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spa-server/spa/handler.go

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feat(spa-server): initial implementation — SPA/PWA container server (v1.0.0) Introduces code.nochebuena.dev/einherjar/spa-server — a container-first HTTP server for single-page applications and progressive web apps. Produces a Docker base image; downstream SPA Dockerfiles require only a single COPY instruction. Interfaces and types (CT-6: one TypeSpec per file): - Config — Port (EINHERJAR_SPA_PORT, default 8080) and StaticDir (EINHERJAR_SPA_STATIC_DIR, default /srv/www); parsed via os.Getenv - Server — implements lifecycle.Component; registered with launcher.New Implementation: - NewServer(logger, cfg) *Server — returns a lifecycle-managed HTTP server - OnInit: builds http.NewServeMux with GET /health and /* routes - OnStart: binds TCP listener synchronously via net.Listen (port conflicts surface immediately), then serves in a background goroutine - OnStop: graceful shutdown via http.Server.Shutdown with 10s timeout spa.NewHandler(logger, staticDir) http.Handler: - Uses http.Dir.Open for path sanitisation (prevents directory traversal) - File exists and is not a directory → served by http.FileServer - File missing or is a directory → serves index.html (SPA router owns all routes) - Directory listing is disabled health.NewHandler(logger) http.Handler: - Always responds 200 {"status":"UP","components":{}} - Wire format matches web/health.Response without importing the web module - No external checks — process reachability is the only meaningful health signal Config (EINHERJAR_SPA_* env vars): Port(8080), StaticDir(/srv/www) Docker: - Multi-stage: golang:1.26-alpine builder → alpine:3.21 runtime - Image published as: code.nochebuena.dev/einherjar/spa-server:v1.0.0 code.nochebuena.dev/einherjar/spa-server:latest - VOLUME ["/srv/www"] declared; consumer overrides via COPY or volume mount No external dependencies beyond contracts, core, and the Go standard library.
2026-06-02 18:49:05 +00:00
// Package spa provides the HTTP handler that serves a single-page application.
package spa
import (
"net/http"
"path/filepath"
"code.nochebuena.dev/einherjar/contracts/logging"
)
type handler struct {
logger logging.Logger
staticDir string
fs http.Handler
}
// NewHandler returns an http.Handler that serves static files from staticDir.
// Requests for paths that exist on disk are served directly.
// Any other path receives index.html, delegating routing to the SPA.
func NewHandler(logger logging.Logger, staticDir string) http.Handler {
return &handler{
logger: logger,
staticDir: staticDir,
fs: http.FileServer(http.Dir(staticDir)),
}
}
func (h *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
// http.Dir.Open sanitises the path, preventing directory traversal.
f, err := http.Dir(h.staticDir).Open(r.URL.Path)
if err != nil {
// Path does not exist — hand off to the SPA router.
http.ServeFile(w, r, filepath.Join(h.staticDir, "index.html"))
return
}
defer f.Close()
stat, err := f.Stat()
if err != nil || stat.IsDir() {
// Directory listing is disabled; treat directories as SPA routes.
http.ServeFile(w, r, filepath.Join(h.staticDir, "index.html"))
return
}
h.fs.ServeHTTP(w, r)
}