Disable logging when pulling on python integration tests (elastic#20397)

Docker compose library is quite verbose, and it prints many messages
when logging is enabled. On integration tests we make a pull before
trying to build the images in case the image is already pre-built. If
this pull doesn't work, the image is built, so we ignore errors on this
pull. But, even when ignoring errors, these errors are logged, and when
investigating problems with tests this may lead to think that the
problem is with the unavailability of some image. Disable logging on the
compose logger while this previous pull is being done.

libbeat/tests/system/beat/compose.py

@@ -1,8 +1,11 @@
+import io
+import logging
 import os
 import sys
 import tarfile
 import time
-import io
+
+from contextlib import contextmanager
 
 
 INTEGRATION_TESTS = os.environ.get('INTEGRATION_TESTS', False)
@@ -54,9 +57,12 @@ def is_healthy(container):
             return container.inspect()['State']['Health']['Status'] == 'healthy'
 
         project = cls.compose_project()
-        project.pull(
-            ignore_pull_failures=True,
-            service_names=cls.COMPOSE_SERVICES)
+
+        with disabled_logger('compose.service'):
+            project.pull(
+                ignore_pull_failures=True,
+                service_names=cls.COMPOSE_SERVICES)
+
         project.up(
             strategy=ConvergenceStrategy.always,
             service_names=cls.COMPOSE_SERVICES,
@@ -231,3 +237,14 @@ def service_log_contains(cls, service, msg):
             if line.find(msg.encode("utf-8")) >= 0:
                 counter += 1
         return counter > 0
+
+
+@contextmanager
+def disabled_logger(name):
+    logger = logging.getLogger(name)
+    old_level = logger.getEffectiveLevel()
+    logger.setLevel(logging.CRITICAL)
+    try:
+        yield logger
+    finally:
+        logger.setLevel(old_level)