feat: Import tenacity library and use it in cluster_read.py

Use it to retry POST requests to Grafana which seems to close/reset
connections under load.

[Tenacity](https://tenacity.readthedocs.io/en/latest/)

core/opl/cluster_read.py

@@ -11,9 +11,11 @@
 import jinja2.exceptions
 import boto3
 import urllib3
+import tenacity
 
 from . import data
 from . import date
+from tenacity import retry
 
 
 def execute(command):
@@ -178,6 +180,7 @@ def _sanitize_target(self, target):
         target = target.replace("$Cloud", self.args.grafana_prefix)
         return target
 
+    @retry
     def measure(self, ri, name, grafana_target):
         assert (
             ri.start is not None and ri.end is not None

opl/cluster_read.py

@@ -11,9 +11,11 @@
 import jinja2.exceptions
 import boto3
 import urllib3
+import tenacity
 
 from . import data
 from . import date
+from tenacity import retry
 
 
 def execute(command):
@@ -178,6 +180,7 @@ def _sanitize_target(self, target):
         target = target.replace("$Cloud", self.args.grafana_prefix)
         return target
 
+    @retry
     def measure(self, ri, name, grafana_target):
         assert (
             ri.start is not None and ri.end is not None

setup.py

@@ -34,6 +34,7 @@
         "requests",
         "tabulate",
         "deepdiff",
+        "tenacity",
     ],
     package_data={
         "opl": [