cmd/cgitd: HTTP server for cgit CGIHEADmain

This program can be built into single binary, provides as an alternatives
to common setup that require second application (web server with their own
configuration).

3 files changed, 215 insertions, 0 deletions

diff --git a/cmd/cgitd/main.go b/cmd/cgitd/main.go
new file mode 100644
index 0000000..9abced6
--- /dev/null
+++ b/cmd/cgitd/main.go
@@ -0,0 +1,200 @@
+// Copyright (C) 2026 cgit Development Team <cgit@lists.zx2c4.com>
+// Licensed under GNU General Public License v2
+// (see COPYING for full license text)
+
+// Program cgitd is the HTTP server for cgit CGI.
+// This program can be built into single binary, provides as an alternatives
+// to common setup that require second application (web server with their own
+// configuration).
+//
+// cgitd application can be customized through environment variables or by
+// modifying this code directly before build.
+//
+// # Environment variables
+//
+// The following environment variables affect on cgitd only.
+//
+// CGITD_CGIT_BIN - The full path to cgit.cgi.
+// It should be in the same directory that contains the "filters" scripts.
+// This environment is required, default to "/usr/lib/cgit/cgit.cgi".
+//
+// CGITD_CGIT_STATIC_DIR - The full path to directory that contains cgit
+// resources (cgit.css, cgit.js, cgit.png).
+// This environment is required, default to "/usr/share/webapps/cgit/".
+//
+// CGITD_LISTEN - IP address and port to accept HTTP connections.
+// This environment is required, default to "127.0.0.1:10010".
+//
+// CGITD_REPO_PREFIXES - Comma separated repo URL prefixes that will be
+// handled by cgit.
+// This environment is optional, no default value.
+//
+// CGITD_STATIC_DIR - The full path to serve static files, like favicon and
+// logo.
+// If set, the content of this directory will be served under "/static/" path,
+// so make sure to add prefix to favicon= and logo= in cgitrc.
+// This environment is optional, no default value.
+//
+// # Environment passed to cgit
+//
+// The following environment variables is passed to cgit process.
+//
+// CGIT_CONFIG - The full path to cgitrc file.
+// This environment is optional.
+//
+// # Environment passed as arguments to cgit
+//
+// The following environment variables is paseed to cgit as arguments.
+//
+// CGIT_CACHE_ROOT - The directory for storing cgit caches, passed in
+// "--cache" argument.
+// This environment is optional.
+package main
+
+import (
+	"log"
+	"net"
+	"net/http"
+	"net/http/cgi"
+	"os"
+	"strings"
+
+	"git.sr.ht/~shulhan/pakakeh.go/lib/systemd"
+)
+
+// List of known environment variables handled by cgitd.
+const (
+	envCgitBin       = `CGITD_CGIT_BIN`
+	envCgitStaticDir = `CGITD_CGIT_STATIC_DIR`
+	envListen        = `CGITD_LISTEN`
+	envRepoPrefixes  = `CGITD_REPO_PREFIXES`
+	envStaticDir     = `CGITD_STATIC_DIR`
+)
+
+const (
+	defCgitBin       = `/usr/lib/cgit/cgit.cgi`
+	defCgitStaticDir = `/usr/share/webapps/cgit/`
+	defListen        = `127.0.0.1:10010`
+	defStaticPrefix  = `/static`
+)
+
+// List of known environment variables passed to cgit process.
+var listCgitEnv = []string{
+	`CGIT_CONFIG`,
+}
+
+type config struct {
+	cgitBin       string // Path to cgit.cgi.
+	cgitStaticDir string // Path to cgit static resources.
+	listen        string // Address for accepting connection.
+	staticDir     string // Path to non-cgit resources like favicon and logo.
+
+	cgitEnvs     []string // List of environment variables for cgit.
+	repoPrefixes []string // List of repo URL prefixes.
+}
+
+func initConfig() (cfg config) {
+	cfg.cgitBin = os.Getenv(envCgitBin)
+	if cfg.cgitBin == "" {
+		cfg.cgitBin = defCgitBin
+	}
+
+	cfg.cgitStaticDir = os.Getenv(envCgitStaticDir)
+	if cfg.cgitStaticDir == "" {
+		cfg.cgitStaticDir = defCgitStaticDir
+	}
+
+	cfg.listen = os.Getenv(envListen)
+	if cfg.listen == "" {
+		cfg.listen = defListen
+	}
+
+	repoPrefixes := os.Getenv(envRepoPrefixes)
+	for _, item := range strings.Split(repoPrefixes, ",") {
+		item = strings.TrimSpace(item)
+		if item != "" {
+			cfg.repoPrefixes = append(cfg.repoPrefixes, item)
+		}
+	}
+
+	cfg.staticDir = os.Getenv(envStaticDir)
+
+	for _, key := range listCgitEnv {
+		val := os.Getenv(key)
+		if val != "" {
+			cfg.cgitEnvs = append(cfg.cgitEnvs, key+`=`+val)
+		}
+	}
+
+	return cfg
+}
+
+func main() {
+	logp := `cgitd`
+	cfg := initConfig()
+
+	log.Printf(`%s: %s=%s`, logp, envCgitBin, cfg.cgitBin)
+	log.Printf(`%s: %s=%s`, logp, envCgitStaticDir, cfg.cgitStaticDir)
+	log.Printf(`%s: %s=%s`, logp, envListen, cfg.listen)
+	log.Printf(`%s: %s=%s`, logp, envRepoPrefixes, cfg.repoPrefixes)
+	log.Printf(`%s: %s=%s`, logp, envStaticDir, cfg.staticDir)
+	log.Printf(`%s: cgitEnvs=%s`, logp, cfg.cgitEnvs)
+
+	rootfs, err := os.OpenRoot(cfg.cgitStaticDir)
+	if err != nil {
+		log.Fatalf(`%s: %s`, logp, err)
+	}
+	cgitStaticFS := http.FileServerFS(rootfs.FS())
+
+	mux := http.NewServeMux()
+	mux.Handle(`GET /cgit.css`, cgitStaticFS)
+	mux.Handle(`GET /cgit.js`, cgitStaticFS)
+	mux.Handle(`GET /cgit.png`, cgitStaticFS)
+	mux.Handle(`GET /robots.txt`, cgitStaticFS)
+
+	if cfg.staticDir != "" {
+		rootfs, err = os.OpenRoot(cfg.staticDir)
+		if err != nil {
+			log.Fatalf(`%s: %s`, logp, err)
+		}
+		staticFS := http.FileServerFS(rootfs.FS())
+		mux.Handle(`GET `+defStaticPrefix+`/`,
+			http.StripPrefix(defStaticPrefix, staticFS))
+	}
+
+	cgitHandler := &cgi.Handler{
+		Path: cfg.cgitBin,
+		Env:  cfg.cgitEnvs,
+	}
+	for _, prefix := range cfg.repoPrefixes {
+		mux.Handle(`GET `+prefix, cgitHandler)
+	}
+	mux.Handle(`GET /`, cgitHandler)
+
+	httpd := http.Server{
+		Addr:    cfg.listen,
+		Handler: mux,
+	}
+
+	// Allow activation through systemd socket.
+	var listener net.Listener
+	listeners, err := systemd.Listeners(true)
+	if err != nil {
+		log.Fatalf(`%s: %s`, logp, err)
+	}
+	for _, l := range listeners {
+		if l.Addr().String() == cfg.listen {
+			listener = l
+		}
+	}
+	if listener == nil {
+		log.Printf(`%s: listening on address %s`, logp, cfg.listen)
+		err = httpd.ListenAndServe()
+	} else {
+		log.Printf(`%s: activated throught systemd socket`, logp)
+		err = httpd.Serve(listener)
+	}
+	if err != nil {
+		log.Fatalf(`%s: %s`, logp, err)
+	}
+}
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..6807df0
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,11 @@
+// Copyright (C) 2026 cgit Development Team <cgit@lists.zx2c4.com>
+// Licensed under GNU General Public License v2
+// (see COPYING for full license text)
+
+module git.zx2c4.com/cgit
+
+go 1.26.0
+
+require git.sr.ht/~shulhan/pakakeh.go v0.62.0
+
+require golang.org/x/sys v0.42.0 // indirect
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..c6b687e
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,4 @@
+git.sr.ht/~shulhan/pakakeh.go v0.62.0 h1:rAX0NpfxGbRfe6YhG7I9mmETmcafAreXUZqwPWNDvw4=
+git.sr.ht/~shulhan/pakakeh.go v0.62.0/go.mod h1:M8FG29UN+TMqRsOvKFTjsBuZDiGeBzYlAFxHjBM03Rs=
+golang.org/x/sys v0.42.0 h1:omrd2nAlyT5ESRdCLYdm3+fMfNFE/+Rf4bDIQImRJeo=
+golang.org/x/sys v0.42.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=