UI Bundle URL

A UI bundle is a ZIP archive or directory that contains one or more UIs for a site. The only required file in the UI bundle is the default layout for pages (e.g., layouts/default.hbs) (and, if the 404 page is enabled, layouts/404.hbs as well). Antora automatically fetches and loads a UI bundle when generating a site.

url key

The url key is required. This key is configured under the bundle key of the ui category key in a playbook. The url key accepts a URL or filesystem path from where Antora can locate and fetch the site’s UI bundle. The filesystem path must point to a ZIP archive or a local directory where the ZIP archive has been extracted.

Example 1. antora-playbook.adoc
ui: (1)
  bundle: (2)
    url: https://repo.org/path/to/a-ui-bundle.zip (3)
1 Enter the parent key ui, followed by a colon (:), and then press Enter.
2 The bundle key is a child of ui. Enter the key’s name, bundle, followed by a colon (:), and then press Enter.
3 The url key is a child of bundle. Enter url, followed by a colon and a blank space (: ), and then enter a URL or filesystem path value.

Alternatively, the url key can be assigned from the CLI.

The UI bundle can be augmented using a supplemental UI.

Load a remote bundle

When the value of url is a remote URL, Antora downloads and caches the UI bundle the first time it runs. In this case, the target must be a ZIP archive.

Example 2. Remote UI bundle
    url: https://repo.org/path/to/a-ui-bundle.zip

The UI bundle is cached based on the signature of the URL. On subsequent runs, Antora loads the bundle from the cache as long as the value of url remains unchanged. This saves Antora from having to download the bundle each time you generate your site.

Use a snapshot

Antora won’t download the UI bundle again if it exists in the cache, even when fetch is enabled. If the url value remains the same, but the archive it points to changes over time, the UI bundle needs to be identified as a snapshot to bypass this cache.

In order to retrieve UI bundle updates without changing the url value, you need to enable the snapshot key adjacent to the url key. By default, snapshot is not enabled (set to false). When snapshot is set to true, Antora will download the UI bundle whenever the fetch key under the runtime category of the playbook is enabled. The fetch key instructs Antora to retrieve updates (including the UI bundle snapshot).

Example 3. Remote UI bundle marked as a snapshot
    url: https://gitlab.com/antora/antora-ui-default/-/jobs/artifacts/HEAD/raw/build/ui-bundle.zip?job=bundle-stable
    snapshot: true
If you’re using Antora’s reference UI bundle, you should mark the bundle as a snapshot because its URL never changes.

If you want to control when Antora retrieves updates, pass the --fetch option when invoking the antora command. To make this setting permanent, set the runtime.fetch key in the playbook to true.

Example 4. Fetch updates as persistent setting
  fetch: true

The snapshot key is only required if you’re referring to a remote bundle (which Antora caches by default). If you’re referencing a bundle from the filesystem, Antora will always use the file specified.

Load a bundle from the filesystem

The url key can reference a local UI bundle using an absolute or relative filesystem path.

Example 5. Relative UI bundle path
    url: ./../docs-ui/build/ui-bundle.zip

A relative path is expanded to an absolute path using the following rules:

  • If the first path segment is a tilde (~), the remaining path is resolved relative to the user’s home directory.

  • If the first path segment is a dot (.), the remaining path is resolved relative to the location of the playbook file.

  • If the first path segment is a tilde directly followed by a plus sign (~+), or does not begin with an aforementioned prefix, the remaining path is resolved relative to the current working directory.

Here’s the path to the same UI bundle, but using an absolute path instead.

Example 6. Absolute UI bundle path
    url: /home/user/projects/docs-ui/build/ui-bundle.zip

Here’s the path to the location where the UI bundle has been extracted (or it was organized with the same layout as an extracted archive).

Example 7. Extracted UI bundle path
    url: ./../docs-ui/build/ui-bundle-extracted

Loading the UI bundle from a local directory is a good way to debug the logic.

start_path key

The start_path key is mapped to the bundle key. It accepts a the relative path inside the UI bundle from where Antora should start reading files. This key is useful when a UI bundle packages multiple UIs (e.g., light, dark, etc.).

Example 8. Select UI from start_path
    url: /home/user/projects/docs-ui/build/ui-bundle-with-themes.zip
    start_path: dark

In this example, Antora will ignore all of the files in the UI bundle that fall outside the dark directory.