Add metric to breached-password check

tildes/tests/test_metrics.py

@@ -1,12 +1,12 @@
 # Copyright (c) 2018 Tildes contributors <code@tildes.net>
 # SPDX-License-Identifier: AGPL-3.0-or-later
 
-from tildes.metrics import _COUNTERS, _HISTOGRAMS
+from tildes.metrics import _COUNTERS, _HISTOGRAMS, _SUMMARIES
 
 
 def test_all_metric_names_prefixed():
     """Ensure all metric names have the 'tildes_' prefix."""
-    for metric_dict in (_COUNTERS, _HISTOGRAMS):
+    for metric_dict in (_COUNTERS, _HISTOGRAMS, _SUMMARIES):
         metrics = metric_dict.values()
         for metric in metrics:
             # this is ugly, but seems to be the "generic" way to get the name

tildes/tildes/lib/password.py

@@ -7,6 +7,8 @@ from hashlib import sha1
 
 from redis import ConnectionError, Redis, ResponseError  # noqa
 
+from tildes.metrics import summary_timer
+
 
 # unix socket path for redis server with the breached passwords bloom filter
 BREACHED_PASSWORDS_REDIS_SOCKET = "/run/redis_breached_passwords/socket"
@@ -15,6 +17,7 @@ BREACHED_PASSWORDS_REDIS_SOCKET = "/run/redis_breached_passwords/socket"
 BREACHED_PASSWORDS_BF_KEY = "breached_passwords_bloom"
 
 
+@summary_timer("breached_password_check")
 def is_breached_password(password: str) -> bool:
     """Return whether the password is in the breached-passwords list."""
     redis = Redis(unix_socket_path=BREACHED_PASSWORDS_REDIS_SOCKET)

tildes/tildes/metrics.py

@@ -9,7 +9,7 @@
 
 from typing import Callable
 
-from prometheus_client import Counter, Histogram
+from prometheus_client import Counter, Histogram, Summary
 
 
 _COUNTERS = {
@@ -50,6 +50,13 @@ _HISTOGRAMS = {
     ),
 }
 
+_SUMMARIES = {
+    "breached_password_check": Summary(
+        "tildes_breached_password_check_seconds",
+        "Time spent checking whether a password is in the breached list",
+    ),
+}
+
 
 def incr_counter(name: str, amount: int = 1, **labels: str) -> None:
     """Increment a Prometheus counter."""
@@ -80,3 +87,21 @@ def get_histogram(name: str, **labels: str) -> Histogram:
 def histogram_timer(name: str) -> Callable:
     """Return the .time() decorator for a Prometheus histogram."""
     return get_histogram(name).time()
+
+
+def get_summary(name: str, **labels: str) -> Summary:
+    """Return an (optionally labeled) Prometheus summary by name."""
+    try:
+        hist = _SUMMARIES[name]
+    except KeyError:
+        raise ValueError("Invalid summary name")
+
+    if labels:
+        hist = hist.labels(**labels)
+
+    return hist
+
+
+def summary_timer(name: str) -> Callable:
+    """Return the .time() decorator for a Prometheus summary."""
+    return get_summary(name).time()