Use template mechanism of nginx image
diff --git a/nginx/id.sa.conf b/nginx/id.sa.conf
index 9dbac41..b64cc7d 100644
--- a/nginx/id.sa.conf
+++ b/nginx/id.sa.conf
@@ -2,7 +2,7 @@
     listen 443 ssl;
     listen [::]:443 ssl;
 
-    server_name id.miau.local;
+    server_name id.${SA_PUBLIC_DOMAIN_NAME};
 
     location /auth/ {   # Gerrit adds this prefix for Keycloak...
         rewrite ^/auth(.*)$ $1 last;