Feature Request: Proxy Fallback

[adrianb93]

Feature Request:

Adding fallback support to proxies to fall back to valet (or specify something else to fall back to) when the proxied host is not available.

Suggestion:

To the valet proxy command, adding a third argument for fallback, or a --loopback/--fallback option to fall back to the valet loopback (http://127.0.0.1:60).

Fallbacks appear to be possible in Nginx: https://serverfault.com/questions/765483/how-to-add-a-fallback-to-my-proxy-in-nginx/765498

Context/Use Case:

I have a Vue SPA in my Laravel project. The Laravel app can serve the SPA dist which is handy for local development when the Vue dev server is not running. This isn't complex to achieve:

• We symlinked the frontend/dist/css/frontend/dist/js/frontend/dist/static assets in the ./public folder.
• Added a fallback Laravel route to stream the contents of frontend/dist/index.html.

If we want client.example.test to proxy to the Vue dev server, we can do that with Valet:

valet proxy --secure client.example http://localhost:8081

The problem is that now if we stop the Vue dev server, client.example.test will not serve the dist build anymore (as was previously set up), it will instead show an Nginx 502 error page.

What would be an ideal solution is if valet proxy could accept an optional 3rd argument for fallback or an option for --loopback/--fallback to fall back to valet:

valet proxy --secure --loopback client.example http://localhost:8081
valet proxy --secure --fallback client.example http://localhost:8081
valet proxy --secure client.example http://localhost:8081 http://127.0.0.1:60

Now:

• When the Vue dev server is running, client.example.test proxies to http://localhost:8081 (the Vue dev server)
• When the Vue dev server is not running, client.example.test proxies to http://localhost:60 (a regular Valet site), then the Laravel app can serve the dist/production build.

The API requests aren't on the same subdomain, they're on api.example.test, so there's no weirdness there.

[adrianb93]

Gave this a go and it worked 😁:

error_page 502 @fallback;

location @fallback {
    proxy_pass http://localhost:60;
    proxy_set_header   Host              $host;
    proxy_set_header   X-Real-IP         $remote_addr;
    proxy_set_header   X-Forwarded-For   $proxy_add_x_forwarded_for;
    proxy_set_header   X-Forwarded-Proto $scheme;
    proxy_set_header   X-Client-Verify   SUCCESS;
    proxy_set_header   X-Client-DN       $ssl_client_s_dn;
    proxy_set_header   X-SSL-Subject     $ssl_client_s_dn;
    proxy_set_header   X-SSL-Issuer      $ssl_client_i_dn;
    proxy_set_header   X-NginX-Proxy true;
    proxy_set_header   Upgrade $http_upgrade;
    proxy_set_header   Connection "upgrade";
    proxy_http_version 1.1;
    proxy_read_timeout 1800;
    proxy_connect_timeout 1800;
    chunked_transfer_encoding on;
    proxy_redirect off;
    proxy_buffering off;
}