diff --git a/buildstream/_frontend/cli.py b/buildstream/_frontend/cli.py
index e9eecd9..c8df181 100644
--- a/buildstream/_frontend/cli.py
+++ b/buildstream/_frontend/cli.py
@@ -354,6 +354,7 @@
                          track_cross_junctions=track_cross_junctions,
                          build_all=all_)
 
+
 ##################################################################
 #                         Format Command                         #
 ##################################################################
diff --git a/buildstream/_yaml.py b/buildstream/_yaml.py
index 8d7302b..2d659c7 100644
--- a/buildstream/_yaml.py
+++ b/buildstream/_yaml.py
@@ -51,6 +51,31 @@
         self.project = project
 
 
+# A custom yaml dumper to reorder keys in dicts to a canonical order, defined
+# in each plugin
+class BstFormatter(yaml.RoundTripDumper):
+
+    keyorder = []
+
+    @classmethod
+    def _iter_in_global_order(cls, mapping):
+        for key in cls.keyorder:
+            if key in mapping.keys():
+                yield key, mapping[key]
+        for key in sorted(mapping.keys()):
+            if key not in cls.keyorder:
+                yield key, mapping[key]
+
+    @classmethod
+    def _represent_dict(cls, dumper, mapping):
+        return dumper.represent_mapping('tag:yaml.org,2002:map', cls._iter_in_global_order(mapping))
+
+    def __init__(self, *args, **kwargs):
+        yaml.RoundTripDumper.__init__(self, *args, **kwargs)
+        self.no_newline = False
+        self.add_representer(dict, self._represent_dict)
+
+
 # Provenance tracks the origin of a given node in the parsed dictionary.
 #
 # Args:
@@ -244,15 +269,16 @@
 # Args:
 #    node (dict): A node previously loaded with _yaml.load() above
 #    filename (str): The YAML file to load
+#    dumper (yaml.Dumper): The yaml dumper to be used
 #
-def dump(node, filename=None):
+def dump(node, filename=None, dumper=yaml.RoundTripDumper):
     with ExitStack() as stack:
         if filename:
             from . import utils
             f = stack.enter_context(utils.save_file_atomic(filename, 'w'))
         else:
             f = sys.stdout
-        yaml.round_trip_dump(node, f)
+        yaml.round_trip_dump(node, f, Dumper=dumper)
 
 
 # node_decorated_copy()
diff --git a/buildstream/buildelement.py b/buildstream/buildelement.py
index 6ef060f..0b83ea0 100644
--- a/buildstream/buildelement.py
+++ b/buildstream/buildelement.py
@@ -172,6 +172,7 @@
         for command_name in _legacy_command_steps:
             if command_name in _command_steps:
                 self.__commands[command_name] = self.__get_commands(node, command_name)
+                self.keyorder.append(command_name)
             else:
                 self.__commands[command_name] = []
 
diff --git a/buildstream/element.py b/buildstream/element.py
index 9a9e015..a8ee747 100644
--- a/buildstream/element.py
+++ b/buildstream/element.py
@@ -269,6 +269,9 @@
                 # This will taint the artifact, disable pushing.
                 self.__sandbox_config_supported = False
 
+        self.keyorder = ['kind', 'description', 'depends', 'variables',
+                         'environment', 'config', 'public', 'sandbox', 'sources']
+
     def __lt__(self, other):
         return self.name < other.name
 
@@ -1338,7 +1341,17 @@
     #
     def _format(self):
         provenance = self._get_provenance()
-        _yaml.dump(provenance.toplevel, provenance.filename.name)
+
+        _yaml.BstFormatter.keyorder = self.keyorder
+
+        # We need to add the key orders for each source into the
+        # global keyorder, as sources are dumped with the element.
+        for s in self.sources():
+            for key in s.keyorder:
+                if key not in _yaml.BstFormatter.keyorder:
+                    _yaml.BstFormatter.keyorder += s.keyorder
+
+        _yaml.dump(provenance.toplevel, provenance.filename.name, dumper=_yaml.BstFormatter)
 
     # _prepare_sandbox():
     #
diff --git a/buildstream/plugin.py b/buildstream/plugin.py
index 2f51c88..181a319 100644
--- a/buildstream/plugin.py
+++ b/buildstream/plugin.py
@@ -188,6 +188,8 @@
         self.__kind = modulename.split('.')[-1]
         self.debug("Created: {}".format(self))
 
+        self.keyorder = []
+
     def __del__(self):
         # Dont send anything through the Message() pipeline at destruction time,
         # any subsequent lookup of plugin by unique id would raise KeyError.
diff --git a/buildstream/plugins/elements/compose.py b/buildstream/plugins/elements/compose.py
index d61a324..ed4da4d 100644
--- a/buildstream/plugins/elements/compose.py
+++ b/buildstream/plugins/elements/compose.py
@@ -70,6 +70,8 @@
         self.exclude = self.node_get_member(node, list, 'exclude')
         self.include_orphans = self.node_get_member(node, bool, 'include-orphans')
 
+        self.keyorder += ['integrate', 'include', 'exclude', 'include-orphans']
+
     def preflight(self):
         pass
 
diff --git a/buildstream/plugins/elements/filter.py b/buildstream/plugins/elements/filter.py
index 6723253..9f86baa 100644
--- a/buildstream/plugins/elements/filter.py
+++ b/buildstream/plugins/elements/filter.py
@@ -65,6 +65,8 @@
         self.exclude = self.node_get_member(node, list, 'exclude')
         self.include_orphans = self.node_get_member(node, bool, 'include-orphans')
 
+        self.keyorder += ['include', 'exclude', 'include-orphans']
+
     def preflight(self):
         # Exactly one build-depend is permitted
         build_deps = list(self.dependencies(Scope.BUILD, recurse=False))
diff --git a/buildstream/plugins/elements/junction.py b/buildstream/plugins/elements/junction.py
index 7f98173..2a5b17f 100644
--- a/buildstream/plugins/elements/junction.py
+++ b/buildstream/plugins/elements/junction.py
@@ -140,6 +140,7 @@
     def configure(self, node):
         self.path = self.node_get_member(node, str, 'path', default='')
         self.options = self.node_get_member(node, Mapping, 'options', default={})
+        self.keyorder += ['path', 'options']
 
     def preflight(self):
         pass
diff --git a/buildstream/plugins/elements/script.py b/buildstream/plugins/elements/script.py
index 4e422c5..b695fad 100644
--- a/buildstream/plugins/elements/script.py
+++ b/buildstream/plugins/elements/script.py
@@ -51,6 +51,7 @@
         self.node_validate(node, [
             'commands', 'root-read-only', 'layout'
         ])
+        self.keyorder += ['layout', 'root-read-only', 'commands']
 
         cmds = self.node_subst_list(node, "commands")
         self.add_commands("commands", cmds)
diff --git a/buildstream/plugins/sources/_downloadablefilesource.py b/buildstream/plugins/sources/_downloadablefilesource.py
index f5c5b3d..4cb2d50 100644
--- a/buildstream/plugins/sources/_downloadablefilesource.py
+++ b/buildstream/plugins/sources/_downloadablefilesource.py
@@ -82,6 +82,8 @@
         self.url = self.translate_url(self.original_url)
         self._warn_deprecated_etag(node)
 
+        self.keyorder += ['url', 'ref', 'etag']
+
     def preflight(self):
         return
 
diff --git a/buildstream/plugins/sources/bzr.py b/buildstream/plugins/sources/bzr.py
index f524729..544bf2d 100644
--- a/buildstream/plugins/sources/bzr.py
+++ b/buildstream/plugins/sources/bzr.py
@@ -68,6 +68,8 @@
     def configure(self, node):
         self.node_validate(node, ['url', 'track', 'ref'] + Source.COMMON_CONFIG_KEYS)
 
+        self.keyorder += ['url', 'track', 'ref']
+
         self.original_url = self.node_get_member(node, str, 'url')
         self.tracking = self.node_get_member(node, str, 'track')
         self.ref = self.node_get_member(node, str, 'ref', None)
diff --git a/buildstream/plugins/sources/git.py b/buildstream/plugins/sources/git.py
index 74d632b..e93517c 100644
--- a/buildstream/plugins/sources/git.py
+++ b/buildstream/plugins/sources/git.py
@@ -506,6 +506,8 @@
                        'track-tags', 'tags']
         self.node_validate(node, config_keys + Source.COMMON_CONFIG_KEYS)
 
+        self.keyorder += config_keys
+
         tags_node = self.node_get_member(node, list, 'tags', [])
         for tag_node in tags_node:
             self.node_validate(tag_node, ['tag', 'commit', 'annotated'])
diff --git a/buildstream/plugins/sources/local.py b/buildstream/plugins/sources/local.py
index 55cdc14..c6b6963 100644
--- a/buildstream/plugins/sources/local.py
+++ b/buildstream/plugins/sources/local.py
@@ -53,6 +53,7 @@
 
     def configure(self, node):
         self.node_validate(node, ['path'] + Source.COMMON_CONFIG_KEYS)
+        self.keyorder += ['path']
         self.path = self.node_get_project_path(node, 'path')
         self.fullpath = os.path.join(self.get_project_directory(), self.path)
 
diff --git a/buildstream/plugins/sources/ostree.py b/buildstream/plugins/sources/ostree.py
index 770cfd5..1bc4ef6 100644
--- a/buildstream/plugins/sources/ostree.py
+++ b/buildstream/plugins/sources/ostree.py
@@ -65,6 +65,7 @@
     def configure(self, node):
 
         self.node_validate(node, ['url', 'ref', 'track', 'gpg-key'] + Source.COMMON_CONFIG_KEYS)
+        self.keyorder += ['url', 'track', 'ref', 'gpg-key']
 
         self.original_url = self.node_get_member(node, str, 'url')
         self.url = self.translate_url(self.original_url)
diff --git a/buildstream/plugins/sources/patch.py b/buildstream/plugins/sources/patch.py
index 8e833b4..48aab13 100644
--- a/buildstream/plugins/sources/patch.py
+++ b/buildstream/plugins/sources/patch.py
@@ -53,6 +53,7 @@
     # pylint: disable=attribute-defined-outside-init
 
     def configure(self, node):
+        self.keyorder += ['strip-level', 'path']
         self.path = self.node_get_project_path(node, 'path',
                                                check_is_file=True)
         self.strip_level = self.node_get_member(node, int, "strip-level", 1)
diff --git a/buildstream/plugins/sources/pip.py b/buildstream/plugins/sources/pip.py
index abef1fd..04e8bab 100644
--- a/buildstream/plugins/sources/pip.py
+++ b/buildstream/plugins/sources/pip.py
@@ -111,6 +111,7 @@
     def configure(self, node):
         self.node_validate(node, ['url', 'packages', 'ref', 'requirements-files'] +
                            Source.COMMON_CONFIG_KEYS)
+        self.keyorder += ['url', 'packages', 'ref', 'requirements-files']
         self.ref = self.node_get_member(node, str, 'ref', None)
         self.original_url = self.node_get_member(node, str, 'url', _PYPI_INDEX_URL)
         self.index_url = self.translate_url(self.original_url)
diff --git a/buildstream/plugins/sources/remote.py b/buildstream/plugins/sources/remote.py
index a6b02fd..9247c12 100644
--- a/buildstream/plugins/sources/remote.py
+++ b/buildstream/plugins/sources/remote.py
@@ -61,6 +61,7 @@
 
     def configure(self, node):
         super().configure(node)
+        self.keyorder += ['filename']
 
         self.filename = self.node_get_member(node, str, 'filename', os.path.basename(self.url))
         self.executable = self.node_get_member(node, bool, 'executable', False)
diff --git a/buildstream/plugins/sources/tar.py b/buildstream/plugins/sources/tar.py
index 195c059..a830df8 100644
--- a/buildstream/plugins/sources/tar.py
+++ b/buildstream/plugins/sources/tar.py
@@ -75,6 +75,7 @@
         self.base_dir = self.node_get_member(node, str, 'base-dir', '*') or None
 
         self.node_validate(node, DownloadableFileSource.COMMON_CONFIG_KEYS + ['base-dir'])
+        self.keyorder += ['base-dir']
 
     def preflight(self):
         self.host_lzip = None
diff --git a/buildstream/plugins/sources/zip.py b/buildstream/plugins/sources/zip.py
index f5fac3a..27e5fd9 100644
--- a/buildstream/plugins/sources/zip.py
+++ b/buildstream/plugins/sources/zip.py
@@ -75,6 +75,7 @@
         self.base_dir = self.node_get_member(node, str, 'base-dir', '*') or None
 
         self.node_validate(node, DownloadableFileSource.COMMON_CONFIG_KEYS + ['base-dir'])
+        self.keyorder += ['base-dir']
 
     def get_unique_key(self):
         return super().get_unique_key() + [self.base_dir]
diff --git a/buildstream/source.py b/buildstream/source.py
index bb54110..bc4bae9 100644
--- a/buildstream/source.py
+++ b/buildstream/source.py
@@ -302,6 +302,8 @@
         # FIXME: Reconstruct a MetaSource from a Source instead of storing it.
         self.__meta = meta                              # MetaSource stored so we can copy this source later.
 
+        self.keyorder = ['directory'] + self.keyorder
+
         # Collect the composited element configuration and
         # ask the element to configure itself.
         self.__init_defaults(meta)