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spa-server/server.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 spaserver
import (
"context"
"fmt"
"net"
"net/http"
"time"
"code.nochebuena.dev/einherjar/contracts/logging"
"code.nochebuena.dev/einherjar/spa-server/health"
"code.nochebuena.dev/einherjar/spa-server/spa"
)
const shutdownTimeout = 10 * time.Second
// Server is a lifecycle-managed HTTP server that serves a single-page application.
// Register with [launcher.New] via Append — it implements [lifecycle.Component].
type Server struct {
logger logging.Logger
cfg Config
srv *http.Server
}
// NewServer returns a Server configured by cfg.
func NewServer(logger logging.Logger, cfg Config) *Server {
return &Server{logger: logger, cfg: cfg}
}
// OnInit builds the HTTP mux and configures the underlying http.Server.
func (s *Server) OnInit() error {
mux := http.NewServeMux()
mux.Handle("GET /health", health.NewHandler(s.logger))
mux.Handle("/", spa.NewHandler(s.logger, s.cfg.StaticDir))
s.srv = &http.Server{
Addr: fmt.Sprintf(":%d", s.cfg.Port),
Handler: mux,
}
return nil
}
// OnStart begins serving HTTP requests in a background goroutine.
// The TCP listener binds synchronously so a port conflict surfaces immediately.
func (s *Server) OnStart() error {
ln, err := newListener(s.srv.Addr)
if err != nil {
return err
}
s.logger.Info("spa-server: listening", "addr", s.srv.Addr, "static_dir", s.cfg.StaticDir)
go func() {
if err := s.srv.Serve(ln); err != nil && err != http.ErrServerClosed {
s.logger.Error("spa-server: serve error", err)
}
}()
return nil
}
func newListener(addr string) (net.Listener, error) {
ln, err := net.Listen("tcp", addr)
if err != nil {
return nil, fmt.Errorf("spa-server: bind %s: %w", addr, err)
}
return ln, nil
}
// OnStop performs a graceful shutdown, waiting up to 10 seconds for in-flight
// requests to complete before forcefully closing connections.
func (s *Server) OnStop() error {
s.logger.Info("spa-server: shutting down")
ctx, cancel := context.WithTimeout(context.Background(), shutdownTimeout)
defer cancel()
return s.srv.Shutdown(ctx)
}