Completely redo how mxisd configuration gets generated

This change is provoked by a few different things:

- #54 (Github Pull Request), which rightfully says that we need a
way to support ALL mxisd configuration options easily

- the upcoming mxisd 1.3.0 release, which drops support for
property-style configuration (dot-notation), forcing us to
redo the way we generate the configuration file

With this, mxisd is much more easily configurable now
and much more easily maintaneable by us in the future
(no need to introduce additional playbook variables and logic).

roles/matrix-server/defaults/main.yml

@@ -239,44 +239,73 @@ matrix_mxisd_data_path: "{{ matrix_mxisd_base_path }}/data"
 matrix_mxisd_matrixorg_forwarding_enabled: false
 
 # mxisd has serveral supported identity stores.
-# One of them is storing identities directly in Synapse's database.
+# One of them (which we enable by default) is storing identities directly in Synapse's database.
 # Learn more here: https://github.com/kamax-matrix/mxisd/blob/master/docs/stores/synapse.md
+#
+# If you need to disable this in favor of some other store, you can toggle it to disabled here
+# and add your own mxisd configuration for the other store in `matrix_mxisd_configuration_extension_yaml`.
 matrix_mxisd_synapsesql_enabled: true
 matrix_mxisd_synapsesql_type: postgresql
 matrix_mxisd_synapsesql_connection: //{{ matrix_postgres_connection_hostname }}/{{ matrix_postgres_db_name }}?user={{ matrix_postgres_connection_username }}&password={{ matrix_postgres_connection_password }}
 
-# LDAP is another identity store that's supported by mxisd.
-# Learn more here: https://github.com/kamax-matrix/mxisd/blob/master/docs/stores/ldap.md
-matrix_mxisd_ldap_enabled: false
-matrix_mxisd_ldap_connection_host: ldapHostnameOrIp
-matrix_mxisd_ldap_connection_tls: false
-matrix_mxisd_ldap_connection_port: 389
-matrix_mxisd_ldap_connection_baseDns: ['OU=Users,DC=example,DC=org']
-matrix_mxisd_ldap_connection_bindDn: CN=My Mxisd User,OU=Users,DC=example,DC=org
-matrix_mxisd_ldap_connection_bindPassword: TheUserPassword
-# The following keys are optional:
-# matrix_mxisd_ldap_filter: ""
-# matrix_mxisd_ldap_attribute_uid_type: uid
-# matrix_mxisd_ldap_attribute_uid_value: sAMAccountName
-# matrix_mxisd_ldap_attribute_name: cn
-# matrix_mxisd_ldap_attribute_threepid_email:
-#   - mail
-#   - otherMailAttribute
-# matrix_mxisd_ldap_attribute_threepid_msisdn:
-#   - phone
-#   - otherPhoneAttribute
-# matrix_mxisd_ldap_identity_filter: ""
-# matrix_mxisd_ldap_identity_medium: ""
-# matrix_mxisd_ldap_auth_filter: ""
-# matrix_mxisd_ldap_directory_filter: ""
+# Default mxisd configuration template which covers the generic use case.
+# You can customize it by controlling the various variables inside it.
+#
+# For a more advanced customization, you can extend the default (see `matrix_mxisd_configuration_extension_yaml`)
+# or completely replace this variable with your own template.
+matrix_mxisd_configuration_yaml: |
+  matrix:
+    domain: {{ hostname_identity }}
 
+  server:
+    name: {{ hostname_matrix }}
 
-# Specifies which template files to use when configuring mxisd.
-# If you'd like to have your own different configuration, feel free to copy and paste
-# the original files into your inventory (e.g. in `inventory/host_vars/<host>/`)
-# and then change the specific host's `vars.yaml` file like this:
-# matrix_mxisd_template_config: "{{ playbook_dir }}/inventory/host_vars/<host>/mxisd.yaml.j2"
-matrix_mxisd_template_config: "{{ role_path }}/templates/mxisd/mxisd.yaml.j2"
+  key:
+    path: /var/mxisd/sign.key
+
+  storage:
+    provider:
+      sqlite:
+        database: /var/mxisd/mxisd.db
+
+  {% if matrix_mxisd_matrixorg_forwarding_enabled %}
+  forward:
+    servers: ['matrix-org']
+  {% endif %}
+
+  synapseSql:
+    enabled: {{ matrix_mxisd_synapsesql_enabled }}
+    type: {{ matrix_mxisd_synapsesql_type }}
+    connection: {{ matrix_mxisd_synapsesql_connection }}
+
+matrix_mxisd_configuration_extension_yaml: |
+  # Your custom YAML configuration for mxisd goes here.
+  # This configuration extends the default starting configuration (`matrix_mxisd_configuration_yaml`).
+  #
+  # You can override individual variables from the default configuration, or introduce new ones.
+  #
+  # If you need something more special, you can take full control by
+  # completely redefining `matrix_mxisd_configuration_yaml`.
+  #
+  # Example configuration extension follows:
+  #
+  # ldap:
+  #   enabled: true
+  #   connection:
+  #     host: ldapHostnameOrIp
+  #     tls: false
+  #     port: 389
+  #     baseDns: ['OU=Users,DC=example,DC=org']
+  #     bindDn: CN=My Mxisd User,OU=Users,DC=example,DC=org
+  #     bindPassword: TheUserPassword
+
+# Doing `|from_yaml` when the extension contains nothing yields an empty string ("").
+# We need to ensure it's a dictionary or `|combine` (when building `matrix_mxisd_configuration`) will fail later.
+matrix_mxisd_configuration_extension: "{{ matrix_mxisd_configuration_extension_yaml|from_yaml if matrix_mxisd_configuration_extension_yaml|from_yaml else {} }}"
+
+# Holds the final mxisd configuration (a combination of the default and its extension).
+# You most likely don't need to touch this variable. Instead, see `matrix_mxisd_configuration_yaml`.
+matrix_mxisd_configuration: "{{ matrix_mxisd_configuration_yaml|from_yaml|combine(matrix_mxisd_configuration_extension, recursive=True) }}"
 
 
 # Enable this to add support for matrix-corporal.