Deprecate option to disable SSH expiration

This announces the deprecation of the option to disable enforcement
of expiration on SSH keys at the administrator level.

data/deprecations/14-8-enforce-ssh-expiration.yml

+- name: "Optional enforcement of SSH expiration" # The name of the feature to be deprecated
+  announcement_milestone: "14.8" # The milestone when this feature was first announced as deprecated.
+  announcement_date: "2022-02-22" # The date of the milestone release when this feature was first announced as deprecated. This should almost always be the 22nd of a month (YYYY-MM-22), unless you did an out of band blog post.
+  removal_milestone: "15.0" # The milestone when this feature is planned to be removed
+  removal_date: "2022-05-22" # The date of the milestone release when this feature is planned to be removed. This should almost always be the 22nd of a month (YYYY-MM-22), unless you did an out of band blog post.
+  breaking_change: true # If this deprecation is a breaking change, set this value to true
+  reporter: djensen # GitLab username of the person reporting the deprecation
+  body: | # Do not modify this line, instead modify the lines below.
+    The feature to disable enforcement of SSH expiration is unusual from a security perspective.
+    We have become concerned that this unusual feature could create unexpected behavior for users.
+    Unexpected behavior in a security feature is inherently dangerous, so we have decided to remove this feature.
+  issue_url: "https://gitlab.com/gitlab-org/gitlab/-/issues/351963" # (optional) This is a link to the deprecation issue in GitLab
+  documentation_url: "https://docs.gitlab.com/ee/user/admin_area/settings/account_and_limit_settings.html#allow-expired-ssh-keys-to-be-used-deprecated" # (optional) This is a link to the current documentation page

doc/ssh/index.md

@@ -219,7 +219,7 @@ To use SSH with GitLab, copy your public key to your GitLab account.
      you from using the key. Administrators can view expiration dates and use them for
      guidance when [deleting keys](../user/admin_area/credentials_inventory.md#delete-a-users-ssh-key).
    - GitLab 14.0 and later, the expiration date is enforced. Administrators can
-     [allow expired keys to be used](../user/admin_area/settings/account_and_limit_settings.md#allow-expired-ssh-keys-to-be-used).
+     [allow expired keys to be used](../user/admin_area/settings/account_and_limit_settings.md#allow-expired-ssh-keys-to-be-used-deprecated).
    - GitLab checks all SSH keys at 02:00 AM UTC every day. It emails an expiration notice for all SSH keys that expire on the current date. ([Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/322637) in GitLab 13.11.)
    - GitLab checks all SSH keys at 01:00 AM UTC every day. It emails an expiration notice for all SSH keys that are scheduled to expire seven days from now. ([Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/322637) in GitLab 13.11.)
 1. Select **Add key**.

doc/update/deprecations.md

@@ -767,6 +767,20 @@ Unexpected behavior in a security feature is inherently dangerous, so we have de
 
 **Planned removal milestone: 15.0 (2022-05-22)**
 
+### Optional enforcement of SSH expiration
+
+WARNING:
+This feature will be changed or removed in 15.0
+as a [breaking change](https://docs.gitlab.com/ee/development/contributing/#breaking-changes).
+Before updating GitLab, review the details carefully to determine if you need to make any
+changes to your code, settings, or workflow.
+
+The feature to disable enforcement of SSH expiration is unusual from a security perspective.
+We have become concerned that this unusual feature could create unexpected behavior for users.
+Unexpected behavior in a security feature is inherently dangerous, so we have decided to remove this feature.
+
+**Planned removal milestone: 15.0 (2022-05-22)**
+
 ### Querying Usage Trends via the `instanceStatisticsMeasurements` GraphQL node
 
 WARNING:

doc/user/admin_area/settings/account_and_limit_settings.md

@@ -234,10 +234,14 @@ Once a lifetime for SSH keys is set, GitLab:
 NOTE:
 When a user's SSH key becomes invalid they can delete and re-add the same key again.
 
-## Allow expired SSH keys to be used **(ULTIMATE SELF)**
+## Allow expired SSH keys to be used (DEPRECATED) **(ULTIMATE SELF)**
 
 > - [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/250480) in GitLab 13.9.
 > - [Enabled by default](https://gitlab.com/gitlab-org/gitlab/-/issues/320970) in GitLab 14.0.
+> - [Deprecated](https://gitlab.com/gitlab-org/gitlab/-/issues/351963) in GitLab 14.8.
+
+WARNING:
+This feature was [deprecated](https://gitlab.com/gitlab-org/gitlab/-/issues/351963) in GitLab 14.8.
 
 By default, expired SSH keys **are not usable**.