Change: use build graphs in build resources, instead of action list

10 files changed, 743 insertions, 98 deletions

diff --git a/ick2/__init__.py b/ick2/__init__.py
index 18615a4..59344a3 100644
--- a/ick2/__init__.py
+++ b/ick2/__init__.py
@@ -22,6 +22,8 @@ from .persistent import (
     resource_from_dict,
 )
 from .trans import TransactionalState
+from .build import Build, WrongBuildStatusChange
+from .buildgraph import BuildGraph
 from .exceptions import (
     BadUpdate,
     ExistsAlready,
diff --git a/ick2/build.py b/ick2/build.py
new file mode 100644
index 0000000..cfb1f71
--- /dev/null
+++ b/ick2/build.py
@@ -0,0 +1,53 @@
+# Copyright (C) 2018  Lars Wirzenius
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+import ick2
+
+
+class Build:
+
+    acceptable = {
+        'triggered': ['building'],
+        'building': ['done', 'failed'],
+    }
+
+    def __init__(self, resource):
+        self.resource = resource
+        self.graph = ick2.BuildGraph(graph=self.resource.get('graph', {}))
+        self.graph.set_observer(self.update_graph_in_resource)
+
+    def get_status(self):
+        return self.resource['status']
+
+    def set_status(self, status):
+        current = self.get_status()
+        if status not in self.acceptable[current]:
+            raise WrongBuildStatusChange(current, status)
+        self.resource['status'] = status
+
+    def get_graph(self):
+        return self.graph
+
+    def update_graph_in_resource(self):
+        self.resource['graph'] = self.graph.get_actions()
+
+
+class WrongBuildStatusChange(Exception):
+
+    def __init__(self, current, new):
+        super().__init__(
+            'Unacceptable build status change from {} to {}'.format(
+                current, new))
diff --git a/ick2/build_tests.py b/ick2/build_tests.py
new file mode 100644
index 0000000..47b2db8
--- /dev/null
+++ b/ick2/build_tests.py
@@ -0,0 +1,120 @@
+# Copyright (C) 2018  Lars Wirzenius
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+import unittest
+
+
+import ick2
+
+
+class BuildTests(unittest.TestCase):
+
+    def setUp(self):
+        as_dict = {
+            'status': 'triggered',
+        }
+        self.resource = ick2.resource_from_dict(as_dict)
+
+    def test_sets_status_from_triggered_only_when_acceptable(self):
+        build = ick2.Build(self.resource)
+
+        with self.assertRaises(ick2.WrongBuildStatusChange):
+            build.set_status('triggered')
+        self.assertEqual(build.get_status(), 'triggered')
+
+        with self.assertRaises(ick2.WrongBuildStatusChange):
+            build.set_status('done')
+        self.assertEqual(build.get_status(), 'triggered')
+
+        with self.assertRaises(ick2.WrongBuildStatusChange):
+            build.set_status('failed')
+        self.assertEqual(build.get_status(), 'triggered')
+
+        build.set_status('building')
+        self.assertEqual(build.get_status(), 'building')
+
+    def test_refuses_changing_status_from_building_when_unacceptable(self):
+        build = ick2.Build(self.resource)
+        build.set_status('building')
+
+        with self.assertRaises(ick2.WrongBuildStatusChange):
+            build.set_status('triggered')
+        self.assertEqual(build.get_status(), 'building')
+
+        with self.assertRaises(ick2.WrongBuildStatusChange):
+            build.set_status('building')
+        self.assertEqual(build.get_status(), 'building')
+
+    def test_changes_status_from_building_to_done(self):
+        build = ick2.Build(self.resource)
+        build.set_status('building')
+        build.set_status('done')
+        self.assertEqual(build.get_status(), 'done')
+
+    def test_changes_status_from_building_to_failed(self):
+        build = ick2.Build(self.resource)
+        build.set_status('building')
+        build.set_status('failed')
+        self.assertEqual(build.get_status(), 'failed')
+
+    def test_has_empty_build_graph_initially(self):
+        build = ick2.Build(self.resource)
+        graph = build.get_graph()
+        self.assertTrue(isinstance(graph, ick2.BuildGraph))
+        self.assertEqual(graph.get_actions(), {})
+
+    def test_has_build_graph_from_resource(self):
+        self.resource['graph'] = {
+            1: {
+                'action': {'action': 'foo'},
+                'status': 'ready',
+                'depends': [],
+            },
+        }
+        build = ick2.Build(self.resource)
+        graph = build.get_graph()
+        self.assertEqual(graph.get_actions(), self.resource['graph'])
+
+    def test_appending_actions_to_build_graph_shows_in_build_resource(self):
+        build = ick2.Build(self.resource)
+        graph = build.get_graph()
+        action_id = graph.append_action({'action': 'foo'})
+        self.assertEqual(
+            self.resource['graph'],
+            {
+                action_id: {
+                    'action': {'action': 'foo'},
+                    'status': 'ready',
+                    'depends': [],
+                },
+            }
+        )
+
+    def test_updating_actions_in_build_graph_changes_build_resource(self):
+        build = ick2.Build(self.resource)
+        graph = build.get_graph()
+        action_id = graph.append_action({'action': 'foo'})
+        graph.set_action_status(action_id, 'building')
+        self.assertEqual(
+            self.resource['graph'],
+            {
+                action_id: {
+                    'action': {'action': 'foo'},
+                    'status': 'building',
+                    'depends': [],
+                },
+            }
+        )
diff --git a/ick2/buildgraph.py b/ick2/buildgraph.py
new file mode 100644
index 0000000..ddcfbfb
--- /dev/null
+++ b/ick2/buildgraph.py
@@ -0,0 +1,102 @@
+# Copyright (C) 2018  Lars Wirzenius
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+import copy
+
+
+class BuildGraph:
+
+    def __init__(self, graph=None):
+        self.observer = None
+        self.actions = graph or {}
+        self.idgen = IdGenerator(self.actions.keys())
+
+    def set_observer(self, observer):
+        self.observer = observer
+
+    def get_actions(self):
+        return copy.deepcopy(self.actions)
+
+    def get_action(self, action_id):
+        return self.actions[action_id]['action']
+
+    def get_action_status(self, action_id):
+        return self.actions[action_id]['status']
+
+    def set_action_status(self, action_id, status):
+        self.actions[action_id]['status'] = status
+        self.trigger_observer()
+
+    def unblock(self):
+        blocked_ids = self.find_actions('blocked')
+        for blocked_id in blocked_ids:
+            blocked = self.actions[blocked_id]
+            if self.is_unblockable(blocked):
+                self.set_action_status(blocked_id, 'ready')
+
+    def is_unblockable(self, action):
+        return all(
+            self.get_action_status(dep) == 'done'
+            for dep in action['depends']
+        )
+
+    def trigger_observer(self):
+        if self.observer is not None:
+            self.observer()
+
+    def append_action(self, action):
+        prev_id, action_id = self.idgen.next_id()
+
+        graph_node = {
+            'action': copy.deepcopy(action),
+        }
+
+        if not self.actions:
+            graph_node['status'] = 'ready'
+            graph_node['depends'] = []
+        else:
+            graph_node['status'] = 'blocked'
+            graph_node['depends'] = [prev_id]
+
+        self.actions[action_id] = graph_node
+        self.trigger_observer()
+        return action_id
+
+    def append_pipeline(self, pipeline):
+        for action in pipeline.get('actions', []):
+            self.append_action(action)
+
+    def find_actions(self, status):
+        return [
+            action_id
+            for action_id, action in self.actions.items()
+            if action['status'] == status
+        ]
+
+
+class IdGenerator:
+
+    def __init__(self, action_ids):
+        self.current = 0
+        if action_ids:
+            action_ids = [int(an_id) for an_id in action_ids]
+            action_ids.sort()
+            self.current = action_ids[-1]
+
+    def next_id(self):
+        prev = self.current
+        self.current += 1
+        return str(prev), str(self.current)
diff --git a/ick2/buildgraph_tests.py b/ick2/buildgraph_tests.py
new file mode 100644
index 0000000..a81d2c6
--- /dev/null
+++ b/ick2/buildgraph_tests.py
@@ -0,0 +1,206 @@
+# Copyright (C) 2018  Lars Wirzenius
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+import unittest
+
+
+import ick2
+
+
+class BuildGraphTests(unittest.TestCase):
+
+    def test_has_no_actions_initially(self):
+        graph = ick2.BuildGraph()
+        self.assertEqual(graph.get_actions(), {})
+
+    def test_initialises_from_existing_graph(self):
+        as_dict = {
+            '1': {
+                'action': {'action': 'foo'},
+                'status': 'ready',
+                'depends': [],
+            },
+            '2': {
+                'action': {'action': 'bar'},
+                'status': 'blocked',
+                'depends': ['1'],
+            },
+        }
+        graph = ick2.BuildGraph(graph=as_dict)
+        self.assertEqual(graph.get_actions(), as_dict)
+
+    def test_appends_first_action(self):
+        action = {
+            'action': 'foo',
+        }
+
+        graph = ick2.BuildGraph()
+        action_id = graph.append_action(action)
+        self.assertEqual(action_id, '1')
+        self.assertEqual(
+            graph.get_actions(),
+            {
+                action_id: {
+                    'action': {'action': 'foo'},
+                    'status': 'ready',
+                    'depends': []
+                }
+            }
+        )
+        self.assertEqual(graph.get_action(action_id), action)
+
+    def test_appends_second_action(self):
+        action1 = {
+            'action': 'foo',
+        }
+        action2 = {
+            'action': 'bar',
+        }
+
+        graph = ick2.BuildGraph()
+        action_id1 = graph.append_action(action1)
+        action_id2 = graph.append_action(action2)
+        self.assertEqual(action_id1, '1')
+        self.assertEqual(action_id2, '2')
+        self.assertEqual(
+            graph.get_actions(),
+            {
+                action_id1: {
+                    'action': {'action': 'foo'},
+                    'status': 'ready',
+                    'depends': [],
+                },
+                action_id2: {
+                    'action': {'action': 'bar'},
+                    'status': 'blocked',
+                    'depends': [action_id1],
+                },
+            }
+        )
+
+    def test_changes_action_status(self):
+        action = {
+            'action': 'foo',
+        }
+
+        graph = ick2.BuildGraph()
+        action_id = graph.append_action(action)
+        self.assertEqual(graph.get_action_status(action_id), 'ready')
+
+        graph.set_action_status(action_id, 'building')
+        self.assertEqual(graph.get_action_status(action_id), 'building')
+
+    def test_appends_pipeline_actions(self):
+        pipeline_as_dict = {
+            'actions': [
+                {
+                    'action': 'foo',
+                },
+                {
+                    'action': 'bar',
+                },
+            ],
+        }
+        pipeline = ick2.resource_from_dict(pipeline_as_dict)
+        graph = ick2.BuildGraph()
+        graph.append_pipeline(pipeline)
+        self.assertEqual(
+            graph.get_actions(),
+            {
+                '1': {
+                    'action': {'action': 'foo'},
+                    'depends': [],
+                    'status': 'ready',
+                },
+                '2': {
+                    'action': {'action': 'bar'},
+                    'depends': ['1'],
+                    'status': 'blocked',
+                },
+            }
+        )
+
+    def test_appending_action_triggers_observer(self):
+
+        def observer():
+            setattr(self, 'observed', True)
+
+        action = {}
+
+        setattr(self, 'observed', False)
+        graph = ick2.BuildGraph()
+        graph.set_observer(observer)
+        self.assertFalse(getattr(self, 'observed'))
+        action_id = graph.append_action(action)
+        self.assertTrue(getattr(self, 'observed'))
+
+    def test_finds_actions(self):
+        pipeline_as_dict = {
+            'actions': [
+                {
+                    'action': 'foo',
+                },
+                {
+                    'action': 'bar',
+                },
+            ],
+        }
+        pipeline = ick2.resource_from_dict(pipeline_as_dict)
+        graph = ick2.BuildGraph()
+        graph.append_pipeline(pipeline)
+
+        self.assertEqual(graph.find_actions('no-such-state'), [])
+        self.assertEqual(graph.find_actions('ready'), ['1'])
+        self.assertEqual(graph.find_actions('blocked'), ['2'])
+
+    def test_doesnt_unblock_when_deps_are_not_done(self):
+        pipeline_as_dict = {
+            'actions': [
+                {
+                    'action': 'foo',
+                },
+                {
+                    'action': 'bar',
+                },
+            ],
+        }
+        pipeline = ick2.resource_from_dict(pipeline_as_dict)
+        graph = ick2.BuildGraph()
+        graph.append_pipeline(pipeline)
+
+        graph.unblock()
+        self.assertEqual(graph.get_action_status('1'), 'ready')
+        self.assertEqual(graph.get_action_status('2'), 'blocked')
+
+    def test_unblocks_when_deps_are_done(self):
+        pipeline_as_dict = {
+            'actions': [
+                {
+                    'action': 'foo',
+                },
+                {
+                    'action': 'bar',
+                },
+            ],
+        }
+        pipeline = ick2.resource_from_dict(pipeline_as_dict)
+        graph = ick2.BuildGraph()
+        graph.append_pipeline(pipeline)
+
+        graph.set_action_status('1', 'done')
+        graph.unblock()
+        self.assertEqual(graph.get_action_status('1'), 'done')
+        self.assertEqual(graph.get_action_status('2'), 'ready')
diff --git a/ick2/projectapi.py b/ick2/projectapi.py
index 22a5bb6..ffa46bb 100644
--- a/ick2/projectapi.py
+++ b/ick2/projectapi.py
@@ -63,11 +63,6 @@ class ProjectAPI(ick2.ResourceApiBase):
 
         with self._trans.new('builds', build_id) as build:
             parameters = project.get('parameters', {})
-            create_workspace = {
-                'action': 'create_workspace',
-                'where': 'host',
-            }
-            actions = [create_workspace] + self._get_actions(project)
             build.from_dict({
                 'build_id': build_id,
                 'build_number': build_no,
@@ -76,9 +71,26 @@ class ProjectAPI(ick2.ResourceApiBase):
                 'project': project['project'],
                 'parameters': parameters,
                 'status': 'triggered',
-                'actions': actions,
-                'current_action': 0,
+                'graph': {},
             })
+
+            create_workspace = {
+                'action': 'create_workspace',
+                'where': 'host',
+            }
+
+            build_obj = ick2.Build(build)
+            graph = build_obj.get_graph()
+            graph.append_action(create_workspace)
+            for action in self._get_actions(project):
+                graph.append_action(action)
+
+            with self._trans.new('log', build_id) as r:
+                r.from_dict({
+                    'build_id': build_id,
+                    'log': '',
+                })
+
             return build_id, build_no
 
     def _pick_build_number(self, project):  # pragma: no cover
diff --git a/ick2/workapi.py b/ick2/workapi.py
index d254515..a2d76d9 100644
--- a/ick2/workapi.py
+++ b/ick2/workapi.py
@@ -51,17 +51,23 @@ class WorkAPI(ick2.APIbase):
                 build['status'] = 'building'
                 build['worker'] = worker_id
 
-                self._start_log(build_id)
+                build_obj = ick2.Build(build)
+                graph = build_obj.get_graph()
+                action_id = self._pick_next_action(graph)
+                if action_id is None:  # pragma: no cover
+                    return {}
+
+                graph.set_action_status(action_id, 'building')
+                action = graph.get_action(action_id)
 
-                actions = build['actions']
-                current_action = build['current_action']
                 doing = {
                     'build_id': build_id,
                     'build_number': build['build_number'],
                     'worker': worker_id,
                     'project': build['project'],
                     'parameters': build['parameters'],
-                    'step': actions[current_action],
+                    'action_id': action_id,
+                    'step': action,
                     'log': build['log'],
                 }
 
@@ -102,13 +108,11 @@ class WorkAPI(ick2.APIbase):
                 return build['build_id']
         return None
 
-    def _start_log(self, build_id):
-        ick2.log.log('info', msg_text='Starting new log', build_id=build_id)
-        with self._trans.new('log', build_id) as r:
-            r.from_dict({
-                'build_id': build_id,
-                'log': '',
-            })
+    def _pick_next_action(self, graph):
+        action_ids = graph.find_actions('ready')
+        if not action_ids:  # pragma: no cover
+            return None
+        return action_ids[0]
 
     def update_work(self, update, **kwargs):
         try:
@@ -121,24 +125,25 @@ class WorkAPI(ick2.APIbase):
 
         with self._trans.modify('workers', worker_id) as worker:
             with self._trans.modify('builds', build_id) as build:
+                build_obj = ick2.Build(build)
+                graph = build_obj.get_graph()
                 doing = worker.get('doing', {})
                 self._check_work_update(doing, update)
                 self._append_to_build_log(update)
+                action_id = doing['action_id']
 
                 if exit_code is not None:
                     if exit_code == 0:
-                        action = self._move_to_next_action(build)
-                        if action is None:
-                            doing = {}
-                            self._finish_build(build, exit_code)
-                        else:
-                            doing['step'] = action
+                        self._finish_action(graph, action_id, 'done')
+                        if self._build_finished(graph):
+                            self._finish_build(build, 0)
 
                         worker.from_dict({
                             'worker': worker_id,
-                            'doing': doing,
+                            'doing': {},
                         })
                     elif exit_code is not None:
+                        graph.set_action_status(action_id, 'failed')
                         self._finish_build(build, exit_code)
                         worker.from_dict({
                             'worker': worker_id,
@@ -160,22 +165,21 @@ class WorkAPI(ick2.APIbase):
         with self._trans.modify('log', build_id) as log:
             for stream in ['stdout', 'stderr']:
                 text = update.get(stream, '')
-                if text is not None:
-                    log['log'] += text
+                log['log'] = log.get('log', '') + text
 
-    def _move_to_next_action(self, build):
-        actions = build['actions']
-        current_action = build['current_action']
-        if current_action + 1 >= len(actions):
-            return None
+    def _finish_action(self, graph, action_id, status):
+        graph.set_action_status(action_id, status)
+        if status == 'done':
+            graph.unblock()
 
-        index = current_action + 1
-        build['current_action'] = index
-        return actions[index]
+    def _build_finished(self, graph):
+        return (
+            graph.find_actions('ready') == [] and
+            graph.find_actions('blocked') == []
+        )
 
     def _finish_build(self, build, exit_code):
         build['status'] = exit_code
-        build['current_action'] = None
 
     def create(self, body, **kwargs):  # pragma: no cover
         pass
diff --git a/ick2/workapi_tests.py b/ick2/workapi_tests.py
index 05e91a0..b4d72a7 100644
--- a/ick2/workapi_tests.py
+++ b/ick2/workapi_tests.py
@@ -90,6 +90,7 @@ class WorkAPITests(unittest.TestCase):
             'parameters': {
                 'foo': 'bar',
             },
+            'action_id': '1',
             'step': {
                 'action': 'create_workspace',
                 'where': 'host',
@@ -124,6 +125,7 @@ class WorkAPITests(unittest.TestCase):
             'parameters': {
                 'foo': 'bar',
             },
+            'action_id': '1',
             'step': {
                 'action': 'create_workspace',
                 'where': 'host',
@@ -156,6 +158,7 @@ class WorkAPITests(unittest.TestCase):
 
         # We should get the next step now.
         got = work.get_work(claims=claims)
+        expected['action_id'] = '2'
         expected['step'] = {'shell': 'step-1', 'where': 'host'}
         self.assertEqual(got, expected)
 
@@ -164,6 +167,7 @@ class WorkAPITests(unittest.TestCase):
         work.update_work(done)
 
         # We should get the next step now.
+        expected['action_id'] = '3'
         expected['step'] = {'shell': 'step-2', 'where': 'host'}
         self.assertEqual(work.get_work(claims=claims), expected)
 
@@ -189,6 +193,7 @@ class WorkAPITests(unittest.TestCase):
             'parameters': {
                 'foo': 'bar',
             },
+            'action_id': '1',
             'step': {
                 'action': 'create_workspace',
                 'where': 'host',
diff --git a/yarns/400-build.yarn b/yarns/400-build.yarn
index 4b3c085..5ab5895 100644
--- a/yarns/400-build.yarn
+++ b/yarns/400-build.yarn
@@ -115,6 +115,7 @@ the worker to construct a new workspace for the build.
     ...     "parameters": {
     ...         "foo": "bar"
     ...     },
+    ...     "action_id": "1",
     ...     "step": {
     ...         "action": "create_workspace",
     ...         "where": "host"
@@ -133,6 +134,7 @@ the worker to construct a new workspace for the build.
     ...     "parameters": {
     ...         "foo": "bar"
     ...     },
+    ...     "action_id": "1",
     ...     "step": {
     ...         "action": "create_workspace",
     ...         "where": "host"
@@ -155,6 +157,7 @@ User can now see pipeline is running and which worker is building it.
     ...         "parameters": {
     ...             "foo": "bar"
     ...         },
+    ...         "action_id": "1",
     ...         "step": {
     ...             "action": "create_workspace",
     ...              "where": "host"
@@ -173,12 +176,23 @@ User can now see pipeline is running and which worker is building it.
     ...             "log": "/logs/rome/1",
     ...             "worker": "obelix",
     ...             "project": "rome",
-    ...             "actions": [
-    ...                 { "where": "host", "action": "create_workspace" },
-    ...                 { "where": "host", "shell": "day 1" },
-    ...                 { "where": "host", "shell": "day 2" }
-    ...             ],
-    ...             "current_action": 0,
+    ...             "graph": {
+    ...                 "1": {
+    ...                     "status": "building",
+    ...                     "depends": [],
+    ...                     "action": {"where": "host", "action": "create_workspace" }
+    ...                 },
+    ...                 "2": {
+    ...                     "status": "blocked",
+    ...                     "depends": ["1"],
+    ...                     "action": {"where": "host", "shell": "day 1" }
+    ...                 },
+    ...                 "3": {
+    ...                     "status": "blocked",
+    ...                     "depends": ["2"],
+    ...                     "action": {"where": "host", "shell": "day 2" }
+    ...                 }
+    ...             },
     ...             "parameters": {
     ...                 "foo": "bar"
     ...             },
@@ -198,6 +212,7 @@ Worker reports workspace creation is done. Note the zero exit code.
     WHEN obelix makes request POST /work with a valid token and body
     ... {
     ...     "build_id": "rome/1",
+    ...     "action_id": "1",
     ...     "worker": "obelix",
     ...     "project": "rome",
     ...     "exit_code": 0,
@@ -221,6 +236,7 @@ Worker requests more work, and gets the first actual build step.
     ...     "parameters": {
     ...         "foo": "bar"
     ...     },
+    ...     "action_id": "2",
     ...     "step": {
     ...         "shell": "day 1",
     ...         "where": "host"
@@ -233,6 +249,7 @@ hasn't finished yet.
     WHEN obelix makes request POST /work with a valid token and body
     ... {
     ...     "build_id": "rome/1",
+    ...     "action_id": "2",
     ...     "worker": "obelix",
     ...     "project": "rome",
     ...     "exit_code": null,
@@ -242,8 +259,8 @@ hasn't finished yet.
     ... }
     THEN result has status code 201
 
-Worker-manager still gets the same step, since the first build step
-didnt't finish.
+Worker-manager still gets the same step, since the build step
+didn't finish.
 
     WHEN obelix makes request GET /work
     THEN result has status code 200
@@ -257,6 +274,7 @@ didnt't finish.
     ...     "parameters": {
     ...         "foo": "bar"
     ...     },
+    ...     "action_id": "2",
     ...     "step": {
     ...         "shell": "day 1",
     ...         "where": "host"
@@ -275,6 +293,7 @@ Report the step is done, and successfully.
     WHEN obelix makes request POST /work with a valid token and body
     ... {
     ...     "build_id": "rome/1",
+    ...     "action_id": "2",
     ...     "worker": "obelix",
     ...     "project": "rome",
     ...     "exit_code": 0,
@@ -302,15 +321,26 @@ The build status now shows the next step as the active one.
     ...             "log": "/logs/rome/1",
     ...             "worker": "obelix",
     ...             "project": "rome",
-    ...             "actions": [
-    ...                 { "where": "host", "action": "create_workspace" },
-    ...                 { "where": "host", "shell": "day 1" },
-    ...                 { "where": "host", "shell": "day 2" }
-    ...             ],
-    ...             "current_action": 2,
     ...             "parameters": {
     ...                 "foo": "bar"
     ...             },
+    ...             "graph": {
+    ...                 "1": {
+    ...                     "status": "done",
+    ...                     "depends": [],
+    ...                     "action": {"where": "host", "action": "create_workspace" }
+    ...                 },
+    ...                 "2": {
+    ...                     "status": "done",
+    ...                     "depends": ["1"],
+    ...                     "action": {"where": "host", "shell": "day 1" }
+    ...                 },
+    ...                 "3": {
+    ...                     "status": "ready",
+    ...                     "depends": ["2"],
+    ...                     "action": {"where": "host", "shell": "day 2" }
+    ...                 }
+    ...             },
     ...             "status": "building",
     ...             "log": "/logs/rome/1"
     ...         }
@@ -331,6 +361,7 @@ Now there's another step to do.
     ...     "parameters": {
     ...         "foo": "bar"
     ...     },
+    ...     "action_id": "3",
     ...     "step": {
     ...         "shell": "day 2",
     ...         "where": "host"
@@ -352,6 +383,7 @@ User sees changed status.
     ...         "parameters": {
     ...             "foo": "bar"
     ...         },
+    ...         "action_id": "3",
     ...         "step": {
     ...             "shell": "day 2",
     ...             "where": "host"
@@ -365,6 +397,7 @@ Report it done.
     WHEN obelix makes request POST /work with a valid token and body
     ... {
     ...     "build_id": "rome/1",
+    ...     "action_id": "3",
     ...     "worker": "obelix",
     ...     "project": "rome",
     ...     "exit_code": 0,
@@ -394,15 +427,26 @@ current action.
     ...             "log": "/logs/rome/1",
     ...             "worker": "obelix",
     ...             "project": "rome",
-    ...             "actions": [
-    ...                 { "where": "host", "action": "create_workspace" },
-    ...                 { "where": "host", "shell": "day 1" },
-    ...                 { "where": "host", "shell": "day 2" }
-    ...             ],
-    ...             "current_action": null,
     ...             "parameters": {
     ...                 "foo": "bar"
     ...             },
+    ...             "graph": {
+    ...                 "1": {
+    ...                     "status": "done",
+    ...                     "depends": [],
+    ...                     "action": {"where": "host", "action": "create_workspace" }
+    ...                 },
+    ...                 "2": {
+    ...                     "status": "done",
+    ...                     "depends": ["1"],
+    ...                     "action": {"where": "host", "shell": "day 1" }
+    ...                 },
+    ...                 "3": {
+    ...                     "status": "done",
+    ...                     "depends": ["2"],
+    ...                     "action": {"where": "host", "shell": "day 2" }
+    ...                 }
+    ...             },
     ...             "status": 0
     ...         }
     ...     ]
@@ -417,15 +461,26 @@ current action.
     ...     "log": "/logs/rome/1",
     ...     "worker": "obelix",
     ...     "project": "rome",
-    ...     "actions": [
-    ...         { "where": "host", "action": "create_workspace" },
-    ...         { "where": "host", "shell": "day 1" },
-    ...         { "where": "host", "shell": "day 2" }
-    ...     ],
-    ...     "current_action": null,
     ...     "parameters": {
     ...         "foo": "bar"
     ...     },
+    ...     "graph": {
+    ...         "1": {
+    ...             "status": "done",
+    ...             "depends": [],
+    ...             "action": {"where": "host", "action": "create_workspace" }
+    ...         },
+    ...         "2": {
+    ...             "status": "done",
+    ...             "depends": ["1"],
+    ...             "action": {"where": "host", "shell": "day 1" }
+    ...         },
+    ...         "3": {
+    ...             "status": "done",
+    ...             "depends": ["2"],
+    ...             "action": {"where": "host", "shell": "day 2" }
+    ...         }
+    ...     },
     ...     "status": 0
     ... }
 
@@ -451,6 +506,7 @@ Start build again. This should become build number 2.
     ...     "parameters": {
     ...         "foo": "bar"
     ...     },
+    ...     "action_id": "1",
     ...     "step": {
     ...         "action": "create_workspace",
     ...         "where": "host"
@@ -468,15 +524,26 @@ Start build again. This should become build number 2.
     ...             "log": "/logs/rome/1",
     ...             "worker": "obelix",
     ...             "project": "rome",
-    ...             "actions": [
-    ...                 { "where": "host", "action": "create_workspace" },
-    ...                 { "where": "host", "shell": "day 1" },
-    ...                 { "where": "host", "shell": "day 2" }
-    ...             ],
-    ...             "current_action": null,
     ...             "parameters": {
     ...                 "foo": "bar"
     ...             },
+    ...             "graph": {
+    ...                 "1": {
+    ...                     "status": "done",
+    ...                     "depends": [],
+    ...                     "action": {"where": "host", "action": "create_workspace" }
+    ...                 },
+    ...                 "2": {
+    ...                     "status": "done",
+    ...                     "depends": ["1"],
+    ...                     "action": {"where": "host", "shell": "day 1" }
+    ...                 },
+    ...                 "3": {
+    ...                     "status": "done",
+    ...                     "depends": ["2"],
+    ...                     "action": {"where": "host", "shell": "day 2" }
+    ...                 }
+    ...             },
     ...             "status": 0
     ...         },
     ...         {
@@ -485,15 +552,26 @@ Start build again. This should become build number 2.
     ...             "log": "/logs/rome/2",
     ...             "worker": "obelix",
     ...             "project": "rome",
-    ...             "actions": [
-    ...                 { "where": "host", "action": "create_workspace" },
-    ...                 { "where": "host", "shell": "day 1" },
-    ...                 { "where": "host", "shell": "day 2" }
-    ...             ],
-    ...             "current_action": 0,
     ...             "parameters": {
     ...                 "foo": "bar"
     ...             },
+    ...             "graph": {
+    ...                 "1": {
+    ...                     "status": "building",
+    ...                     "depends": [],
+    ...                     "action": {"where": "host", "action": "create_workspace" }
+    ...                 },
+    ...                 "2": {
+    ...                     "status": "blocked",
+    ...                     "depends": ["1"],
+    ...                     "action": {"where": "host", "shell": "day 1" }
+    ...                 },
+    ...                 "3": {
+    ...                     "status": "blocked",
+    ...                     "depends": ["2"],
+    ...                     "action": {"where": "host", "shell": "day 2" }
+    ...                 }
+    ...             },
     ...             "status": "building"
     ...         }
     ...     ]
@@ -502,6 +580,7 @@ Start build again. This should become build number 2.
     WHEN obelix makes request POST /work with a valid token and body
     ... {
     ...     "build_id": "rome/2",
+    ...     "action_id": "1",
     ...     "worker": "obelix",
     ...     "project": "rome",
     ...     "exit_code": 0,
@@ -523,6 +602,7 @@ Start build again. This should become build number 2.
     ...     "parameters": {
     ...         "foo": "bar"
     ...     },
+    ...     "action_id": "2",
     ...     "step": {
     ...         "shell": "day 1",
     ...         "where": "host"
@@ -532,6 +612,7 @@ Start build again. This should become build number 2.
     WHEN obelix makes request POST /work with a valid token and body
     ... {
     ...     "build_id": "rome/2",
+    ...     "action_id": "2",
     ...     "worker": "obelix",
     ...     "project": "rome",
     ...     "exit_code": 0,
@@ -547,6 +628,7 @@ Start build again. This should become build number 2.
     WHEN obelix makes request POST /work with a valid token and body
     ... {
     ...     "build_id": "rome/2",
+    ...     "action_id": "3",
     ...     "worker": "obelix",
     ...     "project": "rome",
     ...     "exit_code": 0,
@@ -567,15 +649,26 @@ Start build again. This should become build number 2.
     ...             "log": "/logs/rome/1",
     ...             "worker": "obelix",
     ...             "project": "rome",
-    ...             "actions": [
-    ...                 { "where": "host", "action": "create_workspace" },
-    ...                 { "where": "host", "shell": "day 1" },
-    ...                 { "where": "host", "shell": "day 2" }
-    ...             ],
-    ...             "current_action": null,
     ...             "parameters": {
     ...                 "foo": "bar"
     ...             },
+    ...             "graph": {
+    ...                 "1": {
+    ...                     "status": "done",
+    ...                     "depends": [],
+    ...                     "action": {"where": "host", "action": "create_workspace" }
+    ...                 },
+    ...                 "2": {
+    ...                     "status": "done",
+    ...                     "depends": ["1"],
+    ...                     "action": {"where": "host", "shell": "day 1" }
+    ...                 },
+    ...                 "3": {
+    ...                     "status": "done",
+    ...                     "depends": ["2"],
+    ...                     "action": {"where": "host", "shell": "day 2" }
+    ...                 }
+    ...             },
     ...             "status": 0
     ...         },
     ...         {
@@ -584,15 +677,26 @@ Start build again. This should become build number 2.
     ...             "log": "/logs/rome/2",
     ...             "worker": "obelix",
     ...             "project": "rome",
-    ...             "actions": [
-    ...                 { "where": "host", "action": "create_workspace" },
-    ...                 { "where": "host", "shell": "day 1" },
-    ...                 { "where": "host", "shell": "day 2" }
-    ...             ],
-    ...             "current_action": null,
     ...             "parameters": {
     ...                 "foo": "bar"
     ...             },
+    ...             "graph": {
+    ...                 "1": {
+    ...                     "status": "done",
+    ...                     "depends": [],
+    ...                     "action": {"where": "host", "action": "create_workspace" }
+    ...                 },
+    ...                 "2": {
+    ...                     "status": "done",
+    ...                     "depends": ["1"],
+    ...                     "action": {"where": "host", "shell": "day 1" }
+    ...                 },
+    ...                 "3": {
+    ...                     "status": "done",
+    ...                     "depends": ["2"],
+    ...                     "action": {"where": "host", "shell": "day 2" }
+    ...                 }
+    ...             },
     ...             "status": 0
     ...         }
     ...     ]
@@ -674,6 +778,7 @@ Build the first project.
     WHEN obelix makes request POST /work with a valid token and body
     ... {
     ...     "build_id": "first/1",
+    ...     "action_id": "1",
     ...     "build_number": 1,
     ...     "worker": "obelix",
     ...     "project": "first",
@@ -694,6 +799,7 @@ Build the first project.
     WHEN obelix makes request POST /work with a valid token and body
     ... {
     ...     "build_id": "first/1",
+    ...     "action_id": "2",
     ...     "build_number": 1,
     ...     "worker": "obelix",
     ...     "project": "first",
@@ -722,6 +828,7 @@ Build second project.
     WHEN obelix makes request POST /work with a valid token and body
     ... {
     ...     "build_id": "second/1",
+    ...     "action_id": "1",
     ...     "worker": "obelix",
     ...     "project": "second",
     ...     "exit_code": 0,
@@ -741,6 +848,7 @@ Build second project.
     WHEN obelix makes request POST /work with a valid token and body
     ... {
     ...     "build_id": "second/1",
+    ...     "action_id": "2",
     ...     "worker": "obelix",
     ...     "project": "second",
     ...     "exit_code": 0,
@@ -861,6 +969,7 @@ Trigger both projects.
     WHEN asterix makes request POST /work with a valid token and body
     ... {
     ...     "build_id": "first/1",
+    ...     "action_id": "1",
     ...     "build_number": 1,
     ...     "worker": "asterix",
     ...     "project": "first",
@@ -888,6 +997,7 @@ Trigger both projects.
     WHEN obelix makes request POST /work with a valid token and body
     ... {
     ...     "build_id": "second/1",
+    ...     "action_id": "1",
     ...     "build_number": 1,
     ...     "worker": "obelix",
     ...     "project": "second",
@@ -908,6 +1018,7 @@ Trigger both projects.
     WHEN asterix makes request POST /work with a valid token and body
     ... {
     ...     "build_id": "first/1",
+    ...     "action_id": "2",
     ...     "worker": "asterix",
     ...     "project": "first",
     ...     "exit_code": 0,
@@ -923,6 +1034,7 @@ Trigger both projects.
     WHEN obelix makes request POST /work with a valid token and body
     ... {
     ...     "build_id": "second/1",
+    ...     "action_id": "2",
     ...     "worker": "obelix",
     ...     "project": "second",
     ...     "exit_code": 0,
diff --git a/yarns/500-build-fail.yarn b/yarns/500-build-fail.yarn
index 59a2e67..4d4071a 100644
--- a/yarns/500-build-fail.yarn
+++ b/yarns/500-build-fail.yarn
@@ -88,6 +88,7 @@ Worker wants work and gets the first step to run.
     ...     "worker": "obelix",
     ...     "project": "rome",
     ...     "parameters": {},
+    ...     "action_id": "1",
     ...     "step": {
     ...         "action": "create_workspace",
     ...         "where": "host"
@@ -139,13 +140,27 @@ There's a build with a log.
     ...             "log": "/logs/rome/1",
     ...             "worker": "obelix",
     ...             "project": "rome",
-    ...             "actions": [
-    ...                 { "where": "host", "action": "create_workspace" },
-    ...                 { "where": "host", "shell": "day 1" },
-    ...                 { "where": "host", "shell": "day 2" }
-    ...             ],
-    ...             "current_action": null,
     ...             "parameters": {},
+    ...             "graph": {
+    ...                 "1": {
+    ...                     "status": "failed",
+    ...                     "depends": [],
+    ...                     "action": {
+    ...                         "action": "create_workspace", 
+    ...                         "where": "host"
+    ...                     }
+    ...                 },
+    ...                 "2": {
+    ...                     "status": "blocked",
+    ...                     "depends": ["1"],
+    ...                     "action": {"shell": "day 1", "where": "host"}
+    ...                 },
+    ...                 "3": {
+    ...                     "status": "blocked",
+    ...                     "depends": ["2"],
+    ...                     "action": {"shell": "day 2", "where": "host"}
+    ...                 }
+    ...             },
     ...             "status": 1
     ...         }
     ...     ]
@@ -160,13 +175,27 @@ There's a build with a log.
     ...     "log": "/logs/rome/1",
     ...     "worker": "obelix",
     ...     "project": "rome",
-    ...     "actions": [
-    ...         { "where": "host", "action": "create_workspace" },
-    ...         { "where": "host", "shell": "day 1" },
-    ...         { "where": "host", "shell": "day 2" }
-    ...     ],
-    ...     "current_action": null,
     ...     "parameters": {},
+    ...     "graph": {
+    ...         "1": {
+    ...             "status": "failed",
+    ...             "depends": [],
+    ...             "action": {
+    ...                 "action": "create_workspace", 
+    ...                 "where": "host"
+    ...             }
+    ...         },
+    ...         "2": {
+    ...             "status": "blocked",
+    ...             "depends": ["1"],
+    ...             "action": {"shell": "day 1", "where": "host"}
+    ...         },
+    ...         "3": {
+    ...             "status": "blocked",
+    ...             "depends": ["2"],
+    ...             "action": {"shell": "day 2", "where": "host"}
+    ...         }
+    ...     },
     ...     "status": 1
     ... }