Add pause support for diskimages

There are times where you want to disable diskimage builds happening
by nodepool-builder. For example, if diskimage-builder is producing
broken images.  In this example, we'd want to pause image builds and
roll back to a good image.

This prevents nodepool-builder from replacing the good image with a
potentially bad one.

Change-Id: Ib39e1914598a8007cccc31e261099dd7565b7527
Signed-off-by: Paul Belanger <pabelanger@redhat.com>

doc/source/configuration.rst

@@ -237,6 +237,7 @@ on this configuration::
 
   diskimages:
   - name: devstack-precise
+    pause: False
     rebuild-age: 86400
       - ubuntu
       - vm
@@ -274,6 +275,9 @@ on this configuration::
     Arbitrary environment variables that will be available in the spawned
     diskimage-builder child process.
 
+  ``pause`` (bool)
+    When set to True, nodepool-builder will not build the diskimage.
+
 .. _provider:
 
 provider

nodepool/builder.py

@@ -457,6 +457,10 @@ class BuildWorker(BaseWorker):
         if diskimage.name not in self._config.images_in_use:
             return
 
+        # Check if diskimage builds are paused.
+        if diskimage.pause:
+            return
+
         now = int(time.time())
         builds = self._zk.getMostRecentBuilds(1, diskimage.name, zk.READY)
 
@@ -512,6 +516,10 @@ class BuildWorker(BaseWorker):
         '''
         Query ZooKeeper for a manual image build request for one image.
         '''
+        # Check if diskimage builds are paused.
+        if diskimage.pause:
+            return
+
         # Reduce use of locks by adding an initial check here and
         # a redundant check after lock acquisition.
         if not self._zk.hasBuildRequest(diskimage.name):

nodepool/cmd/nodepoolcmd.py

@@ -174,6 +174,10 @@ class NodePoolCmd(NodepoolApp):
             raise Exception("Trying to build a non disk-image-builder "
                             "image: %s" % diskimage)
 
+        if self.pool.config.diskimages[diskimage].pause:
+            raise Exception(
+                "Skipping build request for image %s; paused" % diskimage)
+
         self.zk.submitBuildRequest(diskimage)
 
     def alien_list(self):

nodepool/config.py

@@ -264,6 +264,7 @@ def loadConfig(config_path):
                 #               "should be a dict" % d.name)
                 d.env_vars = {}
             d.image_types = set()
+            d.pause = bool(diskimage.get('pause', False))
         # Do this after providers to build the image-types
         for provider in newconfig.providers.values():
             for image in provider.images.values():

nodepool/tests/fixtures/node_diskimage_pause.yaml

@@ -0,0 +1,80 @@
+script-dir: .
+elements-dir: .
+images-dir: '{images_dir}'
+
+cron:
+  check: '*/15 * * * *'
+  cleanup: '*/1 * * * *'
+
+zmq-publishers:
+  - tcp://localhost:8881
+
+gearman-servers:
+  - host: localhost
+    port: {gearman_port}
+
+zookeeper-servers:
+  - host: {zookeeper_host}
+    port: {zookeeper_port}
+    chroot: {zookeeper_chroot}
+
+labels:
+  - name: fake-label
+    image: fake-image
+    min-ready: 1
+    providers:
+      - name: fake-provider
+  - name: fake-label2
+    image: fake-image2
+    min-ready: 1
+    providers:
+      - name: fake-provider
+
+providers:
+  - name: fake-provider
+    region-name: fake-region
+    keypair: 'if-present-use-this-keypair'
+    username: 'fake'
+    password: 'fake'
+    auth-url: 'fake'
+    project-id: 'fake'
+    max-servers: 96
+    pool: 'fake'
+    networks:
+      - net-id: 'some-uuid'
+    rate: 0.0001
+    images:
+      - name: fake-image
+        min-ram: 8192
+        name-filter: 'Fake'
+        meta:
+          key: value
+          key2: value
+      - name: fake-image2
+        min-ram: 8192
+
+targets:
+  - name: fake-target
+
+diskimages:
+  - name: fake-image
+    pause: True
+    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
+  - name: fake-image2
+    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/test_commands.py

@@ -20,6 +20,7 @@ from unittest import skip
 
 import fixtures
 import mock
+import testtools
 
 from nodepool.cmd import nodepoolcmd
 from nodepool import tests
@@ -121,6 +122,23 @@ class TestNodepoolCMD(tests.DBTestCase):
         self.waitForImage('fake-provider', 'fake-image')
         self.assert_listed(configfile, ['dib-image-list'], 4, zk.READY, 1)
 
+    def test_dib_image_build_pause(self):
+        configfile = self.setup_config('node_diskimage_pause.yaml')
+        self._useBuilder(configfile)
+        self.patch_argv("-c", configfile, "image-build", "fake-image")
+        with testtools.ExpectedException(Exception):
+            nodepoolcmd.main()
+        self.assert_listed(configfile, ['dib-image-list'], 1, 'fake-image', 0)
+
+    def test_dib_image_pause(self):
+        configfile = self.setup_config('node_diskimage_pause.yaml')
+        self._useBuilder(configfile)
+        pool = self.useNodepool(configfile, watermark_sleep=1)
+        pool.start()
+        self.waitForNodes(pool)
+        self.assert_listed(configfile, ['dib-image-list'], 1, 'fake-image', 0)
+        self.assert_listed(configfile, ['dib-image-list'], 1, 'fake-image2', 1)
+
     def test_dib_image_delete(self):
         configfile = self.setup_config('node.yaml')
         pool = self.useNodepool(configfile, watermark_sleep=1)