diff --git a/resources/sql/patches/20131107.buildlog.sql b/resources/sql/patches/20131107.buildlog.sql
new file mode 100644
index 0000000000..e761b46c9a
--- /dev/null
+++ b/resources/sql/patches/20131107.buildlog.sql
@@ -0,0 +1,26 @@
+CREATE TABLE {$NAMESPACE}_harbormaster.harbormaster_buildlog (
+  id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
+  phid VARCHAR(64) NOT NULL COLLATE utf8_bin,
+  buildPHID VARCHAR(64) NOT NULL COLLATE utf8_bin,
+  buildStepPHID VARCHAR(64) NOT NULL COLLATE utf8_bin,
+  logSource VARCHAR(255) NULL COLLATE utf8_bin,
+  logType VARCHAR(255) NULL COLLATE utf8_bin,
+  duration INT UNSIGNED NULL,
+  live BOOLEAN NOT NULL,
+  dateCreated INT UNSIGNED NOT NULL,
+  dateModified INT UNSIGNED NOT NULL,
+  KEY `key_build` (buildPHID, buildStepPHID),
+  UNIQUE KEY `key_phid` (phid)
+) ENGINE=InnoDB, COLLATE utf8_general_ci;
+
+ALTER TABLE {$NAMESPACE}_harbormaster.harbormaster_build
+ADD COLUMN cancelRequested BOOLEAN NOT NULL;
+
+CREATE TABLE {$NAMESPACE}_harbormaster.harbormaster_buildlogchunk (
+  id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
+  logID INT UNSIGNED NOT NULL COLLATE utf8_bin,
+  encoding VARCHAR(30) NOT NULL COLLATE utf8_bin,
+  size LONG NULL,
+  chunk LONGBLOB NOT NULL,
+  KEY `key_log` (logID)
+) ENGINE=InnoDB, COLLATE utf8_general_ci;
diff --git a/src/__celerity_resource_map__.php b/src/__celerity_resource_map__.php
index d266852b22..0746bd8bb5 100644
--- a/src/__celerity_resource_map__.php
+++ b/src/__celerity_resource_map__.php
@@ -569,22 +569,22 @@ celerity_register_resource_map(array(
   ),
   '/rsrc/image/sprite-apps-X2.png' =>
   array(
-    'hash' => '68bbb3f409d0eb42d65dd94769813044',
-    'uri' => '/res/68bbb3f4/rsrc/image/sprite-apps-X2.png',
+    'hash' => '67e8a6bf2d7fbb0b7961f1a0dcf8592b',
+    'uri' => '/res/67e8a6bf/rsrc/image/sprite-apps-X2.png',
     'disk' => '/rsrc/image/sprite-apps-X2.png',
     'type' => 'png',
   ),
   '/rsrc/image/sprite-apps-large-X2.png' =>
   array(
-    'hash' => '15368afbac0e1402c20f99f3166cdb11',
-    'uri' => '/res/15368afb/rsrc/image/sprite-apps-large-X2.png',
+    'hash' => '9bed1778022e2bd25d658842be54844d',
+    'uri' => '/res/9bed1778/rsrc/image/sprite-apps-large-X2.png',
     'disk' => '/rsrc/image/sprite-apps-large-X2.png',
     'type' => 'png',
   ),
   '/rsrc/image/sprite-apps-large.png' =>
   array(
-    'hash' => 'b1f1de55803cf22eb3beb391fff17b04',
-    'uri' => '/res/b1f1de55/rsrc/image/sprite-apps-large.png',
+    'hash' => '518d6e5487c8d3758921ad85c1bb7d60',
+    'uri' => '/res/518d6e54/rsrc/image/sprite-apps-large.png',
     'disk' => '/rsrc/image/sprite-apps-large.png',
     'type' => 'png',
   ),
@@ -597,8 +597,8 @@ celerity_register_resource_map(array(
   ),
   '/rsrc/image/sprite-apps.png' =>
   array(
-    'hash' => 'bf7feaae848d44a461e63123c28e402f',
-    'uri' => '/res/bf7feaae/rsrc/image/sprite-apps.png',
+    'hash' => '9024ab95247f936f41c0b51c75e2e228',
+    'uri' => '/res/9024ab95/rsrc/image/sprite-apps.png',
     'disk' => '/rsrc/image/sprite-apps.png',
     'type' => 'png',
   ),
@@ -1197,7 +1197,7 @@ celerity_register_resource_map(array(
   ),
   'herald-rule-editor' =>
   array(
-    'uri' => '/res/a561eb19/rsrc/js/application/herald/HeraldRuleEditor.js',
+    'uri' => '/res/928275b4/rsrc/js/application/herald/HeraldRuleEditor.js',
     'type' => 'js',
     'requires' =>
     array(
@@ -4183,7 +4183,7 @@ celerity_register_resource_map(array(
   ),
   'sprite-apps-css' =>
   array(
-    'uri' => '/res/37c55e75/rsrc/css/sprite-apps.css',
+    'uri' => '/res/774f4bad/rsrc/css/sprite-apps.css',
     'type' => 'css',
     'requires' =>
     array(
@@ -4192,7 +4192,7 @@ celerity_register_resource_map(array(
   ),
   'sprite-apps-large-css' =>
   array(
-    'uri' => '/res/8ddded36/rsrc/css/sprite-apps-large.css',
+    'uri' => '/res/b547fab1/rsrc/css/sprite-apps-large.css',
     'type' => 'css',
     'requires' =>
     array(
@@ -4328,7 +4328,7 @@ celerity_register_resource_map(array(
 ), array(
   'packages' =>
   array(
-    'f350af41' =>
+    'f0d63822' =>
     array(
       'name' => 'core.pkg.css',
       'symbols' =>
@@ -4377,7 +4377,7 @@ celerity_register_resource_map(array(
         41 => 'phabricator-tag-view-css',
         42 => 'phui-list-view-css',
       ),
-      'uri' => '/res/pkg/f350af41/core.pkg.css',
+      'uri' => '/res/pkg/f0d63822/core.pkg.css',
       'type' => 'css',
     ),
     '2c1dba03' =>
@@ -4569,15 +4569,15 @@ celerity_register_resource_map(array(
   ),
   'reverse' =>
   array(
-    'aphront-dialog-view-css' => 'f350af41',
-    'aphront-error-view-css' => 'f350af41',
-    'aphront-list-filter-view-css' => 'f350af41',
-    'aphront-pager-view-css' => 'f350af41',
-    'aphront-panel-view-css' => 'f350af41',
-    'aphront-table-view-css' => 'f350af41',
-    'aphront-tokenizer-control-css' => 'f350af41',
-    'aphront-tooltip-css' => 'f350af41',
-    'aphront-typeahead-control-css' => 'f350af41',
+    'aphront-dialog-view-css' => 'f0d63822',
+    'aphront-error-view-css' => 'f0d63822',
+    'aphront-list-filter-view-css' => 'f0d63822',
+    'aphront-pager-view-css' => 'f0d63822',
+    'aphront-panel-view-css' => 'f0d63822',
+    'aphront-table-view-css' => 'f0d63822',
+    'aphront-tokenizer-control-css' => 'f0d63822',
+    'aphront-tooltip-css' => 'f0d63822',
+    'aphront-typeahead-control-css' => 'f0d63822',
     'differential-changeset-view-css' => '1084b12b',
     'differential-core-view-css' => '1084b12b',
     'differential-inline-comment-editor' => '5e9e5c4e',
@@ -4591,7 +4591,7 @@ celerity_register_resource_map(array(
     'differential-table-of-contents-css' => '1084b12b',
     'diffusion-commit-view-css' => '7aa115b4',
     'diffusion-icons-css' => '7aa115b4',
-    'global-drag-and-drop-css' => 'f350af41',
+    'global-drag-and-drop-css' => 'f0d63822',
     'inline-comment-summary-css' => '1084b12b',
     'javelin-aphlict' => '2c1dba03',
     'javelin-behavior' => '3e3be199',
@@ -4666,56 +4666,56 @@ celerity_register_resource_map(array(
     'javelin-util' => '3e3be199',
     'javelin-vector' => '3e3be199',
     'javelin-workflow' => '3e3be199',
-    'lightbox-attachment-css' => 'f350af41',
+    'lightbox-attachment-css' => 'f0d63822',
     'maniphest-task-summary-css' => '49898640',
-    'phabricator-action-list-view-css' => 'f350af41',
-    'phabricator-application-launch-view-css' => 'f350af41',
+    'phabricator-action-list-view-css' => 'f0d63822',
+    'phabricator-application-launch-view-css' => 'f0d63822',
     'phabricator-busy' => '2c1dba03',
     'phabricator-content-source-view-css' => '1084b12b',
-    'phabricator-core-css' => 'f350af41',
-    'phabricator-crumbs-view-css' => 'f350af41',
+    'phabricator-core-css' => 'f0d63822',
+    'phabricator-crumbs-view-css' => 'f0d63822',
     'phabricator-drag-and-drop-file-upload' => '5e9e5c4e',
     'phabricator-dropdown-menu' => '2c1dba03',
     'phabricator-file-upload' => '2c1dba03',
-    'phabricator-filetree-view-css' => 'f350af41',
-    'phabricator-flag-css' => 'f350af41',
+    'phabricator-filetree-view-css' => 'f0d63822',
+    'phabricator-flag-css' => 'f0d63822',
     'phabricator-hovercard' => '2c1dba03',
-    'phabricator-jump-nav' => 'f350af41',
+    'phabricator-jump-nav' => 'f0d63822',
     'phabricator-keyboard-shortcut' => '2c1dba03',
     'phabricator-keyboard-shortcut-manager' => '2c1dba03',
-    'phabricator-main-menu-view' => 'f350af41',
+    'phabricator-main-menu-view' => 'f0d63822',
     'phabricator-menu-item' => '2c1dba03',
-    'phabricator-nav-view-css' => 'f350af41',
+    'phabricator-nav-view-css' => 'f0d63822',
     'phabricator-notification' => '2c1dba03',
-    'phabricator-notification-css' => 'f350af41',
-    'phabricator-notification-menu-css' => 'f350af41',
+    'phabricator-notification-css' => 'f0d63822',
+    'phabricator-notification-menu-css' => 'f0d63822',
     'phabricator-object-selector-css' => '1084b12b',
     'phabricator-phtize' => '2c1dba03',
     'phabricator-prefab' => '2c1dba03',
     'phabricator-project-tag-css' => '49898640',
-    'phabricator-remarkup-css' => 'f350af41',
+    'phabricator-remarkup-css' => 'f0d63822',
     'phabricator-shaped-request' => '5e9e5c4e',
-    'phabricator-side-menu-view-css' => 'f350af41',
-    'phabricator-standard-page-view' => 'f350af41',
-    'phabricator-tag-view-css' => 'f350af41',
+    'phabricator-side-menu-view-css' => 'f0d63822',
+    'phabricator-standard-page-view' => 'f0d63822',
+    'phabricator-tag-view-css' => 'f0d63822',
     'phabricator-textareautils' => '2c1dba03',
     'phabricator-tooltip' => '2c1dba03',
-    'phabricator-transaction-view-css' => 'f350af41',
-    'phabricator-zindex-css' => 'f350af41',
-    'phui-button-css' => 'f350af41',
-    'phui-form-css' => 'f350af41',
-    'phui-form-view-css' => 'f350af41',
-    'phui-header-view-css' => 'f350af41',
-    'phui-icon-view-css' => 'f350af41',
-    'phui-list-view-css' => 'f350af41',
-    'phui-object-item-list-view-css' => 'f350af41',
-    'phui-property-list-view-css' => 'f350af41',
-    'phui-spacing-css' => 'f350af41',
-    'sprite-apps-large-css' => 'f350af41',
-    'sprite-gradient-css' => 'f350af41',
-    'sprite-icons-css' => 'f350af41',
-    'sprite-menu-css' => 'f350af41',
-    'sprite-status-css' => 'f350af41',
-    'syntax-highlighting-css' => 'f350af41',
+    'phabricator-transaction-view-css' => 'f0d63822',
+    'phabricator-zindex-css' => 'f0d63822',
+    'phui-button-css' => 'f0d63822',
+    'phui-form-css' => 'f0d63822',
+    'phui-form-view-css' => 'f0d63822',
+    'phui-header-view-css' => 'f0d63822',
+    'phui-icon-view-css' => 'f0d63822',
+    'phui-list-view-css' => 'f0d63822',
+    'phui-object-item-list-view-css' => 'f0d63822',
+    'phui-property-list-view-css' => 'f0d63822',
+    'phui-spacing-css' => 'f0d63822',
+    'sprite-apps-large-css' => 'f0d63822',
+    'sprite-gradient-css' => 'f0d63822',
+    'sprite-icons-css' => 'f0d63822',
+    'sprite-menu-css' => 'f0d63822',
+    'sprite-status-css' => 'f0d63822',
+    'syntax-highlighting-css' => 'f0d63822',
   ),
 ));
diff --git a/src/__phutil_library_map__.php b/src/__phutil_library_map__.php
index c6e75cd973..1d7911f388 100644
--- a/src/__phutil_library_map__.php
+++ b/src/__phutil_library_map__.php
@@ -652,9 +652,11 @@ phutil_register_library_map(array(
     'FileReplyHandler' => 'applications/files/mail/FileReplyHandler.php',
     'HarbormasterBuild' => 'applications/harbormaster/storage/build/HarbormasterBuild.php',
     'HarbormasterBuildArtifact' => 'applications/harbormaster/storage/build/HarbormasterBuildArtifact.php',
+    'HarbormasterBuildCancelController' => 'applications/harbormaster/controller/HarbormasterBuildCancelController.php',
     'HarbormasterBuildItem' => 'applications/harbormaster/storage/build/HarbormasterBuildItem.php',
     'HarbormasterBuildItemQuery' => 'applications/harbormaster/query/HarbormasterBuildItemQuery.php',
     'HarbormasterBuildLog' => 'applications/harbormaster/storage/build/HarbormasterBuildLog.php',
+    'HarbormasterBuildLogQuery' => 'applications/harbormaster/query/HarbormasterBuildLogQuery.php',
     'HarbormasterBuildPlan' => 'applications/harbormaster/storage/configuration/HarbormasterBuildPlan.php',
     'HarbormasterBuildPlanEditor' => 'applications/harbormaster/editor/HarbormasterBuildPlanEditor.php',
     'HarbormasterBuildPlanQuery' => 'applications/harbormaster/query/HarbormasterBuildPlanQuery.php',
@@ -667,6 +669,7 @@ phutil_register_library_map(array(
     'HarbormasterBuildStepQuery' => 'applications/harbormaster/query/HarbormasterBuildStepQuery.php',
     'HarbormasterBuildTarget' => 'applications/harbormaster/storage/build/HarbormasterBuildTarget.php',
     'HarbormasterBuildTargetQuery' => 'applications/harbormaster/query/HarbormasterBuildTargetQuery.php',
+    'HarbormasterBuildViewController' => 'applications/harbormaster/controller/HarbormasterBuildViewController.php',
     'HarbormasterBuildWorker' => 'applications/harbormaster/worker/HarbormasterBuildWorker.php',
     'HarbormasterBuildable' => 'applications/harbormaster/storage/HarbormasterBuildable.php',
     'HarbormasterBuildableApplyController' => 'applications/harbormaster/controller/HarbormasterBuildableApplyController.php',
@@ -682,6 +685,7 @@ phutil_register_library_map(array(
     'HarbormasterObject' => 'applications/harbormaster/storage/HarbormasterObject.php',
     'HarbormasterPHIDTypeBuild' => 'applications/harbormaster/phid/HarbormasterPHIDTypeBuild.php',
     'HarbormasterPHIDTypeBuildItem' => 'applications/harbormaster/phid/HarbormasterPHIDTypeBuildItem.php',
+    'HarbormasterPHIDTypeBuildLog' => 'applications/harbormaster/phid/HarbormasterPHIDTypeBuildLog.php',
     'HarbormasterPHIDTypeBuildPlan' => 'applications/harbormaster/phid/HarbormasterPHIDTypeBuildPlan.php',
     'HarbormasterPHIDTypeBuildStep' => 'applications/harbormaster/phid/HarbormasterPHIDTypeBuildStep.php',
     'HarbormasterPHIDTypeBuildTarget' => 'applications/harbormaster/phid/HarbormasterPHIDTypeBuildTarget.php',
@@ -1392,6 +1396,7 @@ phutil_register_library_map(array(
     'PhabricatorGlobalUploadTargetView' => 'applications/files/view/PhabricatorGlobalUploadTargetView.php',
     'PhabricatorHandleObjectSelectorDataView' => 'applications/phid/handle/view/PhabricatorHandleObjectSelectorDataView.php',
     'PhabricatorHandleQuery' => 'applications/phid/query/PhabricatorHandleQuery.php',
+    'PhabricatorHarbormasterConfigOptions' => 'applications/harbormaster/config/PhabricatorHarbormasterConfigOptions.php',
     'PhabricatorHash' => 'infrastructure/util/PhabricatorHash.php',
     'PhabricatorHashTestCase' => 'infrastructure/util/__tests__/PhabricatorHashTestCase.php',
     'PhabricatorHelpController' => 'applications/help/controller/PhabricatorHelpController.php',
@@ -2254,9 +2259,11 @@ phutil_register_library_map(array(
     'ReleephStatusFieldSpecification' => 'applications/releeph/field/specification/ReleephStatusFieldSpecification.php',
     'ReleephSummaryFieldSpecification' => 'applications/releeph/field/specification/ReleephSummaryFieldSpecification.php',
     'ReleephUserView' => 'applications/releeph/view/user/ReleephUserView.php',
+    'ShellLogView' => 'applications/harbormaster/view/ShellLogView.php',
     'SleepBuildStepImplementation' => 'applications/harbormaster/step/SleepBuildStepImplementation.php',
     'SlowvoteEmbedView' => 'applications/slowvote/view/SlowvoteEmbedView.php',
     'SlowvoteRemarkupRule' => 'applications/slowvote/remarkup/SlowvoteRemarkupRule.php',
+    'VariableBuildStepImplementation' => 'applications/harbormaster/step/VariableBuildStepImplementation.php',
   ),
   'function' =>
   array(
@@ -2920,9 +2927,15 @@ phutil_register_library_map(array(
       0 => 'HarbormasterDAO',
       1 => 'PhabricatorPolicyInterface',
     ),
+    'HarbormasterBuildCancelController' => 'HarbormasterController',
     'HarbormasterBuildItem' => 'HarbormasterDAO',
     'HarbormasterBuildItemQuery' => 'PhabricatorCursorPagedPolicyAwareQuery',
-    'HarbormasterBuildLog' => 'HarbormasterDAO',
+    'HarbormasterBuildLog' =>
+    array(
+      0 => 'HarbormasterDAO',
+      1 => 'PhabricatorPolicyInterface',
+    ),
+    'HarbormasterBuildLogQuery' => 'PhabricatorCursorPagedPolicyAwareQuery',
     'HarbormasterBuildPlan' =>
     array(
       0 => 'HarbormasterDAO',
@@ -2944,6 +2957,7 @@ phutil_register_library_map(array(
     'HarbormasterBuildStepQuery' => 'PhabricatorCursorPagedPolicyAwareQuery',
     'HarbormasterBuildTarget' => 'HarbormasterDAO',
     'HarbormasterBuildTargetQuery' => 'PhabricatorCursorPagedPolicyAwareQuery',
+    'HarbormasterBuildViewController' => 'HarbormasterController',
     'HarbormasterBuildWorker' => 'PhabricatorWorker',
     'HarbormasterBuildable' =>
     array(
@@ -2967,6 +2981,7 @@ phutil_register_library_map(array(
     'HarbormasterObject' => 'HarbormasterDAO',
     'HarbormasterPHIDTypeBuild' => 'PhabricatorPHIDType',
     'HarbormasterPHIDTypeBuildItem' => 'PhabricatorPHIDType',
+    'HarbormasterPHIDTypeBuildLog' => 'PhabricatorPHIDType',
     'HarbormasterPHIDTypeBuildPlan' => 'PhabricatorPHIDType',
     'HarbormasterPHIDTypeBuildStep' => 'PhabricatorPHIDType',
     'HarbormasterPHIDTypeBuildTarget' => 'PhabricatorPHIDType',
@@ -3776,6 +3791,7 @@ phutil_register_library_map(array(
     'PhabricatorGlobalLock' => 'PhutilLock',
     'PhabricatorGlobalUploadTargetView' => 'AphrontView',
     'PhabricatorHandleQuery' => 'PhabricatorCursorPagedPolicyAwareQuery',
+    'PhabricatorHarbormasterConfigOptions' => 'PhabricatorApplicationConfigOptions',
     'PhabricatorHashTestCase' => 'PhabricatorTestCase',
     'PhabricatorHelpController' => 'PhabricatorController',
     'PhabricatorHelpKeyboardShortcutController' => 'PhabricatorHelpController',
@@ -4783,8 +4799,10 @@ phutil_register_library_map(array(
     'ReleephStatusFieldSpecification' => 'ReleephFieldSpecification',
     'ReleephSummaryFieldSpecification' => 'ReleephFieldSpecification',
     'ReleephUserView' => 'AphrontView',
+    'ShellLogView' => 'AphrontView',
     'SleepBuildStepImplementation' => 'BuildStepImplementation',
     'SlowvoteEmbedView' => 'AphrontView',
     'SlowvoteRemarkupRule' => 'PhabricatorRemarkupRuleObject',
+    'VariableBuildStepImplementation' => 'BuildStepImplementation',
   ),
 ));
diff --git a/src/applications/harbormaster/application/PhabricatorApplicationHarbormaster.php b/src/applications/harbormaster/application/PhabricatorApplicationHarbormaster.php
index bf0d7c21ac..cbf9ed908e 100644
--- a/src/applications/harbormaster/application/PhabricatorApplicationHarbormaster.php
+++ b/src/applications/harbormaster/application/PhabricatorApplicationHarbormaster.php
@@ -51,6 +51,10 @@ final class PhabricatorApplicationHarbormaster extends PhabricatorApplication {
           'edit/(?:(?P<id>\d+)/)?' => 'HarbormasterStepEditController',
           'delete/(?:(?P<id>\d+)/)?' => 'HarbormasterStepDeleteController',
         ),
+        'build/' => array(
+          '(?:(?P<id>\d+)/)?' => 'HarbormasterBuildViewController',
+          'cancel/(?:(?P<id>\d+)/)?' => 'HarbormasterBuildCancelController',
+        ),
         'plan/' => array(
           '(?:query/(?P<queryKey>[^/]+)/)?'
             => 'HarbormasterPlanListController',
diff --git a/src/applications/harbormaster/config/PhabricatorHarbormasterConfigOptions.php b/src/applications/harbormaster/config/PhabricatorHarbormasterConfigOptions.php
new file mode 100644
index 0000000000..fdfa27152e
--- /dev/null
+++ b/src/applications/harbormaster/config/PhabricatorHarbormasterConfigOptions.php
@@ -0,0 +1,35 @@
+<?php
+
+final class PhabricatorHarbormasterConfigOptions
+  extends PhabricatorApplicationConfigOptions {
+
+  public function getName() {
+    return pht('Harbormaster');
+  }
+
+  public function getDescription() {
+    return pht('Configure Harbormaster build engine.');
+  }
+
+  public function getOptions() {
+    return array(
+      $this->newOption(
+        'harbormaster.temporary.hosts.whitelist',
+        'list<string>',
+        array())
+        ->setSummary('Temporary configuration value.')
+        ->setLocked(true)
+        ->setDescription(
+          pht(
+            "This specifies a whitelist of remote hosts that the \"Run ".
+            "Remote Command\" may connect to.  This is a temporary ".
+            "configuration option as Drydock is not yet available.".
+            "\n\n".
+            "**This configuration option will be removed in the future and ".
+            "your build configuration will no longer work when Drydock ".
+            "replaces this option.  There is ABSOLUTELY NO SUPPORT for ".
+            "using this functionality!**"))
+    );
+  }
+
+}
diff --git a/src/applications/harbormaster/controller/HarbormasterBuildCancelController.php b/src/applications/harbormaster/controller/HarbormasterBuildCancelController.php
new file mode 100644
index 0000000000..961d243be6
--- /dev/null
+++ b/src/applications/harbormaster/controller/HarbormasterBuildCancelController.php
@@ -0,0 +1,49 @@
+<?php
+
+final class HarbormasterBuildCancelController
+  extends HarbormasterController {
+
+  private $id;
+
+  public function willProcessRequest(array $data) {
+    $this->id = $data['id'];
+  }
+
+  public function processRequest() {
+    $request = $this->getRequest();
+    $viewer = $request->getUser();
+
+    $id = $this->id;
+
+    $build = id(new HarbormasterBuildQuery())
+      ->setViewer($viewer)
+      ->withIDs(array($id))
+      ->executeOne();
+    if ($build === null) {
+      return new Aphront404Response();
+    }
+
+    $build_uri = $this->getApplicationURI('/build/'.$build->getID());
+
+    if ($request->isDialogFormPost()) {
+      $build->setCancelRequested(true);
+      $build->save();
+
+      return id(new AphrontRedirectResponse())->setURI($build_uri);
+    }
+
+    $dialog = new AphrontDialogView();
+    $dialog->setTitle(pht('Really cancel build?'))
+      ->setUser($viewer)
+      ->addSubmitButton(pht('Cancel'))
+      ->addCancelButton($build_uri, pht('Don\'t Cancel'));
+    $dialog->appendChild(
+      phutil_tag(
+        'p',
+        array(),
+        pht(
+          'Really cancel this build?')));
+    return id(new AphrontDialogResponse())->setDialog($dialog);
+  }
+
+}
diff --git a/src/applications/harbormaster/controller/HarbormasterBuildViewController.php b/src/applications/harbormaster/controller/HarbormasterBuildViewController.php
new file mode 100644
index 0000000000..4eb5d39d3d
--- /dev/null
+++ b/src/applications/harbormaster/controller/HarbormasterBuildViewController.php
@@ -0,0 +1,218 @@
+<?php
+
+final class HarbormasterBuildViewController
+  extends HarbormasterController {
+
+  private $id;
+
+  public function willProcessRequest(array $data) {
+    $this->id = $data['id'];
+  }
+
+  public function processRequest() {
+    $request = $this->getRequest();
+    $viewer = $request->getUser();
+
+    $id = $this->id;
+
+    $build = id(new HarbormasterBuildQuery())
+      ->setViewer($viewer)
+      ->withIDs(array($id))
+      ->executeOne();
+    if (!$build) {
+      return new Aphront404Response();
+    }
+
+    $title = pht("Build %d", $id);
+
+    $header = id(new PHUIHeaderView())
+      ->setHeader($title)
+      ->setUser($viewer)
+      ->setPolicyObject($build);
+
+    $box = id(new PHUIObjectBoxView())
+      ->setHeader($header);
+
+    $actions = $this->buildActionList($build);
+    $this->buildPropertyLists($box, $build, $actions);
+
+    $crumbs = $this->buildApplicationCrumbs();
+    $crumbs->addCrumb(
+      id(new PhabricatorCrumbView())
+        ->setName($title));
+
+    $logs = $this->buildLog($build);
+
+    return $this->buildApplicationPage(
+      array(
+        $crumbs,
+        $box,
+        $logs
+      ),
+      array(
+        'title' => $title,
+        'device' => true,
+      ));
+  }
+
+  private function buildLog(HarbormasterBuild $build) {
+    $request = $this->getRequest();
+    $viewer = $request->getUser();
+    $limit = $request->getInt('l', 25);
+
+    $logs = id(new HarbormasterBuildLogQuery())
+      ->setViewer($viewer)
+      ->withBuildPHIDs(array($build->getPHID()))
+      ->execute();
+
+    $log_boxes = array();
+    foreach ($logs as $log) {
+      $start = 1;
+      $lines = preg_split("/\r\n|\r|\n/", $log->getLogText());
+      if ($limit !== 0) {
+        $start = count($lines) - $limit;
+        if ($start >= 1) {
+          $lines = array_slice($lines, -$limit, $limit);
+        } else {
+          $start = 1;
+        }
+      }
+      $log_view = new ShellLogView();
+      $log_view->setLines($lines);
+      $log_view->setStart($start);
+
+      $header = id(new PHUIHeaderView())
+        ->setHeader(pht(
+          'Build Log %d (%s - %s)',
+          $log->getID(),
+          $log->getLogSource(),
+          $log->getLogType()))
+        ->setSubheader($this->createLogHeader($build, $log))
+        ->setUser($viewer);
+
+      $log_boxes[] = id(new PHUIObjectBoxView())
+        ->setHeader($header)
+        ->setForm($log_view);
+    }
+
+    return $log_boxes;
+  }
+
+  private function createLogHeader($build, $log) {
+    $request = $this->getRequest();
+    $limit = $request->getInt('l', 25);
+
+    $lines_25 = $this->getApplicationURI('/build/'.$build->getID().'/?l=25');
+    $lines_50 = $this->getApplicationURI('/build/'.$build->getID().'/?l=50');
+    $lines_100 =
+      $this->getApplicationURI('/build/'.$build->getID().'/?l=100');
+    $lines_0 = $this->getApplicationURI('/build/'.$build->getID().'/?l=0');
+
+    $link_25 = phutil_tag('a', array('href' => $lines_25), pht('25'));
+    $link_50 = phutil_tag('a', array('href' => $lines_50), pht('50'));
+    $link_100 = phutil_tag('a', array('href' => $lines_100), pht('100'));
+    $link_0 = phutil_tag('a', array('href' => $lines_0), pht('Unlimited'));
+
+    if ($limit === 25) {
+      $link_25 = phutil_tag('strong', array(), $link_25);
+    } else if ($limit === 50) {
+      $link_50 = phutil_tag('strong', array(), $link_50);
+    } else if ($limit === 100) {
+      $link_100 = phutil_tag('strong', array(), $link_100);
+    } else if ($limit === 0) {
+      $link_0 = phutil_tag('strong', array(), $link_0);
+    }
+
+    return phutil_tag(
+      'span',
+      array(),
+      array(
+        $link_25,
+        ' - ',
+        $link_50,
+        ' - ',
+        $link_100,
+        ' - ',
+        $link_0,
+        ' Lines'));
+  }
+
+  private function buildActionList(HarbormasterBuild $build) {
+    $request = $this->getRequest();
+    $viewer = $request->getUser();
+    $id = $build->getID();
+
+    $list = id(new PhabricatorActionListView())
+      ->setUser($viewer)
+      ->setObject($build)
+      ->setObjectURI("/build/{$id}");
+
+    $action =
+      id(new PhabricatorActionView())
+        ->setName(pht('Cancel Build'))
+        ->setIcon('delete');
+    switch ($build->getBuildStatus()) {
+      case HarbormasterBuild::STATUS_PENDING:
+      case HarbormasterBuild::STATUS_WAITING:
+      case HarbormasterBuild::STATUS_BUILDING:
+        $cancel_uri = $this->getApplicationURI('/build/cancel/'.$id.'/');
+        $action
+          ->setHref($cancel_uri)
+          ->setWorkflow(true);
+        break;
+      default:
+        $action
+          ->setDisabled(true);
+        break;
+    }
+    $list->addAction($action);
+
+    return $list;
+  }
+
+  private function buildPropertyLists(
+    PHUIObjectBoxView $box,
+    HarbormasterBuild $build,
+    PhabricatorActionListView $actions) {
+    $request = $this->getRequest();
+    $viewer = $request->getUser();
+
+    $properties = id(new PHUIPropertyListView())
+      ->setUser($viewer)
+      ->setObject($build)
+      ->setActionList($actions);
+    $box->addPropertyList($properties);
+
+    $properties->addProperty(
+      pht('Status'),
+      $this->getStatus($build));
+
+  }
+
+  private function getStatus(HarbormasterBuild $build) {
+    if ($build->getCancelRequested()) {
+      return pht('Cancelling');
+    }
+    switch ($build->getBuildStatus()) {
+      case HarbormasterBuild::STATUS_INACTIVE:
+        return pht('Inactive');
+      case HarbormasterBuild::STATUS_PENDING:
+        return pht('Pending');
+      case HarbormasterBuild::STATUS_WAITING:
+        return pht('Waiting on Resource');
+      case HarbormasterBuild::STATUS_BUILDING:
+        return pht('Building');
+      case HarbormasterBuild::STATUS_PASSED:
+        return pht('Passed');
+      case HarbormasterBuild::STATUS_FAILED:
+        return pht('Failed');
+      case HarbormasterBuild::STATUS_ERROR:
+        return pht('Unexpected Error');
+      case HarbormasterBuild::STATUS_CANCELLED:
+        return pht('Cancelled');
+      default:
+        return pht('Unknown');
+    }
+  }
+
+}
diff --git a/src/applications/harbormaster/controller/HarbormasterBuildableViewController.php b/src/applications/harbormaster/controller/HarbormasterBuildableViewController.php
index c1eb56496a..adae866dfe 100644
--- a/src/applications/harbormaster/controller/HarbormasterBuildableViewController.php
+++ b/src/applications/harbormaster/controller/HarbormasterBuildableViewController.php
@@ -34,38 +34,49 @@ final class HarbormasterBuildableViewController
     $build_list = id(new PHUIObjectItemListView())
       ->setUser($viewer);
     foreach ($builds as $build) {
+      $view_uri = $this->getApplicationURI('/build/'.$build->getID().'/');
       $item = id(new PHUIObjectItemView())
         ->setObjectName(pht('Build %d', $build->getID()))
-        ->setHeader($build->getName());
-      switch ($build->getBuildStatus()) {
-        case HarbormasterBuild::STATUS_INACTIVE:
-          $item->setBarColor('grey');
-          $item->addAttribute(pht('Inactive'));
-          break;
-        case HarbormasterBuild::STATUS_PENDING:
-          $item->setBarColor('blue');
-          $item->addAttribute(pht('Pending'));
-          break;
-        case HarbormasterBuild::STATUS_WAITING:
-          $item->setBarColor('blue');
-          $item->addAttribute(pht('Waiting on Resource'));
-          break;
-        case HarbormasterBuild::STATUS_BUILDING:
-          $item->setBarColor('yellow');
-          $item->addAttribute(pht('Building'));
-          break;
-        case HarbormasterBuild::STATUS_PASSED:
-          $item->setBarColor('green');
-          $item->addAttribute(pht('Passed'));
-          break;
-        case HarbormasterBuild::STATUS_FAILED:
-          $item->setBarColor('red');
-          $item->addAttribute(pht('Failed'));
-          break;
-        case HarbormasterBuild::STATUS_ERROR:
-          $item->setBarColor('red');
-          $item->addAttribute(pht('Unexpected Error'));
-          break;
+        ->setHeader($build->getName())
+        ->setHref($view_uri);
+      if ($build->getCancelRequested()) {
+        $item->setBarColor('black');
+        $item->addAttribute(pht('Cancelling'));
+      } else {
+        switch ($build->getBuildStatus()) {
+          case HarbormasterBuild::STATUS_INACTIVE:
+            $item->setBarColor('grey');
+            $item->addAttribute(pht('Inactive'));
+            break;
+          case HarbormasterBuild::STATUS_PENDING:
+            $item->setBarColor('blue');
+            $item->addAttribute(pht('Pending'));
+            break;
+          case HarbormasterBuild::STATUS_WAITING:
+            $item->setBarColor('blue');
+            $item->addAttribute(pht('Waiting on Resource'));
+            break;
+          case HarbormasterBuild::STATUS_BUILDING:
+            $item->setBarColor('yellow');
+            $item->addAttribute(pht('Building'));
+            break;
+          case HarbormasterBuild::STATUS_PASSED:
+            $item->setBarColor('green');
+            $item->addAttribute(pht('Passed'));
+            break;
+          case HarbormasterBuild::STATUS_FAILED:
+            $item->setBarColor('red');
+            $item->addAttribute(pht('Failed'));
+            break;
+          case HarbormasterBuild::STATUS_ERROR:
+            $item->setBarColor('red');
+            $item->addAttribute(pht('Unexpected Error'));
+            break;
+          case HarbormasterBuild::STATUS_CANCELLED:
+            $item->setBarColor('black');
+            $item->addAttribute(pht('Cancelled'));
+            break;
+        }
       }
       $build_list->addItem($item);
     }
diff --git a/src/applications/harbormaster/controller/HarbormasterStepEditController.php b/src/applications/harbormaster/controller/HarbormasterStepEditController.php
index 81d3f0b2a8..db98d7e858 100644
--- a/src/applications/harbormaster/controller/HarbormasterStepEditController.php
+++ b/src/applications/harbormaster/controller/HarbormasterStepEditController.php
@@ -63,6 +63,11 @@ final class HarbormasterStepEditController
     $form = id(new AphrontFormView())
       ->setUser($viewer);
 
+    $instructions = $implementation->getSettingRemarkupInstructions();
+    if ($instructions !== null) {
+      $form->appendRemarkupInstructions($instructions);
+    }
+
     // We need to render out all of the fields for the settings that
     // the implementation has.
     foreach ($implementation->getSettingDefinitions() as $name => $opt) {
diff --git a/src/applications/harbormaster/phid/HarbormasterPHIDTypeBuildLog.php b/src/applications/harbormaster/phid/HarbormasterPHIDTypeBuildLog.php
new file mode 100644
index 0000000000..385cbcaac6
--- /dev/null
+++ b/src/applications/harbormaster/phid/HarbormasterPHIDTypeBuildLog.php
@@ -0,0 +1,37 @@
+<?php
+
+final class HarbormasterPHIDTypeBuildLog extends PhabricatorPHIDType {
+
+  const TYPECONST = 'HMCL';
+
+  public function getTypeConstant() {
+    return self::TYPECONST;
+  }
+
+  public function getTypeName() {
+    return pht('Build Log');
+  }
+
+  public function newObject() {
+    return new HarbormasterBuildLog();
+  }
+
+  protected function buildQueryForObjects(
+    PhabricatorObjectQuery $query,
+    array $phids) {
+
+    return id(new HarbormasterBuildLogQuery())
+      ->withPHIDs($phids);
+  }
+
+  public function loadHandles(
+    PhabricatorHandleQuery $query,
+    array $handles,
+    array $objects) {
+
+    foreach ($handles as $phid => $handle) {
+      $build_log = $objects[$phid];
+    }
+  }
+
+}
diff --git a/src/applications/harbormaster/query/HarbormasterBuildLogQuery.php b/src/applications/harbormaster/query/HarbormasterBuildLogQuery.php
new file mode 100644
index 0000000000..000b267f9f
--- /dev/null
+++ b/src/applications/harbormaster/query/HarbormasterBuildLogQuery.php
@@ -0,0 +1,98 @@
+<?php
+
+final class HarbormasterBuildLogQuery
+  extends PhabricatorCursorPagedPolicyAwareQuery {
+
+  private $ids;
+  private $phids;
+  private $buildPHIDs;
+
+  public function withIDs(array $ids) {
+    $this->ids = $ids;
+    return $this;
+  }
+
+  public function withPHIDs(array $phids) {
+    $this->phids = $phids;
+    return $this;
+  }
+
+  public function withBuildPHIDs(array $build_phids) {
+    $this->buildPHIDs = $build_phids;
+    return $this;
+  }
+
+  protected function loadPage() {
+    $table = new HarbormasterBuildLog();
+    $conn_r = $table->establishConnection('r');
+
+    $data = queryfx_all(
+      $conn_r,
+      'SELECT * FROM %T %Q %Q %Q',
+      $table->getTableName(),
+      $this->buildWhereClause($conn_r),
+      $this->buildOrderClause($conn_r),
+      $this->buildLimitClause($conn_r));
+
+    return $table->loadAllFromArray($data);
+  }
+
+  protected function willFilterPage(array $page) {
+    $builds = array();
+
+    $build_phids = array_filter(mpull($page, 'getBuildPHID'));
+    if ($build_phids) {
+      $builds = id(new HarbormasterBuildQuery())
+        ->setViewer($this->getViewer())
+        ->withPHIDs($build_phids)
+        ->setParentQuery($this)
+        ->execute();
+      $builds = mpull($builds, null, 'getPHID');
+    }
+
+    foreach ($page as $key => $build_log) {
+      $build_phid = $build_log->getBuildPHID();
+      if (empty($builds[$build_phid])) {
+        unset($page[$key]);
+        continue;
+      }
+      $build_log->attachBuild($builds[$build_phid]);
+    }
+
+    return $page;
+  }
+
+  private function buildWhereClause(AphrontDatabaseConnection $conn_r) {
+    $where = array();
+
+    if ($this->ids) {
+      $where[] = qsprintf(
+        $conn_r,
+        'id IN (%Ld)',
+        $this->ids);
+    }
+
+    if ($this->phids) {
+      $where[] = qsprintf(
+        $conn_r,
+        'phid IN (%Ls)',
+        $this->phids);
+    }
+
+    if ($this->buildPHIDs) {
+      $where[] = qsprintf(
+        $conn_r,
+        'buildPHID IN (%Ls)',
+        $this->buildPHIDs);
+    }
+
+    $where[] = $this->buildPagingClause($conn_r);
+
+    return $this->formatWhereClause($where);
+  }
+
+  public function getQueryApplicationClass() {
+    return 'PhabricatorApplicationHarbormaster';
+  }
+
+}
diff --git a/src/applications/harbormaster/step/BuildStepImplementation.php b/src/applications/harbormaster/step/BuildStepImplementation.php
index 6a524f4e39..8e1df82abf 100644
--- a/src/applications/harbormaster/step/BuildStepImplementation.php
+++ b/src/applications/harbormaster/step/BuildStepImplementation.php
@@ -38,7 +38,9 @@ abstract class BuildStepImplementation {
   /**
    * Run the build step against the specified build.
    */
-  abstract public function execute(HarbormasterBuild $build);
+  abstract public function execute(
+    HarbormasterBuild $build,
+    HarbormasterBuildStep $build_step);
 
   /**
    * Gets the settings for this build step.
@@ -85,4 +87,11 @@ abstract class BuildStepImplementation {
   public function getSettingDefinitions() {
     return array();
   }
+
+  /**
+   * Return relevant setting instructions as Remarkup.
+   */
+  public function getSettingRemarkupInstructions() {
+    return null;
+  }
 }
diff --git a/src/applications/harbormaster/step/SleepBuildStepImplementation.php b/src/applications/harbormaster/step/SleepBuildStepImplementation.php
index e80f559e29..0c51eaa881 100644
--- a/src/applications/harbormaster/step/SleepBuildStepImplementation.php
+++ b/src/applications/harbormaster/step/SleepBuildStepImplementation.php
@@ -16,7 +16,10 @@ final class SleepBuildStepImplementation extends BuildStepImplementation {
     return pht('Sleep for %s seconds.', $settings['seconds']);
   }
 
-  public function execute(HarbormasterBuild $build) {
+  public function execute(
+    HarbormasterBuild $build,
+    HarbormasterBuildStep $build_step) {
+
     $settings = $this->getSettings();
 
     sleep($settings['seconds']);
diff --git a/src/applications/harbormaster/step/VariableBuildStepImplementation.php b/src/applications/harbormaster/step/VariableBuildStepImplementation.php
new file mode 100644
index 0000000000..7f91518282
--- /dev/null
+++ b/src/applications/harbormaster/step/VariableBuildStepImplementation.php
@@ -0,0 +1,67 @@
+<?php
+
+abstract class VariableBuildStepImplementation extends BuildStepImplementation {
+
+  public function retrieveVariablesFromBuild(HarbormasterBuild $build) {
+    $results = array(
+      'revision' => null,
+      'commit' => null,
+      'repository' => null,
+      'vcs' => null,
+      'uri' => null,
+      'timestamp' => null);
+
+    $buildable = $build->getBuildable();
+    $object = $buildable->getBuildableObject();
+
+    $repo = null;
+    if ($object instanceof DifferentialRevision) {
+      $results['revision'] = $object->getID();
+      $repo = $object->getRepository();
+    } else if ($object instanceof PhabricatorRepositoryCommit) {
+      $results['commit'] = $object->getCommitIdentifier();
+      $repo = $object->getRepository();
+    }
+
+    $results['repository'] = $repo->getCallsign();
+    $results['vcs'] = $repo->getVersionControlSystem();
+    $results['uri'] = $repo->getPublicRemoteURI();
+    $results['timestamp'] = time();
+
+    return $results;
+  }
+
+  public function mergeVariables(HarbormasterBuild $build, $string) {
+    $variables = $this->retrieveVariablesFromBuild($build);
+    foreach ($variables as $name => $value) {
+      if ($value === null) {
+        $value = '';
+      }
+      $string = str_replace('${'.$name.'}', $value, $string);
+    }
+    return $string;
+  }
+
+  public function getAvailableVariables() {
+    return array(
+      'revision' => pht('The differential revision ID, if applicable.'),
+      'commit' => pht('The commit identifier, if applicable.'),
+      'repository' => pht('The callsign of the repository in Phabricator.'),
+      'vcs' => pht('The version control system, either "svn", "hg" or "git".'),
+      'uri' => pht('The URI to clone or checkout the repository from.'),
+      'timestamp' => pht('The current UNIX timestamp.'));
+  }
+
+  public function getSettingRemarkupInstructions() {
+    $text = '';
+    $text .= pht('The following variables are available: ')."\n";
+    $text .= "\n";
+    foreach ($this->getAvailableVariables() as $name => $desc) {
+      $text .= '  - `'.$name.'`: '.$desc."\n";
+    }
+    $text .= "\n";
+    $text .= "Use `\${name}` to merge a variable into a setting.";
+    return $text;
+  }
+
+}
diff --git a/src/applications/harbormaster/storage/build/HarbormasterBuild.php b/src/applications/harbormaster/storage/build/HarbormasterBuild.php
index aa8e6c4f53..0d789d46d9 100644
--- a/src/applications/harbormaster/storage/build/HarbormasterBuild.php
+++ b/src/applications/harbormaster/storage/build/HarbormasterBuild.php
@@ -6,6 +6,7 @@ final class HarbormasterBuild extends HarbormasterDAO
   protected $buildablePHID;
   protected $buildPlanPHID;
   protected $buildStatus;
+  protected $cancelRequested;
 
   private $buildable = self::ATTACHABLE;
   private $buildPlan = self::ATTACHABLE;
@@ -45,9 +46,15 @@ final class HarbormasterBuild extends HarbormasterDAO
    */
   const STATUS_ERROR = 'error';
 
+  /**
+   * The build has been cancelled.
+   */
+  const STATUS_CANCELLED = 'cancelled';
+
   public static function initializeNewBuild(PhabricatorUser $actor) {
     return id(new HarbormasterBuild())
-      ->setBuildStatus(self::STATUS_INACTIVE);
+      ->setBuildStatus(self::STATUS_INACTIVE)
+      ->setCancelRequested(false);
   }
 
   public function getConfiguration() {
@@ -87,6 +94,37 @@ final class HarbormasterBuild extends HarbormasterDAO
     return $this->assertAttached($this->buildPlan);
   }
 
+  public function createLog(
+    HarbormasterBuildStep $build_step,
+    $log_source,
+    $log_type) {
+
+    $log = HarbormasterBuildLog::initializeNewBuildLog($this, $build_step);
+    $log->setLogSource($log_source);
+    $log->setLogType($log_type);
+    $log->save();
+    return $log;
+  }
+
+  /**
+   * Checks for and handles build cancellation.  If this method returns
+   * true, the caller should stop any current operations and return control
+   * as quickly as possible.
+   */
+  public function checkForCancellation() {
+    // Here we load a copy of the current build and check whether
+    // the user requested cancellation.  We can't do `reload()` here
+    // in case there are changes that have not yet been saved.
+    $copy = id(new HarbormasterBuild())->load($this->getID());
+    if ($copy->getCancelRequested()) {
+      $this->setBuildStatus(HarbormasterBuild::STATUS_CANCELLED);
+      $this->setCancelRequested(false);
+      $this->save();
+      return true;
+    }
+    return false;
+  }
+
 
 /* -(  PhabricatorPolicyInterface  )----------------------------------------- */
 
diff --git a/src/applications/harbormaster/storage/build/HarbormasterBuildLog.php b/src/applications/harbormaster/storage/build/HarbormasterBuildLog.php
index 2e5d05d7eb..bd00dc5d6d 100644
--- a/src/applications/harbormaster/storage/build/HarbormasterBuildLog.php
+++ b/src/applications/harbormaster/storage/build/HarbormasterBuildLog.php
@@ -1,7 +1,206 @@
 <?php
 
-final class HarbormasterBuildLog extends HarbormasterDAO {
+final class HarbormasterBuildLog extends HarbormasterDAO
+  implements PhabricatorPolicyInterface {
+
+  protected $buildPHID;
+  protected $buildStepPHID;
+  protected $logSource;
+  protected $logType;
+  protected $duration;
+  protected $live;
+
+  private $build = self::ATTACHABLE;
+  private $buildStep = self::ATTACHABLE;
+
+  const CHUNK_BYTE_LIMIT = 102400;
+
+  /**
+   * The log is encoded as plain text.
+   */
+  const ENCODING_TEXT = 'text';
+
+  public static function initializeNewBuildLog(
+    HarbormasterBuild $build,
+    HarbormasterBuildStep $build_step) {
+
+    return id(new HarbormasterBuildLog())
+      ->setBuildPHID($build->getPHID())
+      ->setBuildStepPHID($build_step->getPHID())
+      ->setDuration(null)
+      ->setLive(false);
+  }
+
+  public function getConfiguration() {
+    return array(
+      self::CONFIG_AUX_PHID => true,
+    ) + parent::getConfiguration();
+  }
+
+  public function generatePHID() {
+    return PhabricatorPHID::generateNewPHID(
+      HarbormasterPHIDTypeBuildLog::TYPECONST);
+  }
+
+  public function attachBuild(HarbormasterBuild $build) {
+    $this->build = $build;
+    return $this;
+  }
+
+  public function getBuild() {
+    return $this->assertAttached($this->build);
+  }
+
+  public function getName() {
+    return pht('Build Log');
+  }
+
+  public function attachBuildStep(
+    HarbormasterBuildStep $build_step = null) {
+    $this->buildStep = $build_step;
+    return $this;
+  }
+
+  public function getBuildStep() {
+    return $this->assertAttached($this->buildStep);
+  }
+
+  public function start() {
+    if ($this->getLive()) {
+      throw new Exception("Live logging has already started for this log.");
+    }
+
+    $this->setLive(true);
+    $this->save();
+
+    return time();
+  }
+
+  public function append($content) {
+    if (!$this->getLive()) {
+      throw new Exception("Start logging before appending data to the log.");
+    }
+    if (strlen($content) === 0) {
+      return;
+    }
+
+    // If the length of the content is greater than the chunk size limit,
+    // then we can never fit the content in a single record.  We need to
+    // split our content out and call append on it for as many parts as there
+    // are to the content.
+    if (strlen($content) > self::CHUNK_BYTE_LIMIT) {
+      $current = $content;
+      while (strlen($current) > self::CHUNK_BYTE_LIMIT) {
+        $part = substr($current, 0, self::CHUNK_BYTE_LIMIT);
+        $current = substr($current, self::CHUNK_BYTE_LIMIT);
+        $this->append($part);
+      }
+      return;
+    }
+
+    // Retrieve the size of last chunk from the DB for this log.  If the
+    // chunk is over 500K, then we need to create a new log entry.
+    $conn = $this->establishConnection('w');
+    $result = queryfx_all(
+      $conn,
+      'SELECT id, size, encoding '.
+      'FROM harbormaster_buildlogchunk '.
+      'WHERE logID = %d '.
+      'ORDER BY id DESC '.
+      'LIMIT 1',
+      $this->getID());
+    if (count($result) === 0 ||
+      $result[0]["size"] + strlen($content) > self::CHUNK_BYTE_LIMIT ||
+      $result[0]["encoding"] !== self::ENCODING_TEXT) {
+
+      // We must insert a new chunk because the data we are appending
+      // won't fit into the existing one, or we don't have any existing
+      // chunk data.
+      queryfx(
+        $conn,
+        'INSERT INTO harbormaster_buildlogchunk '.
+        '(logID, encoding, size, chunk) '.
+        'VALUES '.
+        '(%d, %s, %d, %s)',
+        $this->getID(),
+        self::ENCODING_TEXT,
+        strlen($content),
+        $content);
+    } else {
+      // We have a resulting record that we can append our content onto.
+      queryfx(
+        $conn,
+        'UPDATE harbormaster_buildlogchunk '.
+        'SET chunk = CONCAT(chunk, %s), size = LENGTH(CONCAT(chunk, %s))'.
+        'WHERE id = %d',
+        $content,
+        $content,
+        $result[0]["id"]);
+    }
+  }
+
+  public function finalize($start = 0) {
+    if (!$this->getLive()) {
+      throw new Exception("Start logging before finalizing it.");
+    }
+
+    // TODO: Encode the log contents in a gzipped format.
+    $this->reload();
+    if ($start > 0) {
+      $this->setDuration(time() - $start);
+    }
+    $this->setLive(false);
+    $this->save();
+  }
+
+  public function getLogText() {
+    // TODO: This won't cope very well if we're pulling like a 700MB
+    // log file out of the DB.  We should probably implement some sort
+    // of optional limit parameter so that when we're rendering out only
+    // 25 lines in the UI, we don't wastefully read in the whole log.
+
+    // We have to read our content out of the database and stitch all of
+    // the log data back together.
+    $conn = $this->establishConnection('r');
+    $result = queryfx_all(
+      $conn,
+      'SELECT chunk '.
+      'FROM harbormaster_buildlogchunk '.
+      'WHERE logID = %d '.
+      'ORDER BY id ASC',
+      $this->getID());
+
+    $content = "";
+    foreach ($result as $row) {
+      $content .= $row["chunk"];
+    }
+    return $content;
+  }
+
+
+/* -(  PhabricatorPolicyInterface  )----------------------------------------- */
+
+
+  public function getCapabilities() {
+    return array(
+      PhabricatorPolicyCapability::CAN_VIEW,
+    );
+  }
+
+  public function getPolicy($capability) {
+    return $this->getBuild()->getPolicy($capability);
+  }
+
+  public function hasAutomaticCapability($capability, PhabricatorUser $viewer) {
+    return $this->getBuild()->hasAutomaticCapability(
+      $capability,
+      $viewer);
+  }
+
+  public function describeAutomaticCapability($capability) {
+    return pht(
+      'Users must be able to see a build to view it\'s build log.');
+  }
 
-  protected $buildItemPHID;
 
 }
diff --git a/src/applications/harbormaster/view/ShellLogView.php b/src/applications/harbormaster/view/ShellLogView.php
new file mode 100644
index 0000000000..db7f85548f
--- /dev/null
+++ b/src/applications/harbormaster/view/ShellLogView.php
@@ -0,0 +1,101 @@
+<?php
+
+final class ShellLogView extends AphrontView {
+
+  private $start = 1;
+  private $lines;
+  private $limit;
+  private $highlights = array();
+
+  public function setStart($start) {
+    $this->start = $start;
+    return $this;
+  }
+
+  public function setLimit($limit) {
+    $this->limit = $limit;
+    return $this;
+  }
+
+  public function setLines(array $lines) {
+    $this->lines = $lines;
+    return $this;
+  }
+
+  public function setHighlights(array $highlights) {
+    $this->highlights = array_fuse($highlights);
+    return $this;
+  }
+
+  public function render() {
+    require_celerity_resource('phabricator-source-code-view-css');
+    require_celerity_resource('syntax-highlighting-css');
+
+    Javelin::initBehavior('phabricator-oncopy', array());
+
+    $line_number = $this->start;
+
+    $rows = array();
+    foreach ($this->lines as $line) {
+      $hit_limit = $this->limit &&
+                   ($line_number == $this->limit) &&
+                   (count($this->lines) != $this->limit);
+
+      if ($hit_limit) {
+        $content_number = '';
+        $content_line = phutil_tag(
+          'span',
+          array(
+            'class' => 'c',
+          ),
+          pht('...'));
+      } else {
+        $content_number = $line_number;
+        $content_line = $line;
+      }
+
+      $row_attributes = array();
+      if (isset($this->highlights[$line_number])) {
+        $row_attributes['class'] = 'phabricator-source-highlight';
+      }
+
+      // TODO: Provide nice links.
+
+      $rows[] = phutil_tag(
+        'tr',
+        $row_attributes,
+        hsprintf(
+          '<th class="phabricator-source-line" '.
+          'style="background-color: #fff;">%s</th>'.
+          '<td class="phabricator-source-code">%s</td>',
+          $content_number,
+          $content_line));
+
+      if ($hit_limit) {
+        break;
+      }
+
+      $line_number++;
+    }
+
+    $classes = array();
+    $classes[] = 'phabricator-source-code-view';
+    $classes[] = 'remarkup-code';
+    $classes[] = 'PhabricatorMonospaced';
+
+    return phutil_tag(
+      'div',
+      array(
+        'class' => 'phabricator-source-code-container',
+        'style' => 'background-color: black; color: white;'
+      ),
+      phutil_tag(
+        'table',
+        array(
+          'class' => implode(' ', $classes),
+          'style' => 'background-color: black'
+        ),
+        phutil_implode_html('', $rows)));
+  }
+
+}
diff --git a/src/applications/harbormaster/worker/HarbormasterBuildWorker.php b/src/applications/harbormaster/worker/HarbormasterBuildWorker.php
index 0306c18d8f..2f8a31605d 100644
--- a/src/applications/harbormaster/worker/HarbormasterBuildWorker.php
+++ b/src/applications/harbormaster/worker/HarbormasterBuildWorker.php
@@ -25,6 +25,13 @@ final class HarbormasterBuildWorker extends PhabricatorWorker {
         pht('Invalid build ID "%s".', $id));
     }
 
+    // It's possible for the user to request cancellation before
+    // a worker picks up a build.  We check to see if the build
+    // is already cancelled, and return if it is.
+    if ($build->checkForCancellation()) {
+      return;
+    }
+
     try {
       $build->setBuildStatus(HarbormasterBuild::STATUS_BUILDING);
       $build->save();
@@ -44,12 +51,21 @@ final class HarbormasterBuildWorker extends PhabricatorWorker {
           $build->setBuildStatus(HarbormasterBuild::STATUS_ERROR);
           break;
         }
-        $implementation->execute($build);
+        $implementation->execute($build, $step);
         if ($build->getBuildStatus() !== HarbormasterBuild::STATUS_BUILDING) {
           break;
         }
+        if ($build->checkForCancellation()) {
+          break;
+        }
       }
 
+      // Check to see if the user requested cancellation.  If they did and
+      // we get to here, they might have either cancelled too late, or the
+      // step isn't cancellation aware.  In either case we ignore the result
+      // and move to a cancelled state.
+      $build->checkForCancellation();
+
       // If we get to here, then the build has finished.  Set it to passed
       // if no build step explicitly set the status.
       if ($build->getBuildStatus() === HarbormasterBuild::STATUS_BUILDING) {
diff --git a/src/infrastructure/storage/patch/PhabricatorBuiltinPatchList.php b/src/infrastructure/storage/patch/PhabricatorBuiltinPatchList.php
index 6f5e699c98..08a4c21349 100644
--- a/src/infrastructure/storage/patch/PhabricatorBuiltinPatchList.php
+++ b/src/infrastructure/storage/patch/PhabricatorBuiltinPatchList.php
@@ -1744,6 +1744,10 @@ final class PhabricatorBuiltinPatchList extends PhabricatorSQLPatchList {
         'type' => 'sql',
         'name' => $this->getPatchPath('20131106.nuance-v0.sql'),
       ),
+      '20131107.buildlog.sql' => array(
+        'type' => 'sql',
+        'name' => $this->getPatchPath('20131107.buildlog.sql'),
+      ),
     );
   }
 }