- Add proper error handling,
- Use flash[:alert] and flash[:notice],
- Use `resource` instead of `resources`,

[ci skip]

[ci skip]

Mattermost configuration frontend

## What does this MR do?

Adds mattermost configuration frontend.

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

⚠ NOTE: ⚠ We can review @zj's MR (!8070) and this one asynchronously, we should wait for @zj's MR to complete it's backend review before we merge this branch into his. We would like @zj to do the merge.

## Why was this MR needed?

## Screenshots (if relevant)

## Does this MR meet the acceptance criteria?

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

## What are the relevant issue numbers?

Closes #24769

See merge request !8079

Accept environment variables from the `pre-receive` script

## Summary

1. Starting version 2.11, git changed the way the pre-receive flow works.
  - Previously, the new potential objects would be added to the main repo. If the pre-receive passes, the new objects stay in the repo but are linked up. If the pre-receive fails, the new objects stay orphaned in the repo, and are cleaned up during the next `git gc`.
  - In 2.11, the new potential objects are added to a temporary "alternate object directory", that git creates for this purpose. If the pre-receive passes, the objects from the alternate object directory are migrated to the main repo. If the pre-receive fails the alternate object directory is simply deleted.
2. In our workflow, the pre-recieve script (in `gitlab-shell`) calls the
   `/allowed` endpoint, which calls out directly to git to perform
   various checks. These direct calls to git do _not_ have the necessary
   environment variables set which allow access to the "alternate object
   directory" (explained above). Therefore these calls to git are not able to
   access any of the new potential objects to be added during this push.

3. We fix this by accepting the relevant environment variables
   (`GIT_ALTERNATE_OBJECT_DIRECTORIES`, `GIT_OBJECT_DIRECTORY`, and
   `GIT_QUARANTINE_PATH`) on the `/allowed` endpoint, and then include
   these environment variables while calling out to git.

4. This commit includes these environment variables while making the "force
   push" check.

## Issue Numbers

- Closes #25301 (assuming the corresponding `gitlab-shell` MR has been merged in first)
- Corresponding `gitlab-shell` MR: gitlab-org/gitlab-shell!112
- Corresponding EE MR: gitlab-org/gitlab-ee!964

## Tasks

-  [#25301/!7967/!112] Git version 2.11.0 - Can't push to protected branch as master or developer
    - [x]  Investigate
    - [x]  Implementation
        - [x]  `force_push.rb` should use the relevant environment variables
        - [x]  Any other instances of `/allowed` calling out to git directly? 
        - [x]  Verify that the fix works over SSH as well
        - [x]  Can we trim the number of env variables? Do we need all 3?
        - [x]  Whitelist variables. Server shouldn't pass through _any_ env variable passed in
        - [x]  Any security implications?
        - [x]  Check for force push return code
        - [x]  Shouldn't be able to opt-out from the force push check by passing an env variable
    - [x]  Tests
        - [x]  CE
            - [x]  Added
            - [x]  Passing
        - [x]  Shell
            - [x]  Added
            - [x]  Passing
    - [x]  Meta
        - [x]  CHANGELOG entry created
        - [x]  Branch has no merge conflicts with `master`
        - [x]  Squashed related commits together
        - [x]  EE merge request
    - [x]  Review
        - [x]  Endboss
    - [ ]  Follow-up
        - [x]  Make sure EE is working as expected
        - [x]  [CE] Gitlab changes without gitlab-shell changes shouldn't raise any exceptions
        - [x]  [CE] Gitlab-shell changes without gitlab changes shouldn't raise any exceptions
        - [x]  [EE] Gitlab changes without gitlab-shell changes shouldn't raise any exceptions
        - [x]  [EE] Gitlab-shell changes without gitlab changes shouldn't raise any exceptions
    - [ ]  Wait for merge
        - [ ]  CE
        - [ ]  EE
        - [x]  Shell


See merge request !7967

Allow to use Dockerfile templates

See merge request !7247

Move admin application spinach test to RSpec

Part of #23036

See merge request !8140

Move admin deploy keys spinach test to RSpec

Part of #23036

See merge request !8141

Always use `fixture_file_upload` helper to upload files in tests.

## What does this MR do?

Fix a broken spec.

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

## Why was this MR needed?

## Screenshots (if relevant)

## Does this MR meet the acceptance criteria?

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

## What are the relevant issue numbers?

See merge request !8164

* Also is not a good idea to use File.open without closing the file
  handler. We should use it with a block or close it explicitly.

Update NGINX configuration files to add websocket support

## What does this MR do?

Changes the bundled NGINX configuration files to support websockets introduced in https://gitlab.com/gitlab-org/gitlab-workhorse/merge_requests/83

These changes are also going into omnibus: https://gitlab.com/gitlab-org/omnibus-gitlab/merge_requests/1146

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

Best to wait until the omnibus MR is merged as the method may be changed.

## Why was this MR needed?

Without it, NGINX won't let websockets through to workhorse.

## Screenshots (if relevant)

## Does this MR meet the acceptance criteria?

- [x] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- Tests
  - [x] All builds are passing
- [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?

Related to #22864

See merge request !8039

Correct mattermost slash commands pretty path

## What does this MR do?

Corrects the pretty path used for mattermost slash commands.

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

## Why was this MR needed?

## Screenshots (if relevant)

![Screen_Shot_2016-12-14_at_13.31.18](/uploads/61b0cbe11bf747d566ed7959efa704b8/Screen_Shot_2016-12-14_at_13.31.18.png)

## Does this MR meet the acceptance criteria?

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

## What are the relevant issue numbers?

See merge request !8085

Add new runner script attempts docs and update .gitlab-ci.yml

Related: https://gitlab.com/gitlab-org/gitlab-ci-multi-runner/issues/1907 and https://gitlab.com/gitlab-com/infrastructure/issues/685

Adds missing docs about the new script attempts variables in the runner.

See merge request !8100

# Conflicts:
#   config/gitlab.yml.example
#   lib/mattermost/session.rb
#   spec/lib/mattermost/session_spec.rb

Enable Style/MultilineOperationIndentation in Rubocop

Fixes #25741

See merge request !8125

https://gitlab.com/gitlab-org/gitlab-ce/issues/23036

https://gitlab.com/gitlab-org/gitlab-ce/issues/23036

Mattermost session

This branch is based of tag v8.14.4 so I could test on an instance better.

But stuck on the tests, as setting up the whole doorkeeper stuff doesn't seem to be supported for testing.

See merge request !8033