diff --git a/.gitpod.yml b/.gitpod.yml
index 2c6aa2a962d..6a771e77769 100644
--- a/.gitpod.yml
+++ b/.gitpod.yml
@@ -49,6 +49,9 @@ tasks:
         if [ "$GITLAB_RUN_DB_MIGRATIONS" == true ]; then
           make gitlab-db-migrate
         fi
+        cd ../gitlab
+        git checkout db/structure.sql
+        cd ../gitlab-development-kit
         # Waiting for GitLab ...
         gp await-port 3000
         printf "Waiting for GitLab at $(gp url 3000) ..."
diff --git a/Gemfile b/Gemfile
index e4ddff2a803..deedaff52be 100644
--- a/Gemfile
+++ b/Gemfile
@@ -173,7 +173,7 @@ gem 'diffy', '~> 3.3'
 gem 'diff_match_patch', '~> 0.1.0'
 
 # Application server
-gem 'rack', '~> 2.1.4'
+gem 'rack', '~> 2.2.3'
 # https://github.com/sharpstone/rack-timeout/blob/master/README.md#rails-apps-manually
 gem 'rack-timeout', '~> 0.5.1', require: 'rack/timeout/base'
 
diff --git a/Gemfile.lock b/Gemfile.lock
index 271c1950ca1..579fd2c8e88 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -867,7 +867,7 @@ GEM
     public_suffix (4.0.6)
     pyu-ruby-sasl (0.0.3.3)
     raabro (1.1.6)
-    rack (2.1.4)
+    rack (2.2.3)
     rack-accept (0.4.5)
       rack (>= 0.4)
     rack-attack (6.3.0)
@@ -1446,7 +1446,7 @@ DEPENDENCIES
   prometheus-client-mmap (~> 0.12.0)
   pry-byebug (~> 3.9.0)
   pry-rails (~> 0.3.9)
-  rack (~> 2.1.4)
+  rack (~> 2.2.3)
   rack-attack (~> 6.3.0)
   rack-cors (~> 1.0.6)
   rack-oauth2 (~> 1.9.3)
diff --git a/app/assets/javascripts/boards/components/modal/empty_state.vue b/app/assets/javascripts/boards/components/modal/empty_state.vue
index cd4512f320f..eb2db260717 100644
--- a/app/assets/javascripts/boards/components/modal/empty_state.vue
+++ b/app/assets/javascripts/boards/components/modal/empty_state.vue
@@ -1,13 +1,13 @@
 <script>
-/* eslint-disable vue/no-v-html */
-import { GlButton } from '@gitlab/ui';
-import { __, sprintf } from '~/locale';
+import { GlButton, GlSprintf } from '@gitlab/ui';
+import { __ } from '~/locale';
 import ModalStore from '../../stores/modal_store';
 import modalMixin from '../../mixins/modal_mixins';
 
 export default {
   components: {
     GlButton,
+    GlSprintf,
   },
   mixins: [modalMixin],
   props: {
@@ -34,11 +34,8 @@ export default {
 
       if (this.activeTab === 'selected') {
         obj.title = __("You haven't selected any issues yet");
-        obj.content = sprintf(
-          __(
-            'Go back to %{startTag}Open issues%{endTag} and select some issues to add to your board.',
-          ),
-          { startTag: '<strong>', endTag: '</strong>' },
+        obj.content = __(
+          'Go back to %{tagStart}Open issues%{tagEnd} and select some issues to add to your board.',
         );
       }
 
@@ -57,7 +54,13 @@ export default {
       <div class="col-12 col-md-6 order-md-first">
         <div class="text-content">
           <h4>{{ contents.title }}</h4>
-          <p v-html="contents.content"></p>
+          <p>
+            <gl-sprintf :message="contents.content">
+              <template #tag="{ content }">
+                <strong>{{ content }}</strong>
+              </template>
+            </gl-sprintf>
+          </p>
           <gl-button
             v-if="activeTab === 'all'"
             :href="newIssuePath"
diff --git a/app/assets/javascripts/vue_shared/components/gl_mentions.vue b/app/assets/javascripts/vue_shared/components/gl_mentions.vue
index 6d07eaa9c2f..dde7e3ebe13 100644
--- a/app/assets/javascripts/vue_shared/components/gl_mentions.vue
+++ b/app/assets/javascripts/vue_shared/components/gl_mentions.vue
@@ -11,6 +11,7 @@ const AutoComplete = {
   Members: 'members',
   MergeRequests: 'mergeRequests',
   Milestones: 'milestones',
+  Snippets: 'snippets',
 };
 
 const groupType = 'Group'; // eslint-disable-line @gitlab/require-i18n-strings
@@ -129,6 +130,14 @@ const autoCompleteMap = {
       return escape(original.title);
     },
   },
+  [AutoComplete.Snippets]: {
+    filterValues() {
+      return this[AutoComplete.Snippets];
+    },
+    menuItemTemplate({ original }) {
+      return `<small>${original.id}</small> ${escape(original.title)}`;
+    },
+  },
 };
 
 export default {
@@ -184,6 +193,13 @@ export default {
           selectTemplate: ({ original }) => `%"${escape(original.title)}"`,
           values: this.getValues(AutoComplete.Milestones),
         },
+        {
+          trigger: '$',
+          fillAttr: 'id',
+          lookup: value => value.id + value.title,
+          menuItemTemplate: autoCompleteMap[AutoComplete.Snippets].menuItemTemplate,
+          values: this.getValues(AutoComplete.Snippets),
+        },
       ],
     });
 
diff --git a/app/assets/javascripts/vue_shared/components/markdown/field.vue b/app/assets/javascripts/vue_shared/components/markdown/field.vue
index 6a36ca162dd..1808e4d6ad4 100644
--- a/app/assets/javascripts/vue_shared/components/markdown/field.vue
+++ b/app/assets/javascripts/vue_shared/components/markdown/field.vue
@@ -177,7 +177,7 @@ export default {
         epics: this.enableAutocomplete,
         milestones: this.enableAutocomplete && !this.glFeatures.tributeAutocomplete,
         labels: this.enableAutocomplete && !this.glFeatures.tributeAutocomplete,
-        snippets: this.enableAutocomplete,
+        snippets: this.enableAutocomplete && !this.glFeatures.tributeAutocomplete,
       },
       true,
     );
diff --git a/changelogs/unreleased/Fix-bad-escape-in-empty_state-vue.yml b/changelogs/unreleased/Fix-bad-escape-in-empty_state-vue.yml
new file mode 100644
index 00000000000..68b65df96d9
--- /dev/null
+++ b/changelogs/unreleased/Fix-bad-escape-in-empty_state-vue.yml
@@ -0,0 +1,5 @@
+---
+title: Fix Bad Escape in Issue Board Empty State
+merge_request: 45465
+author: Kev @KevSlashNull
+type: fixed
diff --git a/changelogs/unreleased/sh-update-rack-2-2-3.yml b/changelogs/unreleased/sh-update-rack-2-2-3.yml
new file mode 100644
index 00000000000..e4d44b1c72f
--- /dev/null
+++ b/changelogs/unreleased/sh-update-rack-2-2-3.yml
@@ -0,0 +1,5 @@
+---
+title: Update Rack to v2.2.3
+merge_request: 45183
+author:
+type: changed
diff --git a/doc/ci/variables/predefined_variables.md b/doc/ci/variables/predefined_variables.md
index 08aaacd2620..7ee602c6799 100644
--- a/doc/ci/variables/predefined_variables.md
+++ b/doc/ci/variables/predefined_variables.md
@@ -75,8 +75,8 @@ Kubernetes-specific environment variables are detailed in the
 | `CI_JOB_URL`                                  | 11.1   | 0.5    | Job details URL                                                                                                                                                                                                                                                                                                                                            |
 | `CI_KUBERNETES_ACTIVE`                        | 13.0   | all    | Included with the value `true` only if the pipeline has a Kubernetes cluster available for deployments. Not included if no cluster is available. Can be used as an alternative to [`only:kubernetes`/`except:kubernetes`](../yaml/README.md#onlykubernetesexceptkubernetes) with [`rules:if`](../yaml/README.md#rulesif)                                    |
 | `CI_MERGE_REQUEST_ASSIGNEES`                  | 11.9   | all    | Comma-separated list of username(s) of assignee(s) for the merge request if [the pipelines are for merge requests](../merge_request_pipelines/index.md). Available only if `only: [merge_requests]` or [`rules`](../yaml/README.md#rules) syntax is used and the merge request is created.                                                                                                              |
-| `CI_MERGE_REQUEST_ID`                         | 11.6   | all    | The instance-level ID of the merge request. Only available if [the pipelines are for merge requests](../merge_request_pipelines/index.md) and the merge request is created.                                                                                                                                                           |
-| `CI_MERGE_REQUEST_IID`                        | 11.6   | all    | The project-level IID (internal ID) of the merge request. Only available If [the pipelines are for merge requests](../merge_request_pipelines/index.md) and the merge request is created.                                                                                                                                                          |
+| `CI_MERGE_REQUEST_ID`                         | 11.6   | all    | The instance-level ID of the merge request. Only available if [the pipelines are for merge requests](../merge_request_pipelines/index.md) and the merge request is created. This is a unique ID across all projects on GitLab.                                                                                                                                                         |
+| `CI_MERGE_REQUEST_IID`                        | 11.6   | all    | The project-level IID (internal ID) of the merge request. Only available If [the pipelines are for merge requests](../merge_request_pipelines/index.md) and the merge request is created. This ID is unique for the current project.                                                                                                                                                         |
 | `CI_MERGE_REQUEST_LABELS`                     | 11.9   | all    | Comma-separated label names of the merge request if [the pipelines are for merge requests](../merge_request_pipelines/index.md). Available only if `only: [merge_requests]` or [`rules`](../yaml/README.md#rules) syntax is used and the merge request is created.                                                                                                                                      |
 | `CI_MERGE_REQUEST_MILESTONE`                  | 11.9   | all    | The milestone title of the merge request if [the pipelines are for merge requests](../merge_request_pipelines/index.md). Available only if `only: [merge_requests]` or [`rules`](../yaml/README.md#rules) syntax is used and the merge request is created.                                                                                                                                              |
 | `CI_MERGE_REQUEST_PROJECT_ID`                 | 11.6   | all    | The ID of the project of the merge request if [the pipelines are for merge requests](../merge_request_pipelines/index.md). Available only if `only: [merge_requests]` or [`rules`](../yaml/README.md#rules) syntax is used and the merge request is created.                                                                                                                                            |
@@ -96,8 +96,8 @@ Kubernetes-specific environment variables are detailed in the
 | `CI_NODE_TOTAL`                               | 11.5   | all    | Total number of instances of this job running in parallel. If the job is not parallelized, this variable is set to `1`.                                                                                                                                                                                                                                    |
 | `CI_PAGES_DOMAIN`                             | 11.8   | all    | The configured domain that hosts GitLab Pages.                                                                                                                                                                                                                                                                                                             |
 | `CI_PAGES_URL`                                | 11.8   | all    | URL to GitLab Pages-built pages. Always belongs to a subdomain of `CI_PAGES_DOMAIN`.                                                                                                                                                                                                                                                                       |
-| `CI_PIPELINE_ID`                              | 8.10   | all    | The instance-level ID of the current pipeline.                                                                                                                                                                                                                                                                                                             |
-| `CI_PIPELINE_IID`                             | 11.0   | all    | The project-level IID (internal ID) of the current pipeline.                                                                                                                                                                                                                                                                                               |
+| `CI_PIPELINE_ID`                              | 8.10   | all    | The instance-level ID of the current pipeline. This is a unique ID across all projects on GitLab.                                                                                                                                                                                                                                                                                                            |
+| `CI_PIPELINE_IID`                             | 11.0   | all    | The project-level IID (internal ID) of the current pipeline. This ID is unique for the current project.                                                                                                                                                                                                                                                                                              |
 | `CI_PIPELINE_SOURCE`                          | 10.0   | all    | Indicates how the pipeline was triggered. Possible options are: `push`, `web`, `schedule`, `api`, `external`, `chat`, `webide`, `merge_request_event`, `external_pull_request_event`, `parent_pipeline`, [`trigger`, or `pipeline`](../triggers/README.md#authentication-tokens) (renamed to `cross_project_pipeline` since 13.0). For pipelines created before GitLab 9.5, this is displayed as `unknown`. |
 | `CI_PIPELINE_TRIGGERED`                       | all    | all    | The flag to indicate that job was [triggered](../triggers/README.md)                                                                                                                                                                                                                                                                                       |
 | `CI_PIPELINE_URL`                             | 11.1   | 0.5    | Pipeline details URL                                                                                                                                                                                                                                                                                                                                       |
diff --git a/doc/development/documentation/index.md b/doc/development/documentation/index.md
index 864dfdf3484..15fd21ac32e 100644
--- a/doc/development/documentation/index.md
+++ b/doc/development/documentation/index.md
@@ -472,287 +472,7 @@ The following GitLab features are used among others:
 
 ## Testing
 
-We treat documentation as code, and so use tests in our CI pipeline to maintain the
-standards and quality of the docs. The current tests, which run in CI jobs when a
-merge request with new or changed docs is submitted, are:
-
-- [`docs lint`](https://gitlab.com/gitlab-org/gitlab/-/blob/0b562014f7b71f98540e682c8d662275f0011f2f/.gitlab/ci/docs.gitlab-ci.yml#L41):
-  Runs several tests on the content of the docs themselves:
-  - [`lint-doc.sh` script](https://gitlab.com/gitlab-org/gitlab/blob/master/scripts/lint-doc.sh)
-    runs the following checks and linters:
-    - All cURL examples use the long flags (ex: `--header`, not `-H`).
-    - The `CHANGELOG.md` does not contain duplicate versions.
-    - No files in `doc/` are executable.
-    - No new `README.md` was added.
-    - [markdownlint](#markdownlint).
-    - [Vale](#vale).
-  - Nanoc tests:
-    - [`internal_links`](https://gitlab.com/gitlab-org/gitlab/-/blob/0b562014f7b71f98540e682c8d662275f0011f2f/.gitlab/ci/docs.gitlab-ci.yml#L58)
-      checks that all internal links (ex: `[link](../index.md)`) are valid.
-    - [`internal_anchors`](https://gitlab.com/gitlab-org/gitlab/-/blob/0b562014f7b71f98540e682c8d662275f0011f2f/.gitlab/ci/docs.gitlab-ci.yml#L60)
-      checks that all internal anchors (ex: `[link](../index.md#internal_anchor)`)
-      are valid.
-  - [`ui-docs-links lint`](https://gitlab.com/gitlab-org/gitlab/-/blob/0b562014f7b71f98540e682c8d662275f0011f2f/.gitlab/ci/docs.gitlab-ci.yml#L62)
-    checks that all links to docs from UI elements (`app/views` files, for example)
-    are linking to valid docs and anchors.
-
-### Run tests locally
-
-Apart from [previewing your changes locally](#previewing-the-changes-live), you can also run all lint checks
-and Nanoc tests locally.
-
-#### Lint checks
-
-Lint checks are performed by the [`lint-doc.sh`](https://gitlab.com/gitlab-org/gitlab/blob/master/scripts/lint-doc.sh)
-script and can be executed as follows:
-
-1. Navigate to the `gitlab` directory.
-1. Run:
-
-   ```shell
-   MD_DOC_PATH=path/to/my_doc.md scripts/lint-doc.sh
-   ```
-
-Where `MD_DOC_PATH` points to the file or directory you would like to run lint checks for.
-If you omit it completely, it will default to the `doc/` directory.
-The output should be similar to:
-
-```plaintext
-=> Linting documents at path /path/to/gitlab as <user>...
-=> Checking for cURL short options...
-=> Checking for CHANGELOG.md duplicate entries...
-=> Checking /path/to/gitlab/doc for executable permissions...
-=> Checking for new README.md files...
-=> Linting markdown style...
-=> Linting prose...
-✔ 0 errors, 0 warnings and 0 suggestions in 1 file.
-✔ Linting passed
-```
-
-Note that this requires you to either have the required lint tools installed on your machine,
-or a working Docker installation, in which case an image with these tools pre-installed will be used.
-
-#### Nanoc tests
-
-To execute Nanoc tests locally:
-
-1. Navigate to the [`gitlab-docs`](https://gitlab.com/gitlab-org/gitlab-docs) directory.
-1. Run:
-
-   ```shell
-   # Check for broken internal links
-   bundle exec nanoc check internal_links
-
-   # Check for broken external links (might take a lot of time to complete).
-   # This test is set to be allowed to fail and is run only in the gitlab-docs project CI
-   bundle exec nanoc check internal_anchors
-   ```
-
-#### `ui-docs-links` test
-
-The `ui-docs-links lint` job uses `haml-lint` to test that all links to docs from
-UI elements (`app/views` files, for example) are linking to valid docs and anchors.
-
-To run the `ui-docs-links` test locally:
-
-1. Open the `gitlab` directory in a terminal window.
-1. Run:
-
-   ```shell
-   bundle exec haml-lint -i DocumentationLinks
-   ```
-
-If you receive an error the first time you run this test, run `bundle install`, which
-installs GitLab's dependencies, and try again.
-
-If you don't want to install all of GitLab's dependencies to test the links, you can:
-
-1. Open the `gitlab` directory in a terminal window.
-1. Install `haml-lint`:
-
-   ```shell
-   gem install haml_lint
-   ```
-
-1. Run:
-
-   ```shell
-   haml-lint -i DocumentationLinks
-   ```
-
-If you manually install `haml-lint` with this process, it will not update automatically
-and you should make sure your version matches the version used by GitLab.
-
-### Local linters
-
-To help adhere to the [documentation style guidelines](styleguide.md), and improve the content
-added to documentation, [install documentation linters](#install-linters) and
-[integrate them with your code editor](#configure-editors).
-
-At GitLab, we mostly use:
-
-- [markdownlint](#markdownlint)
-- [Vale](#vale)
-
-#### markdownlint
-
-[markdownlint](https://github.com/DavidAnson/markdownlint) checks that Markdown syntax follows
-[certain rules](https://github.com/DavidAnson/markdownlint/blob/master/doc/Rules.md#rules), and is
-used by the [`docs-lint` test](#testing).
-
-Our [Documentation Style Guide](styleguide.md#markdown) and
-[Markdown Guide](https://about.gitlab.com/handbook/markdown-guide/) elaborate on which choices must
-be made when selecting Markdown syntax for GitLab documentation. This tool helps catch deviations
-from those guidelines.
-
-markdownlint configuration is found in the following projects:
-
-- [`gitlab`](https://gitlab.com/gitlab-org/gitlab/blob/master/.markdownlint.json)
-- [`gitlab-runner`](https://gitlab.com/gitlab-org/gitlab-runner/blob/master/.markdownlint.json)
-- [`omnibus-gitlab`](https://gitlab.com/gitlab-org/omnibus-gitlab/blob/master/.markdownlint.json)
-- [`charts`](https://gitlab.com/gitlab-org/charts/gitlab/-/blob/master/.markdownlint.json)
-- [`gitlab-development-kit`](https://gitlab.com/gitlab-org/gitlab-development-kit/-/blob/master/.markdownlint.json)
-
-This configuration is also used within build pipelines.
-
-You can use markdownlint:
-
-- [On the command line](https://github.com/igorshubovych/markdownlint-cli#markdownlint-cli--).
-- [Within a code editor](#configure-editors).
-- [In a `pre-commit` hook](#configure-pre-commit-hooks).
-
-#### Vale
-
-[Vale](https://errata-ai.gitbook.io/vale/) is a grammar, style, and word usage linter for the
-English language. Vale's configuration is stored in the
-[`.vale.ini`](https://gitlab.com/gitlab-org/gitlab/blob/master/.vale.ini) file located in the root
-directory of projects.
-
-Vale supports creating [custom tests](https://errata-ai.github.io/vale/styles/) that extend any of
-several types of checks, which we store in the `.linting/vale/styles/gitlab` directory within the
-documentation directory of projects.
-
-Vale configuration is found in the following projects:
-
-- [`gitlab`](https://gitlab.com/gitlab-org/gitlab/-/tree/master/doc/.vale/gitlab)
-- [`gitlab-runner`](https://gitlab.com/gitlab-org/gitlab-runner/-/tree/master/docs/.vale/gitlab)
-- [`omnibus-gitlab`](https://gitlab.com/gitlab-org/omnibus-gitlab/-/tree/master/doc/.vale/gitlab)
-- [`charts`](https://gitlab.com/gitlab-org/charts/gitlab/-/tree/master/doc/.vale/gitlab)
-- [`gitlab-development-kit`](https://gitlab.com/gitlab-org/gitlab-development-kit/-/tree/master/doc/.vale/gitlab)
-
-This configuration is also used within build pipelines.
-
-You can use Vale:
-
-- [On the command line](https://errata-ai.gitbook.io/vale/getting-started/usage).
-- [Within a code editor](#configure-editors).
-- [In a `pre-commit` hook](#configure-pre-commit-hooks). Vale only reports errors in the
-  `pre-commit` hook (the same configuration as the CI/CD pipelines), and does not report suggestions
-  or warnings.
-
-#### Install linters
-
-At a minimum, install [markdownlint](#markdownlint) and [Vale](#vale) to match the checks run in
-build pipelines:
-
-1. Install `markdownlint-cli`, using either:
-
-   - `npm`:
-
-     ```shell
-     npm install -g markdownlint-cli
-     ```
-
-   - `yarn`:
-
-     ```shell
-     yarn global add markdownlint-cli
-     ```
-
-     We recommend installing the version of `markdownlint-cli` currently used in the documentation
-     linting [Docker image](https://gitlab.com/gitlab-org/gitlab-docs/-/blob/master/.gitlab-ci.yml#L420).
-
-1. Install [`vale`](https://github.com/errata-ai/vale/releases). For example, to install using
-   `brew` for macOS, run:
-
-   ```shell
-   brew install vale
-   ```
-
-   We recommend installing the version of Vale currently used in the documentation linting
-   [Docker image](https://gitlab.com/gitlab-org/gitlab-docs/-/blob/master/.gitlab-ci.yml#L419).
-
-In addition to using markdownlint and Vale at the command line, these tools can be
-[integrated with your code editor](#configure-editors).
-
-#### Configure editors
-
-To configure markdownlint within your editor, install one of the following as appropriate:
-
-- [Sublime Text](https://packagecontrol.io/packages/SublimeLinter-contrib-markdownlint)
-- [Visual Studio Code](https://marketplace.visualstudio.com/items?itemName=DavidAnson.vscode-markdownlint)
-- [Atom](https://atom.io/packages/linter-node-markdownlint)
-- [Vim](https://github.com/dense-analysis/ale)
-
-To configure Vale within your editor, install one of the following as appropriate:
-
-- The Sublime Text [`SublimeLinter-contrib-vale` plugin](https://packagecontrol.io/packages/SublimeLinter-contrib-vale).
-- The Visual Studio Code [`errata-ai.vale-server` extension](https://marketplace.visualstudio.com/items?itemName=errata-ai.vale-server).
-  You don't need Vale Server to use the plugin. You can configure the plugin to
-  [display only a subset of alerts](#show-subset-of-vale-alerts).
-- [Vim](https://github.com/dense-analysis/ale).
-
-We don't use [Vale Server](https://errata-ai.github.io/vale/#using-vale-with-a-text-editor-or-another-third-party-application).
-
-#### Configure pre-commit hooks
-
-Git [pre-commit hooks](https://git-scm.com/book/en/v2/Customizing-Git-Git-Hooks) allow Git users to
-run tests or other processes before committing to a branch, with the ability to not commit to the branch if
-failures occur with these tests.
-
-[`lefthook`](https://github.com/Arkweid/lefthook) is a Git hooks manager, making configuring,
-installing, and removing Git hooks easy.
-
-Configuration for `left` is available in the [`lefthook.yml`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/lefthook.yml)
-file for the [`gitlab`](https://gitlab.com/gitlab-org/gitlab) project.
-
-To set up `lefthook` for documentation linting, see
-[Pre-push static analysis](../contributing/style_guides.md#pre-push-static-analysis).
-
-#### Show subset of Vale alerts
-
-You can set Visual Studio Code to display only a subset of Vale alerts when viewing files:
-
-1. Go to **Preferences > Settings > Extensions > Vale**.
-1. In **Vale CLI: Min Alert Level**, select the minimum alert level you want displayed in files.
-
-To display only a subset of Vale alerts when running Vale from the command line, use
-the `--minAlertLevel` flag, which accepts `error`, `warning`, or `suggestion`. Combine it with `--config`
-to point to the configuration file within the project, if needed:
-
-```shell
-vale --config .vale.ini --minAlertLevel error doc/**/*.md
-```
-
-Omit the flag to display all alerts, including `suggestion` level alerts.
-
-#### Disable Vale tests
-
-You can disable a specific Vale linting rule or all Vale linting rules for any portion of a
-document:
-
-- To disable a specific rule, add a `<!-- vale gitlab.rulename = NO -->` tag before the text, and a
-  `<!-- vale gitlab.rulename = YES -->` tag after the text, replacing `rulename` with the filename
-  of a test in the
-  [GitLab styles](https://gitlab.com/gitlab-org/gitlab/-/tree/master/doc/.linting/vale/styles/gitlab)
-  directory.
-- To disable all Vale linting rules, add a `<!-- vale off -->` tag before the text, and a
-  `<!-- vale on -->` tag after the text.
-
-Whenever possible, exclude only the problematic rule and line(s).
-
-For more information, see
-[Vale's documentation](https://errata-ai.gitbook.io/vale/getting-started/markup#markup-based-configuration).
+For more information on documentation testing, see [Documentation testing](testing.md)
 
 ## Danger Bot
 
diff --git a/doc/development/documentation/styleguide.md b/doc/development/documentation/styleguide.md
index e6cea6bad1c..38d7b2bcfb7 100644
--- a/doc/development/documentation/styleguide.md
+++ b/doc/development/documentation/styleguide.md
@@ -181,8 +181,8 @@ have `/help`. HTML is permitted if:
 ### Markdown Rules
 
 GitLab ensures that the Markdown used across all documentation is consistent, as
-well as easy to review and maintain, by [testing documentation changes](index.md#testing)
-with [markdownlint](index.md#markdownlint). This lint test fails when any
+well as easy to review and maintain, by [testing documentation changes](testing.md)
+with [markdownlint](testing.md#markdownlint). This lint test fails when any
 document has an issue with Markdown formatting that may cause the page to render
 incorrectly within GitLab. It will also fail when a document is using
 non-standard Markdown (which may render correctly, but is not the current
diff --git a/doc/development/documentation/testing.md b/doc/development/documentation/testing.md
new file mode 100644
index 00000000000..8894d7f9ca8
--- /dev/null
+++ b/doc/development/documentation/testing.md
@@ -0,0 +1,292 @@
+---
+stage: none
+group: Documentation Guidelines
+info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#designated-technical-writers
+description: Learn how to contribute to GitLab Documentation.
+---
+
+# Documentation testing
+
+We treat documentation as code, and so use tests in our CI pipeline to maintain the
+standards and quality of the docs. The current tests, which run in CI jobs when a
+merge request with new or changed docs is submitted, are:
+
+- [`docs lint`](https://gitlab.com/gitlab-org/gitlab/-/blob/0b562014f7b71f98540e682c8d662275f0011f2f/.gitlab/ci/docs.gitlab-ci.yml#L41):
+  Runs several tests on the content of the docs themselves:
+  - [`lint-doc.sh` script](https://gitlab.com/gitlab-org/gitlab/blob/master/scripts/lint-doc.sh)
+    runs the following checks and linters:
+    - All cURL examples use the long flags (ex: `--header`, not `-H`).
+    - The `CHANGELOG.md` does not contain duplicate versions.
+    - No files in `doc/` are executable.
+    - No new `README.md` was added.
+    - [markdownlint](#markdownlint).
+    - [Vale](#vale).
+  - Nanoc tests:
+    - [`internal_links`](https://gitlab.com/gitlab-org/gitlab/-/blob/0b562014f7b71f98540e682c8d662275f0011f2f/.gitlab/ci/docs.gitlab-ci.yml#L58)
+      checks that all internal links (ex: `[link](../index.md)`) are valid.
+    - [`internal_anchors`](https://gitlab.com/gitlab-org/gitlab/-/blob/0b562014f7b71f98540e682c8d662275f0011f2f/.gitlab/ci/docs.gitlab-ci.yml#L60)
+      checks that all internal anchors (ex: `[link](../index.md#internal_anchor)`)
+      are valid.
+  - [`ui-docs-links lint`](https://gitlab.com/gitlab-org/gitlab/-/blob/0b562014f7b71f98540e682c8d662275f0011f2f/.gitlab/ci/docs.gitlab-ci.yml#L62)
+    checks that all links to docs from UI elements (`app/views` files, for example)
+    are linking to valid docs and anchors.
+
+## Run tests locally
+
+Apart from [previewing your changes locally](index.md#previewing-the-changes-live), you can also run all lint checks
+and Nanoc tests locally.
+
+### Lint checks
+
+Lint checks are performed by the [`lint-doc.sh`](https://gitlab.com/gitlab-org/gitlab/blob/master/scripts/lint-doc.sh)
+script and can be executed as follows:
+
+1. Navigate to the `gitlab` directory.
+1. Run:
+
+   ```shell
+   MD_DOC_PATH=path/to/my_doc.md scripts/lint-doc.sh
+   ```
+
+Where `MD_DOC_PATH` points to the file or directory you would like to run lint checks for.
+If you omit it completely, it defaults to the `doc/` directory.
+The output should be similar to:
+
+```plaintext
+=> Linting documents at path /path/to/gitlab as <user>...
+=> Checking for cURL short options...
+=> Checking for CHANGELOG.md duplicate entries...
+=> Checking /path/to/gitlab/doc for executable permissions...
+=> Checking for new README.md files...
+=> Linting markdown style...
+=> Linting prose...
+✔ 0 errors, 0 warnings and 0 suggestions in 1 file.
+✔ Linting passed
+```
+
+This requires you to either:
+
+- Have the required lint tools installed on your machine.
+- A working Docker installation, in which case an image with these tools pre-installed is used.
+
+### Nanoc tests
+
+To execute Nanoc tests locally:
+
+1. Navigate to the [`gitlab-docs`](https://gitlab.com/gitlab-org/gitlab-docs) directory.
+1. Run:
+
+   ```shell
+   # Check for broken internal links
+   bundle exec nanoc check internal_links
+
+   # Check for broken external links (might take a lot of time to complete).
+   # This test is set to be allowed to fail and is run only in the gitlab-docs project CI
+   bundle exec nanoc check internal_anchors
+   ```
+
+### `ui-docs-links` test
+
+The `ui-docs-links lint` job uses `haml-lint` to test that all links to docs from
+UI elements (`app/views` files, for example) are linking to valid docs and anchors.
+
+To run the `ui-docs-links` test locally:
+
+1. Open the `gitlab` directory in a terminal window.
+1. Run:
+
+   ```shell
+   bundle exec haml-lint -i DocumentationLinks
+   ```
+
+If you receive an error the first time you run this test, run `bundle install`, which
+installs GitLab's dependencies, and try again.
+
+If you don't want to install all of GitLab's dependencies to test the links, you can:
+
+1. Open the `gitlab` directory in a terminal window.
+1. Install `haml-lint`:
+
+   ```shell
+   gem install haml_lint
+   ```
+
+1. Run:
+
+   ```shell
+   haml-lint -i DocumentationLinks
+   ```
+
+If you manually install `haml-lint` with this process, it does not update automatically
+and you should make sure your version matches the version used by GitLab.
+
+## Local linters
+
+To help adhere to the [documentation style guidelines](styleguide.md), and improve the content
+added to documentation, [install documentation linters](#install-linters) and
+[integrate them with your code editor](#configure-editors).
+
+At GitLab, we mostly use:
+
+- [markdownlint](#markdownlint)
+- [Vale](#vale)
+
+### markdownlint
+
+[markdownlint](https://github.com/DavidAnson/markdownlint) checks that Markdown syntax follows
+[certain rules](https://github.com/DavidAnson/markdownlint/blob/master/doc/Rules.md#rules), and is
+used by the `docs-lint` test.
+
+Our [Documentation Style Guide](styleguide.md#markdown) and
+[Markdown Guide](https://about.gitlab.com/handbook/markdown-guide/) elaborate on which choices must
+be made when selecting Markdown syntax for GitLab documentation. This tool helps catch deviations
+from those guidelines.
+
+markdownlint configuration is found in the following projects:
+
+- [`gitlab`](https://gitlab.com/gitlab-org/gitlab/blob/master/.markdownlint.json)
+- [`gitlab-runner`](https://gitlab.com/gitlab-org/gitlab-runner/blob/master/.markdownlint.json)
+- [`omnibus-gitlab`](https://gitlab.com/gitlab-org/omnibus-gitlab/blob/master/.markdownlint.json)
+- [`charts`](https://gitlab.com/gitlab-org/charts/gitlab/-/blob/master/.markdownlint.json)
+- [`gitlab-development-kit`](https://gitlab.com/gitlab-org/gitlab-development-kit/-/blob/master/.markdownlint.json)
+
+This configuration is also used within build pipelines.
+
+You can use markdownlint:
+
+- [On the command line](https://github.com/igorshubovych/markdownlint-cli#markdownlint-cli--).
+- [Within a code editor](#configure-editors).
+- [In a `pre-push` hook](#configure-pre-push-hooks).
+
+### Vale
+
+[Vale](https://errata-ai.gitbook.io/vale/) is a grammar, style, and word usage linter for the
+English language. Vale's configuration is stored in the
+[`.vale.ini`](https://gitlab.com/gitlab-org/gitlab/blob/master/.vale.ini) file located in the root
+directory of projects.
+
+Vale supports creating [custom tests](https://errata-ai.github.io/vale/styles/) that extend any of
+several types of checks, which we store in the `.linting/vale/styles/gitlab` directory within the
+documentation directory of projects.
+
+Vale configuration is found in the following projects:
+
+- [`gitlab`](https://gitlab.com/gitlab-org/gitlab/-/tree/master/doc/.vale/gitlab)
+- [`gitlab-runner`](https://gitlab.com/gitlab-org/gitlab-runner/-/tree/master/docs/.vale/gitlab)
+- [`omnibus-gitlab`](https://gitlab.com/gitlab-org/omnibus-gitlab/-/tree/master/doc/.vale/gitlab)
+- [`charts`](https://gitlab.com/gitlab-org/charts/gitlab/-/tree/master/doc/.vale/gitlab)
+- [`gitlab-development-kit`](https://gitlab.com/gitlab-org/gitlab-development-kit/-/tree/master/doc/.vale/gitlab)
+
+This configuration is also used within build pipelines.
+
+You can use Vale:
+
+- [On the command line](https://errata-ai.gitbook.io/vale/getting-started/usage).
+- [Within a code editor](#configure-editors).
+- [In a Git hook](#configure-pre-push-hooks). Vale only reports errors in the Git hook (the same
+  configuration as the CI/CD pipelines), and does not report suggestions or warnings.
+
+### Install linters
+
+At a minimum, install [markdownlint](#markdownlint) and [Vale](#vale) to match the checks run in
+build pipelines:
+
+1. Install `markdownlint-cli`, using either:
+
+   - `npm`:
+
+     ```shell
+     npm install -g markdownlint-cli
+     ```
+
+   - `yarn`:
+
+     ```shell
+     yarn global add markdownlint-cli
+     ```
+
+     We recommend installing the version of `markdownlint-cli` currently used in the documentation
+     linting [Docker image](https://gitlab.com/gitlab-org/gitlab-docs/-/blob/master/.gitlab-ci.yml#L420).
+
+1. Install [`vale`](https://github.com/errata-ai/vale/releases). For example, to install using
+   `brew` for macOS, run:
+
+   ```shell
+   brew install vale
+   ```
+
+   We recommend installing the version of Vale currently used in the documentation linting
+   [Docker image](https://gitlab.com/gitlab-org/gitlab-docs/-/blob/master/.gitlab-ci.yml#L419).
+
+In addition to using markdownlint and Vale at the command line, these tools can be
+[integrated with your code editor](#configure-editors).
+
+### Configure editors
+
+To configure markdownlint within your editor, install one of the following as appropriate:
+
+- [Sublime Text](https://packagecontrol.io/packages/SublimeLinter-contrib-markdownlint)
+- [Visual Studio Code](https://marketplace.visualstudio.com/items?itemName=DavidAnson.vscode-markdownlint)
+- [Atom](https://atom.io/packages/linter-node-markdownlint)
+- [Vim](https://github.com/dense-analysis/ale)
+
+To configure Vale within your editor, install one of the following as appropriate:
+
+- The Sublime Text [`SublimeLinter-contrib-vale` plugin](https://packagecontrol.io/packages/SublimeLinter-contrib-vale).
+- The Visual Studio Code [`errata-ai.vale-server` extension](https://marketplace.visualstudio.com/items?itemName=errata-ai.vale-server).
+  You don't need Vale Server to use the plugin. You can configure the plugin to
+  [display only a subset of alerts](#show-subset-of-vale-alerts).
+- [Vim](https://github.com/dense-analysis/ale).
+
+We don't use [Vale Server](https://errata-ai.github.io/vale/#using-vale-with-a-text-editor-or-another-third-party-application).
+
+### Configure pre-push hooks
+
+Git [pre-push hooks](https://git-scm.com/book/en/v2/Customizing-Git-Git-Hooks) allow Git users to:
+
+- Run tests or other processes before pushing a branch.
+- Avoid pushing a branch if failures occur with these tests.
+
+[`lefthook`](https://github.com/Arkweid/lefthook) is a Git hooks manager, making configuring,
+installing, and removing Git hooks easy.
+
+Configuration for `lefthook` is available in the [`lefthook.yml`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/lefthook.yml)
+file for the [`gitlab`](https://gitlab.com/gitlab-org/gitlab) project.
+
+To set up `lefthook` for documentation linting, see
+[Pre-push static analysis](../contributing/style_guides.md#pre-push-static-analysis).
+
+### Show subset of Vale alerts
+
+You can set Visual Studio Code to display only a subset of Vale alerts when viewing files:
+
+1. Go to **Preferences > Settings > Extensions > Vale**.
+1. In **Vale CLI: Min Alert Level**, select the minimum alert level you want displayed in files.
+
+To display only a subset of Vale alerts when running Vale from the command line, use
+the `--minAlertLevel` flag, which accepts `error`, `warning`, or `suggestion`. Combine it with `--config`
+to point to the configuration file within the project, if needed:
+
+```shell
+vale --config .vale.ini --minAlertLevel error doc/**/*.md
+```
+
+Omit the flag to display all alerts, including `suggestion` level alerts.
+
+### Disable Vale tests
+
+You can disable a specific Vale linting rule or all Vale linting rules for any portion of a
+document:
+
+- To disable a specific rule, add a `<!-- vale gitlab.rulename = NO -->` tag before the text, and a
+  `<!-- vale gitlab.rulename = YES -->` tag after the text, replacing `rulename` with the filename
+  of a test in the
+  [GitLab styles](https://gitlab.com/gitlab-org/gitlab/-/tree/master/doc/.linting/vale/styles/gitlab)
+  directory.
+- To disable all Vale linting rules, add a `<!-- vale off -->` tag before the text, and a
+  `<!-- vale on -->` tag after the text.
+
+Whenever possible, exclude only the problematic rule and line(s).
+
+For more information, see
+[Vale's documentation](https://errata-ai.gitbook.io/vale/getting-started/markup#markup-based-configuration).
diff --git a/locale/gitlab.pot b/locale/gitlab.pot
index 675c700c3e7..60a987778d5 100644
--- a/locale/gitlab.pot
+++ b/locale/gitlab.pot
@@ -7129,6 +7129,9 @@ msgstr ""
 msgid "Consistency guarantee method"
 msgstr ""
 
+msgid "Contact Sales to upgrade"
+msgstr ""
+
 msgid "Contact sales to upgrade"
 msgstr ""
 
@@ -12801,7 +12804,7 @@ msgstr ""
 msgid "Go back (while searching for files)"
 msgstr ""
 
-msgid "Go back to %{startTag}Open issues%{endTag} and select some issues to add to your board."
+msgid "Go back to %{tagStart}Open issues%{tagEnd} and select some issues to add to your board."
 msgstr ""
 
 msgid "Go full screen"
@@ -13789,9 +13792,6 @@ msgstr ""
 msgid "How many users will be evaluating the trial?"
 msgstr ""
 
-msgid "How to upgrade"
-msgstr ""
-
 msgid "However, you are already a member of this %{member_source}. Sign in using a different account to accept the invitation."
 msgstr ""
 
diff --git a/spec/features/boards/add_issues_modal_spec.rb b/spec/features/boards/add_issues_modal_spec.rb
index 00efca5d3a8..f941adca233 100644
--- a/spec/features/boards/add_issues_modal_spec.rb
+++ b/spec/features/boards/add_issues_modal_spec.rb
@@ -87,11 +87,12 @@ RSpec.describe 'Issue Boards add issue modal', :js do
       end
     end
 
-    it 'shows selected issues' do
+    it 'shows selected issues tab and empty state message' do
       page.within('.add-issues-modal') do
         click_link 'Selected issues'
 
         expect(page).not_to have_selector('.board-card')
+        expect(page).to have_content("Go back to Open issues and select some issues to add to your board.")
       end
     end
 
@@ -147,7 +148,7 @@ RSpec.describe 'Issue Boards add issue modal', :js do
       end
     end
 
-    context 'selecing issues' do
+    context 'selecting issues' do
       it 'selects single issue' do
         page.within('.add-issues-modal') do
           first('.board-card .board-card-number').click
@@ -206,7 +207,7 @@ RSpec.describe 'Issue Boards add issue modal', :js do
         end
       end
 
-      it 'selects all that arent already selected' do
+      it "selects all that aren't already selected" do
         page.within('.add-issues-modal') do
           first('.board-card .board-card-number').click
 
diff --git a/spec/features/issues/gfm_autocomplete_spec.rb b/spec/features/issues/gfm_autocomplete_spec.rb
index 3b81f199267..06f79f94e8d 100644
--- a/spec/features/issues/gfm_autocomplete_spec.rb
+++ b/spec/features/issues/gfm_autocomplete_spec.rb
@@ -814,6 +814,13 @@ RSpec.describe 'GFM autocomplete', :js do
       end
     end
 
+    context 'issues' do
+      let(:object) { issue }
+      let(:expected_body) { object.to_reference }
+
+      it_behaves_like 'autocomplete suggestions'
+    end
+
     context 'merge requests' do
       let(:object) { create(:merge_request, source_project: project) }
       let(:expected_body) { object.to_reference }
@@ -821,6 +828,27 @@ RSpec.describe 'GFM autocomplete', :js do
       it_behaves_like 'autocomplete suggestions'
     end
 
+    context 'project snippets' do
+      let!(:object) { create(:project_snippet, project: project, title: 'code snippet') }
+      let(:expected_body) { object.to_reference }
+
+      it_behaves_like 'autocomplete suggestions'
+    end
+
+    context 'label' do
+      let!(:object) { label }
+      let(:expected_body) { object.title }
+
+      it_behaves_like 'autocomplete suggestions'
+    end
+
+    context 'milestone' do
+      let!(:object) { create(:milestone, project: project) }
+      let(:expected_body) { object.to_reference }
+
+      it_behaves_like 'autocomplete suggestions'
+    end
+
     context 'when other notes are destroyed' do
       let!(:discussion) { create(:discussion_note_on_issue, noteable: issue, project: issue.project) }