Adding extra_sans option to load balancer to allow custom SAN entries on the certificate

cluster/juju/layers/kubeapi-load-balancer/config.yaml

@@ -3,3 +3,9 @@ options:
     type: int
     default: 443
     description: The port to run the loadbalancer
+  extra_sans:
+    type: string
+    default: ""
+    description: |
+      Space-separated list of extra SAN entries to add to the x509 certificate
+      created for the load balancers.

cluster/juju/layers/kubeapi-load-balancer/reactive/load_balancer.py

@@ -22,7 +22,9 @@ from charms import layer
 from charms.reactive import when, when_any, when_not
 from charms.reactive import set_state, remove_state
 from charmhelpers.core import hookenv
+from charmhelpers.core import host
 from charmhelpers.contrib.charmsupport import nrpe
+from charms.reactive.helpers import data_changed
 
 from charms.layer import nginx
 
@@ -44,12 +46,36 @@ def request_server_certificates(tls):
         hookenv.unit_private_ip(),
         socket.gethostname(),
     ]
+    # maybe they have extra names they want as SANs
+    extra_sans = hookenv.config('extra_sans')
+    if extra_sans and not extra_sans == "":
+      sans.extend(extra_sans.split())
     # Create a path safe name by removing path characters from the unit name.
     certificate_name = hookenv.local_unit().replace('/', '_')
     # Request a server cert with this information.
     tls.request_server_cert(common_name, sans, certificate_name)
 
 
+@when('config.changed.extra_sans', 'certificates.available')
+def update_certificate(tls):
+    # Using the config.changed.extra_sans flag to catch changes.
+    # IP changes will take ~5 minutes or so to propagate, but
+    # it will update.
+    request_server_certificates(tls)
+
+
+@when('certificates.server.cert.available',
+      'nginx.available', 'tls_client.server.certificate.written')
+def kick_nginx(tls):
+    # we are just going to sighup it, but still want to avoid kicking it
+    # without need
+    if data_changed('cert', tls.get_server_cert()):
+        # certificate changed, so sighup nginx
+        hookenv.log("Certificate information changed, sending SIGHUP to nginx")
+        host.service_restart('nginx')
+    remove_state('tls_client.server.certificate.written')
+
+
 @when('config.changed.port')
 def close_old_port():
     config = hookenv.config()

cluster/juju/layers/kubernetes-master/reactive/kubernetes_master.py

@@ -469,17 +469,17 @@ def send_data(tls):
     tls.request_server_cert(common_name, sans, certificate_name)
 
 
-@when('config.changed', 'certificates.available')
+@when('config.changed.extra_sans', 'certificates.available')
 def update_certificate(tls):
-    # I using the config.changed flag instead of something more
-    # specific to try and catch ip changes. Being a little
-    # spammy here is ok because the cert layer checks for
-    # changes to the cert before issuing a new one
+    # Using the config.changed.extra_sans flag to catch changes.
+    # IP changes will take ~5 minutes or so to propagate, but
+    # it will update.
     send_data(tls)
 
 
 @when('certificates.server.cert.available',
-      'kubernetes-master.components.started')
+      'kubernetes-master.components.started',
+      'tls_client.server.certificate.written')
 def kick_api_server(tls):
     # need to be idempotent and don't want to kick the api server
     # without need
@@ -487,6 +487,7 @@ def kick_api_server(tls):
         # certificate changed, so restart the api server
         hookenv.log("Certificate information changed, restarting api server")
         set_state('kube-apiserver.do-restart')
+    remove_state('tls_client.server.certificate.written')
 
 
 @when('kubernetes-master.components.started')