Merge ~ballot/charm-telegraf/+git/telegraf-charm:cRT135443 into charm-telegraf:master

[Benjamin Allot]

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

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

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

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[Tianqi Xiao (txiao)]

Thanks for the contribution. This proposed branch broke off from master at commit dec0633e (2021-04-09), which is pretty outdated. Could you please rebase it to the latest master and run tests again?

Please also see my inline comment.

[Tianqi Xiao (txiao)]

review: Needs Fixing

[Robert Gildein (rgildein)]

I don't think we should add new features without unittests and functional tests. Unittests are definitely essential.

[Robert Gildein (rgildein)]

review: Needs Fixing

[Eric Chen (eric-chen)]

Mark this review as WIP until the unit test available.

Unmerged commits

c9af14d... by Benjamin Allot on 2022-04-09

Add charmcraft support

ff1683c... by Benjamin Allot on 2022-04-08

Add cassandra relation

Relation with cassandra will configure a basic tcp check on the
listening address and the native_transport_port of cassandra to check
its readiness.

diff --git a/src/charmcraft.yaml b/src/charmcraft.yaml
new file mode 100644
index 0000000..40922e4
--- /dev/null
+++ b/src/charmcraft.yaml
@@ -0,0 +1,18 @@
+type: "charm"
+bases:
+  - build-on:
+    - name: "ubuntu"
+      channel: "20.04"
+    run-on:
+    - name: "ubuntu"
+      channel: "20.04"
+    - name: "ubuntu"
+      channel: "18.04"
+    - name: "ubuntu"
+      channel: "16.04"
+
+parts:
+  charm:
+    source: .
+    plugin: reactive
+    build-snaps: [charm]
diff --git a/src/metadata.yaml b/src/metadata.yaml
index bb9361d..1844733 100644
--- a/src/metadata.yaml
+++ b/src/metadata.yaml
@@ -77,6 +77,9 @@ requires:
   sentry:
     interface: sentry-metrics
     scope: container
+  cassandra:
+    interface: cassandra-metrics
+    scope: container
 provides:
   dashboards:
     interface: grafana-dashboard
diff --git a/src/reactive/telegraf.py b/src/reactive/telegraf.py
index 00051ca..5f19f26 100644
--- a/src/reactive/telegraf.py
+++ b/src/reactive/telegraf.py
@@ -47,6 +47,7 @@ from charms.reactive import (
     set_flag,
     toggle_flag,
     when,
+    when_any,
     when_not,
 )
 from charms.reactive.bus import get_states
@@ -1913,6 +1914,49 @@ def grafana_dashboard_import_failed():
     clear_flag("grafana.configured")
 
 
+@when_any(
+    "endpoint.cassandra.changed",
+    "endpoint.cassandra.joined")
+@when("telegraf.installed")
+def cassandra_input():
+    template = """
+[[inputs.net_response]]
+  protocol = "tcp"
+  address = "{{ listen_address }}:{{ port }}"
+"""
+    config_path = "{}/{}.conf".format(get_configs_dir(), "cassandra")
+
+    rels = hookenv.relations_of_type("cassandra")
+    if rels:
+        for rel in rels:
+            addr = rel["listen_address"]
+            port = rel["native_transport_port"]
+            input_config = render_template(template, {
+                "listen_address": addr,
+                "port": port,
+            })
+            hookenv.log("Updating {} plugin config file".format("cassandra"))
+            host.write_file(config_path, input_config.encode("utf-8"))
+            set_flag("plugins.cassandra.configured")
+    elif os.path.exists(config_path):
+        os.unlink(config_path)
+        clear_flag("plugins.cassandra.configured")
+
+    set_flag("telegraf.needs_reload")
+
+
+@when_not("cassandra.available")
+@when("plugins.exec.configured")
+def cassandra_input_departed():
+    config_path = "{}/{}.conf".format(get_configs_dir(), "cassandra")
+    rels = hookenv.relations_of_type("cassandra")
+    if not rels:
+        clear_flag("plugins.cassandra.configured")
+        if os.path.exists(config_path):
+            os.unlink(config_path)
+        set_flag("telegraf.needs_reload")
+
+
 @when("telegraf.needs_reload")
 @when("telegraf.installed")
 @when("telegraf.configured")