Merge ~vultaire/charm-grafana:cmr-app-dashboard-titles into charm-grafana:candidate/21.07

[Paul Goins]

Skip "remote-<hash>" remote app names on dashboards

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FAILED: Continuous integration, rev:7e533f6299998ac95ff02def43ad9fdb909229a4

No commit message was specified in the merge proposal. Click on the following link and set the commit message (if you want jenkins to rebuild you need to trigger it yourself):
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https://jenkins.canonical.com/bootstack/job/lp-charm-grafana-ci/33/
Executed test runs:
    FAILURE: https://jenkins.canonical.com/bootstack/job/lp-charm-test-unit-withcompiler/118/
    None: https://jenkins.canonical.com/bootstack/job/lp-update-mp/330/

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review: Needs Fixing (continuous-integration)

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FAILED: Continuous integration, rev:40b7d0e6a7a2848404775f3d88fa727a024e6d4d

No commit message was specified in the merge proposal. Click on the following link and set the commit message (if you want jenkins to rebuild you need to trigger it yourself):
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https://jenkins.canonical.com/bootstack/job/lp-charm-grafana-ci/34/
Executed test runs:
    SUCCESS: https://jenkins.canonical.com/bootstack/job/lp-charm-test-unit-withcompiler/119/
    None: https://jenkins.canonical.com/bootstack/job/lp-update-mp/331/

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review: Needs Fixing (continuous-integration)

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FAILED: Continuous integration, rev:7e533f6299998ac95ff02def43ad9fdb909229a4
https://jenkins.canonical.com/bootstack/job/lp-charm-grafana-ci/35/
Executed test runs:
    FAILURE: https://jenkins.canonical.com/bootstack/job/lp-charm-test-unit-withcompiler/120/
    None: https://jenkins.canonical.com/bootstack/job/lp-update-mp/332/

Click here to trigger a rebuild:
https://jenkins.canonical.com/bootstack/job/lp-charm-grafana-ci/35//rebuild

review: Needs Fixing (continuous-integration)

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A CI job is currently in progress. A follow up comment will be added when it completes.

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PASSED: Continuous integration, rev:40b7d0e6a7a2848404775f3d88fa727a024e6d4d
https://jenkins.canonical.com/bootstack/job/lp-charm-grafana-ci/36/
Executed test runs:
    SUCCESS: https://jenkins.canonical.com/bootstack/job/lp-charm-test-unit-withcompiler/121/
    None: https://jenkins.canonical.com/bootstack/job/lp-update-mp/333/

Click here to trigger a rebuild:
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review: Approve (continuous-integration)

[Celia Wang (ziyiwang)]

lgtm

review: Approve

[Xav Paice (xavpaice)]

lgtm

review: Approve

diff --git a/src/lib/charms/layer/grafana.py b/src/lib/charms/layer/grafana.py
index 009c812..d8fc7b8 100644
--- a/src/lib/charms/layer/grafana.py
+++ b/src/lib/charms/layer/grafana.py
@@ -43,21 +43,38 @@ def get_admin_password():
 
 
 def compute_dash_title(title, remote_app=None):
-    """Compute title for dashboards."""
+    """Compute title for dashboards.
+
+    The returned title will typically be of the form "[<prefix>-<appname>] <title>",
+    although there are some exceptions where the header portion will be shortened or
+    omitted.
+
+    """
     if remote_app is None:
         # "local" / backward compat case -- we don't have a remote app
         return title or "Untitled"
 
     if not title:
         title = remote_app
+
+    prefix = "juju"
+    # For titles with an embedded prefix (e.g. of form "[prefix] title"), extract the
+    # components.
     mat = TITLE_PAT.search(title)
     if mat and len(mat.groups()) == 2:
-        # If the title already is in the form "[xxx] Footitle" enrich
-        # the [xxx] tag with remote_app
-        new_title = "[{}-{}] {}".format(mat.group(1), remote_app, mat.group(2))
-    else:
-        new_title = "[juju-{}] {}".format(remote_app, title)
-    return new_title
+        prefix, title = mat.groups()
+
+    # Header is of form "<prefix>-<app>", unless <app> is not suitable for display for
+    # some reason, in which case we simply use the prefix.
+    header_tokens = [prefix]
+    # Apps seen via cross-model relationships show up with names like
+    # remote-<128-bit hash>; omit the app name in this case.
+    skip_app_name = remote_app.startswith("remote-")
+    if not skip_app_name:
+        header_tokens.append(remote_app)
+    header = "-".join(header_tokens)
+
+    return "[{}] {}".format(header, title)
 
 
 def get_folders():
diff --git a/src/tests/unit/test_grafana.py b/src/tests/unit/test_grafana.py
index 2645b53..663fa17 100644
--- a/src/tests/unit/test_grafana.py
+++ b/src/tests/unit/test_grafana.py
@@ -95,6 +95,9 @@ class GrafanaTestCase(unittest.TestCase):
             ((None, "app"), "[juju-app] app"),
             (("bar", None), "bar"),
             ((None, None), "Untitled"),
+            # Cross-model relation cases (detected via remote-<128-bit hash> names)
+            (("foo", "remote-0123456789abcdef0123456789abcdef"), "[juju] foo"),
+            (("[x] foo", "remote-0123456789abcdef0123456789abcdef"), "[x] foo"),
         )
         for inputs, expect in inputs_expect:
             self.assertEqual(compute_dash_title(*inputs), expect)