Wrong preview url used when `_quarto.yml` is present

[skwde]

Bug description

When _quarto.yml is present (even if empty) a wrong preview url is used even though the correct one is displayed after running quarto preview test.qmd. (I use the VSCode extension)

Possibly related: https://github.com/quarto-dev/quarto-cli/issues/6409

Steps to reproduce

Create an empty _quarto.yml and a test.qmd like

---
title: "Test"
---

# abc

and run quarto preview test.qmd.

When choosing either preview option (Editor / Browser) it tries to open the URL http://127.0.0.1:<port>/ while the preview command actually shows http://localhost:<port>/test.html as the correct URL.

Expected behavior

Use correct URL to preview

Actual behavior

Wrong URL is used to preview

Your environment

• IDE: VSCode Version: 1.91.0
• devcontainer on Macos running debian 12 (bookworm)

Quarto check output

# quarto check
Quarto 1.5.54
[✓] Checking versions of quarto binary dependencies...
      Pandoc version 3.2.0: OK
      Dart Sass version 1.70.0: OK
      Deno version 1.41.0: OK
      Typst version 0.11.0: OK
[✓] Checking versions of quarto dependencies......OK
[✓] Checking Quarto installation......OK
      Version: 1.5.54
      Path: /opt/quarto/bin

[✓] Checking tools....................OK
      TinyTeX: v2024.07.03
      Chromium: (not installed)

[✓] Checking LaTeX....................OK
      Using: TinyTex
      Path: /root/.TinyTeX/bin/x86_64-linux
      Version: 2024

[✓] Checking basic markdown render....OK

[✓] Checking Python 3 installation....OK
      Version: 3.12.4 (Conda)
      Path: /opt/conda/bin/python
      Jupyter: 5.7.2
      Kernels: python3

[✓] Checking Jupyter engine render....OK

[✓] Checking R installation...........(None)

      Unable to locate an installed version of R.
      Install R from https://cloud.r-project.org/

[cderv]

it tries to open the URL http://127.0.0.1:/ while the preview

127.0.0.1 is supposed to be equivalent to localhost. What does the url get you too exactly ? What is the wrong preview showing exactly ?

I believe we use localhost for preview URL only , but the host really binds to 127.0.0.1

I found this discussion with history on this : https://github.com/quarto-dev/quarto-cli/pull/947

[skwde]

The preview just gives a 404 error.

Can you reproduce the error?

I think the problem is not with 127.0.0.1 / localhost but the missing document name (test.html).

Compare

• http://127.0.0.1:<port>/ (tried by preview, giving 404)

with

• http://localhost:<port>/test.html (shown by quarto preview working when copying.)

Note that in the quarto preview version we have the test.html which is missing in the url used by the preview.

When I append test.html to the url used in the preview (http://127.0.0.1:<port>/) it renders properly.

[cderv]

I think the problem is not with 127.0.0.1 / localhost but the missing document name (test.html).

Oh thanks for making this clearer - I missed this. Definitely something wrong here...

[cderv]

Though I can't reproduce right now

This is with Quarto: preview menu command.

Same result with quarto preview test.qmd in VSCODE terminal, though it opened in eternal browser.

In VSCODE we do special handling where the url does not show test.html but this si the file shown. So somehow this processing may not work for you.

Can you be sure to use latest version to tools ?

Does quarto preview test.qmd works for you outside of VSCODE in a standalone terminal ? Thanks

[skwde]

I confirm that the VSCode command Quarto: Preview works.

Here are the related versions

• Quarto: 1.5.54
• VSCode: 1.91.1 (just updated)
• vscode-quarto: 1.113.0

Since I am using a devcontainer it is not working outside VSCode.

Note also, that when _quarto.yml is not present quarto preview shows the same URL as used by VSCode when opening via the dialog

So it seems to be a project specific problem with this dialog.

[skwde]

@cderv

I just noticed an additional wrong behavior.

The --port option seems to be ignored when serving.

When I run

quarto preview test.qmd --port 8010

I get the following output in VSCode

and everything looks fine. But when I now click on "Preview in Editor" the following is opened

The page is only accessible when I use http://localhost:58637/test.html.

[cderv]

If you click Open in Browser, or look at http://localhost:8010/test.html inside a browser does it works ?

[skwde]

@cdrev just realized that there was a response.

No, it doesn't matter wheter "Open in Borwser" or "Preview in Editor" is used.

[cderv]

look at http://localhost:8010/test.html inside a browser does it works ?

So nothing shows on 8010 port in browser ? (Outside of VSCODE)

[skwde]

I tested it again. So running

quarto preview test.qmd --port 8010

shows

When I click "Open in Browser" a tab opens at http://localhost:8011/ which just shows Not Found.

If I connect to http://localhost:8011/test.html it works even though Is specified port 8010?!.

When I do the same but click "Preview in Editor" I get the same behavior.

Weirdly, VSCode also shows

[cderv]

Interesting that it says localhost:8011 when you set 8010 🤔

Can you confirm that `quarto preview test.qmd --port 8010``work outside of VSCODE ?

This is to confirm this is Quarto CLI directly, or VSOCDE integration. Thanks.

[skwde]

@cderv outside of VSCode (on MacOS) it just works.