Update README.md

README.md

@@ -41,17 +41,43 @@ The build output is **static files** - no application server, no socket, nothing
 for nginx to proxy to. The app does all its work in the browser, which is why
 upstream can live on GitHub Pages.
 
-One-time setup on the server:
+One-time setup on the server. It is in two stages because of a chicken and egg:
+the real config names a certificate, and nginx refuses to load a config whose
+certificate does not exist yet - so nginx first comes up on port 80 only, just
+far enough for certbot to answer the challenge there.
 
 ```sh
-sudo mkdir -p /var/www/brevyscribe
+sudo mkdir -p /var/www/brevyscribe /var/www/certbot
 sudo chown "$USER" /var/www/brevyscribe
-sudo cp deploy/nginx-scribe.luxick.de.conf /etc/nginx/sites-available/scribe.luxick.de
+
+# Stage 1: HTTP only, so nginx starts without a certificate.
+sudo tee /etc/nginx/sites-available/scribe.luxick.de >/dev/null <<'EOF'
+server {
+	listen 80;
+	listen [::]:80;
+	server_name scribe.luxick.de;
+	location /.well-known/acme-challenge/ { root /var/www/certbot; }
+}
+EOF
 sudo ln -s /etc/nginx/sites-available/scribe.luxick.de /etc/nginx/sites-enabled/
+sudo nginx -t && sudo systemctl reload nginx
+
 sudo certbot --nginx -d scribe.luxick.de
+
+# Stage 2: the real config, now that the certificate is on disk.
+sudo cp deploy/nginx-scribe.luxick.de.conf /etc/nginx/sites-available/scribe.luxick.de
 sudo nginx -t && sudo systemctl reload nginx
 ```
 
+`certonly --webroot` rather than `--nginx`: the config already carries its own
+redirect and TLS block, and the nginx plugin would rewrite the installed file,
+leaving it drifted from the one in the repo. The port 80 block keeps its
+`acme-challenge` location for exactly this reason, so renewals go on working
+unattended - but certbot's timer will not reload nginx by itself, so drop a
+one-line hook in `/etc/letsencrypt/renewal-hooks/deploy/` that runs
+`systemctl reload nginx`, or a renewed certificate will not be served until the
+next restart.
+
 Then every deploy is one command from a checkout on your own machine - it runs
 the tests, builds, and rsyncs `dist/` over. The server needs no Node.