Prefect UI overwrites the url of my link Artifact

[liviumanea]

Bug summary

In my prefect deployment I have to run it behind nginx in order to be able to serve the link artifacts and I have to configure prefect as follows so that it works behind nginx:

ENV PREFECT_SERVER_API_BASE_PATH=/prefect/api \
    PREFECT_API_URL=http://localhost:4200/prefect/api \
    PREFECT_UI_API_URL=/prefect/api \
    PREFECT_UI_SERVE_BASE=/prefect

In my flows, I am creating artifacts with the following code:

    await create_link_artifact(
        key="pga-report",
        link="http://localhost:8200/prefect/products/2025/05/04/pga-report.pdf",
        link_text="PGA Report",
        description="""
        # PGA Report

        this is the pga report
        """,
    )

When I go look at this artifact, I see the following data from the backend

{"id":"4a61752c-1735-41c6-a7d7-ea4a16604f24","created":"2025-05-04T19:03:20.506642Z","updated":"2025-05-04T19:03:20.506642Z","key":"pga-report","type":"markdown","description":"\n        # PGA Report\n\n        this is the pga report\n        ","data":"[PGA Report](http://localhost:8200/prefect/products/2025/05/04/pga-report.pdf)","metadata_":null,"flow_run_id":"c6750171-cf29-4089-8a0c-0c79122e8ad4","task_run_id":null}

If I visit localhost:8200/prefect/products/2025/05/04/pga-report.pdf in my browser then I can access the pdf file just fine. If I hover over the link on the artifact page the link looks like this:
http://localhost:8200/prefect/prefect/products/2025/05/04/pga-report.pdf. So it somehow adds another "prefect" in there and I don't know how to stop that. If I click that link, the UI tries to navigate as a single page app to that instead of just rendering the file in a new tab as I would like.

If I add a link that's completely unrelated to my prefect paths, for example

link="https://www.prefect.io/"

Then it's not messing with it.

Also, here is how I'm forwarding traffic with nginx onto Prefect

  server {
    listen 80;

    # Serve static PDFs
    location /prefect/products/ {
      alias /usr/share/nginx/html/products/;
      autoindex on;
    }

    # Proxy to Prefect (UI and API)
    location /prefect {
      proxy_pass http://prefect:4200/prefect;
      proxy_http_version 1.1;

      proxy_set_header Host $host;
      proxy_set_header X-Real-IP $remote_addr;
      proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
      proxy_set_header X-Forwarded-Proto $scheme;

    }

What I really wanted to do is set the link to something unrelated to prefect like

http://localhost:8200/products/2025/05/04/pga-report.pdf

Version info

Version:             3.3.7
API version:         0.8.4
Python version:      3.13.3
Git commit:          8f86aaee
Built:               Mon, Apr 28, 2025 03:04 PM
OS/Arch:             linux/aarch64
Profile:             ephemeral
Server type:         server
Pydantic version:    2.11.4

Additional context

No response

[liviumanea]

It seems that adding PREFECT_UI_SERVE_BASE causes this issue but I do need that in order to expose prefect's ui on another prefix. Am I doing it wrong ? Am I misusing this setting or where should I store the static files so that the link Artifact will serve it properly ?

[znicholasbrown]

Hi @liviumanea - thanks for the report; I'm looking into this. For context I think this component is responsible for this behavior but I'm not totally sure what the fix is yet

[liviumanea]

Hi, @znicholasbrown . Thanks for taking the time. Seeing as this is some user provided content inside of that component, and seeing that we can't store generated assets on prefect itself (please correct me if I'm wrong), shouldn't we not normalize the hrefs that are rendered there and just rely on the user to provide proper hrefs (be it absolute or relative) at all times ?

[znicholasbrown]

@liviumanea yeah I think that's sensible; PrefectHQ/prefect-design#1618 this PR should fix that issue

[znicholasbrown]

Thanks for the issue @liviumanea - this update should go out with tonight's dev release