cloud_tests: emit dots on Travis while fetching images

This ensures that Travis will not kill our tests if fetching images is
taking a long time.

In implementation terms, this introduces a context manager which will
spin up a multiprocessing.Process in the background and print a dot to
stdout every 10 seconds.  The process is terminated when the context
manager exits.

This also drop the use of travis_wait, which was being used to work
around this issue.

.travis.yml

@@ -72,7 +72,7 @@ matrix:
             - sudo -E su $USER -c 'mk-sbuild xenial'
             - sudo -E su $USER -c 'sbuild --nolog --verbose --dist=xenial cloud-init_*.dsc'
             # Ubuntu LTS: Integration
-            - travis_wait 30 sg lxd -c 'tox -e citest -- run --verbose --preserve-data --data-dir results --os-name xenial --test modules/apt_configure_sources_list.yaml --test modules/ntp_servers --test modules/set_password_list --test modules/user_groups --deb cloud-init_*_all.deb'
+            - sg lxd -c 'tox -e citest -- run --verbose --preserve-data --data-dir results --os-name xenial --test modules/apt_configure_sources_list.yaml --test modules/ntp_servers --test modules/set_password_list --test modules/user_groups --deb cloud-init_*_all.deb'
         - python: 3.5
           env:
               TOXENV=xenial

tests/cloud_tests/platforms/__init__.py

@@ -6,6 +6,7 @@
 from .lxd import platform as lxd
 from .nocloudkvm import platform as nocloudkvm
 from .azurecloud import platform as azurecloud
+from ..util import emit_dots_on_travis
 
 PLATFORMS = {
     'ec2': ec2.EC2Platform,
@@ -17,7 +18,8 @@
 
 def get_image(platform, config):
     """Get image from platform object using os_name."""
-    return platform.get_image(config)
+    with emit_dots_on_travis():
+        return platform.get_image(config)
 
 
 def get_instance(snapshot, *args, **kwargs):

tests/cloud_tests/util.py

@@ -5,14 +5,17 @@
 import base64
 import copy
 import glob
+import multiprocessing
 import os
 import random
 import shlex
 import shutil
 import string
 import subprocess
 import tempfile
+import time
 import yaml
+from contextlib import contextmanager
 
 from cloudinit import util as c_util
 from tests.cloud_tests import LOG
@@ -118,6 +121,36 @@ def current_verbosity():
     return max(min(3 - int(LOG.level / 10), 2), 0)
 
 
+@contextmanager
+def emit_dots_on_travis():
+    """
+    A context manager that emits a dot every 10 seconds if running on Travis.
+
+    Travis will kill jobs that don't emit output for a certain amount of time.
+    This context manager spins up a background process which will emit a dot to
+    stdout every 10 seconds to avoid being killed.
+
+    It should be wrapped selectively around operations that are known to take a
+    long time.
+    """
+    if os.environ.get('TRAVIS') != "true":
+        # If we aren't on Travis, don't do anything.
+        yield
+        return
+
+    def emit_dots():
+        while True:
+            print(".")
+            time.sleep(10)
+
+    dot_process = multiprocessing.Process(target=emit_dots)
+    dot_process.start()
+    try:
+        yield
+    finally:
+        dot_process.terminate()
+
+
 def is_writable_dir(path):
     """Make sure dir is writable.
 

tox.ini

@@ -134,6 +134,6 @@ deps =
 [testenv:citest]
 basepython = python3
 commands = {envpython} -m tests.cloud_tests {posargs}
-passenv = HOME
+passenv = HOME TRAVIS
 deps =
     -r{toxinidir}/integration-requirements.txt