From d5c70878c5fcaeb8a0b524fc9be50f65edf5de01 Mon Sep 17 00:00:00 2001
From: Joseph Schorr <joseph.schorr@coreos.com>
Date: Wed, 29 Apr 2015 17:04:52 -0400
Subject: [PATCH] Get build preparation working for bitbucket and do a lot of
 code cleanup around this process across all the triggers. Note: tests are not
 yet updated.

---
 endpoints/api/build.py   |  17 +-
 endpoints/api/trigger.py |  12 +-
 endpoints/building.py    | 186 ++++++++++++++++++++
 endpoints/common.py      |  78 +--------
 endpoints/trigger.py     | 357 +++++++++++++++++++++++++--------------
 endpoints/webhooks.py    |   8 +-
 6 files changed, 432 insertions(+), 226 deletions(-)
 create mode 100644 endpoints/building.py

diff --git a/endpoints/api/build.py b/endpoints/api/build.py
index f6a4b05fb..0a5319a5c 100644
--- a/endpoints/api/build.py
+++ b/endpoints/api/build.py
@@ -10,7 +10,7 @@ from endpoints.api import (RepositoryParamResource, parse_args, query_param, nic
                            require_repo_read, require_repo_write, validate_json_request,
                            ApiResource, internal_only, format_date, api, Unauthorized, NotFound,
                            path_param, InvalidRequest, require_repo_admin)
-from endpoints.common import start_build
+from endpoints.building import start_build, PreparedBuild
 from endpoints.trigger import BuildTriggerHandler
 from data import model, database
 from auth.auth_context import get_authenticated_user
@@ -191,8 +191,8 @@ class RepositoryBuildList(RepositoryParamResource):
         raise Unauthorized()
 
     # Check if the dockerfile resource has already been used. If so, then it
-    # can only be reused if the user has access to the repository for which it
-    # was used.
+    # can only be reused if the user has access to the repository in which the
+    # dockerfile was previously built.
     associated_repository = model.get_repository_for_resource(dockerfile_id)
     if associated_repository:
       if not ModifyRepositoryPermission(associated_repository.namespace_user.username,
@@ -201,11 +201,16 @@ class RepositoryBuildList(RepositoryParamResource):
 
     # Start the build.
     repo = model.get_repository(namespace, repository)
-    display_name = user_files.get_file_checksum(dockerfile_id)
 
-    build_request = start_build(repo, dockerfile_id, tags, display_name, subdir, True,
-                                pull_robot_name=pull_robot_name)
+    prepared = PreparedBuild()
+    prepared.build_name = user_files.get_file_checksum(dockerfile_id)
+    prepared.dockerfile_id = dockerfile_id
+    prepared.tags = tags
+    prepared.subdirectory = subdir
+    prepared.is_manual = True
+    prepared.metadata = {}
 
+    build_request = start_build(repo, prepared, pull_robot_name=pull_robot_name)
     resp = build_status_view(build_request, can_write=True)
     repo_string = '%s/%s' % (namespace, repository)
     headers = {
diff --git a/endpoints/api/trigger.py b/endpoints/api/trigger.py
index dc7ae3bba..805ea08bc 100644
--- a/endpoints/api/trigger.py
+++ b/endpoints/api/trigger.py
@@ -12,7 +12,7 @@ from endpoints.api import (RepositoryParamResource, nickname, resource, require_
                            path_param)
 from endpoints.api.build import (build_status_view, trigger_view, RepositoryBuildStatus,
                                  get_trigger_config)
-from endpoints.common import start_build
+from endpoints.building import start_build
 from endpoints.trigger import (BuildTriggerHandler, TriggerDeactivationException,
                                TriggerActivationException, EmptyRepositoryException,
                                RepositoryReadException, TriggerStartException)
@@ -423,16 +423,12 @@ class ActivateBuildTrigger(RepositoryParamResource):
       raise InvalidRequest('Trigger is not active.')
 
     try:
-      run_parameters = request.get_json()
-      specs = handler.manual_start(run_parameters=run_parameters)
-      dockerfile_id, tags, name, subdir, metadata = specs
-
       repo = model.get_repository(namespace, repository)
       pull_robot_name = model.get_pull_robot_name(trigger)
 
-      build_request = start_build(repo, dockerfile_id, tags, name, subdir, True,
-                                  trigger=trigger, pull_robot_name=pull_robot_name,
-                                  trigger_metadata=metadata)
+      run_parameters = request.get_json()
+      prepared = handler.manual_start(run_parameters=run_parameters)
+      build_request = start_build(repo, prepared, pull_robot_name=pull_robot_name)
     except TriggerStartException as tse:
       raise InvalidRequest(tse.message)
 
diff --git a/endpoints/building.py b/endpoints/building.py
new file mode 100644
index 000000000..6dc010cc9
--- /dev/null
+++ b/endpoints/building.py
@@ -0,0 +1,186 @@
+import logging
+import json
+
+from app import app, dockerfile_build_queue
+from data import model
+from data.database import db
+from auth.auth_context import get_authenticated_user
+from endpoints.notificationhelper import spawn_notification
+from flask import request
+
+logger = logging.getLogger(__name__)
+
+def start_build(repository, prepared_build, pull_robot_name=None):
+  host = app.config['SERVER_HOSTNAME']
+  repo_path = '%s/%s/%s' % (host, repository.namespace_user.username, repository.name)
+
+  token = model.create_access_token(repository, 'write', kind='build-worker',
+                                    friendly_name='Repository Build Token')
+  logger.debug('Creating build %s with repo %s tags %s',
+               prepared_build.build_name, repo_path, prepared_build.tags)
+
+  job_config = {
+    'docker_tags': prepared_build.tags,
+    'registry': host,
+    'build_subdir': prepared_build.subdirectory,
+    'trigger_metadata': prepared_build.metadata or {},
+    'is_manual': prepared_build.is_manual,
+    'manual_user': get_authenticated_user().username if get_authenticated_user() else None
+  }
+
+  with app.config['DB_TRANSACTION_FACTORY'](db):
+    build_request = model.create_repository_build(repository, token, job_config,
+                                                  prepared_build.dockerfile_id,
+                                                  prepared_build.build_name,
+                                                  prepared_build.trigger,
+                                                  pull_robot_name=pull_robot_name)
+
+    json_data = json.dumps({
+      'build_uuid': build_request.uuid,
+      'pull_credentials': model.get_pull_credentials(pull_robot_name) if pull_robot_name else None
+    })
+
+    queue_id = dockerfile_build_queue.put([repository.namespace_user.username, repository.name],
+                                          json_data,
+                                          retries_remaining=3)
+
+    build_request.queue_id = queue_id
+    build_request.save()
+
+  # Add the build to the repo's log and spawn the build_queued notification.
+  event_log_metadata = {
+    'build_uuid': build_request.uuid,
+    'docker_tags': prepared_build.tags,
+    'repo': repository.name,
+    'namespace': repository.namespace_user.username,
+    'is_manual': prepared_build.is_manual,
+    'manual_user': get_authenticated_user().username if get_authenticated_user() else None
+  }
+
+  if prepared_build.trigger:
+    event_log_metadata['trigger_id'] = prepared_build.trigger.uuid
+    event_log_metadata['trigger_kind'] = prepared_build.trigger.service.name
+
+  model.log_action('build_dockerfile', repository.namespace_user.username, ip=request.remote_addr,
+                   metadata=event_log_metadata, repository=repository)
+
+  spawn_notification(repository, 'build_queued', event_log_metadata,
+                     subpage='build?current=%s' % build_request.uuid,
+                     pathargs=['build', build_request.uuid])
+
+  return build_request
+
+
+class PreparedBuild(object):
+  """ Class which holds all the information about a prepared build. The build queuing service
+      will use this result to actually invoke the build.
+  """
+  def __init__(self, trigger=None):
+    self._dockerfile_id = None
+    self._tags = None
+    self._build_name = None
+    self._subdirectory = None
+    self._metadata = None
+    self._trigger = trigger
+    self._is_manual = None
+
+  @staticmethod
+  def get_display_name(sha):
+    return sha[0:7]
+
+  def tags_from_ref(self, ref, default_branch='master'):
+    branch = ref.split('/')[-1]
+    tags = {branch}
+
+    if branch == default_branch:
+      tags.add('latest')
+
+    self.tags = tags
+
+  def name_from_sha(self, sha):
+    self.build_name = PreparedBuild.get_display_name(sha)
+
+  @property
+  def is_manual(self):
+    if self._is_manual is None:
+      raise Exception('Property is_manual not set')
+
+    return self._is_manual
+
+  @is_manual.setter
+  def is_manual(self, value):
+    if self._is_manual is not None:
+      raise Exception('Property is_manual already set')
+
+    self._is_manual = value
+
+  @property
+  def trigger(self):
+    return self._trigger
+
+  @property
+  def dockerfile_id(self):
+    return self._dockerfile_id
+
+  @dockerfile_id.setter
+  def dockerfile_id(self, value):
+    if self._dockerfile_id:
+      raise Exception('Property dockerfile_id already set')
+
+    self._dockerfile_id = value
+
+  @property
+  def tags(self):
+    if not self._tags:
+      raise Exception('Missing property tags')
+
+    return self._tags
+
+  @tags.setter
+  def tags(self, value):
+    if self._tags:
+      raise Exception('Property tags already set')
+
+    self._tags = list(value)
+
+  @property
+  def build_name(self):
+    if not self._build_name:
+      raise Exception('Missing property build_name')
+
+    return self._build_name
+
+  @build_name.setter
+  def build_name(self, value):
+    if self._build_name:
+      raise Exception('Property build_name already set')
+
+    self._build_name = value
+
+  @property
+  def subdirectory(self):
+    if self._subdirectory is None:
+      raise Exception('Missing property subdirectory')
+
+    return self._subdirectory
+
+  @subdirectory.setter
+  def subdirectory(self, value):
+    if self._subdirectory:
+      raise Exception('Property subdirectory already set')
+
+    self._subdirectory = value
+
+  @property
+  def metadata(self):
+    if self._metadata is None:
+      raise Exception('Missing property metadata')
+
+    return self._metadata
+
+  @metadata.setter
+  def metadata(self, value):
+    if self._metadata:
+      raise Exception('Property metadata already set')
+
+    self._metadata = value
diff --git a/endpoints/common.py b/endpoints/common.py
index 5f40e48ed..faeccee41 100644
--- a/endpoints/common.py
+++ b/endpoints/common.py
@@ -1,5 +1,4 @@
 import logging
-import urlparse
 import json
 import string
 import datetime
@@ -14,18 +13,15 @@ from flask.ext.principal import identity_changed
 from random import SystemRandom
 
 from data import model
-from data.database import db
-from app import app, oauth_apps, dockerfile_build_queue, LoginWrappedDBUser
+from app import app, oauth_apps, LoginWrappedDBUser
 
 from auth.permissions import QuayDeferredPermissionUser
 from auth import scopes
-from auth.auth_context import get_authenticated_user
 from endpoints.api.discovery import swagger_route_data
 from werkzeug.routing import BaseConverter
 from functools import wraps
 from config import getFrontendVisibleConfig
 from external_libraries import get_external_javascript, get_external_css
-from endpoints.notificationhelper import spawn_notification
 
 import features
 
@@ -210,75 +206,3 @@ def check_repository_usage(user_or_org, plan_found):
   else:
     model.delete_notifications_by_kind(user_or_org, 'over_private_usage')
 
-
-def start_build(repository, dockerfile_id, tags, build_name, subdir, manual,
-                trigger=None, pull_robot_name=None, trigger_metadata=None):
-  host = urlparse.urlparse(request.url).netloc
-  repo_path = '%s/%s/%s' % (host, repository.namespace_user.username, repository.name)
-
-  token = model.create_access_token(repository, 'write', kind='build-worker',
-                                    friendly_name='Repository Build Token')
-  logger.debug('Creating build %s with repo %s tags %s and dockerfile_id %s',
-               build_name, repo_path, tags, dockerfile_id)
-
-  job_config = {
-    'docker_tags': tags,
-    'registry': host,
-    'build_subdir': subdir,
-    'trigger_metadata': trigger_metadata or {},
-    'is_manual': manual,
-    'manual_user': get_authenticated_user().username if get_authenticated_user() else None
-  }
-
-  with app.config['DB_TRANSACTION_FACTORY'](db):
-    build_request = model.create_repository_build(repository, token, job_config,
-                                                  dockerfile_id, build_name,
-                                                  trigger, pull_robot_name=pull_robot_name)
-
-    json_data = json.dumps({
-      'build_uuid': build_request.uuid,
-      'pull_credentials': model.get_pull_credentials(pull_robot_name) if pull_robot_name else None
-    })
-
-    queue_id = dockerfile_build_queue.put([repository.namespace_user.username, repository.name],
-                                          json_data,
-                                          retries_remaining=3)
-
-    build_request.queue_id = queue_id
-    build_request.save()
-
-  # Add the build to the repo's log.
-  metadata = {
-    'repo': repository.name,
-    'namespace': repository.namespace_user.username,
-    'fileid': dockerfile_id,
-    'is_manual': manual,
-    'manual_user': get_authenticated_user().username if get_authenticated_user() else None
-  }
-
-  if trigger:
-    metadata['trigger_id'] = trigger.uuid
-    metadata['config'] = json.loads(trigger.config)
-    metadata['service'] = trigger.service.name
-
-  model.log_action('build_dockerfile', repository.namespace_user.username, ip=request.remote_addr,
-                   metadata=metadata, repository=repository)
-
-  # Add notifications for the build queue.
-  logger.debug('Adding notifications for repository')
-  event_data = {
-    'build_id': build_request.uuid,
-    'build_name': build_name,
-    'docker_tags': tags,
-    'is_manual': manual,
-    'manual_user': get_authenticated_user().username if get_authenticated_user() else None
-  }
-
-  if trigger:
-    event_data['trigger_id'] = trigger.uuid
-    event_data['trigger_kind'] = trigger.service.name
-
-  spawn_notification(repository, 'build_queued', event_data,
-                     subpage='build?current=%s' % build_request.uuid,
-                     pathargs=['build', build_request.uuid])
-  return build_request
diff --git a/endpoints/trigger.py b/endpoints/trigger.py
index 2882c494f..cb8d7622f 100644
--- a/endpoints/trigger.py
+++ b/endpoints/trigger.py
@@ -6,6 +6,7 @@ import base64
 import re
 import json
 
+from endpoints.building import PreparedBuild
 from github import Github, UnknownObjectException, GithubException
 from bitbucket import BitBucket
 from tempfile import SpooledTemporaryFile
@@ -27,9 +28,6 @@ TARBALL_MIME = 'application/gzip'
 CHUNK_SIZE = 512 * 1024
 
 
-def should_skip_commit(message):
-  return '[skip build]' in message or '[build skip]' in message
-
 class InvalidPayloadException(Exception):
   pass
 
@@ -64,6 +62,42 @@ class TriggerProviderException(Exception):
   pass
 
 
+def find_matching_branches(config, branches):
+  if 'branchtag_regex' in config:
+    try:
+      regex = re.compile(config['branchtag_regex'])
+      return [branch for branch in branches
+              if matches_ref('refs/heads/' + branch, regex)]
+    except:
+      pass
+
+  return branches
+
+def raise_if_skipped(config, ref):
+  """ Raises a SkipRequestException if the given ref should be skipped. """
+  if 'branchtag_regex' in config:
+    try:
+      regex = re.compile(config['branchtag_regex'])
+    except:
+      regex = re.compile('.*')
+
+    if not matches_ref(ref, regex):
+      raise SkipRequestException()
+
+def matches_ref(ref, regex):
+  match_string = ref.split('/', 1)[1]
+  if not regex:
+    return False
+
+  m = regex.match(match_string)
+  if not m:
+    return False
+
+  return len(m.group(0)) == len(match_string)
+
+def should_skip_commit(message):
+  return '[skip build]' in message or '[build skip]' in message
+
 def raise_unsupported():
   raise io.UnsupportedOperation
 
@@ -113,8 +147,7 @@ class BuildTriggerHandler(object):
 
   def handle_trigger_request(self):
     """
-    Transform the incoming request data into a set of actions. Returns a tuple
-    of usefiles resource id, docker tags, build name, and resource subdir.
+    Transform the incoming request data into a set of actions. Returns a PreparedBuild.
     """
     raise NotImplementedError
 
@@ -142,7 +175,7 @@ class BuildTriggerHandler(object):
 
   def manual_start(self, run_parameters=None):
     """
-    Manually creates a repository build for this trigger.
+    Manually creates a repository build for this trigger. Returns a PreparedBuild.
     """
     raise NotImplementedError
 
@@ -166,7 +199,7 @@ class BuildTriggerHandler(object):
       if subc.service_name() == trigger.service.name:
         return subc(trigger, override_config)
 
-    raise InvalidServiceException('Unable to find service: %s' % service)
+    raise InvalidServiceException('Unable to find service: %s' % trigger.service.name)
 
   def put_config_key(self, key, value):
     """ Updates a config key in the trigger, saving it to the DB. """
@@ -272,7 +305,6 @@ class BitbucketBuildTrigger(BuildTriggerHandler):
     config['hook_id'] = data['id']
     return config, {'private_key': private_key}
 
-
   def deactivate(self):
     config = self.config
     repository = self._get_repository_client()
@@ -294,7 +326,6 @@ class BitbucketBuildTrigger(BuildTriggerHandler):
 
     return config
 
-
   def list_build_sources(self):
     bitbucket_client = self._get_authorized_client()
     (result, data, err_msg) = bitbucket_client.get_visible_repositories()
@@ -321,12 +352,16 @@ class BitbucketBuildTrigger(BuildTriggerHandler):
     return namespaces.values()
 
   def list_build_subdirs(self):
+    config = self.config
     repository = self._get_repository_client()
-    (result, data, err_msg) = repository.get_path_contents('', revision='master')
+
+    # Find the first matching branch.
+    repo_branches = self.list_field_values('branch_name') or []
+    branches = find_matching_branches(config, repo_branches)
+    (result, data, err_msg) = repository.get_path_contents('', revision=branches[0])
     if not result:
       raise RepositoryReadException(err_msg)
 
-
     files = set([f['path'] for f in data['files']])
     if 'Dockerfile' in files:
       return ['/']
@@ -392,29 +427,114 @@ class BitbucketBuildTrigger(BuildTriggerHandler):
 
     return None
 
-
-  def handle_trigger_request(self, request):
-    return
-
-
-  def manual_start(self, run_parameters=None):
+  def _prepare_build(self, commit_sha, ref, is_manual):
     config = self.config
     repository = self._get_repository_client()
 
-    source = config['build_source']
-    run_parameters = run_parameters or {}
-
-    # Lookup the branch to build.
-    master_branch = 'master'
+    # Lookup the default branch associated with the repository. We use this when building
+    # the tags.
+    default_branch = ''
     (result, data, _) = repository.get_main_branch()
     if result:
-      master_branch = data['name']
+      default_branch = data['name']
 
-    branch_name = run_parameters.get('branch_name') or master_branch
+    # Lookup the commit sha.
+    (result, data, _) = repository.changesets().get(commit_sha)
+    if not result:
+      raise TriggerStartException('Could not lookup commit SHA')
 
-    # Find the SHA for the branch.
-    # TODO
-    return None
+    namespace = repository.namespace
+    name = repository.repository_name
+
+    commit_info = {
+      'url': 'https://bitbucket.org/%s/%s/commits/%s' % (namespace, name, commit_sha),
+      'message': data['message'],
+      'date': data['timestamp']
+    }
+
+    # Try to lookup the author by email address. The raw_author field (if it exists) is returned
+    # in the form: "Joseph Schorr <joseph.schorr@coreos.com>"
+    if data.get('raw_author'):
+      match = re.compile(r'.*<(.+)>').match(data['raw_author'])
+      if match:
+        email_address = match.group(1)
+        bitbucket_client = self._get_authorized_client()
+        (result, data, _) = bitbucket_client.accounts().get_profile(email_address)
+        if result:
+          commit_info['author'] = {
+            'username': data['user']['username'],
+            'url': 'https://bitbucket.org/%s/' % data['user']['username'],
+            'avatar_url': data['user']['avatar']
+          }
+
+    metadata = {
+      'commit_sha': commit_sha,
+      'ref': ref,
+      'default_branch': default_branch,
+      'git_url': 'git@bitbucket.org:%s/%s.git' % (namespace, name),
+      'commit_info': commit_info
+    }
+
+    prepared = PreparedBuild(self.trigger)
+    prepared.tags_from_ref(ref, default_branch)
+    prepared.name_from_sha(commit_sha)
+    prepared.subdirectory = config['subdir']
+    prepared.metadata = metadata
+    prepared.is_manual = is_manual
+
+    return prepared
+
+
+  def handle_trigger_request(self, request):
+    # Parse the JSON payload.
+    payload_json = request.form.get('payload')
+    if not payload_json:
+      raise SkipRequestException()
+
+    try:
+      payload = json.loads(payload_json)
+    except ValueError:
+      raise SkipRequestException()
+
+    logger.debug('BitBucket trigger payload %s', payload)
+
+    # Make sure we have a commit in the payload.
+    if not payload.get('commits'):
+      raise SkipRequestException()
+
+    # Check if this build should be skipped by commit message.
+    commit = payload['commits'][0]
+    commit_message = commit['message']
+    if should_skip_commit(commit_message):
+      raise SkipRequestException()
+
+    # Check to see if this build should be skipped by ref.
+    ref = 'refs/heads/' + commit['branch'] if commit.get('branch') else 'refs/tags/' + commit['tag']
+    raise_if_skipped(self.config, ref)
+
+    commit_sha = commit['node']
+    return self._prepare_build(commit_sha, ref, False)
+
+
+  def manual_start(self, run_parameters=None):
+    run_parameters = run_parameters or {}
+    repository = self._get_repository_client()
+
+    # Find the branch to build.
+    branch_name = run_parameters.get('branch_name')
+    (result, data, _) = repository.get_main_branch()
+    if result:
+      branch_name = data['name'] or branch_name
+
+    # Lookup the commit SHA for the branch.
+    (result, data, _) = repository.get_branches()
+    if not result or not branch_name in data:
+      raise TriggerStartException('Could not find branch commit SHA')
+
+    commit_sha = data[branch_name]['node']
+    ref = 'refs/heads/%s' % (branch_name)
+
+    return self._prepare_build(commit_sha, ref, True)
 
 
 class GithubBuildTrigger(BuildTriggerHandler):
@@ -543,18 +663,6 @@ class GithubBuildTrigger(BuildTriggerHandler):
 
     return repos_by_org
 
-  @staticmethod
-  def matches_ref(ref, regex):
-    match_string = ref.split('/', 1)[1]
-    if not regex:
-      return False
-
-    m = regex.match(match_string)
-    if not m:
-      return False
-
-    return len(m.group(0)) == len(match_string)
-
   def list_build_subdirs(self):
     config = self.config
     gh_client = self._get_client()
@@ -564,15 +672,8 @@ class GithubBuildTrigger(BuildTriggerHandler):
       repo = gh_client.get_repo(source)
 
       # Find the first matching branch.
-      branches = None
-      if 'branchtag_regex' in config:
-        try:
-          regex = re.compile(config['branchtag_regex'])
-          branches = [branch.name for branch in repo.get_branches()
-                      if GithubBuildTrigger.matches_ref('refs/heads/' + branch.name, regex)]
-        except:
-          pass
-
+      repo_branches = self.list_field_values('branch_name') or []
+      branches = find_matching_branches(config, repo_branches)
       branches = branches or [repo.default_branch or 'master']
       default_commit = repo.get_branch(branches[0]).commit
       commit_tree = repo.get_git_tree(default_commit.sha, recursive=True)
@@ -691,37 +792,31 @@ class GithubBuildTrigger(BuildTriggerHandler):
     return tarball_subdir, dockerfile_id
 
 
-  @staticmethod
-  def _prepare_build(trigger, config, repo, commit_sha, build_name, ref, git_url):
-    repo_subdir = config['subdir']
-    joined_subdir = repo_subdir
-    dockerfile_id = None
+  def _prepare_build(self, repo, ref, commit_sha, is_manual):
+    config = self.config
+    prepared = PreparedBuild(self.trigger)
 
-    if trigger.private_key is None:
-      # If the trigger isn't using git, prepare the buildpack.
+    # If the trigger isn't using git, prepare the buildpack.
+    if self.trigger.private_key is None:
       tarball_subdir, dockerfile_id = GithubBuildTrigger._prepare_tarball(repo, commit_sha)
-      logger.debug('Successfully prepared job')
 
-      # Join provided subdir with the tarball subdir.
-      joined_subdir = os.path.join(tarball_subdir, repo_subdir)
+      prepared.subdirectory = os.path.join(tarball_subdir, config['subdir'])
+      prepared.dockerfile_id = dockerfile_id
+    else:
+      prepared.subdirectory = config['subdir']
 
-    logger.debug('Final subdir: %s', joined_subdir)
+    # Set the name.
+    prepared.name_from_sha(commit_sha)
 
-    # compute the tag(s)
-    branch = ref.split('/')[-1]
-    tags = {branch}
+    # Set the tag(s).
+    prepared.tags_from_ref(ref, repo.default_branch)
 
-    if branch == repo.default_branch:
-      tags.add('latest')
-
-    logger.debug('Pushing to tags: %s', tags)
-
-    # compute the metadata
+    # Build and set the metadata.
     metadata = {
       'commit_sha': commit_sha,
       'ref': ref,
       'default_branch': repo.default_branch,
-      'git_url': git_url,
+      'git_url': repo.git_url,
     }
 
     # add the commit info.
@@ -729,71 +824,63 @@ class GithubBuildTrigger(BuildTriggerHandler):
     if commit_info is not None:
       metadata['commit_info'] = commit_info
 
-    return dockerfile_id, list(tags), build_name, joined_subdir, metadata
+    prepared.metadata = metadata
+    prepared.is_manual = is_manual
+    return prepared
 
-  @staticmethod
-  def get_display_name(sha):
-    return sha[0:7]
 
   def handle_trigger_request(self, request):
+    # Check the payload to see if we should skip it based on the lack of a head_commit.
     payload = request.get_json()
     if not payload or payload.get('head_commit') is None:
       raise SkipRequestException()
 
+    # This is for GitHub's probing/testing.
     if 'zen' in payload:
       raise ValidationRequestException()
 
-    logger.debug('Payload %s', payload)
+    logger.debug('GitHub trigger payload %s', payload)
+
     ref = payload['ref']
     commit_sha = payload['head_commit']['id']
     commit_message = payload['head_commit'].get('message', '')
-    git_url = payload['repository']['git_url']
-
-    config = self.config
-    if 'branchtag_regex' in config:
-      try:
-        regex = re.compile(config['branchtag_regex'])
-      except:
-        regex = re.compile('.*')
-
-      if not GithubBuildTrigger.matches_ref(ref, regex):
-        raise SkipRequestException()
 
+    # Check if this build should be skipped by commit message.
     if should_skip_commit(commit_message):
       raise SkipRequestException()
 
-    short_sha = GithubBuildTrigger.get_display_name(commit_sha)
+    # Check to see if this build should be skipped by ref.
+    raise_if_skipped(self.config, ref)
 
-    gh_client = self._get_client()
-
-    repo_full_name = '%s/%s' % (payload['repository']['owner']['name'],
-                                payload['repository']['name'])
-    repo = gh_client.get_repo(repo_full_name)
-
-    logger.debug('Github repo: %s', repo)
-
-    return GithubBuildTrigger._prepare_build(self.trigger, config, repo, commit_sha, short_sha,
-                                             ref, git_url)
-
-  def manual_start(self, run_parameters=None):
-    config = self.config
     try:
-      source = config['build_source']
-      run_parameters = run_parameters or {}
+      repo_full_name = '%s/%s' % (payload['repository']['owner']['name'],
+                                  payload['repository']['name'])
 
       gh_client = self._get_client()
-      repo = gh_client.get_repo(source)
-      branch_name = run_parameters.get('branch_name') or repo.default_branch
-      branch = repo.get_branch(branch_name)
-      branch_sha = branch.commit.sha
-      short_sha = GithubBuildTrigger.get_display_name(branch_sha)
-      ref = 'refs/heads/%s' % (branch_name)
-      git_url = repo.git_url
+      repo = gh_client.get_repo(repo_full_name)
 
-      return self._prepare_build(self.trigger, config, repo, branch_sha, short_sha, ref, git_url)
+      return self._prepare_build(repo, ref, commit_sha, False)
     except GithubException as ghe:
       raise TriggerStartException(ghe.data['message'])
 
+  def manual_start(self, run_parameters=None):
+    config = self.config
+    source = config['build_source']
+    run_parameters = run_parameters or {}
+
+    try:
+      gh_client = self._get_client()
+
+      # Lookup the branch and its associated current SHA.
+      repo = gh_client.get_repo(source)
+      branch_name = run_parameters.get('branch_name') or repo.default_branch
+      branch = repo.get_branch(branch_name)
+      commit_sha = branch.commit.sha
+      ref = 'refs/heads/%s' % (branch_name)
+
+      return self._prepare_build(repo, ref, commit_sha, True)
+    except GithubException as ghe:
+      raise TriggerStartException(ghe.data['message'])
 
   def list_field_values(self, field_name):
     if field_name == 'refs':
@@ -922,24 +1009,50 @@ class CustomBuildTrigger(BuildTriggerHandler):
     return metadata
 
   def handle_trigger_request(self, request):
+    # Skip if there is no payload.
     payload = request.get_json()
     if not payload:
       raise SkipRequestException()
 
     logger.debug('Payload %s', payload)
+
+    # Skip if the commit message matches.
     metadata = self._metadata_from_payload(payload)
+    if should_skip_commit(metadata.get('commit_info', {}).get('message', '')):
+      raise SkipRequestException()
 
     # The build source is the canonical git URL used to clone.
     config = self.config
     metadata['git_url'] = config['build_source']
 
-    branch = metadata['ref'].split('/')[-1]
-    tags = {branch}
+    prepared = PreparedBuild(self.trigger)
+    prepared.tags_from_ref(metadata['ref'])
+    prepared.name_from_sha(metadata['commit_sha'])
+    prepared.subdirectory = config['subdir']
+    prepared.metadata = metadata
 
-    build_name = metadata['commit_sha'][:6]
-    dockerfile_id = None
+    return prepared
 
-    return dockerfile_id, tags, build_name, config['subdir'], metadata
+  def manual_start(self, run_parameters=None):
+    # commit_sha is the only required parameter
+    commit_sha = run_parameters.get('commit_sha')
+    if commit_sha is None:
+      raise TriggerStartException('missing required parameter')
+
+    config = self.config
+    metadata = {
+      'commit_sha': commit_sha,
+      'git_url': config['build_source'],
+    }
+
+    prepared = PreparedBuild(self.trigger)
+    prepared.tags = [commit_sha]
+    prepared.name_from_sha(commit_sha)
+    prepared.subdirectory = config['subdir']
+    prepared.metadata = metadata
+    prepared.is_manual = True
+
+    return prepared
 
   def activate(self, standard_webhook_url):
     config = self.config
@@ -962,19 +1075,3 @@ class CustomBuildTrigger(BuildTriggerHandler):
     config.pop('credentials', None)
     self.config = config
     return config
-
-  def manual_start(self, run_parameters=None):
-    # commit_sha is the only required parameter
-    if 'commit_sha' not in run_parameters:
-      raise TriggerStartException('missing required parameter')
-
-    config = self.config
-    dockerfile_id = None
-    tags = {run_parameters['commit_sha']}
-    build_name = run_parameters['commit_sha']
-    metadata = {
-      'commit_sha': run_parameters['commit_sha'],
-      'git_url': config['build_source'],
-    }
-
-    return dockerfile_id, list(tags), build_name, config['subdir'], metadata
diff --git a/endpoints/webhooks.py b/endpoints/webhooks.py
index 8804e8ef1..913b00fb0 100644
--- a/endpoints/webhooks.py
+++ b/endpoints/webhooks.py
@@ -11,7 +11,7 @@ from util.useremails import send_invoice_email, send_subscription_change, send_p
 from util.http import abort
 from endpoints.trigger import (BuildTriggerHandler, ValidationRequestException,
                                SkipRequestException, InvalidPayloadException)
-from endpoints.common import start_build
+from endpoints.building import start_build
 
 
 logger = logging.getLogger(__name__)
@@ -87,8 +87,7 @@ def build_trigger_webhook(trigger_uuid, **kwargs):
 
     logger.debug('Passing webhook request to handler %s', handler)
     try:
-      specs = handler.handle_trigger_request(request)
-      dockerfile_id, tags, name, subdir, metadata = specs
+      prepared = handler.handle_trigger_request(request)
     except ValidationRequestException:
       # This was just a validation request, we don't need to build anything
       return make_response('Okay')
@@ -101,8 +100,7 @@ def build_trigger_webhook(trigger_uuid, **kwargs):
 
     pull_robot_name = model.get_pull_robot_name(trigger)
     repo = model.get_repository(namespace, repository)
-    start_build(repo, dockerfile_id, tags, name, subdir, False, trigger,
-                pull_robot_name=pull_robot_name, trigger_metadata=metadata)
+    start_build(repo, prepared, pull_robot_name=pull_robot_name)
 
     return make_response('Okay')