Merge ~axino/charm-telegraf/+git/telegraf-charm:redis_relation into ~telegraf-charmers/charm-telegraf:master

[Junien F]

add redis relation

[🤖 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)]

Change successfully merged at revision e6cc90d9da7f3b406b2799592a57300843da2f78

diff --git a/layer.yaml b/layer.yaml
index 7af7077..7c1b2bd 100644
--- a/layer.yaml
+++ b/layer.yaml
@@ -15,20 +15,21 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 includes:
-    - layer:basic
     - layer:apt
+    - layer:basic
     - layer:ntpmon
     - layer:promreg-client
     - interface:elasticsearch
+    - interface:http
     - interface:influxdb-api
+    - interface:juju-info
     - interface:memcache
     - interface:mongodb
-    - interface:pgsql
     - interface:mysql-root
-    - interface:juju-info
-    - interface:http
+    - interface:pgsql
     - interface:prometheus-rules
     - interface:rabbitmq
+    - interface:redis
 options:
     basic:
         use_venv: true
diff --git a/metadata.yaml b/metadata.yaml
index 93ad11f..912f6f5 100644
--- a/metadata.yaml
+++ b/metadata.yaml
@@ -36,35 +36,38 @@ series:
   - bionic
 subordinate: true
 requires:
-  mysql:
-    interface: mysql-root
-  postgresql: 
-    interface: pgsql
-  mongodb: 
-    interface: mongodb
+  amqp:
+    interface: rabbitmq
     scope: container
-  memcached: 
-    interface: memcache
+  apache: 
+    interface: apache-website
     scope: container
   elasticsearch: 
     interface: elasticsearch
     scope: container
+  exec:
+    interface: telegraf-exec
+    scope: container
   haproxy: 
     interface: statistics
     scope: container
-  apache: 
-    interface: apache-website
-    scope: container
   influxdb-api:
     interface: influxdb-api
   juju-info:
     interface: juju-info
     scope: container
-  exec:
-    interface: telegraf-exec
+  memcached: 
+    interface: memcache
     scope: container
-  amqp:
-    interface: rabbitmq
+  mongodb: 
+    interface: mongodb
+    scope: container
+  mysql:
+    interface: mysql-root
+  postgresql: 
+    interface: pgsql
+  redis:
+    interface: redis
     scope: container
 provides:
   prometheus-client:
diff --git a/reactive/telegraf.py b/reactive/telegraf.py
index afcf181..a4cae51 100644
--- a/reactive/telegraf.py
+++ b/reactive/telegraf.py
@@ -588,6 +588,43 @@ def apache_input(apache):
     set_state('telegraf.needs_reload')
 
 
+@when('endpoint.redis.available')
+def add_redis_input(redis):
+    template = """
+[[inputs.redis]]
+  servers = ["tcp://{{ host }}:{{ port }}"]
+  # Until https://github.com/influxdata/telegraf/issues/5036 is fixed
+  fielddrop = ["aof_last_bgrewrite_status","aof_last_write_status","maxmemory_policy","rdb_last_bgsave_status","used_memory_dataset_perc","used_memory_peak_perc"]
+"""
+    config_path = '{}/{}.conf'.format(get_configs_dir(), 'redis')
+
+    rels = hookenv.relations_of_type('redis')
+    if len(rels) != 1:
+        hookenv.log("Unexpected number of units in the redis relation."
+                    "Expected 1, got {}".format(len(rels)), "WARNING")
+
+    ctxt = {}
+    ctxt["host"] = rels[0]['host'].strip('"')
+    ctxt["port"] = rels[0]['port']
+    input_config = render_template(template, ctxt) + \
+        render_extra_options("inputs", "redis")
+    hookenv.log("Updating {} plugin config file".format('redis'))
+    host.write_file(config_path, input_config.encode('utf-8'))
+    set_state('plugins.redis.configured')
+    set_state('telegraf.needs_reload')
+
+
+@when_not('endpoint.redis.available')
+@when('plugins.redis.configured')
+def remove_redis_input():
+    config_path = '{}/{}.conf'.format(get_configs_dir(), 'redis')
+
+    if os.path.exists(config_path):
+        os.unlink(config_path)
+    remove_state('plugins.redis.configured')
+    set_state('telegraf.needs_reload')
+
+
 @when('exec.available')
 def exec_input(exec_rel):
     template = """