Vampira is a Plan9 HTTP server that uses namespaces to serve static web content.

Vampira much like the original Plan9 httpd(8) becomes the none user then it uses the AddNS function to contruct a new namespace.

One place vampira doesnt' follow the original plan9 version is that it uses -map flags to do rewrites. As vampira is able to bind any arbirtrary path to another what it really has to do is figure out base paths for hosts. In order to do that vampira needs a url to be passed with the aforementioned map flag. This is the RC script I use to run vampira on my server.

#!/bin/rc

fn start_vampira {
	rfork
	vampira/vampira -n /n/camdvax/lib/namespace.httpd \
	-map sevki.io/tmp/vampira/www \
	-map fistfulofbytes.com/tmp/vampira/blog
}

srv -q tcp!192.168.162.243 camdvax
mount  -q /srv/camdvax /n/camdvax
bind -b /n/camdvax/bin /bin
start_vampira &

The -map sevki.io/tmp/vampira/www tells vampira that when a request comes in for sevki.io the root directory will be /tmp/vampira/www. No mad config formats just a URL.

The path rewriting and everything else happens in the namespace file.

mount /srv/wiki.sevki /n/sevki.wiki
mount /srv/camdvax /n/camdvax
bind -c /n/camdvax/usr/sevki/blog /tmp/vampira/blog
bind -c /n/camdvax/usr/sevki/www /tmp/vampira/www
bind -c /n/sevki.wiki /tmp/vampira/www/wiki

cd /tmp/vampira

In the code above vampira mounts servers, /srv/wiki.sevki and /srv/camdvax. Then files served by those servers are bound to the appropriate places as defined with the -map flags.

Then vampira serves everything from the filesystem, cause unlike unix, in plan9 everything implements a file.

package main

import (
	"flag"
	"fmt"
	"net/http"
	"net/url"
	"runtime"

	"sevki.org/namespace"
)

type sitemap map[string]string

func (s sitemap) String() string {
	return fmt.Sprint(map[string]string(s))
}

func (s sitemap) Set(value string) error {
	u, err := url.Parse("https://" + value)
	if err != nil {
		panic(err)
	}
	s[u.Host] = u.Path
	return nil
}

func (s sitemap) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	dir := "/tmp/vampira"
	if d, ok := s[r.Host]; ok {
		dir = d
	}
	w.Header().Add("Server-Agent", fmt.Sprintf("vampira/master (%s; %s);", runtime.GOOS, runtime.GOARCH))
	http.FileServer(http.Dir(dir)).ServeHTTP(w, r)
	return
}

func main() {
	var sitemap = sitemap{}
	nsfile := flag.String("n", "/lib/namespace.httpd", "namespace file")
	addr := flag.String("http", ":3000", "http address to listen to")
	flag.Var(&sitemap, "map", "urls")
	flag.Parse()

	if err := namespace.AddNS(*nsfile, "none"); err != nil {
		fmt.Printf("couldn't build namespace: %v\n", err)
		return
	}

	fmt.Printf("Listening on %s...\n", *addr)

	if err := http.ListenAndServe(*addr, sitemap); err != nil {
		fmt.Printf("couldn't start httpserver: %v\n", err)
		return
	}
}