acme_forward: send services' ACME challenges to Traefik on ops

The XMPP certificate covers xmpp.asxp.io and conference.asxp.io, which
point at asxpio-services, so Let's Encrypt validates them there. A small
nginx on port 80 passes /.well-known/acme-challenge/ over the VPC to
Traefik, which holds all certificates, and answers 404 to the rest.

Assisted-by: Claude:opus-5-5

ansible/inventory/group_vars/all/xmpp_cert.yaml

@@ -0,0 +1,8 @@
+---
+# The XMPP certificate is issued by Traefik on asxpio-ops (HTTP challenge;
+# services forwards its challenges there, role acme_forward) and pushed to
+# ejabberd on asxpio-services on every renewal (role xmpp_cert_sync).
+xmpp_cert_main: xmpp.asxp.io
+xmpp_cert_sans: [asxp.io, conference.asxp.io]
+# renovate: datasource=docker depName=nginx
+acme_forward_nginx_version: "1.31.8-alpine-slim"

ansible/roles/acme_forward/tasks/main.yaml

@@ -0,0 +1,14 @@
+---
+# Port 80 on asxpio-services exists only for Let's Encrypt: HTTP challenges
+# for names pointing here (xmpp., conference.) go to Traefik on ops, which
+# holds the certificates. Anything else gets a 404.
+- name: Deploy the ACME challenge forwarder
+  ansible.builtin.include_role:
+    name: docker_service
+  vars:
+    service_name: acme-forward
+    service_base_path: "{{ services_base_path }}/acme-forward"
+    service_templates:
+      - { src: docker-compose.yml.j2, dest: docker-compose.yml }
+      - { src: nginx.conf.j2, dest: nginx.conf }
+    health_check_port: 80

ansible/roles/acme_forward/templates/docker-compose.yml.j2

@@ -0,0 +1,11 @@
+# Managed by Ansible (role acme_forward).
+services:
+  acme-forward:
+    image: nginx:{{ acme_forward_nginx_version }}
+    container_name: acme-forward
+    ports:
+      - "80:80"
+    volumes:
+      - ./nginx.conf:/etc/nginx/conf.d/default.conf:ro
+    restart: unless-stopped
+    mem_limit: 32m

ansible/roles/acme_forward/templates/nginx.conf.j2

@@ -0,0 +1,16 @@
+# Managed by Ansible (role acme_forward).
+server {
+    listen 80 default_server;
+    listen [::]:80 default_server;
+    server_tokens off;
+    access_log off;
+
+    location /.well-known/acme-challenge/ {
+        proxy_pass http://{{ asxpio_ops_vpc_ip }};
+        proxy_set_header Host $host;
+    }
+
+    location / {
+        return 404;
+    }
+}

ansible/site.yaml

@@ -35,6 +35,7 @@
     - { role: sillytavern, tags: [sillytavern] }
     - { role: minecraft, tags: [minecraft] }
     - { role: xmpp, tags: [xmpp] }
+    - { role: acme_forward, tags: [acme_forward, xmpp] }
     - { role: xray, tags: [xray] }
 
 # Late: restarting Forgejo briefly cuts the runner off from its job log