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, 41 insertions, 25 deletions

diff --git a/doc/api/enviroments.md b/doc/api/enviroments.md
index 87a5fa67124..1299aca8c45 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/doc/ci/environments.md b/doc/ci/environments.md
index 705bca6cc1f..bad0233a9ce 100644
--- a/doc/ci/environments.md
+++ b/doc/ci/environments.md
@@ -86,6 +86,13 @@ will later see, is exposed in various places within GitLab. Each time a job that
 has an environment specified and succeeds, a deployment is recorded, remembering
 the Git SHA and environment name.
 
+>**Note:**
+Starting with GitLab 8.15, the environment name is exposed to the Runner in
+two forms: `$CI_ENVIRONMENT_NAME`, and `$CI_ENVIRONMENT_SLUG`. The first is
+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.
+
 To sum up, with the above `.gitlab-ci.yml` we have achieved that:
 
 - All branches will run the `test` and `build` jobs.
@@ -157,7 +164,7 @@ that can be found in the deployments page
 job with the commit associated with it.
 
 >**Note:**
-Bare in mind that your mileage will vary and it's entirely up to how you define
+Bear in mind that your mileage will vary and it's entirely up to how you define
 the deployment process in the job's `script` whether the rollback succeeds or not.
 GitLab CI is just following orders.
 
@@ -248,7 +255,7 @@ deploy_review:
     - echo "Deploy a review app"
   environment:
     name: review/$CI_BUILD_REF_NAME
-    url: https://$CI_BUILD_REF_SLUG.example.com
+    url: https://$CI_BUILD_REF_SLUG.review.example.com
   only:
     - branches
   except:
@@ -266,9 +273,18 @@ ones.
 So, the first part is `review`, followed by a `/` and then `$CI_BUILD_REF_NAME`
 which takes the value of the branch name. Since `$CI_BUILD_REF_NAME` itself may
 also contain `/`, or other characters that would be invalid in a domain name or
-URL, we use `$CI_BUILD_REF_SLUG` in the `environment:url` so that the environment
-can get a specific and distinct URL for each branch. Again, the way you set up
-the webserver to serve these requests is based on your setup.
+URL, we use `$CI_ENVIRONMENT_SLUG` in the `environment:url` so that the
+environment can get a specific and distinct URL for each branch. In this case,
+given a `$CI_BUILD_REF_NAME` of `100-Do-The-Thing`, the URL will be something
+like `https://review-100-do-the-4f99a2.example.com`. Again, the way you set up
+the web server to serve these requests is based on your setup.
+
+You could also use `$CI_BUILD_REF_SLUG` in `environment:url`, e.g.:
+`https://$CI_BUILD_REF_SLUG.review.example.com`. We use `$CI_ENVIRONMENT_SLUG`
+here because it is guaranteed to be unique, but if you're using a workflow like
+[GitLab Flow][gitlab-flow], collisions are very unlikely, and you may prefer
+environment names to be more closely based on the branch name - the example
+above would give you an URL like `https://100-do-the-thing.review.example.com`
 
 Last but not least, we tell the job to run [`only`][only] on branches
 [`except`][only] master.
@@ -300,7 +316,7 @@ deploy_review:
     - echo "Deploy a review app"
   environment:
     name: review/$CI_BUILD_REF_NAME
-    url: https://$CI_BUILD_REF_SLUG.example.com
+    url: https://$CI_ENVIRONMENT_SLUG.example.com
   only:
     - branches
   except:
@@ -419,7 +435,7 @@ deploy_review:
     - echo "Deploy a review app"
   environment:
     name: review/$CI_BUILD_REF_NAME
-    url: https://$CI_BUILD_REF_SLUG.example.com
+    url: https://$CI_ENVIRONMENT_SLUG.example.com
     on_stop: stop_review
   only:
     - branches
@@ -493,10 +509,6 @@ fetch = +refs/environments/*:refs/remotes/origin/environments/*
 
 ## Limitations
 
-1. `$CI_BUILD_REF_SLUG` is not *guaranteed* to be unique, so there is a small
-    chance of collisions between similarly-named branches (`fix-foo` would
-    conflict with `fix/foo`, for instance). Following a well-defined workflow
-    such as [GitLab Flow][gitlab-flow] can keep this from being a problem.
 1. You are limited to use only the [CI predefined variables][variables] in the
    `environment: name`. If you try to re-use variables defined inside `script`
    as part of the environment name, it will not work.
diff --git a/doc/ci/variables/README.md b/doc/ci/variables/README.md
index e0ff9756868..eb540a50606 100644
--- a/doc/ci/variables/README.md
+++ b/doc/ci/variables/README.md
@@ -52,6 +52,8 @@ version of Runner required.
 | **CI_PROJECT_PATH**     | 8.10   | 0.5    | The namespace with project name |
 | **CI_PROJECT_URL**      | 8.10   | 0.5    | The HTTP address to access project |
 | **CI_PROJECT_DIR**      | all    | all    | The full path where the repository is cloned and where the build is run |
+| **CI_ENVIRONMENT_NAME** | 8.15   | all    | The name of the environment for this build |
+| **CI_ENVIRONMENT_SLUG** | 8.15   | all    | A simplified version of the environment name, suitable for inclusion in DNS, URLs, Kubernetes labels, etc. |
 | **CI_REGISTRY**         | 8.10   | 0.5    | If the Container Registry is enabled it returns the address of GitLab's Container Registry |
 | **CI_REGISTRY_IMAGE**   | 8.10   | 0.5    | If the Container Registry is enabled for the project it returns the address of the registry tied to the specific project |
 | **CI_RUNNER_ID**        | 8.10   | 0.5    | The unique id of runner being used |
diff --git a/doc/ci/yaml/README.md b/doc/ci/yaml/README.md
index 5e8d888e555..a62193700fc 100644
--- a/doc/ci/yaml/README.md
+++ b/doc/ci/yaml/README.md
@@ -690,7 +690,7 @@ The `stop_review_app` job is **required** to have the following keywords defined
 #### dynamic environments
 
 > [Introduced][ce-6323] in GitLab 8.12 and GitLab Runner 1.6.
-  `$CI_BUILD_REF_SLUG` was [introduced][ce-8072] in GitLab 8.15.
+  `$CI_ENVIRONMENT_SLUG` was [introduced][ce-7983] in GitLab 8.15
 
 `environment` can also represent a configuration hash with `name` and `url`.
 These parameters can use any of the defined [CI variables](#variables)
@@ -703,15 +703,17 @@ deploy as review app:
   stage: deploy
   script: make deploy
   environment:
-    name: review-apps/$CI_BUILD_REF_NAME
-    url: https://$CI_BUILD_REF_SLUG.review.example.com/
+    name: review/$CI_BUILD_REF_NAME
+    url: https://$CI_ENVIRONMENT_SLUG.example.com/
 ```
 
 The `deploy as review app` job will be marked as deployment to dynamically
-create the `review-apps/$CI_BUILD_REF_NAME` environment, which `$CI_BUILD_REF_NAME`
-is an [environment variable][variables] set by the Runner. If for example the
-`deploy as review app` job was run in a branch named `pow`, this environment
-should be accessible under `https://pow.review.example.com/`.
+create the `review/$CI_BUILD_REF_NAME` environment, where `$CI_BUILD_REF_NAME`
+is an [environment variable][variables] set by the Runner. The
+`$CI_ENVIRONMENT_SLUG` variable is based on the environment name, but suitable
+for inclusion in URLs. In this case, if the `deploy as review app` job was run
+in a branch named `pow`, this environment would be accessible with an URL like
+`https://review-pow-aaaaaa.example.com/`.
 
 This of course implies that the underlying server which hosts the application
 is properly configured.
@@ -720,10 +722,6 @@ The common use case is to create dynamic environments for branches and use them
 as Review Apps. You can see a simple example using Review Apps at
 https://gitlab.com/gitlab-examples/review-apps-nginx/.
 
-`$CI_BUILD_REF_SLUG` is another environment variable set by the runner, based on
-`$CI_BUILD_REF_NAME` but lower-cased, and with some characters replaced with
-`-`, making it suitable for use in URLs and domain names.
-
 ### artifacts
 
 >**Notes:**
@@ -1243,5 +1241,5 @@ CI with various languages.
 [ce-6323]: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/6323
 [environment]: ../environments.md
 [ce-6669]: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/6669
-[ce-8072]: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/xxxx
 [variables]: ../variables/README.md
+[ce-7983]: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/7983