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import gzip
from unittest import skipUnless, TestCase
from prometheus_client import CollectorRegistry, Counter
from prometheus_client.exposition import CONTENT_TYPE_LATEST
try:
# Python >3.5 only
import asyncio
from asgiref.testing import ApplicationCommunicator
from prometheus_client import make_asgi_app
HAVE_ASYNCIO_AND_ASGI = True
except ImportError:
HAVE_ASYNCIO_AND_ASGI = False
def setup_testing_defaults(scope):
scope.update(
{
"client": ("127.0.0.1", 32767),
"headers": [],
"http_version": "1.0",
"method": "GET",
"path": "/",
"query_string": b"",
"scheme": "http",
"server": ("127.0.0.1", 80),
"type": "http",
}
)
class ASGITest(TestCase):
@skipUnless(HAVE_ASYNCIO_AND_ASGI, "Don't have asyncio/asgi installed.")
def setUp(self):
self.registry = CollectorRegistry()
self.captured_status = None
self.captured_headers = None
# Setup ASGI scope
self.scope = {}
setup_testing_defaults(self.scope)
self.communicator = None
def tearDown(self):
if self.communicator:
asyncio.get_event_loop().run_until_complete(
self.communicator.wait()
)
def seed_app(self, app):
self.communicator = ApplicationCommunicator(app, self.scope)
def send_input(self, payload):
asyncio.get_event_loop().run_until_complete(
self.communicator.send_input(payload)
)
def send_default_request(self):
self.send_input({"type": "http.request", "body": b""})
def get_output(self):
output = asyncio.get_event_loop().run_until_complete(
self.communicator.receive_output(0)
)
return output
def get_all_output(self):
outputs = []
while True:
try:
outputs.append(self.get_output())
except asyncio.TimeoutError:
break
return outputs
def get_all_response_headers(self):
outputs = self.get_all_output()
response_start = next(o for o in outputs if o["type"] == "http.response.start")
return response_start["headers"]
def get_response_header_value(self, header_name):
response_headers = self.get_all_response_headers()
return next(
value.decode("utf-8")
for name, value in response_headers
if name.decode("utf-8") == header_name
)
def increment_metrics(self, metric_name, help_text, increments):
c = Counter(metric_name, help_text, registry=self.registry)
for _ in range(increments):
c.inc()
def assert_outputs(self, outputs, metric_name, help_text, increments, compressed):
self.assertEqual(len(outputs), 2)
response_start = outputs[0]
self.assertEqual(response_start['type'], 'http.response.start')
response_body = outputs[1]
self.assertEqual(response_body['type'], 'http.response.body')
# Status code
self.assertEqual(response_start['status'], 200)
# Headers
num_of_headers = 2 if compressed else 1
self.assertEqual(len(response_start['headers']), num_of_headers)
self.assertIn((b"Content-Type", CONTENT_TYPE_LATEST.encode('utf8')), response_start['headers'])
if compressed:
self.assertIn((b"Content-Encoding", b"gzip"), response_start['headers'])
# Body
if compressed:
output = gzip.decompress(response_body['body']).decode('utf8')
else:
output = response_body['body'].decode('utf8')
self.assertIn("# HELP " + metric_name + "_total " + help_text + "\n", output)
self.assertIn("# TYPE " + metric_name + "_total counter\n", output)
self.assertIn(metric_name + "_total " + str(increments) + ".0\n", output)
def validate_metrics(self, metric_name, help_text, increments):
"""
ASGI app serves the metrics from the provided registry.
"""
self.increment_metrics(metric_name, help_text, increments)
# Create and run ASGI app
app = make_asgi_app(self.registry)
self.seed_app(app)
self.send_default_request()
# Assert outputs
outputs = self.get_all_output()
self.assert_outputs(outputs, metric_name, help_text, increments, compressed=False)
def test_report_metrics_1(self):
self.validate_metrics("counter", "A counter", 2)
def test_report_metrics_2(self):
self.validate_metrics("counter", "Another counter", 3)
def test_report_metrics_3(self):
self.validate_metrics("requests", "Number of requests", 5)
def test_report_metrics_4(self):
self.validate_metrics("failed_requests", "Number of failed requests", 7)
def test_gzip(self):
# Increment a metric.
metric_name = "counter"
help_text = "A counter"
increments = 2
self.increment_metrics(metric_name, help_text, increments)
app = make_asgi_app(self.registry)
self.seed_app(app)
# Send input with gzip header.
self.scope["headers"] = [(b"accept-encoding", b"gzip")]
self.send_input({"type": "http.request", "body": b""})
# Assert outputs are compressed.
outputs = self.get_all_output()
self.assert_outputs(outputs, metric_name, help_text, increments, compressed=True)
def test_gzip_disabled(self):
# Increment a metric.
metric_name = "counter"
help_text = "A counter"
increments = 2
self.increment_metrics(metric_name, help_text, increments)
# Disable compression explicitly.
app = make_asgi_app(self.registry, disable_compression=True)
self.seed_app(app)
# Send input with gzip header.
self.scope["headers"] = [(b"accept-encoding", b"gzip")]
self.send_input({"type": "http.request", "body": b""})
# Assert outputs are not compressed.
outputs = self.get_all_output()
self.assert_outputs(outputs, metric_name, help_text, increments, compressed=False)
def test_openmetrics_encoding(self):
"""Response content type is application/openmetrics-text when appropriate Accept header is in request"""
app = make_asgi_app(self.registry)
self.seed_app(app)
self.scope["headers"] = [(b"Accept", b"application/openmetrics-text")]
self.send_input({"type": "http.request", "body": b""})
content_type = self.get_response_header_value('Content-Type').split(";")[0]
assert content_type == "application/openmetrics-text"
def test_plaintext_encoding(self):
"""Response content type is text/plain when Accept header is missing in request"""
app = make_asgi_app(self.registry)
self.seed_app(app)
self.send_input({"type": "http.request", "body": b""})
content_type = self.get_response_header_value('Content-Type').split(";")[0]
assert content_type == "text/plain"
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