Rene Nochebuena
e978d60851
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.
einherjar/spa-server
A shield wall holds because every warrior knows their position. The SPA asks only for the wall — not for every soldier's name.
code.nochebuena.dev/einherjar/spa-server is a container-first HTTP server for single-page applications and progressive web apps. It serves static assets directly and falls back to index.html for any path that does not resolve to a file on disk — the standard SPA routing contract.
The module ships as a ready-to-use Docker base image. Deploying a SPA to a container requires a single COPY instruction. No nginx, no custom configuration, no index.html redirect logic to maintain.
Container usage
FROM code.nochebuena.dev/einherjar/spa-server:v1.0.0
COPY dist/ /srv/www/
That is the complete Dockerfile for a production SPA container.
Environment variables
| Variable | Default | Description |
|---|---|---|
EINHERJAR_SPA_PORT |
8080 |
TCP port the server listens on |
EINHERJAR_SPA_STATIC_DIR |
/srv/www |
Path to the directory containing index.html and assets |
EINHERJAR_LOG_LEVEL |
INFO |
Log level: DEBUG, INFO, WARN, ERROR |
Health endpoint
GET /health returns 200 OK with a JSON body consistent with all Einherjar health responses:
{"status":"UP","components":{}}
503 Service Unavailable is never returned — if the process is alive, it is healthy. Wire /health directly to your container liveness and readiness probes.
Routing behaviour
| Request | Result |
|---|---|
/app.js — file exists |
Served directly with correct Content-Type |
/assets/logo.png — file exists |
Served directly |
/dashboard — no matching file |
index.html served (SPA router handles it) |
/ — directory |
index.html served (directory listing is disabled) |
Dependency graph
contracts (zero dependencies)
↑
core
↑
spa-server (contracts, core, stdlib only)
No external dependencies beyond the Go standard library.
Verification
cd spa-server/
go build ./...
go vet ./...
go test ./...
gofmt -l .
A shield wall holds because every warrior knows their position. The SPA asks only for the wall — not for every soldier's name.