Round robin on all haproxy backup servers for blue-green deploys.

ansible/playbooks/deploy_app.yml

@@ -5,6 +5,7 @@
   # serial: "50%"
   vars_files:
     - ../env_vars/base.yml
+    - roles/letsencrypt/defaults/main.yml
   vars:
     haproxy_host: "{{ 'hstaging' if 'staging' in inventory_hostname else 'hwww' }}"
 
@@ -232,6 +233,7 @@
 
     - name: Update HAProxy config to use new server
       delegate_to: "{{ haproxy_host }}"
+      run_once: true
       block:
         - name: Generate temporary HAProxy config with new server
           template:

docker/haproxy/haproxy.consul.cfg.j2

@@ -103,6 +103,8 @@ backend nginx
     {% endfor %}
 
 backend app_django
+    balance roundrobin
+    option allbackups
     option httpchk GET /_haproxychk
     default-server check inter 1000ms on-error mark-down fall 2 rise 2 resolvers consul resolve-prefer ipv4 resolve-opts allow-dup-ip init-addr none
     {% for host in groups.hdjango %}
@@ -115,6 +117,7 @@ backend app_django
 
 backend app_count
     balance roundrobin
+    option allbackups
     option httpchk GET /_haproxychk
     default-server check inter 1000ms on-error mark-down fall 2 rise 2 resolvers consul resolve-prefer ipv4 resolve-opts allow-dup-ip init-addr none
     {% for host in groups.hcount %}
@@ -128,6 +131,7 @@ backend app_count
     
 backend app_refresh
     balance roundrobin
+    option allbackups
     option httpchk GET /_haproxychk
     default-server check inter 2000ms on-error mark-down fall 2 rise 2 resolvers consul resolve-prefer ipv4 resolve-opts allow-dup-ip init-addr none
     {% for host in groups.hrefresh %}
@@ -141,6 +145,7 @@ backend app_refresh
 
 backend app_push
     balance roundrobin
+    option allbackups
     option httpchk GET /_haproxychk
     default-server check inter 2000ms resolvers consul resolve-prefer ipv4 resolve-opts allow-dup-ip init-addr none
     {% for host in groups.hpush %}