Add statsd logging support to the swift-proxy charm

By default, statsd metrics can be sent by swift-proxy
for diagnostic and monitoring purposes, but are disabled
by default. This change exposes charm config settings
that allow it to be enabled by setting 'statsd_host'
to a non-empty value. 'statsd_port' and 'statsd_sample_rate'
are also supported for changing the destination port
and rate at which metrics are collected.

Closes-Bug: #1729771

Change-Id: I2d5cca233d48022073b5975c06c3da2b1896d8d9

config.yaml

@@ -335,3 +335,22 @@ options:
     type: string
     default: openstack
     description: Rabbitmq vhost name.
+  statsd-host:
+    default: ''
+    type: string
+    description: |
+      Enable statsd metrics to be sent to the specified host.
+      If this value is empty, statsd logging will be disabled.
+  statsd-port:
+    default: 3125
+    type: int
+    description: |
+      Destination port on the provided statsd host to send samples to.
+      Only takes effect if statsd-host is set.
+  statsd-sample-rate:
+    default: 1.0
+    type: float
+    description: |
+      Sample rate determines what percentage of the metric points a
+      client should send to the server.
+      Only takes effect if statsd-host is set.

lib/swift_context.py

@@ -108,6 +108,9 @@ class SwiftIdentityContext(OSContextGenerator):
             'node_timeout': config('node-timeout'),
             'recoverable_node_timeout': config('recoverable-node-timeout'),
             'log_headers': config('log-headers'),
+            'statsd_host': config('statsd-host'),
+            'statsd_port': config('statsd-port'),
+            'statsd_sample_rate': config('statsd-sample-rate')
         }
 
         admin_key = leader_get('swauth-admin-key')

templates/grizzly/proxy-server.conf

@@ -7,6 +7,12 @@ cert_file = {{ ssl_cert }}
 key_file = {{ ssl_key }}
 {% endif %}
 
+{% if statsd_host %}
+log_statsd_host = {{ statsd_host }}
+log_statsd_port = {{ statsd_port }}
+log_statsd_default_sample_rate = {{ statsd_sample_rate }}
+{% endif %}
+
 {% if auth_type == 'keystone' %}
 [pipeline:main]
 pipeline =  healthcheck cache swift3 s3token authtoken keystone container-quotas account-quotas proxy-server

templates/havana/proxy-server.conf

@@ -7,6 +7,12 @@ cert_file = {{ ssl_cert }}
 key_file = {{ ssl_key }}
 {% endif %}
 
+{% if statsd_host %}
+log_statsd_host = {{ statsd_host }}
+log_statsd_port = {{ statsd_port }}
+log_statsd_default_sample_rate = {{ statsd_sample_rate }}
+{% endif %}
+
 {% if auth_type == 'keystone' %}
 [pipeline:main]
 pipeline =  healthcheck cache swift3 authtoken keystoneauth container-quotas account-quotas proxy-server

templates/icehouse/proxy-server.conf

@@ -9,6 +9,12 @@ log_level = {{ log_level }}
 log_address = /dev/log
 log_headers = {{ log_headers }}
 
+{% if statsd_host %}
+log_statsd_host = {{ statsd_host }}
+log_statsd_port = {{ statsd_port }}
+log_statsd_default_sample_rate = {{ statsd_sample_rate }}
+{% endif %}
+
 {% if ssl %}
 cert_file = {{ ssl_cert }}
 key_file = {{ ssl_key }}

templates/kilo/proxy-server.conf

@@ -9,6 +9,12 @@ log_level = {{ log_level }}
 log_address = /dev/log
 log_headers = {{ log_headers }}
 
+{% if statsd_host %}
+log_statsd_host = {{ statsd_host }}
+log_statsd_port = {{ statsd_port }}
+log_statsd_default_sample_rate = {{ statsd_sample_rate }}
+{% endif %}
+
 {% if ssl %}
 cert_file = {{ ssl_cert }}
 key_file = {{ ssl_key }}

templates/mitaka/proxy-server.conf

@@ -9,6 +9,12 @@ log_level = {{ log_level }}
 log_address = /dev/log
 log_headers = {{ log_headers }}
 
+{% if statsd_host %}
+log_statsd_host = {{ statsd_host }}
+log_statsd_port = {{ statsd_port }}
+log_statsd_default_sample_rate = {{ statsd_sample_rate }}
+{% endif %}
+
 {% if ssl %}
 cert_file = {{ ssl_cert }}
 key_file = {{ ssl_key }}
@@ -132,4 +138,4 @@ url = {{ transport_url }}
 driver = messagingv2
 topic = notifications
 log_level = WARN
-{% endif -%}
+{% endif -%}

unit_tests/test_templates.py

@@ -77,3 +77,20 @@ class ProxyServerTemplateTestCase(unittest.TestCase):
             result = template.render()
 
             self.assertTrue(result.startswith("[DEFAULT]"))
+
+    def test_statsd_config_for_all_releases(self):
+        """The configs contain statsd settings if statsd-host is set."""
+        for release in ('grizzly', 'havana', 'icehouse', 'mitaka'):
+            template = self.get_template_for_release(release)
+
+            result = template.render(statsd_host='127.0.0.1')
+
+            self.assertTrue("log_statsd_host" in result)
+            self.assertTrue("log_statsd_port" in result)
+            self.assertTrue("log_statsd_default_sample_rate" in result)
+
+            result = template.render()
+
+            self.assertFalse("log_statsd_host" in result)
+            self.assertFalse("log_statsd_port" in result)
+            self.assertFalse("log_statsd_default_sample_rate" in result)