Revert "Revert "Add a timeout for the image build""

This reverts commit ccf40a462a.

The previous version would not work properly when daemonized
because there was no stdout. This version maintains stdout and
uses select/poll with non-blocking stdout to capture the output
to a log file.

Depends-On: https://review.openstack.org/634266

Change-Id: I7f0617b91e071294fe6051d14475ead1d7df56b7

doc/source/configuration.rst

@@ -277,6 +277,12 @@ Options
       Specifies the distro to be used as a base image to build the image using
       diskimage-builder.
 
+   .. attr:: build-timeout
+      :type: int
+
+      How long (in seconds) to wait for the diskimage build before giving up.
+      The default is 8 hours.
+
    .. attr:: elements
       :type: list
 

nodepool/builder.py

@@ -13,8 +13,10 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
+import fcntl
 import logging
 import os
+import select
 import shutil
 import socket
 import subprocess
@@ -42,6 +44,9 @@ SUSPEND_WAIT_TIME = 30
 # so just hardcode it for all qcow2 building
 DEFAULT_QEMU_IMAGE_COMPAT_OPTIONS = "--qemu-img-options 'compat=0.10'"
 
+# DIB process polling timeout, in milliseconds
+BUILD_PROCESS_POLL_TIMEOUT = 30 * 1000
+
 
 class DibImageFile(object):
     '''
@@ -750,6 +755,7 @@ class BuildWorker(BaseWorker):
         self.log.info('Logging to %s' % (log_fn,))
 
         start_time = time.monotonic()
+
         try:
             p = subprocess.Popen(
                 shlex.split(cmd),
@@ -761,17 +767,73 @@ class BuildWorker(BaseWorker):
                 "Failed to exec '%s'. Error: '%s'" % (cmd, e.strerror)
             )
 
-        with open(log_fn, 'wb') as log:
-            while True:
-                ln = p.stdout.readline()
-                log.write(ln)
-                log.flush()
-                if not ln:
-                    break
+        # Make subprocess stdout non-blocking
+        fd = p.stdout.fileno()
+        fl = fcntl.fcntl(fd, fcntl.F_GETFL)
+        fcntl.fcntl(fd, fcntl.F_SETFL, fl | os.O_NONBLOCK)
 
-            rc = p.wait()
-            m = "Exit code: %s\n" % rc
-            log.write(m.encode('utf8'))
+        # Poll subprocess stdout for readability
+        r, w, e = select.select([fd], [], [], 0)
+        bitmask = (select.POLLIN | select.POLLHUP)
+        poll = select.poll()
+        poll.register(fd, bitmask)
+
+        rc = None
+        did_timeout = False
+        subprocess_done = False
+
+        def buildDidTimeout():
+            build_time = time.monotonic() - start_time
+            if build_time > diskimage.build_timeout:
+                return True
+            return False
+
+        with open(log_fn, 'wb') as log:
+
+            # While the subprocess is running, we will loop through stdout
+            # events. If we can read data, write that out to the log file.
+            # If the subprocess completes, set the flag so we can exit and
+            # write the return code.
+            #
+            # We check for build timeouts in two places: after we have read
+            # all available data in the buffer (which will cause an early exit
+            # of the poll loop), and after a poll timeout. If we did not have
+            # a check after the reads, we would have to have a poll timeout
+            # to occur to check for a build timeout, which may not happen if
+            # there is constantly data available for reading.
+
+            while not subprocess_done:
+                for fd, event in poll.poll(BUILD_PROCESS_POLL_TIMEOUT):
+
+                    # Data available for reading
+                    if event & select.POLLIN:
+                        data = p.stdout.read(1024)
+                        while data:
+                            log.write(data)
+                            log.flush()
+                            data = p.stdout.read(1024)
+                        if buildDidTimeout():
+                            break
+
+                    # Subprocess complete
+                    elif event & select.POLLHUP:
+                        subprocess_done = True
+                        rc = p.wait()
+
+                if not subprocess_done:
+                    if buildDidTimeout():
+                        did_timeout = True
+                        rc = 1
+                        self.log.error(
+                            "Build timeout for image %s, build %s (log: %s)",
+                            diskimage.name, build_id, log_fn)
+                        p.kill()
+                        break
+
+            # Subprocess finished, write return code
+            if not did_timeout:
+                m = "Exit code: %s\n" % rc
+                log.write(m.encode('utf8'))
 
         # It's possible the connection to the ZK cluster could have been
         # interrupted during the build. If so, wait for it to return.
@@ -796,9 +858,10 @@ class BuildWorker(BaseWorker):
             self.log.info("ZooKeeper lost while building %s" % diskimage.name)
             self._zk.resetLostFlag()
             build_data.state = zk.FAILED
-        elif p.returncode:
+        elif p.returncode or did_timeout:
             self.log.info(
-                "DIB failed creating %s (%s)" % (diskimage.name, p.returncode))
+                "DIB failed creating %s (%s) (timeout=%s)" % (
+                    diskimage.name, p.returncode, did_timeout))
             build_data.state = zk.FAILED
         else:
             self.log.info("DIB image %s is built" % diskimage.name)

nodepool/cmd/config_validator.py

@@ -44,6 +44,7 @@ class ConfigValidator:
             'rebuild-age': int,
             'env-vars': {str: str},
             'username': str,
+            'build-timeout': int,
         }
 
         webapp = {

nodepool/config.py

@@ -118,6 +118,7 @@ class Config(ConfigValue):
             d.image_types = set(diskimage.get('formats', []))
             d.pause = bool(diskimage.get('pause', False))
             d.username = diskimage.get('username', 'zuul')
+            d.build_timeout = diskimage.get('build-timeout', (8 * 60 * 60))
             self.diskimages[d.name] = d
 
     def setSecureDiskimageEnv(self, diskimages, secure_config_path):
@@ -179,6 +180,7 @@ class DiskImage(ConfigValue):
         self.image_types = None
         self.pause = False
         self.username = None
+        self.build_timeout = None
 
     def __eq__(self, other):
         if isinstance(other, DiskImage):
@@ -189,7 +191,8 @@ class DiskImage(ConfigValue):
                     other.env_vars == self.env_vars and
                     other.image_types == self.image_types and
                     other.pause == self.pause and
-                    other.username == self.username)
+                    other.username == self.username and
+                    other.build_timeout == self.build_timeout)
         return False
 
     def __repr__(self):

nodepool/tests/__init__.py

@@ -411,20 +411,25 @@ class DBTestCase(BaseTestCase):
             time.sleep(1)
         self.wait_for_threads()
 
-    def waitForBuild(self, image_name, build_id):
+    def waitForBuild(self, image_name, build_id, states=None):
+        if states is None:
+            states = (zk.READY,)
+
         base = "-".join([image_name, build_id])
-        while True:
-            self.wait_for_threads()
-            files = builder.DibImageFile.from_image_id(
-                self._config_images_dir.path, base)
-            if files:
-                break
-            time.sleep(1)
 
         while True:
             self.wait_for_threads()
             build = self.zk.getBuild(image_name, build_id)
-            if build and build.state == zk.READY:
+            if build and build.state in states:
+                break
+            time.sleep(1)
+
+        # We should only expect a dib manifest with a successful build.
+        while build.state == zk.READY:
+            self.wait_for_threads()
+            files = builder.DibImageFile.from_image_id(
+                self._config_images_dir.path, base)
+            if files:
                 break
             time.sleep(1)
 

nodepool/tests/fixtures/config_validate/good.yaml

@@ -152,6 +152,7 @@ diskimages:
       - cache-devstack
     release: trusty
     rebuild-age: 3600
+    build-timeout: 3600
     env-vars:
       TMPDIR: /opt/dib_tmp
       DIB_IMAGE_CACHE: /opt/dib_cache

nodepool/tests/fixtures/diskimage_build_timeout.yaml

@@ -0,0 +1,27 @@
+elements-dir: .
+images-dir: '{images_dir}'
+build-log-dir: '{build_log_dir}'
+
+zookeeper-servers:
+  - host: {zookeeper_host}
+    port: {zookeeper_port}
+    chroot: {zookeeper_chroot}
+
+labels: []
+
+providers: []
+
+diskimages:
+  - name: fake-image
+    build-timeout: 2
+    formats:
+      - tar
+    elements:
+      - fedora
+      - vm
+    release: 21
+    env-vars:
+      TMPDIR: /opt/dib_tmp
+      DIB_IMAGE_CACHE: /opt/dib_cache
+      DIB_CLOUD_IMAGES: http://download.fedoraproject.org/pub/fedora/linux/releases/test/21-Beta/Cloud/Images/x86_64/
+      BASE_IMAGE_FILE: Fedora-Cloud-Base-20141029-21_Beta.x86_64.qcow2

nodepool/tests/unit/test_builder.py

@@ -16,6 +16,7 @@
 import os
 import uuid
 import fixtures
+import mock
 
 from nodepool import builder, exceptions, tests
 from nodepool.driver.fake import provider as fakeprovider
@@ -335,3 +336,10 @@ class TestNodePoolBuilder(tests.DBTestCase):
 
         self.assertEqual(build_default._formats, ['qcow2'])
         self.assertEqual(build_vhd._formats, ['vhd'])
+
+    @mock.patch('select.poll')
+    def test_diskimage_build_timeout(self, mock_poll):
+        configfile = self.setup_config('diskimage_build_timeout.yaml')
+        builder.BUILD_PROCESS_POLL_TIMEOUT = 500
+        self.useBuilder(configfile, cleanup_interval=0)
+        self.waitForBuild('fake-image', '0000000001', states=(zk.FAILED,))

releasenotes/notes/build-timeout-bb68a1fd24f97a10.yaml

@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    A new option (build-timeout) has been added to the builder diskimage
+    configuration to control how long the builder should wait for image
+    builds before giving up. The default is 8 hours.