Redesign the Jenkins header

[janfaracik]

Hey there 👋

This PR redesigns the Jenkins header, bringing it a modern look and new functionality. This was demoed in the latest UX Sig as well as at the 2025 Jenkins Contributor Summit. The goal of this redesign is to simplify the header, whilst also introducing new functionality as well.

What's new?

• New theme, draws less attention to itself vs content on the page
• Breadcrumb bar has been merged with the header, providing roughly 40px in extra vertical real estate, when combined with the removed margin its close to 90px extra

• Top level actions now show in the header
  • For example, Manage Jenkins now appears in the header by default - making it accessible on every page
  • Plugins like Design Library and the infamous Beer plugin behave the same way
  • They can also feature badges - this is currently used to highlight administrative monitors on the Manage Jenkins action
  • These actions collapse into an overflow menu when there's not enough space for them
• The user account action now shows the users avatar
• Breadcrumbs now collapse rather than scroll if theres too many, you'll see an overflow menu when there are too many
  * ➡️ Breadcrumbs no longer feature menus - this is something that can be restored based on user feedback in this thread, let me know if you use them and find them valuable - I personally find them rather fiddly but that could just be me
• For header developers - the header features spots to show additional information now, so for simpler changes you'll no longer need to replace the entire header

Additional screenshots

I've got a branch for Customizable header plugin in the works - it's quite fun:

What's left to do?

• Get thoughts on the changes - discuss away!
• Get tests passing
• Get ATH passing - Forward compatibility for Redesign the Jenkins header acceptance-test-harness#1917
• Get PCT passing - Test for Redesign the Jenkins header #10245 bom#4431
• Update Customizable Header Plugin to work with this

Testing done

• Breadcrumbs work, root actions appear as expected
• Sign in/sign out works
• High contrast mode works
• Breadcrumbs and actions collapse/appear on window resize
• Works with the updated Customisable Header plugin

Proposed changelog entries

• Redesign the Jenkins header

Developer changelog

• Root actions can now display badges in the header, as well as a jumplist of actions by implementing jumplist.jelly

Proposed upgrade guidelines

N/A

### Submitter checklist
- [ ] The Jira issue, if it exists, is well-described.
- [x] The changelog entries and upgrade guidelines are appropriate for the audience affected by the change (users or developers, depending on the change) and are in the imperative mood (see [examples](https://github.com/jenkins-infra/jenkins.io/blob/master/content/_data/changelogs/weekly.yml)). Fill in the **Proposed upgrade guidelines** section only if there are breaking changes or changes that may require extra steps from users during upgrade.
- [x] There is automated testing or an explanation as to why this change has no tests.
- [ ] New public classes, fields, and methods are annotated with `@Restricted` or have `@since TODO` Javadocs, as appropriate.
- [ ] New deprecations are annotated with `@Deprecated(since = "TODO")` or `@Deprecated(forRemoval = true, since = "TODO")`, if applicable.
- [ ] New or substantially changed JavaScript is not defined inline and does not call `eval` to ease future introduction of Content Security Policy (CSP) directives (see [documentation](https://www.jenkins.io/doc/developer/security/csp/)).
- [ ] For dependency updates, there are links to external changelogs and, if possible, full differentials.
- [ ] For new APIs and extension points, there is a link to at least one consumer.

Desired reviewers

@jenkinsci/sig-ux

Before the changes are marked as ready-for-merge:

### Maintainer checklist
- [x] There are at least two (2) approvals for the pull request and no outstanding requests for change.
- [x] Conversations in the pull request are over, or it is explicit that a reviewer is not blocking the change.
- [x] Changelog entries in the pull request title and/or **Proposed changelog entries** are accurate, human-readable, and in the imperative mood.
- [x] Proper changelog labels are set so that the changelog can be generated automatically.
- [ ] If the change needs additional upgrade steps from users, the `upgrade-guide-needed` label is set and there is a **Proposed upgrade guidelines** section in the pull request title (see [example](https://github.com/jenkinsci/jenkins/pull/4387)).
- [ ] If it would make sense to backport the change to LTS, a Jira issue must exist, be a _Bug_ or _Improvement_, and be labeled as `lts-candidate` to be considered (see [query](https://issues.jenkins.io/issues/?filter=12146)).

[daniel-beck]

caused JENKINS-75634

Noting still unanswered #10245 (comment)

[janfaracik]

Thanks - will take a look at the issues.

---

Regarding #10245 (comment) - I apologise, I think that was overlooked in my excitement to get this change merged in. If feedback rolls in that this is impacting users I'll open up a fix for it.

[daniel-beck]

Caused JENKINS-75637

[daniel-beck]

Thanks - will take a look at the issues.

Regarding #10245 (comment) - I apologise, I think that was overlooked in my excitement to get this change merged in. If feedback rolls in that this is impacting users I'll open up a fix for it.

Earlier user feedback, e.g. #9287 (comment) and following comments, wasn't addressed, so users may not bother to provide feedback at this point. So I don't think waiting for feedback is a good option. We should restore the feature and then determine whether it's used.

[daniel-beck]

This is basically following

jenkins/core/src/main/java/hudson/model/Action.java

Lines 53 to 63 in 5e36565

	* On the target {@link ModelObject} page, actions are rendered as an item in the side panel
	* by the "/lib/hudson:actions" jelly tag, but you can override this for your action by
	* writing {@code action.jelly}. See the "actions" tag for what the default handling is and
	* tweak from there. One of the use cases of this is to show nested actions, like where
	* Jenkins show the option to wipe out the workspace inside the workspace link:
	*
	* <pre>{@code
	* <l:task icon="icon-folder icon-md" href="${url}/ws/" title="${%Workspace}">
	* <l:task icon="icon-delete icon-md" href="${url}/wipeOutWorkspace" title="${%Wipe Out Workspace}" />
	* </l:task>
	* }</pre>

This documentation needs to be updated for this PR to point out how the top-level actions now work.

Previously, the action.jelly is rendered in all cases. From the Jenkins dashboard, the lower link would be hidden automatically due to a trick

jenkins/core/src/main/resources/lib/layout/task.jelly

Lines 105 to 109 in 5e36565

	<!--
	Much of the following horrible code is to implement hierarchy support in <task> tag.
	The semantics is that when one of the nested <task> matches, the parent is also considered as a match
	and thus gets a highlight.
	-->

An example of this is https://plugins.jenkins.io/purge-build-queue-plugin/ which is completely gone from the UI now.
https://github.com/jenkinsci/purge-build-queue-plugin/blob/adeca5c614fe060ce9960dce52399c27d6abf64f/src/main/java/io/jenkins/plugins/PurgeBuildQueueAction.java#L86 didn't matter as the docs Jesse linked point out given https://github.com/jenkinsci/purge-build-queue-plugin/blob/master/src/main/resources/io/jenkins/plugins/PurgeBuildQueueAction/action.jelly, but now it's just vanished.

[scherler]

may have caused JENKINS-75635

@jtnord #10629

[grandinj]

Nice work!

However, there is now a "flash" on the header when scrolling down the page, because it dynamically adds a thin border under the header.

IMNSHO I would say the thin border should just be there always, it provides useful visual separation. Otherwise it should be marked invisible when not needed, so it doesn't trigger a size change when it is turned on.

[janfaracik]

Nice work!

However, there is now a "flash" on the header when scrolling down the page, because it dynamically adds a thin border under the header.

IMNSHO I would say the thin border should just be there always, it provides useful visual separation. Otherwise it should be marked invisible when not needed, so it doesn't trigger a size change when it is turned on.

Hey, would you be able to provide a video if poss of the issue? I'm not able to replicate it in Safari/Chrome on macOS.

[grandinj]

All.-.Jenkins.-.Google.Chrome.2025-05-22.14-57-19.mp4

Sure, attaching video. This is Chrome browser running on Windows 10.

[Maxo112]

Hey guys one question is this compatible with the plugin "Customizable Header" ?
For example if you add custom icon and custom title beside the custom icon

[mawinter69]

Hey guys one question is this compatible with the plugin "Customizable Header" ? For example if you add custom icon and custom title beside the custom icon

yes

MyText would be the link to the root. Not perfect when you include a link in the title as well

[daniel-beck]

Caused SECURITY-3625.