Change logic for plugins in grafana image build

Co-authored-by:  Will Szumski <will@stackhpc.com>
Change-Id: I2b1c95395aeefb2ccb1d8edf415eee0f98c52190

doc/source/admin/image-building.rst

@@ -298,6 +298,23 @@ To remove a package from that list, say ``locales``, one would do:
    # Horizon
    {% set horizon_packages_remove = ['locales'] %}
 
+An example of this is the Grafana plugins, which are mentioned in the next
+section.
+
+Grafana plugins
+^^^^^^^^^^^^^^^
+
+Additional Grafana plugins can be installed by adding the plugin name to the
+``grafana_plugins_append`` list. Plugins can also be removed by adding the
+plugin name to the ``grafana_plugins_remove`` list. Additionally the entire
+list can be overridden by setting the ``grafana_plugins_override`` variable.
+
+.. code-block:: ini
+
+   grafana_plugins_append:
+      - grafana-piechart-panel
+      - vonage-status-panel
+
 Python packages build options
 -----------------------------
 
@@ -401,6 +418,7 @@ Some of these plugins used to be enabled by default but, due to
 their release characteristic, have been excluded from the default builds.
 Please read the included ``README.rst`` to learn how to apply them.
 
+
 Additions functionality
 -----------------------
 

docker/grafana/Dockerfile.j2

@@ -22,9 +22,12 @@ COPY extend_start.sh /usr/local/bin/kolla_extend_start
 
 {% block grafana_plugins_install %}
 
-RUN grafana-cli plugins install gnocchixyz-gnocchi-datasource \
+{% set grafana_default_plugins = ['gnocchixyz-gnocchi-datasource', 'grafana-opensearch-datasource']  %}
-    && grafana-cli plugins install grafana-opensearch-datasource
+{% set grafana_plugins =  grafana_default_plugins | customizable("plugins") %}
 
+{% if grafana_plugins | length > 0 %}
+RUN {{ (['grafana-cli plugins install %s'] * grafana_plugins | length ) | join(' && ') | format(*grafana_plugins) }}
+{% endif %}
 {% endblock %}
 
 RUN chmod 750 /etc/sudoers.d \

releasenotes/notes/merge-grafana-plugins-b9a837b9fccff691.yaml

@@ -0,0 +1,8 @@
+---
+features:
+  - |
+    New logic for installing grafana plugins. When building you can pass a
+    variable ``grafana_plugins_append`` that contains a list of plugins you
+    want to install. This will be appended to the default list of plugins. The
+    existing method of overwriting the ``grafana_plugins_install`` block still
+    works.