Add local markdown version

Cached markdown version is composed both from global and local
markdown version. This allows admins to bump version locally when
needed (e.g. when external URL is changed).

1 files changed, 16 insertions, 0 deletions

diff --git a/doc/administration/invalidate_markdown_cache.md b/doc/administration/invalidate_markdown_cache.md
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+# Invalidate Markdown Cache
+
+For performance reasons, GitLab caches the HTML version of markdown text
+(e.g. issue and merge request descriptions, comments). It's possible
+that these cached versions become outdated, for example
+when the `external_url` configuration option is changed - causing links
+in the cached text to refer to the old URL.
+
+To avoid this problem, the administrator can invalidate the existing cache by
+increasing the `local_markdown_version` setting in application settings.  This can
+be done by [changing the application settings through
+the API](../api/settings.md#change-application-settings):
+
+```bash
+curl --request PUT --header "PRIVATE-TOKEN: <your_access_token>" https://gitlab.example.com/api/v4/application/settings?local_markdown_version=<increased_number>
+```