Merge ~gnuoy/charm-grafana:embedded into charm-grafana:master

[Liam Young]

Expose allow_embedding config option.

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

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

[James Troup (elmo)]

Aren't we going to run into issues with the Grafana dashboard rarely being deployed with TLS? Also, are you in a rush to get this rolled out? We're currently in branch freeze for the 21.07 legacy-LMA release...

[Paul Goins (vultaire)]

Looks fine, approving, but not merging at this point. (2nd review needed, plus elmo's point stands as well.)

review: Approve

[Liam Young (gnuoy)]

> Aren't we going to run into issues with the Grafana dashboard rarely being
> deployed with TLS?

Yes, we are. But given TLS will be mandatory for the ceph-dashboard the choice is either users unblock mixed http/https content in their browser or enable SSL/TLS support in Grafana. fwiw SSL/TLS support for grafana is addresses here:

https://code.launchpad.net/~gnuoy/charm-grafana/+git/charm-grafana/+merge/404961
https://code.launchpad.net/~freyes/charm-grafana/+git/charm-grafana/+merge/397611

> Also, are you in a rush to get this rolled out? We're
> currently in branch freeze for the 21.07 legacy-LMA release...

Definitely can wait till after 21.07 legacy-LMA release.

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

Change successfully merged at revision fd58b297d4c740fe8d82be024ccb26138155769a

diff --git a/src/config.yaml b/src/config.yaml
index 69d0116..190dc1c 100644
--- a/src/config.yaml
+++ b/src/config.yaml
@@ -198,3 +198,8 @@ options:
     type: string
     description: \
         Name for the network which hosts the Public IP address space.
+  allow_embedding:
+    default: False
+    type: boolean
+    description: \
+        If false the Grafana HTTP responses will instruct browsers to not allow rendering Grafana in a <frame>, <iframe>, <embed> or <object>.
diff --git a/src/templates/grafana.ini.j2 b/src/templates/grafana.ini.j2
index 06278fc..77280c8 100644
--- a/src/templates/grafana.ini.j2
+++ b/src/templates/grafana.ini.j2
@@ -93,6 +93,10 @@ google_analytics_ua_id = {{ config.google_analytics_ua_id }}
 
 #################################### Security ####################################
 [security]
+{% if config['allow_embedding'] -%}
+allow_embedding = true
+{% endif %}
+
 # default admin user, created on startup
 ;admin_user = admin