bug(dev host binding @next.321): Unable to bind to 0.0.0.0

[ryanrussell]

Describe the bug

I am running SvelteKit in a docker container.

After upgrading to @next.321, I am unable to bind to 0.0.0.0 using npm run dev , which prevents access to SvelteKit inside the container

There appears to be a breaking change around npm run preview and host #4729 on 321. Perhaps there are some side effects to dev mode binding to '0.0.0.0' or the best practices have changed?

#4729

SvelteKit has been working with npm run dev --host to bind to 0.0.0.0 since version ~100.

Reproduction

Attempt 1:

package.json

"scripts": {
    "dev": "svelte-kit dev"
    ...
}

npm run dev -- --host 0.0.0.0

> [email protected] dev
> svelte-kit dev "--host" "0.0.0.0"


  SvelteKit v1.0.0-next.321

  local:   http://localhost:3000
  network: http://192.168.1.159:3000

  Note that all files in the following directories will be accessible to anyone on your network: src/lib, src/routes, .svelte-kit, src, node_modules
  network: http://172.17.0.1:3000

  Note that all files in the following directories will be accessible to anyone on your network: src/lib, src/routes, .svelte-kit, src, node_modules
  network: http://172.22.0.1:3000

  Note that all files in the following directories will be accessible to anyone on your network: src/lib, src/routes, .svelte-kit, src, node_modules

Attempt 2:

package.json

"scripts": {
    "dev": "svelte-kit dev --host 0.0.0.0",
    ...
}

npm run dev

> [email protected] dev
> svelte-kit dev --host 0.0.0.0


  SvelteKit v1.0.0-next.321

  local:   http://localhost:3000
  network: http://192.168.1.159:3000

  Note that all files in the following directories will be accessible to anyone on your network: src/lib, src/routes, .svelte-kit, src, node_modules
  network: http://172.17.0.1:3000

  Note that all files in the following directories will be accessible to anyone on your network: src/lib, src/routes, .svelte-kit, src, node_modules
  network: http://172.22.0.1:3000

  Note that all files in the following directories will be accessible to anyone on your network: src/lib, src/routes, .svelte-kit, src, node_modules

Notice the slightly different rendering of

# Attempt 1 stdout
> svelte-kit dev "--host" "0.0.0.0"
...

# Attempt 2 stdout
> svelte-kit dev --host 0.0.0.0

Logs

In Reproduction.

System Info

lsb_release -a
No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 20.04.4 LTS
Release:	20.04
Codename:	focal

node --version
v14.17.0

npm --version
8.3.2

Severity

serious, but I can work around it

Additional Information

This may be isolated to the dev mode

node build/index.js

Still seems to work and bind to 0.0.0.0 from within docker.

[mrkishi]

As discussed in Discord, this is likely an issue with their Docker network configuration since the bindings appeared to be correct when passing --host, --host 0.0.0.0, and a missing --host (as seen on the screenshots on the Discord thread).

@ryanrussell will attempt to get to the bottom of it and provide a minimal reproduction if an issue is found in SvelteKit.

[moritzebeling]

For me npm run dev --host doesn't work,
but when I add this new command to package.json it does:
"dev-host": "svelte-kit dev --host 0.0.0.0",