Merge ~npochet/charm-telegraf:add-socket-port into ~telegraf-charmers/charm-telegraf:master

[Nicolas Pochet]

Add socket_listener_port config option

* Add socket_listener_port as a config option
* Add unit tests
* Fixes LP:1817406

Add socket_listener_port config option

* Add socket_listener_port as a config option
* Add unit tests
* Fixes LP:1817406

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

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

[Jeremy Lounder (jldev)]

lgtm

review: Approve (+1)

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

Change successfully merged at revision e58f7f408e8287cefb53288811e4e79d194241b6

diff --git a/config.yaml b/config.yaml
index 8fe2608..898a46e 100644
--- a/config.yaml
+++ b/config.yaml
@@ -154,3 +154,9 @@ options:
         Percent of idle CPU at which to generate a Prometheus alert. Default
         10%, i.e. alert if the CPU has less than 10% CPU running idle therefore
         90% used by us+sy+wa+st.
+  socket_listener_port:
+    default: "8094"
+    type: string
+    description: |
+        If set, the input socket_listener will listen on the specified port.
+        The default option is to listen to 8094.
diff --git a/reactive/telegraf.py b/reactive/telegraf.py
index db3b75f..4ad854c 100644
--- a/reactive/telegraf.py
+++ b/reactive/telegraf.py
@@ -236,6 +236,14 @@ def get_prometheus_port():
         return int(config.get('prometheus_output_port'))
 
 
+def get_socket_listener_port():
+    config = hookenv.config()
+    if not config.get('socket_listener_port', False):
+        return 8094
+    else:
+        return int(config.get('socket_listener_port'))
+
+
 def render_socket_listener_config(context):
     # Remove deprecated config file
     old_config_path = '{}/tcp_listener.conf'.format(get_configs_dir())
@@ -302,6 +310,9 @@ def configure_telegraf():
         check_prometheus_port("prometheus_output", get_prometheus_port())
     context['extra_options'] = get_extra_options()
 
+    if get_socket_listener_port():
+        context["socket_listener_port"] = get_socket_listener_port()
+
     render_socket_listener_config(context=context)
     hookenv.log("Updating main config file")
     render(source='telegraf.conf.tmpl', templates_dir=get_templates_dir(),
diff --git a/templates/socket_listener.tmpl b/templates/socket_listener.tmpl
index 8d83e27..41ee2a9 100644
--- a/templates/socket_listener.tmpl
+++ b/templates/socket_listener.tmpl
@@ -1,5 +1,4 @@
 # Enable socket listener on loopback interface
 # Generic socket listener capable of handling multiple socket types.
 [[inputs.socket_listener]]
-  # FIXME: allow configuration
-  service_address = "tcp://127.0.0.1:8094"
+  service_address = "tcp://127.0.0.1:{{ socket_listener_port }}"
diff --git a/unit_tests/test_telegraf.py b/unit_tests/test_telegraf.py
index bab5c31..78e2ff8 100644
--- a/unit_tests/test_telegraf.py
+++ b/unit_tests/test_telegraf.py
@@ -842,6 +842,26 @@ def test_upgrade_charm(mocker):
     assert clear_flag.call_count == 4
 
 
+def test_get_socket_listener_port(monkeypatch, config):
+    config['socket_listener_port'] = ''
+    assert telegraf.get_socket_listener_port() == 8094
+    config['socket_listener_port'] = '9090'
+    assert telegraf.get_socket_listener_port() == 9090
+
+
+def test_socket_listener_config(monkeypatch, config):
+    open_ports = set()
+    monkeypatch.setattr(telegraf.hookenv, 'open_port',
+                        lambda p: open_ports.add(p))
+    monkeypatch.setattr(telegraf.hookenv, 'close_port',
+                        lambda p: open_ports.remove(p))
+    config['prometheus_output_port'] = 'default'
+    telegraf.configure_telegraf()
+    expected = 'service_address = "tcp://127.0.0.1:8094"'
+    config_file = base_dir().join('telegraf.d', 'socket_listener.conf')
+    assert expected in config_file.read()
+
+
 class TestGetHostnameLabel(unittest.TestCase):
     @patch('reactive.telegraf.get_remote_unit_name')
     @patch('charmhelpers.core.hookenv.config')