Merge pull request #66 from uc-cdis/feat/common_metrics

Feat/common metrics

Author: k-burt-uch

.pre-commit-config.yaml

@@ -1,17 +1,17 @@
 repos:
 -   repo: git@github.com:Yelp/detect-secrets
-    rev: v1.1.0
+    rev: v1.5.0
     hooks:
     -   id: detect-secrets
         args: ['--baseline', '.secrets.baseline']
     exclude: poetry.lock
 -   repo: https://github.com/pre-commit/pre-commit-hooks
-    rev: v4.0.1
+    rev: v5.0.0
     hooks:
     -   id: end-of-file-fixer
     -   id: no-commit-to-branch
         args: [--branch, develop, --branch, master, --pattern, release/.*]
 -   repo: https://github.com/psf/black
-    rev: 21.5b2
+    rev: 24.10.0
     hooks:
     -   id: black

.secrets.baseline

@@ -111,7 +111,7 @@
       }
     ]
   },
-  "version": "1.1.0",
+  "version": "1.5.0",
   "filters_used": [
     {
       "path": "detect_secrets.filters.allowlist.is_line_allowlisted"

README.md

@@ -3,6 +3,10 @@
 This package includes several utility Python tools for the Gen3 stack. It is meant to be imported as a means to access
 supplementary tools and resources that are reusable and not exclusive to any specific repo we use. 
 
+## metrics
+
+- Prometheus
+
 
 ## profiling
 

cdispyutils/metrics.py

@@ -0,0 +1,166 @@
+"""
+Small wrapper around the Prometheus client for metrics gathering in a multi-
+process Python environment. This is intended to be extended and instantiated by
+services, stored at some application context level, and then used to add metrics
+(which are likely later exposed at the /metrics endpoint for Prometheus to scrape).
+"""
+
+import os
+import pathlib
+
+from cdislogging import get_logger
+from prometheus_client import (
+    CONTENT_TYPE_LATEST,
+    CollectorRegistry,
+    Counter,
+    Gauge,
+    generate_latest,
+    multiprocess,
+)
+
+logger = get_logger(__name__)
+
+
+class BaseMetrics(object):
+    """
+    Class to handle Prometheus metrics
+
+    Attributes:
+        enabled (bool): If this is false, the class functions will be no-ops (no operations), effectively
+                        doing nothing. This is the behavior when metrics are disabled. Why? So application code
+                        doesn't have to check, it always tries to log a metric.
+        prometheus_metrics (dict): Dictionary to store Prometheus metrics
+        _registry (CollectorRegistry): Prometheus registry
+    """
+
+    def __init__(self, enabled=True, prometheus_dir="/var/tmp/prometheus_metrics"):
+        """
+        Create a metrics class.
+
+        Args:
+            enabled (bool): If this is false, the class functions will be no-ops (no operations), effectively
+                            doing nothing. This is the behavior when metrics are disabled. Why? So application code
+                            doesn't have to check, it always tries to log a metric.
+            prometheus_dir (str): Directory to use when setting PROMETHEUS_MULTIPROC_DIR env var (which prometheus requires
+                                  for multiprocess metrics collection). Note that this the prometheus client is very
+                                  finicky about when the ENV var is set.
+        """
+        self.enabled = enabled
+        self.prometheus_metrics = {}
+        if not enabled:
+            return
+
+        pathlib.Path(prometheus_dir).mkdir(parents=True, exist_ok=True)
+        os.environ["PROMETHEUS_MULTIPROC_DIR"] = prometheus_dir
+
+        logger.info(
+            f"PROMETHEUS_MULTIPROC_DIR is {os.environ['PROMETHEUS_MULTIPROC_DIR']}"
+        )
+
+        self._registry = CollectorRegistry()
+        multiprocess.MultiProcessCollector(self._registry)
+
+    def get_latest_metrics(self):
+        """
+        Generate the latest Prometheus metrics
+        Returns:
+            str: Latest Prometheus metrics
+            str: Content type of the latest Prometheus metrics
+        """
+        # When metrics gathering is not enabled, the metrics endpoint should not error, but it should
+        # not return any data.
+        if not self.enabled:
+            return "", CONTENT_TYPE_LATEST
+
+        return generate_latest(self._registry), CONTENT_TYPE_LATEST
+
+    def increment_counter(self, name, labels, description=""):
+        """
+        Increment a Prometheus counter metric.
+        Note that this function should not be called directly - implement a function like
+        `add_login_event` instead. A metric's labels should always be consistent.
+        Args:
+            name (str): Name of the metric
+            labels (dict): Dictionary of labels for the metric
+        """
+        if not self.enabled:
+            return
+
+        # create the counter if it doesn't already exist
+        if name not in self.prometheus_metrics:
+            logger.info(
+                f"Creating counter '{name}' with description '{description}' and labels: {labels}"
+            )
+            self.prometheus_metrics[name] = Counter(name, description, [*labels.keys()])
+        elif type(self.prometheus_metrics[name]) is not Counter:
+            raise ValueError(
+                f"Trying to create counter '{name}' but a {type(self.prometheus_metrics[name])} with this name already exists"
+            )
+
+        logger.debug(f"Incrementing counter '{name}' with labels: {labels}")
+        self.prometheus_metrics[name].labels(*labels.values()).inc()
+
+    def dec_gauge(self, name, labels, value, description=""):
+        """
+        Decrement a Prometheus gauge metric.
+        Note that this function should not be called directly - implement a function like
+        `add_signed_url_event` instead. A metric's labels should always be consistent.
+        Args:
+            name (str): Name of the metric
+            labels (dict): Dictionary of labels for the metric
+            value (int): Value to set the metric to
+            description (str): describing the gauge in case it doesn't already exist
+        """
+        if not self.enabled:
+            return
+
+        self._create_gauge_if_not_exist(name, labels, value, description)
+        logger.debug(f"Decrementing gauge '{name}' by '{value}' with labels: {labels}")
+        self.prometheus_metrics[name].labels(*labels.values()).dec(value)
+
+    def inc_gauge(self, name, labels, value, description=""):
+        """
+        Increment a Prometheus gauge metric.
+        Note that this function should not be called directly - implement a function like
+        `add_signed_url_event` instead. A metric's labels should always be consistent.
+        Args:
+            name (str): Name of the metric
+            labels (dict): Dictionary of labels for the metric
+            value (int): Value to set the metric to
+            description (str): describing the gauge in case it doesn't already exist
+        """
+        if not self.enabled:
+            return
+
+        self._create_gauge_if_not_exist(name, labels, value, description)
+        logger.debug(f"Incrementing gauge '{name}' by '{value}' with labels: {labels}")
+        self.prometheus_metrics[name].labels(*labels.values()).inc(value)
+
+    def set_gauge(self, name, labels, value, description=""):
+        """
+        Set a Prometheus gauge metric.
+        Note that this function should not be called directly - implement a function like
+        `add_signed_url_event` instead. A metric's labels should always be consistent.
+        Args:
+            name (str): Name of the metric
+            labels (dict): Dictionary of labels for the metric
+            value (int): Value to set the metric to
+        """
+        if not self.enabled:
+            return
+
+        self._create_gauge_if_not_exist(name, labels, value, description)
+        logger.debug(f"Setting gauge '{name}' with '{value}' with labels: {labels}")
+        self.prometheus_metrics[name].labels(*labels.values()).set(value)
+
+    def _create_gauge_if_not_exist(self, name, labels, value, description):
+        # create the gauge if it doesn't already exist
+        if name not in self.prometheus_metrics:
+            logger.info(
+                f"Creating gauge '{name}' with description '{description}' and labels: {labels}"
+            )
+            self.prometheus_metrics[name] = Gauge(name, description, [*labels.keys()])
+        elif type(self.prometheus_metrics[name]) is not Gauge:
+            raise ValueError(
+                f"Trying to create gauge '{name}' but a {type(self.prometheus_metrics[name])} with this name already exists"
+            )