Added Prometheus sample for monitoring (GoogleCloudPlatform#5433)

yuriatgoogle · Takashi Matsuo · web-flow · commit 10649bc0cdaa · 2021-04-05T14:49:21.000-07:00
* initial creation of Prometheus sample - /monitoring

* cleaning up for linting

* tests pass

* adding region tags

* cleaning up nox config

* cleaning up region tags

* updating copyright to get tests to pass

* cleaning up license header

Co-authored-by: Takashi Matsuo &lt;tmatsuo@google.com&gt;
diff --git a/.github/CODEOWNERS b/.github/CODEOWNERS
@@ -50,6 +50,7 @@
 /ml_engine/**/*.py                     @alecglassford @GoogleCloudPlatform/python-samples-owners
 /monitoring/**/*.py                    @GoogleCloudPlatform/python-samples-owners
 /monitoring/opencensus                 @yuriatgoogle @GoogleCloudPlatform/python-samples-owners
+/monitoring/prometheus                 @yuriatgoogle @GoogleCloudPlatform/python-samples-owners
 /notebooks/**/*.py                     @alixhami @sirtorry @GoogleCloudPlatform/python-samples-owners
 /opencensus/**/*.py                    @GoogleCloudPlatform/python-samples-owners
 /profiler/**/*.py                      @kalyanac @GoogleCloudPlatform/python-samples-owners
diff --git a/monitoring/prometheus/README.md b/monitoring/prometheus/README.md
@@ -0,0 +1,21 @@
+This section contains a sample of using [Prometheus](https://prometheus.io) to instrument a Flask application to emit Service Level Indicator metrics.
+
+## Running the samples locally
+
+1.  Many samples require extra libraries to be installed. If there is a `requirements.txt`, you will need to install the dependencies with [`pip`](pip.readthedocs.org).
+
+        pip install -t lib -r requirements.txt
+
+2.  Use `main.py` to run the sample:
+
+        python main.py
+
+3.  Visit `http://localhost:8080` to view your application.
+
+4.  Visit `http://localhost:8080/metrics` to view your metrics.
+
+## Additional resources
+
+For more information on Prometheus:
+
+> https://prometheus.io
diff --git a/monitoring/prometheus/main.py b/monitoring/prometheus/main.py
@@ -0,0 +1,69 @@
+# Copyright 2021 Google LLC
+
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+#     https://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# [START monitoring_sli_metrics_prometheus_setup]
+import random
+import time
+
+from flask import Flask
+
+from prometheus_client import (
+    Counter,
+    generate_latest,
+    Histogram,
+    REGISTRY,
+)
+
+# [END monitoring_sli_metrics_prometheus_setup]
+
+app = Flask(__name__)
+# [START monitoring_sli_metrics_prometheus_create_metrics]
+PYTHON_REQUESTS_COUNTER = Counter("python_requests", "total requests")
+PYTHON_FAILED_REQUESTS_COUNTER = Counter("python_failed_requests", "failed requests")
+PYTHON_LATENCIES_HISTOGRAM = Histogram(
+    "python_request_latency", "request latency by path"
+)
+# [END monitoring_sli_metrics_prometheus_create_metrics]
+
+
+@app.route("/")
+# [START monitoring_sli_metrics_prometheus_latency]
+@PYTHON_LATENCIES_HISTOGRAM.time()
+# [END monitoring_sli_metrics_prometheus_latency]
+def homePage():
+    # count request
+    # [START monitoring_sli_metrics_prometheus_counts]
+    PYTHON_REQUESTS_COUNTER.inc()
+    # fail 10% of the time
+    if random.randint(0, 100) > 90:
+        PYTHON_FAILED_REQUESTS_COUNTER.inc()
+        # [END monitoring_sli_metrics_prometheus_counts]
+        return ("error!", 500)
+    else:
+        random_delay = random.randint(0, 5000) / 1000
+        # delay for a bit to vary latency measurement
+        time.sleep(random_delay)
+        return "home page"
+
+
+# [START monitoring_sli_metrics_prometheus_metrics_endpoint]
+@app.route("/metrics", methods=["GET"])
+def stats():
+    return generate_latest(REGISTRY), 200
+
+
+# [END monitoring_sli_metrics_prometheus_metrics_endpoint]
+
+
+if __name__ == "__main__":
+    app.run(debug=True, host="0.0.0.0", port=8080)
diff --git a/monitoring/prometheus/main_test.py b/monitoring/prometheus/main_test.py
@@ -0,0 +1,41 @@
+# Copyright 2021 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+import main
+
+
+def test_index() -> None:
+    """
+    GIVEN the app
+    WHEN multiple requests to the / endpoint are made
+    THEN check that most of them succeed
+    """
+    client = main.app.test_client()
+    success_counter = 0
+    for x in range(10):
+        r = client.get("/")
+        if r.status_code == 200:
+            success_counter = success_counter + 1
+    assert success_counter >= 5
+
+
+def test_metrics() -> None:
+    """
+    GIVEN the app
+    WHEN a request to the /metrics endpoint is made
+    THEN check that it's a valid Prometheus endpoint
+    """
+    client = main.app.test_client()
+    res = client.get("/metrics")
+    assert res.status_code == 200
+    assert "HELP" in res.data.decode("utf-8")
diff --git a/monitoring/prometheus/requirements-test.txt b/monitoring/prometheus/requirements-test.txt
@@ -0,0 +1 @@
+pytest==6.2.1
diff --git a/monitoring/prometheus/requirements.txt b/monitoring/prometheus/requirements.txt
@@ -0,0 +1,7 @@
+Flask==1.1.2
+google-api-core==1.25.1
+google-auth==1.25.0
+googleapis-common-protos==1.53.0
+prometheus-client==0.9.0
+prometheus-flask-exporter==0.18.1
+requests==2.25.1
