bug-1898341: change HOST_ID to HOSTNAME and add host tag

This changes HOST_ID to HOSTNAME to match the convention and what we get
in GCP.

If the hostname is set, this will add a "host:{hostname}" tag to all
emitted metrics.

antenna/app.py

@@ -5,6 +5,7 @@
 import logging
 import logging.config
 from pathlib import Path
+import socket
 import sys
 
 from everett.manager import (
@@ -69,7 +70,7 @@ def configure_sentry(app_config):
     set_up_sentry(
         sentry_dsn=app_config("secret_sentry_dsn"),
         release=get_release_name(app_config("basedir")),
-        host_id=app_config("host_id"),
+        host_id=app_config("hostname"),
         # Disable frame-local variables
         with_locals=False,
         # Disable request data from being added to Sentry events
@@ -132,14 +133,15 @@ class Config:
                 "will be used instead."
             ),
         )
-        host_id = Option(
-            default="",
+        hostname = Option(
+            default=socket.gethostname(),
             doc=(
                 "Identifier for the host that is running Antenna. This identifies this Antenna "
                 "instance in the logs and makes it easier to correlate Antenna logs with "
-                "other data. For example, the value could be a public hostname, an instance id, "
-                "or something like that. If you do not set this, then socket.gethostname() is "
-                "used instead."
+                "other data. For example, the value could be a an instance id, pod id, "
+                "or something like that.\n"
+                "\n"
+                "If you do not set this, then socket.gethostname() is used instead."
             ),
         )
 
@@ -211,6 +213,7 @@ def setup(self):
         setup_metrics(
             statsd_host=self.config("statsd_host"),
             statsd_port=self.config("statsd_port"),
+            hostname=self.config("hostname"),
             debug=self.config("local_dev_env"),
         )
 
@@ -281,7 +284,7 @@ def get_app(config_manager=None):
     setup_logging(
         logging_level=app_config("logging_level"),
         debug=app_config("local_dev_env"),
-        host_id=app_config("host_id"),
+        host_id=app_config("hostname"),
         processname="antenna",
     )
 

antenna/libmarkus.py

@@ -7,22 +7,25 @@
 import logging
 
 import markus
+from markus.filters import AddTagFilter
 
 
 _IS_MARKUS_SETUP = False
 
 LOGGER = logging.getLogger(__name__)
+METRICS = markus.get_metrics()
 
 
-def setup_metrics(statsd_host, statsd_port, debug=False):
+def setup_metrics(statsd_host, statsd_port, hostname, debug=False):
     """Initialize and configures the metrics system.
 
     :arg statsd_host: the statsd host to send metrics to
     :arg statsd_port: the port on the host to send metrics to
+    :arg hostname: the host name
     :arg debug: whether or not to additionally log metrics to the logger
 
     """
-    global _IS_MARKUS_SETUP
+    global _IS_MARKUS_SETUP, METRICS
     if _IS_MARKUS_SETUP:
         return
 
@@ -45,9 +48,10 @@ def setup_metrics(statsd_host, statsd_port, debug=False):
                 },
             }
         )
-    markus.configure(markus_backends)
 
-    _IS_MARKUS_SETUP = True
+    if hostname:
+        METRICS.filters.append(AddTagFilter(f"host:{hostname}"))
 
+    markus.configure(markus_backends)
 
-METRICS = markus.get_metrics()
+    _IS_MARKUS_SETUP = True

tests/unittest/test_sentry.py

@@ -94,7 +94,7 @@
         "packages": [{"name": "pypi:sentry-sdk", "version": ANY}],
         "version": ANY,
     },
-    "server_name": "",
+    "server_name": ANY,
     "timestamp": ANY,
     "transaction": "/__broken__",
     "transaction_info": {"source": "route"},