How to set a fixed port (e.g., localhost:9999) for Quarto Preview (Ctrl+Shift+K) in Positron?

[e-ruiz]

Hi everyone,

I'm a new Positron user, having recently switched from Vim. I'm frequently using the Quarto preview feature, triggered by Ctrl + Shift + K.

My issue is that whenever there's an error in my Quarto document, after I fix the error and re-trigger the preview, it often launches on a new, different port. I rely on having the preview consistently on the same port (e.g., localhost:9999) because I often keep it open in a browser tab for testing and debugging.

Is there a way to configure Positron so that using the Ctrl + Shift + K shortcut for Quarto preview always uses a specific host and port, for instance, by effectively running quarto preview --host localhost --port 9999?

Any guidance on how to achieve this would be greatly appreciated!

Thanks in advance!

[juliasilge]

Have you tried specifying preview options for your project, like this:

https://quarto.org/docs/reference/projects/options.html#preview

It seems like some folks may be having problems with this feature:

• Add an option to set preview port for VS Code extension quarto-dev/quarto#439
• Project specify port for localhost quarto-dev/quarto-cli#8965

[e-ruiz]

Indeed, my first thought was that is not a Positron issue, but a VSCode/Positron Quarto Extension issue, however I could not found solution for this reading the docs, seems I can't edit the Quarto tasks (by Quarto extension) into Positron. :(

The project configs did not worked here. The task under ctrl+shift+k command seems to ignore our project configs. After set the config into my _quarto.yml and hit ctrl+shift+k I got this log:

# very first line of log
quarto preview /home/e-ruiz/path/to/quarto/prokect/src/index.qmd --no-browser --no-watch-inputs

. . . 

# this is the end of log
metadata
  pagetitle: My project
  document-css: false
  link-citations: true
  date-format: long
  lang: en
  page-layout: custom
  preview:
    host: localhost
    port: 9999
    browse: false
  theme: cosmo
  
Output created: build/index.html

Preparing to preview

Watching files for changes
Browse at http://localhost:3154/
GET: /

So I understand that the quarto preview command is ignoring those lines into _quarto.yml config, so it looks like a Quarto issue, not a Positron or Quarto Extension.

Than I make a new task into Positron to run quarto preview --host --port 9999 --no-browse from my /src. And it is done. I need 5 steps to run it, but it is ok for now. Next step is to set a shortcut to fire this new task.

✅ Any way, this workaround solved the problem.

I hope this journal can help more people.

Thank you @juliasilge your links helps me a lot to understand the real problem.

[e-ruiz]

In the last post my config was wrong.

❌ It will not work:

project:
  type: website
  output-dir: build
preview:
  host: localhost
  port: 9999
  browser: false
  
  . . . 

✅ It works!

Double check yml identation: preview MUST live into project

project:
  type: website
  output-dir: build 
  preview:
    host: localhost
    port: 9999
    browser: false
    
 . . . 

After review configs ctrl + shift + k works perfectly.