├── README.md
└── localhost


/README.md:
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 1 | ### localhost subdomains
 2 | 
 3 | Map subdomains of localhost to ports.
 4 | 
 5 | ```
 6 |   hello.localhost → localhost:1234
 7 |      db.localhost → localhost:5432
 8 | printer.localhost → localhost:9100
 9 | ```
10 | 
11 | This is a direct continuation of Charles' process:
12 | https://inclouds.space/localhost-domains
13 | 
14 | For this to work, we'll need to do two things:
15 | 1. redirect `*.localhost` to `127.0.0.1`
16 | 2. have a server on `127.0.0.1` that reverse proxies to the right port
17 | 
18 | This was tested on Ubuntu 22. Your mileage may vary.
19 | 
20 | #### redirect with `dnsmasq`
21 | 
22 | _NB: You might not actually need this, `systemd-resolved` might already be doing
23 | the redirecting! See [hacker news](https://news.ycombinator.com/item?id=43644434)_.
24 | 
25 | To get `dnsmasq` to redirect all subdomains (*.localhost) to 127.0.0.1, install
26 | it (via brew or apt) and then configure it as follows:
27 | 
28 | ```
29 | echo 'port=5353' | sudo tee -a /etc/dnsmasq.conf
30 | echo 'address=/localhost/127.0.0.1' | sudo tee -a /etc/dnsmasq.conf
31 | sudo systemctl restart dnsmasq
32 | ```
33 | 
34 | NB: we use port 5353 to avoid conflicts with the `systemd-resolved`
35 | 
36 | Next, to further avoid conflicts with `systemd-resolved` add `nameserver
37 | 127.0.0.1` to the top of `/etc/resolv.conf` so that `dnsmasq` becomes the
38 | primary DNS resolver.
39 | 
40 | #### serve with `caddy` + `localhost`
41 | 
42 | Then, we use `caddy` to direct subdomains to particular ports.
43 | 
44 | You can do this by writing a Caddyfile by hand. I've written a little bash
45 | script with Claude's help to do this for me. You can add the bash script
46 | `localhost` to your `PATH`. In my case, I added the following line to my
47 | `.zshrc`.
48 | 
49 | ```
50 | export PATH="$PATH:$HOME/dev/localhost"
51 | ```
52 | 
53 | Now you can `localhost add hello 8000` or `localhost remove`.
54 | 
55 | #### testing it out
56 | 
57 | Run a local server!
58 | ```
59 | echo 'hello.localhost!' > index.html
60 | python3 -m http.server 1234
61 | ```
62 | 
63 | Name the port!
64 | ```
65 | localhost add hello 1234
66 | ```
67 | 
68 | Now open `hello.localhost` in your browser!
69 | 


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/localhost:
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 1 | #!/bin/bash
 2 | 
 3 | SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
 4 | CADDYFILE="$SCRIPT_DIR/Caddyfile"
 5 | 
 6 | add_subdomain() {
 7 |     local subdomain=$1
 8 |     local port=$2
 9 | 
10 |     cat >> $CADDYFILE << EOF
11 | 
12 | $subdomain.localhost {
13 |     reverse_proxy localhost:$port
14 |     tls internal
15 |     encode gzip zstd
16 | }
17 | 
18 | EOF
19 |     echo "Added configuration for $subdomain.localhost pointing to localhost:$port"
20 | }
21 | 
22 | remove_by_name() {
23 |     local subdomain=$1
24 | 
25 |     sed -i "/^$subdomain\.localhost {/,/^}/d" $CADDYFILE
26 |     echo "Removed configuration for $subdomain.localhost"
27 | }
28 | 
29 | remove_by_port() {
30 |     local port=$1
31 |     local subdomain
32 |     
33 |     # Find subdomain matching this port
34 |     subdomain=$(grep -B1 "reverse_proxy localhost:$port" $CADDYFILE | grep -o '[^ ]*\.localhost' | sed 's/\.localhost//')
35 |     
36 |     if [ -n "$subdomain" ]; then
37 |         remove_by_name "$subdomain"
38 |     else
39 |         echo "No configuration found for port $port"
40 |     fi
41 | }
42 | 
43 | reload_caddy() {
44 |    if pgrep -x "caddy" > /dev/null; then
45 |        echo "Reloading Caddy configuration..."
46 |        caddy reload --config "$CADDYFILE"
47 |    else
48 |        echo "Starting Caddy..."
49 |        caddy start --config "$CADDYFILE"
50 |    fi
51 | }
52 | 
53 | case "$1" in
54 |     add)
55 |         if [ $# -ne 3 ]; then
56 |             echo "Usage: $(basename $0) add <subdomain> <port>"
57 |             exit 1
58 |         fi
59 |         add_subdomain "$2" "$3"
60 |         reload_caddy
61 |         ;;
62 |     remove)
63 |         if [ $# -ne 2 ]; then
64 |             echo "Usage: $(basename $0) remove <subdomain or port>"
65 |             exit 1
66 |         fi
67 |         # Check if the argument is a number (port) or string (subdomain)
68 |         if [[ "$2" =~ ^[0-9]+$ ]]; then
69 |             remove_by_port "$2"
70 |         else
71 |             remove_by_name "$2"
72 |         fi
73 |         reload_caddy
74 |         ;;
75 |     list)
76 |         cat $CADDYFILE
77 |         ;;
78 |     *)
79 |         echo "Usage: $(basename $0) add <subdomain> <port>"
80 |         echo "       $(basename $0) remove <subdomain or port>"
81 |         echo "       $(basename $0) list"
82 |         exit 1
83 |         ;;
84 | esac
85 | 


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