Aastro preview doesn't respect vite preview allowedHostnames in astro config

[andrewflbarnes]

Astro Info

Astro                    v5.1.9
Node                     v22.6.0
System                   Linux (x64)
Package Manager          pnpm
Output                   static
Adapter                  none
Integrations             @astrojs/starlight

If this issue only occurs in one browser, which browser is a problem?

No response

Describe the Bug

When running astro preview and visiting the site from another device via the hostname I am met with the below message

Blocked request. This host ("my-hostname") is not allowed.
To allow this host, add "my-hostname" to `preview.allowedHosts` in vite.config.js.

Updating the corresponding part of astro.config.mjs (vite.preview.allowedHosts) does not work, nor does setting it to true or adding a vite.config.js file with this set.

The corresponding property for astro dev (vite.server.allowedHosts) does work.

Note: not reproducible on stackblitz (probably because it forwards direct to the IP).
Can be done with pnpm astro create on the starlight template (unable to check basic template at the moment but suspect it's an issue there too).

astro config:

 export default defineConfig({
   site: "http://my-hostname:54321",
   vite: {
     server: {
       allowedHosts: true,
     },
     preview: {
       allowedHosts: true,
     },
   },
...

package.json scripts

    "dev": "astro dev --port 54321 --host",
    "preview": "astro preview --port 54321 --host",

What's the expected result?

astro preview respects astro config vite.preview.allowedHosts - when I add "my-hostname"/true to this setting I am able to visit the site in a browser at http://my-hostname

Link to Minimal Reproducible Example

https://github.com/andrewflbarnes/bug-astro-preview-allowedhosts

pnpm i
pnpm build
pnpm preview

curl yourhostname:54321

Blocked request. This host ("yourhostname") is not allowed.
To allow this host, add "yourhostname" to `preview.allowedHosts` in vite.config.js.

Participation

• I am willing to submit a pull request for this issue.

[ematipico]

astro preview doesn't use vite under the hoods, you would need to provide those hosts in a different way.

Also, please provide a reproduction. Even if it doesn't work on Stackblitz, we can download it and run it ourselves

[github-actions]

Hello @andrewflbarnes. Please provide a minimal reproduction using a GitHub repository or StackBlitz. Issues marked with needs repro will be closed if they have no activity within 3 days.

[andrewflbarnes]

Thanks for the response @ematipico

astro preview doesn't use vite under the hoods

Should I rename this ticket to something like "incorrect astro preview errors and intellisense for vite preview" given the below?

• the error astro preview reports when visiting the page is to add "yourhostname" to preview.allowedHosts in vite.config.js.
• there is intellisense available on the astro config object for vite.preview... (which aligns with the above error message)

you would need to provide those hosts in a different way.

What is the astro configuration which does this?

I've had a look through the astro docs and done some googling but wasn't able to find any astro config which seemed to address this.

Very possible I missed it since was searching for "allowedHosts" which may have been a red herring given the error message is wrong.

[ematipico]

Yeah, I suppose the bug is that we don't use any preview options on purpose, so maybe we should remove vite.preview from the intellisense