Merge pull request #2041 from charltonaustin/add_cancel_to_building_build

Adding in the behavior for cancelling a build while it is being built.

buildman/manager/buildcanceller.py

@@ -0,0 +1,25 @@
+import logging
+
+from buildman.manager.etcd_canceller import EtcdCanceller
+from buildman.manager.noop_canceller import NoopCanceller
+
+logger = logging.getLogger(__name__)
+
+CANCELLERS = {'ephemeral': EtcdCanceller}
+
+
+class BuildCanceller(object):
+  """ A class to manage cancelling a build """
+
+  def __init__(self, app=None):
+    build_manager_config = app.config.get('BUILD_MANAGER')
+    if app is None or build_manager_config is None:
+      self.handler = NoopCanceller()
+      return
+
+    canceller = CANCELLERS.get(build_manager_config[0], NoopCanceller)
+    self.handler = canceller(build_manager_config[1])
+
+  def try_cancel_build(self, uuid):
+    """ A method to kill a running build """
+    return self.handler.try_cancel_build(uuid)

buildman/manager/etcd_canceller.py

@@ -0,0 +1,37 @@
+import logging
+import etcd
+
+logger = logging.getLogger(__name__)
+
+
+class EtcdCanceller(object):
+  """ A class that sends a message to etcd to cancel a build """
+
+  def __init__(self, config):
+    etcd_host = config.get('ETCD_HOST', '127.0.0.1')
+    etcd_port = config.get('ETCD_PORT', 2379)
+    etcd_ca_cert = config.get('ETCD_CA_CERT', None)
+    etcd_auth = config.get('ETCD_CERT_AND_KEY', None)
+    if etcd_auth is not None:
+      etcd_auth = tuple(etcd_auth)
+
+    etcd_protocol = 'http' if etcd_auth is None else 'https'
+    logger.debug('Connecting to etcd on %s:%s', etcd_host, etcd_port)
+    self._cancel_prefix = config.get('ETCD_CANCEL_PREFIX', 'cancel/')
+    self._etcd_client = etcd.Client(
+      host=etcd_host,
+      port=etcd_port,
+      cert=etcd_auth,
+      ca_cert=etcd_ca_cert,
+      protocol=etcd_protocol,
+      read_timeout=5)
+
+  def try_cancel_build(self, build_uuid):
+    """ Writes etcd message to cancel build_uuid. """
+    logger.info("Cancelling build %s".format(build_uuid))
+    try:
+      self._etcd_client.write("{}{}".format(self._cancel_prefix, build_uuid), build_uuid)
+      return True
+    except etcd.EtcdException:
+      logger.exception("Failed to write to etcd client %s", build_uuid)
+      return False

buildman/manager/noop_canceller.py

@@ -0,0 +1,8 @@
+class NoopCanceller(object):
+  """ A class that can not cancel a build """
+  def __init__(self, config=None):
+    pass
+
+  def try_cancel_build(self, uuid):
+    """ Does nothing and fails to cancel build. """
+    return False