Jenkins URL

[xjjx]

Jenkins and plugins versions report

Theme Manager plugin add JENKINS_URL to css files. When user access Jenkins by different address than that configured as JENKINS_URL, the browser blocks some files because of:

"A cross-origin resource sharing (CORS) request was blocked because of invalid or missing response headers of the request or the associated preflight request ."

I believe links to css should be relative.

Reported also as https://issues.jenkins.io/browse/JENKINS-72816

What Operating System are you using (both controller, and any agents involved in the problem)?

Linux, official docker images for jenkins

Reproduction steps

Access jenkins by URL different that configured as JENKINS_URL

Expected Results

relative links to css files

Actual Results

blocked by browser when accessing via different url than JENKINS_URL or different port. For example we use separate port for HTTP2

Anything else?

No response

Are you interested in contributing a fix?

No response

[timja]

There's been some debate over this over the years,
last one in #76 (comment)

Why can't you access it over the configured Jenkins url?

[xjjx]

For example we use separate port for HTTP2. Also some of users prefer to use just IP address, some use DNS.
Could we have some configuration option to use relative paths?

[timja]

Why can't you access it over 1 port using http/2 for everything?

I would accept a pull request making it configurable as either an advanced option or a system property.

[xjjx]

Because HTTP2 is not supported everywhere. Still we want to test it.
There are more users for this instance than just me :)

Can we turn around the question - why can't we just use relative links and make everyone happy?
I just compiled this plugin and it works well

diff --git a/src/main/java/io/jenkins/plugins/thememanager/ThemeManagerFactory.java b/src/main/java/io/jenkins/plugins/thememanager/ThemeManagerFactory.java
index 9b04d5b..6fd090e 100644
--- a/src/main/java/io/jenkins/plugins/thememanager/ThemeManagerFactory.java
+++ b/src/main/java/io/jenkins/plugins/thememanager/ThemeManagerFactory.java
@@ -40,7 +40,8 @@ public abstract class ThemeManagerFactory extends AbstractDescribableImpl<ThemeM
      */
     public String toAssetUrl(String asset) {
         ThemeManagerFactoryDescriptor descriptor = getDescriptor();
-        return Jenkins.get().getRootUrl() + "theme-" + descriptor.getThemeId() + "/" + asset;
+        //        return Jenkins.get().getRootUrl() + "theme-" + descriptor.getThemeId() + "/" + asset;
+        return "/theme-" + descriptor.getThemeId() + "/" + asset;
     }

     /**

[timja]

Because people run Jenkins on different context paths, you aren't able to use /, and need to use the Jenkins configured URL.

[daniel-beck]

It is very confusing for themes to not apply at all, with no error, when running Jenkins from a different context path than configured. This happened locally for me with some random test Jenkins home where Jenkins URL was set to http://localhost:8080/ and not the actual http://localhost:8080/jenkins/.

UI generally uses Jenkins#getRootUrlFromRequest (or rootURL in Jelly, which is the correct context path) to support access from other URLs than configured. Otherwise, random parts of the UI break.

#76 should not have been merged per #76 (comment).

More generally, it is unclear why #toAssetURL returns an absolute URL. Would a path alone not be enough?

[timja]

Would a path alone not be enough?

Yes, it would and would probably help here, its just getUrl returns the whole URL it would probably suffix to extract the Path though.

[daniel-beck]

it would probably suffix to extract the Path though.

I'd do what Functions does and just grab the actual context path. If this is wrong somehow, the Jenkins UI would fall over in a myriad of ways anyway.