Automatically use a different port if port 8080 is in use

[ChocolateLoverRaj]

Specific Demand

If there's already another http server using port 8080, running dx serve (on the Web app) fails:

Dioxus @ v0.4.1 [20:24:14] 

        > Local : http://localhost:8080/
        > Network : http://192.168.1.3:8080/
        > HTTPS : Disabled

        > Profile : Debug
        > Hot Reload : Normal
        > Index Template : Default
        > URL Rewrite [index_on_404] : True

        > Build Time Use : 63658 millis

[INFO] A perfect compilation!

thread 'main' panicked at /var/home/rajas/.cargo/registry/src/index.crates.io-6f17d22bba15001f/hyper-0.14.28/src/server/server.rs:81:13:
error binding to 0.0.0.0:8080: error creating server listener: Address already in use (os error 98)
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Implement Suggestion

If 8080 isn't available, try using 8081. If that's not available, use 8082, etc. I'm pretty sure Webpack does this and it's convenient.

[alexanderjophus]

I'm looking at implementing this, but I have some questions.

There's a few ways ports can be selected.

• The user specifically requests port 9000 for example, in my opinion this should fail if port 9000 is already taken.
• The user does not specify a port 8080 is taken be default, in my opinion this is where dioxus could look into other open ports.
• The user specifies port 0, this means the OS allocates a free open port.

Right now what happens is the browser (if the option is chosen) is opened on the port, then the server begins. This change would have to start the server first, then open the browser on the port chosen (especially in the case of port 0).

[LiamKarlMitchell]

Improving the error message to suggest that --port can be used to start on a different port if needed would be nice.

[jkelleyrtp]

We now have a better error:

    0: Failed to bind server to: 127.0.0.1:8080, is there another devserver running?
       To run multiple devservers, use the --port flag to specify a different port
    1: Address already in use (os error 48)

[ChocolateLoverRaj]

It's a better error than before, but it doesn't change the motivation behind this issue.

[jkelleyrtp]

Coming soon in 0.6.2 thanks to #3586