feat: Add slo-generator Functions Framework API (#130)

slo_generator/api/main.py

@@ -0,0 +1,112 @@
+# Copyright 2021 Google Inc.
+#
+# 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.
+"""
+`main.py`
+Functions Framework API (Flask).
+See https://github.com/GoogleCloudPlatform/functions-framework-python for
+details on the Functions Framework.
+"""
+import base64
+import os
+import logging
+import pprint
+
+from datetime import datetime
+from flask import jsonify
+
+import yaml
+
+from slo_generator.compute import compute, export
+from slo_generator.utils import setup_logging, load_config, get_exporters
+
+CONFIG_PATH = os.environ['CONFIG_PATH']
+EXPORTERS_PATH = os.environ.get('EXPORTERS_PATH', None)
+LOGGER = logging.getLogger(__name__)
+TIME_FORMAT = '%Y-%m-%dT%H:%M:%SZ'
+API_SIGNATURE_TYPE = os.environ['GOOGLE_FUNCTION_SIGNATURE_TYPE']
+setup_logging()
+
+
+def run_compute(request):
+    """Run slo-generator compute function. Can be configured to export data as
+    well, using the `exporters` key of the SLO config.
+
+    Args:
+        request (cloudevent.CloudEvent, flask.Request): Request object.
+
+    Returns:
+        list: List of SLO reports.
+    """
+    # Get SLO config
+    if API_SIGNATURE_TYPE == 'http':
+        timestamp = None
+        data = str(request.get_json())
+        LOGGER.info('Loading SLO config from Flask request')
+    elif API_SIGNATURE_TYPE == 'cloudevent':
+        timestamp = int(
+            datetime.strptime(request["time"], TIME_FORMAT).timestamp())
+        data = base64.b64decode(request.data).decode('utf-8')
+        LOGGER.info(f'Loading SLO config from Cloud Event "{request["id"]}"')
+
+    slo_config = load_config(data)
+
+    # Get slo-generator config
+    LOGGER.info(f'Loading slo-generator config from {CONFIG_PATH}')
+    config = load_config(CONFIG_PATH)
+
+    # Compute SLO report
+    LOGGER.debug(f'Config: {pprint.pformat(config)}')
+    LOGGER.debug(f'SLO Config: {pprint.pformat(slo_config)}')
+    reports = compute(slo_config,
+                      config,
+                      timestamp=timestamp,
+                      client=None,
+                      do_export=True)
+    if API_SIGNATURE_TYPE == 'http':
+        reports = jsonify(reports)
+    return reports
+
+
+def run_export(request):
+    """Run slo-generator export function. Get the SLO report data from a request
+    object.
+
+    Args:
+        request (cloudevent.CloudEvent, flask.Request): Request object.
+
+    Returns:
+        list: List of SLO reports.
+    """
+    # Get export data
+    if API_SIGNATURE_TYPE == 'http':
+        slo_report = request.get_json()
+    elif API_SIGNATURE_TYPE == 'cloudevent':
+        slo_report = yaml.safe_load(base64.b64decode(request.data))
+
+    # Get SLO config
+    LOGGER.info(f'Downloading SLO config from {CONFIG_PATH}')
+    config = load_config(CONFIG_PATH)
+
+    # Build exporters list
+    if EXPORTERS_PATH:
+        LOGGER.info(f'Loading exporters from {EXPORTERS_PATH}')
+        exporters = load_config(EXPORTERS_PATH)
+    else:
+        LOGGER.info(f'Loading exporters from SLO report data {EXPORTERS_PATH}')
+        exporters = slo_report['exporters']
+    spec = {"exporters": exporters}
+    exporters = get_exporters(config, spec)
+
+    # Export data
+    export(slo_report, exporters)