Use AuthMethod context

Rather than use hard coded auth methods, use the protocal named passed
over the keystone-fid-service-provider relation.

Also, when using federation do not allow the "external" method as they
are mutually exclusive.

Change-Id: I08f0632630d7f0e8d2d7ddb057e02f9febf9ad6f
Closes-Bug: #1828015
Closes-Bug: #1828018

hooks/keystone_context.py

@@ -343,3 +343,26 @@ class WebSSOTrustedDashboardContext(context.OSContextGenerator):
         ctxt = ({'trusted_dashboards': trusted_dashboards}
                 if trusted_dashboards else {})
         return ctxt
+
+
+class AuthMethods(context.OSContextGenerator):
+
+    auth_methods = ["external", "password", "token", "oauth1",
+                    "openid", "totp", "application_credential"]
+
+    def __call__(self):
+
+        _external = "external"
+        _protocol_name = ""
+        for rid in relation_ids("keystone-fid-service-provider"):
+            for unit in related_units(rid):
+                rdata = relation_get(unit=unit, rid=rid)
+                _protocol_name = rdata.get('protocol-name').strip('"')
+                if _protocol_name and _protocol_name not in self.auth_methods:
+                    self.auth_methods.append(_protocol_name)
+                    # We are federated so remove the external method
+                    if _external in self.auth_methods:
+                        self.auth_methods.remove(_external)
+
+        ctxt = {"auth_methods": ",".join(self.auth_methods)}
+        return ctxt

hooks/keystone_utils.py

@@ -239,7 +239,8 @@ BASE_RESOURCE_MAP = OrderedDict([
                          interface=['keystone-middleware'],
                          service='keystone',
                          config_file=KEYSTONE_CONF),
-                     keystone_context.MiddlewareContext()]
+                     keystone_context.MiddlewareContext(),
+                     keystone_context.AuthMethods()]
     }),
     (KEYSTONE_LOGGER_CONF, {
         'contexts': [keystone_context.KeystoneLoggingContext()],

templates/queens/keystone.conf

@@ -73,7 +73,7 @@ driver = {{ assignment_backend }}
 {% include "parts/section-middleware" %}
 {% else %}
 [auth]
-methods = external,password,token,oauth1,mapped,openid,totp,application_credential
+methods = {{ auth_methods }}
 password = keystone.auth.plugins.password.Password
 token = keystone.auth.plugins.token.Token
 oauth1 = keystone.auth.plugins.oauth1.OAuth

templates/rocky/keystone.conf

@@ -58,7 +58,7 @@ driver = sql
 driver = {{ assignment_backend }}
 
 [auth]
-methods = external,password,token,oauth1,mapped,openid,totp,application_credential
+methods = {{ auth_methods }}
 
 [paste_deploy]
 config_file = {{ paste_config_file }}