diff --git a/defaults/main.yml b/defaults/main.yml
index 65d4b86..ba2141e 100644
--- a/defaults/main.yml
+++ b/defaults/main.yml
@@ -16,7 +16,7 @@
 # .. envvar:: checkmk_server__version
 #
 # Check_MK software version.
-checkmk_server__version: '1.2.8p16'
+checkmk_server__version: '1.2.8p20'
 
 
 # .. envvar:: checkmk_server__version_suffix
@@ -460,6 +460,7 @@ checkmk_server__site_config_map: '{{ checkmk_server__site_cfg_contactgroups +
                                      checkmk_server__site_cfg_servicegroups +
                                      checkmk_server__site_cfg_datasource_programs +
                                      checkmk_server__site_cfg_netif_description +
+                                     checkmk_server__site_cfg_notification_defaults +
                                      checkmk_server__site_cfg_software_inventory }}'
 
 
@@ -486,7 +487,7 @@ checkmk_server__contact_defaults:
 checkmk_server__site_cfg_contactgroups:
   - name: 'define_contactgroups'
     value:
-      all: 'Everybody'
+      all: 'Everything'
 
 
 # .. envvar:: checkmk_server__site_cfg_rules
@@ -565,6 +566,20 @@ checkmk_server__site_cfg_software_inventory:
                     else "absent" }}'
 
 
+# .. envvar:: checkmk_server__site_cfg_notification_defaults
+#
+# Set fallback email address for rule based notifications. Must be set
+# including domain otherwise it won't be accepted by Check_MK.
+checkmk_server__site_cfg_notification_defaults:
+  - name: 'notification_fallback_email'
+    filename: 'global.mk'
+    template: 'key_value'
+    value: '{{ ansible_local.core.admin_public_email[0]
+               if ("core" in ansible_local) and
+                  ("admin_public_email" in ansible_local.core)
+               else "root@" + ansible_domain }}'
+
+
 # .. envvar:: checkmk_server__site_cfg_netif_description
 #
 # Set interface name instead of index for network interface check via
@@ -577,6 +592,13 @@ checkmk_server__site_cfg_netif_description:
     wato: False
 
 
+# .. envvar:: checkmk_server__site_packages
+#
+# Additional Check_MK packages (MKP) to be installed. See
+# :ref:`checkmk_server__site_packages` for more information.
+checkmk_server__site_packages: []
+
+
 # -----------------
 # PKI Configuration
 # -----------------
diff --git a/docs/defaults-configuration.rst b/docs/defaults-configuration.rst
index 24b3561..b40a425 100644
--- a/docs/defaults-configuration.rst
+++ b/docs/defaults-configuration.rst
@@ -56,6 +56,40 @@ following keys:
   key set with ``privatekey_file``.
 
 
+.. _checkmk_server__site_packages:
+
+checkmk_server__site_packages
+-----------------------------
+
+Check_MK has a plugin system where site customizations such as additional
+checks can be installed. This is done via ``.mkp`` packages. For more
+information see the upstream documentation about `Check_MK extension packages`_.
+
+.. _Check_MK extension packages: https://mathias-kettner.com/cms_mkps.html
+
+Packages which should be installed for the current Check_MK site are defined
+as a list of YAML dictionaries with the following configuration keys. One of
+``path`` or ``url`` must be given:
+
+``name``
+  Name of the package, required.
+
+``path``
+  Optional. Local file system path of the ``.mkp`` package archive on the
+  Ansible controller. Cannot be combined with the ``url`` parameter.
+
+``url``
+  Optional. Download URL of the ``.mkp`` package archive. Cannot be combined
+  with the ``path`` parameter.
+
+``checksum``
+  Optional. Checksum of the download archive given in the ``url`` parameter.
+  Cannot be combined with the ``path`` parameter. For the accepted parameter
+  format check the Ansible `get_url module`_ documentation.
+
+.. _get_url module: https://docs.ansible.com/ansible/get_url_module.html#options
+
+
 .. _checkmk_server__multisite_users:
 
 checkmk_server__multisite_users
diff --git a/docs/getting-started.rst b/docs/getting-started.rst
index 11da33f..0d451b9 100644
--- a/docs/getting-started.rst
+++ b/docs/getting-started.rst
@@ -52,3 +52,6 @@ Available role tags:
 
 ``role::checkmk_server:multisite``
   Execute tasks which configure the Check_MK multisite Web interface.
+
+``role::checkmk_server:mkp``
+  Execute tasks to install Check_MK packages.
diff --git a/tasks/wato.yml b/tasks/wato.yml
index 4f8242d..e01e06f 100644
--- a/tasks/wato.yml
+++ b/tasks/wato.yml
@@ -3,6 +3,50 @@
 # Check_MK multisite/WATO configuration
 #
 
+- name: Query installed Check_MK packages
+  command: mkp list
+  become_user: '{{ checkmk_server__user }}'
+  become_flags: '-i'
+  changed_when: False
+  always_run: True
+  register: checkmk_server__register_mkp
+  tags:
+    - 'role::checkmk_server:mkp'
+
+- name: Download Check_MK packages
+  get_url:
+    url: '{{ item.url }}'
+    dest: '{{ checkmk_server__site_home }}/tmp'
+    checksum: '{{ item.checksum|d(omit) }}'
+  when: ('url' in item) and
+        (item.name not in checkmk_server__register_mkp.stdout_lines)
+  register: checkmk_server__register_mkp_download
+  with_items: '{{ checkmk_server__site_packages }}'
+  tags:
+    - 'role::checkmk_server:mkp'
+
+- name: Upload Check_MK packages
+  copy:
+    src: '{{ item.path }}'
+    dest: '{{ checkmk_server__site_home }}/tmp'
+  when: ('path' in item) and
+        (item.name not in checkmk_server__register_mkp.stdout_lines)
+  register: checkmk_server__register_mkp_upload
+  with_items: '{{ checkmk_server__site_packages }}'
+  tags:
+    - 'role::checkmk_server:mkp'
+
+- name: Install Check_MK packages
+  command: mkp install '{{ item.dest|d() }}'
+  become_user: '{{ checkmk_server__user }}'
+  become_flags: '-i'
+  when: not (item | skipped)
+  with_flattened:
+    - '{{ checkmk_server__register_mkp_download.results }}'
+    - '{{ checkmk_server__register_mkp_upload.results }}'
+  tags:
+    - 'role::checkmk_server:mkp'
+
 - name: Generate Check_MK WATO multisite definitions
   template:
     src: '{{ lookup("template_src", "etc/check_mk/multisite.d/wato/" + item | basename) }}'
diff --git a/templates/macros/checkmk_config.j2 b/templates/macros/checkmk_config.j2
index d95a3cb..5033af9 100644
--- a/templates/macros/checkmk_config.j2
+++ b/templates/macros/checkmk_config.j2
@@ -120,7 +120,7 @@
 
 {% macro tmpl_var__key_value(_name, _value) %}
 
-{{ _name }} = {{ _value }}
+{{ _name }} = {{ "'" + _value + "'" if (_value is string) else _value }}
 {% endmacro %}
 
 
@@ -305,11 +305,12 @@ if {{ _name }} == None:
 {%   set _rule = "'" + _value + "'" %}
 {% elif (_value is mapping) or (_value is sequence) %}
 {#
- #   Remove unicode hints for dictionary keys.
+ #   Remove unicode hints for dictionary keys and values.
  #   Substitute lists with tuples: ['foo', 'bar'] -> ('foo', 'bar')
  #   Fix nested lists: ({'foo': (bar)}) -> ('foo', ('bar'))
  #}
 {%   set _rule = _value | regex_replace("(, |{)u'", "\\1'") |
+                          regex_replace(": u'", ": '") |
                           replace("[", "(") | replace("]", ")") |
                           regex_replace("\({('[\w]+'):", "(\\1,") | replace(")})", "))") %}
 {% else %}
diff --git a/tests/reference.mk b/tests/reference.mk
index 4d88eea..02c6687 100644
--- a/tests/reference.mk
+++ b/tests/reference.mk
@@ -85,3 +85,8 @@ checkgroup_parameters.setdefault('threads', [])
 checkgroup_parameters['threads'] = [
   ( (4000, 8000), ['physical', ], ALL_HOSTS, {'description': u'Physical servers need to handle a lot of threads'} ),
 ] + checkgroup_parameters['threads']
+
+
+custom_checks = [
+  ( {'service_description': u'Galera Cluster', 'command_line': '$USER1$/check_by_ssh -t 60 -E -H $HOSTADDRESS$ -C "sudo /usr/lib64/nagios/plugins/check_galera_cluster -c 1"'}, [], ['mysql01.example.com', 'mysql02.example.com'] ),
+]
diff --git a/tests/test_templates.yml b/tests/test_templates.yml
index e719a7c..74b451a 100644
--- a/tests/test_templates.yml
+++ b/tests/test_templates.yml
@@ -123,6 +123,16 @@
         value: [ 4000, 8000 ]
         tags: [ 'physical' ]
         description: 'Physical servers need to handle a lot of threads'
+      # custom_checks
+      - name: 'custom_checks'
+        filename: 'rules.mk'
+        template: 'rule'
+        value:
+          service_description: 'Galera Cluster'
+          command_line: '$USER1$/check_by_ssh -t 60 -E -H $HOSTADDRESS$ -C "sudo /usr/lib64/nagios/plugins/check_galera_cluster -c 1"'
+        hosts:
+          - 'mysql01.example.com'
+          - 'mysql02.example.com'
 
   tasks:
     - template:
diff --git a/vars/main.yml b/vars/main.yml
index 519d222..ebbddad 100644
--- a/vars/main.yml
+++ b/vars/main.yml
@@ -37,6 +37,9 @@ checkmk_server__confd_variable_map:
   checkgroup_parameters:
     filename: 'rules.mk'
     template: 'rule_w_default'
+  custom_checks:
+    filename: 'rules.mk'
+    template: 'rule'
   datasource_programs:
     filename: 'rules.mk'
     template: 'rule'