roles/dch-proxy: Deploy reverse HTTP/HTTPS proxy

The *dch-proxy* role sets up HAProxy to provide a revers proxy for all
public-facing web services on the Pyrocufflink network. It uses the TLS
Server Name Indication (SNI) extension to determine the proper backend
server based on the name requested by the client.

For now, only Gitea is configured; the name *git.pyrocufflink.blue* is
proxied to *git0.pyrocufflink.blue*. All other names are proxied to
Myala.

roles/dch-proxy/tasks/main.yml

@@ -0,0 +1,20 @@
+- name: ensure main haproxy frontend is configured
+  template:
+    src=frontend-main.haproxy.cfg.j2
+    dest=/etc/haproxy/50-frontend-main.cfg
+    mode=0644
+  notify: reload haproxy
+
+- name: ensure default haproxy backend is configured
+  template:
+    src=backend-myala.haproxy.cfg.j2
+    dest=/etc/haproxy/70-backend-myala.cfg
+    mode=0644
+  notify: reload haproxy
+
+- name: ensure gitea haproxy backend is configured
+  template:
+    src=backend-gitea.haproxy.cfg.j2
+    dest=/etc/haproxy/70-backend-gitea.cfg
+    mode=0644
+  notify: reload haproxy