Add support for backup LDAP servers (#2650)

* Update homeserver.yaml.j2

* Update configuring-playbook-ldap-auth.md

* Update homeserver.yaml.j2

docs/configuring-playbook-ldap-auth.md

@@ -8,7 +8,9 @@ If you decide that you'd like to let this playbook install it for you, you need
 
 ```yaml
 matrix_synapse_ext_password_provider_ldap_enabled: true
-matrix_synapse_ext_password_provider_ldap_uri: "ldap://ldap.mydomain.tld:389"
+matrix_synapse_ext_password_provider_ldap_uri: 
+  - "ldap://ldap-01.mydomain.tld:389"
+  - "ldap://ldap-02.mydomain.tld:389"
 matrix_synapse_ext_password_provider_ldap_start_tls: true
 matrix_synapse_ext_password_provider_ldap_base: "ou=users,dc=example,dc=com"
 matrix_synapse_ext_password_provider_ldap_attributes_uid: "uid"

roles/custom/matrix-synapse/templates/synapse/homeserver.yaml.j2

@@ -2515,7 +2515,7 @@ password_providers:
     config:
       enabled: true
       mode: {{ matrix_synapse_ext_password_provider_ldap_mode | string | to_json }}
-      uri: {{ matrix_synapse_ext_password_provider_ldap_uri | string|to_json }}
+      uri: {{ matrix_synapse_ext_password_provider_ldap_uri | to_json }}
       start_tls: {{ matrix_synapse_ext_password_provider_ldap_start_tls|to_json }}
       base: {{ matrix_synapse_ext_password_provider_ldap_base | string|to_json }}
       active_directory: {{ matrix_synapse_ext_password_provider_ldap_active_directory|to_json }}