Merge charm-grafana:dashboards_joined into charm-grafana:master

[Joe Guo]

add dashboards-joined hook

when relate an operator based charm, e.g.: cloudstats, to grafana, this hook won't trigger:

    @when("grafana.started", "endpoint.dashboards.has_requests")
    @when_not("grafana.change-block")
    def import_dashboards(dashboards):
        ...

So dashboard will not be imported and there is no error.

Add a normal `joined` hook, query relation data directly with key, so operator based
charm can relate to grafana and import dashboard.

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

This merge proposal is being monitored by mergebot. Change the status to Approved to merge.

[Xav Paice (xavpaice)]

We need to add in a @reactive.when_not("is-update-status-hook") otherwise this will fire for every update-status.

Otherwise, +1 from me.

review: Needs Fixing

[Joe Guo (guoqiao)]

change `when` decorators to `@hook("dashboards-relation-joined")`
So it will only be triggered when relation joined.

[Xav Paice (xavpaice)]

lgtm

review: Approve

[Joe Guo (guoqiao)]

tested in local juju env, working as expected.

[Joe Guo (guoqiao)]

NOTE:
the `dashboards` arg is required by the `reactive.hook` decorator, otherwise it raised an error for missing args.
Although it's not used in code and not recommended by doc.

[James Hebden (ec0)]

+1

review: Approve

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

Change successfully merged at revision c632b1fde22240963c81f338208d4d226638045a

diff --git a/src/reactive/grafana.py b/src/reactive/grafana.py
index 553238c..b0a3bff 100644
--- a/src/reactive/grafana.py
+++ b/src/reactive/grafana.py
@@ -1157,6 +1157,31 @@ def ensure_dash_deserialized(dash):
     return dash
 
 
+@hook("dashboards-relation-joined")
+def dashboards_joined(dashboards):
+    hookenv.log("hook %s triggered" % hookenv.hook_name(), "INFO")
+
+    remote_unit = os.environ.get('JUJU_REMOTE_UNIT', None)
+    if not remote_unit:
+        hookenv.log("remote_unit is None, return", "WARNING")
+        return
+
+    dashboard_str = hookenv.relation_get('dashboard', remote_unit)  # json str
+    if not dashboard_str:
+        hookenv.log("dashboard field is empty, return", "WARNING")
+        return
+
+    dashboard = ensure_dash_deserialized(dashboard_str)
+    name = hookenv.relation_get('name', remote_unit)  # dashboard name
+    remote_app = hookenv.remote_service_name()
+
+    success, reason = import_dashboard(dashboard, remote_app=remote_app, name=name)
+    if success:
+        hookenv.log("import_dashboard {} success".format(name), "INFO")
+    else:
+        hookenv.log("import_dashboard {} failed: {}".format(name, reason), "ERROR")
+
+
 @when("grafana.started", "endpoint.dashboards.has_requests")
 @when_not("grafana.change-block")
 def import_dashboards(dashboards):