }
+      end
+
+      context 'when no URL was set' do
+        it_behaves_like 'containing environment variables'
 
         it 'does not have CI_ENVIRONMENT_URL' do
           keys = subject.map { |var| var[:key] }
 
-          expect(keys).to include('CI_ENVIRONMENT_NAME', 'CI_ENVIRONMENT_SLUG')
           expect(keys).not_to include('CI_ENVIRONMENT_URL')
         end
       end
 
       context 'when an URL was set' do
+        let(:url) { 'http://host/test' }
+
+        before do
+          environment_variables <<
+            { key: 'CI_ENVIRONMENT_URL', value: url, public: true }
+        end
+
+        context 'when the URL was set from the job' do
           before do
             build.update(environment_url: 'http://host/$CI_JOB_NAME')
+          end
 
-          environment_variables <<
-            { key: 'CI_ENVIRONMENT_URL',
-              value: 'http://host/test',
-              public: true }
+          it_behaves_like 'containing environment variables'
         end
 
-        it { environment_variables.each { |v| is_expected.to include(v) } }
+        context 'when the URL was not set from the job, but environment' do
+          before do
+            environment.update(external_url: url)
+          end
+
+          it_behaves_like 'containing environment variables'
+        end
       end
     end