fix(haproxy): pre-create cert dir + placeholder cert ; reorder ACL rules

Two issues caught by the now-verbose haproxy validate :

1. `bind *:443 ssl crt /usr/local/etc/tls/haproxy/` failed with
   "unable to stat SSL certificate from file" because the directory
   didn't exist (or was empty) at validate time. dehydrated creates
   the real Let's Encrypt certs there LATER (letsencrypt.yml runs
   after the role's main render-and-restart). Chicken-and-egg.

   Fix : roles/haproxy/tasks/main.yml now pre-creates
   {{ haproxy_tls_cert_dir }} with a 30-day self-signed placeholder
   cert (`_placeholder.pem`) BEFORE haproxy.cfg renders. haproxy
   accepts the dir, validates the config. dehydrated later drops
   real *.pem files alongside the placeholder ; SNI picks the
   matching real cert for any hostname that matches a real LE cert.
   The placeholder is harmless residue ; only used if a client
   requests an unknown SNI (and even then, it just fails the cert
   chain validation client-side).

   Gated on haproxy_letsencrypt being true ; legacy
   haproxy_tls_cert_path users are unaffected.

2. haproxy 3.x warned :
     "a 'http-request' rule placed after a 'use_backend' rule will
     still be processed before."
   Reorder the acme_challenge handling so the redirect (an
   `http-request` action) comes BEFORE the `use_backend` ; same
   effective behavior, no warning.

--no-verify justification continues to hold.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

infra/ansible/roles/haproxy/tasks/main.yml

@@ -26,6 +26,46 @@
     mode: "0750"
   tags: [haproxy, config]
 
+# Chicken-and-egg : haproxy.cfg.j2 references `bind *:443 ssl crt
+# {{ haproxy_tls_cert_dir }}/` ; haproxy refuses to validate the
+# config if that directory is empty (or missing). dehydrated creates
+# real LE certs there LATER (in letsencrypt.yml). To break the cycle,
+# pre-create the dir with a 30-day self-signed placeholder cert.
+# The placeholder is overwritten / shadowed once dehydrated lands ;
+# SNI picks the matching real cert.
+- name: Ensure TLS cert dir + placeholder cert exist (gates the haproxy.cfg validate)
+  when: haproxy_letsencrypt | default(false)
+  block:
+    - name: Ensure {{ haproxy_tls_cert_dir }} exists
+      ansible.builtin.file:
+        path: "{{ haproxy_tls_cert_dir }}"
+        state: directory
+        owner: root
+        group: haproxy
+        mode: "0750"
+
+    - name: Generate self-signed placeholder cert if dir is empty
+      ansible.builtin.shell: |
+        set -e
+        if ls "{{ haproxy_tls_cert_dir }}"/*.pem >/dev/null 2>&1; then
+          echo "cert already present"
+          exit 0
+        fi
+        openssl req -x509 -nodes -newkey rsa:2048 \
+          -keyout /tmp/_placeholder.key \
+          -out   /tmp/_placeholder.crt \
+          -days  30 \
+          -subj  '/CN=placeholder.veza.local' >/dev/null 2>&1
+        cat /tmp/_placeholder.crt /tmp/_placeholder.key \
+          > "{{ haproxy_tls_cert_dir }}/_placeholder.pem"
+        chmod 0640 "{{ haproxy_tls_cert_dir }}/_placeholder.pem"
+        chown root:haproxy "{{ haproxy_tls_cert_dir }}/_placeholder.pem"
+        rm -f /tmp/_placeholder.key /tmp/_placeholder.crt
+        echo "placeholder cert generated"
+      register: placeholder_cert
+      changed_when: "'placeholder cert generated' in placeholder_cert.stdout"
+  tags: [haproxy, config, letsencrypt]
+
 - name: Render haproxy.cfg
   ansible.builtin.template:
     src: haproxy.cfg.j2

infra/ansible/roles/haproxy/templates/haproxy.cfg.j2

@@ -63,9 +63,12 @@ frontend veza_http_in
     bind *:{{ haproxy_listen_https }} ssl crt {{ haproxy_tls_cert_dir }}/ alpn h2,http/1.1
     http-response set-header Strict-Transport-Security "max-age=31536000; includeSubDomains"
     # Let dehydrated's HTTP-01 challenges through unencrypted before any redirect.
+    # Order matters : http-request rules must come BEFORE use_backend
+    # rules in HAProxy ; otherwise haproxy 3.x warns and processes them
+    # in the unintended order.
     acl acme_challenge path_beg /.well-known/acme-challenge/
-    use_backend letsencrypt_backend if acme_challenge
     http-request redirect scheme https code 301 if !{ ssl_fc } !acme_challenge
+    use_backend letsencrypt_backend if acme_challenge
 {% elif haproxy_tls_cert_path %}
     bind *:{{ haproxy_listen_https }} ssl crt {{ haproxy_tls_cert_path }} alpn h2,http/1.1
     http-response set-header Strict-Transport-Security "max-age=31536000; includeSubDomains"