diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -114,11 +114,9 @@
     [GCC 8.1.0] on linux
     Type "help", "copyright", "credits" or "license" for more information.
     >>> from swh.lister.gitlab.tasks import RangeGitLabLister; RangeGitLabLister().run_task(1, 2,
-    instance='salsa.debian.org', api_baseurl='https://salsa.debian.org/api/v4')
-    >>> from swh.lister.gitlab.tasks import RangeGitLabLister; RangeGitLabLister().run_task(1, 2,
-    instance='gitlab.freedesktop.org', api_baseurl='https://gitlab.freedesktop.org/api/v4')
-    >>> from swh.lister.gitlab.tasks import RangeGitLabLister; RangeGitLabLister().run_task(1, 2,
-    instance='gitlab.gnome.org', api_baseurl='https://gitlab.gnome.org/api/v4')
-    >>> from swh.lister.gitlab.tasks import RangeGitLabLister; RangeGitLabLister().run_task(1, 2,
-    instance='gitlab.inria.fr', api_baseurl='https://gitlab.inria.fr/api/v4')
-    >>>
+      {'instance': 'debian', 'api_baseurl': 'https://salsa.debian.org/api/v4', 'sort': 'asc'})
+    >>> from swh.lister.gitlab.tasks import FullGitLabRelister; FullGitLabRelister().run_task(
+      {'instance':'0xacab', 'api_baseurl':'https://0xacab.org/api/v4', 'sort': 'asc'})
+    >>> from swh.lister.gitlab.tasks import IncrementalGitLabLister; IncrementalGitLabLister().run_task(
+      {'instance': 'freedesktop.org', 'api_baseurl': 'https://gitlab.freedesktop.org/api/v4',
+       'sort': 'asc'})
diff --git a/swh/lister/bitbucket/tasks.py b/swh/lister/bitbucket/tasks.py
--- a/swh/lister/bitbucket/tasks.py
+++ b/swh/lister/bitbucket/tasks.py
@@ -10,8 +10,8 @@
 
 
 class BitBucketListerTask(ListerTaskBase):
-    def new_lister(self):
-        return BitBucketLister(api_baseurl='https://api.bitbucket.org/2.0')
+    def new_lister(self, *, api_baseurl='https://api.bitbucket.org/2.0'):
+        return BitBucketLister(api_baseurl=api_baseurl)
 
 
 class IncrementalBitBucketLister(BitBucketListerTask,
diff --git a/swh/lister/core/tasks.py b/swh/lister/core/tasks.py
--- a/swh/lister/core/tasks.py
+++ b/swh/lister/core/tasks.py
@@ -39,13 +39,13 @@
     task_queue = AbstractAttribute('Celery Task queue name')
 
     @abc.abstractmethod
-    def new_lister(self, *args, **kwargs):
+    def new_lister(self, **lister_args):
         """Return a new lister of the appropriate type.
         """
         pass
 
     @abc.abstractmethod
-    def run_task(self, *args, **kwargs):
+    def run_task(self, *, lister_args=None):
         pass
 
 
@@ -57,8 +57,10 @@
     """Range lister task.
 
     """
-    def run_task(self, start, end, *args, **kwargs):
-        lister = self.new_lister(*args, **kwargs)
+    def run_task(self, start, end, lister_args=None):
+        if lister_args is None:
+            lister_args = {}
+        lister = self.new_lister(**lister_args)
         return lister.run(min_bound=start, max_bound=end)
 
 
@@ -69,8 +71,10 @@
     """Incremental indexing lister task.
 
     """
-    def run_task(self, *args, **kwargs):
-        lister = self.new_lister(*args, **kwargs)
+    def run_task(self, *, lister_args=None):
+        if lister_args is None:
+            lister_args = {}
+        lister = self.new_lister(**lister_args)
         return lister.run(min_bound=lister.db_last_index(), max_bound=None)
 
 
@@ -80,10 +84,12 @@
     """
     GROUP_SPLIT = 10000
 
-    def run_task(self, *args, **kwargs):
-        lister = self.new_lister(*args, **kwargs)
+    def run_task(self, *, lister_args=None):
+        if lister_args is None:
+            lister_args = {}
+        lister = self.new_lister(**lister_args)
         ranges = lister.db_partition_indices(self.GROUP_SPLIT)
         random.shuffle(ranges)
         range_task = RangeListerTask()
-        group(range_task.s(minv, maxv, *args, **kwargs)
+        group(range_task.s(minv, maxv, lister_args)
               for minv, maxv in ranges)()
diff --git a/swh/lister/debian/tasks.py b/swh/lister/debian/tasks.py
--- a/swh/lister/debian/tasks.py
+++ b/swh/lister/debian/tasks.py
@@ -1,4 +1,4 @@
-# Copyright (C) 2017 the Software Heritage developers
+# Copyright (C) 2017-2018 the Software Heritage developers
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
diff --git a/swh/lister/github/tasks.py b/swh/lister/github/tasks.py
--- a/swh/lister/github/tasks.py
+++ b/swh/lister/github/tasks.py
@@ -10,8 +10,8 @@
 
 
 class GitHubListerTask(ListerTaskBase):
-    def new_lister(self):
-        return GitHubLister(api_baseurl='https://api.github.com')
+    def new_lister(self, *, api_baseurl='https://api.github.com'):
+        return GitHubLister(api_baseurl=api_baseurl)
 
 
 class IncrementalGitHubLister(GitHubListerTask, IndexingDiscoveryListerTask):
diff --git a/swh/lister/gitlab/tasks.py b/swh/lister/gitlab/tasks.py
--- a/swh/lister/gitlab/tasks.py
+++ b/swh/lister/gitlab/tasks.py
@@ -12,9 +12,10 @@
 
 
 class GitLabListerTask(ListerTaskBase):
-    def new_lister(self, api_baseurl='https://gitlab.com/api/v4',
-                   instance='gitlab.com'):
-        return GitLabLister(api_baseurl=api_baseurl, instance=instance)
+    def new_lister(self, *, api_baseurl='https://gitlab.com/api/v4',
+                   instance='gitlab.com', sort='asc'):
+        return GitLabLister(
+            api_baseurl=api_baseurl, instance=instance, sort=sort)
 
 
 class RangeGitLabLister(GitLabListerTask, RangeListerTask):
@@ -33,30 +34,29 @@
     # nb pages
     nb_pages = 10
 
-    def run_task(self, *args, **kwargs):
-        lister = self.new_lister(*args, **kwargs)
+    def run_task(self, lister_args=None):
+        if lister_args is None:
+            lister_args = {}
+        lister = self.new_lister(**lister_args)
         _, total_pages, _ = lister.get_pages_information()
         ranges = list(utils.split_range(total_pages, self.nb_pages))
         random.shuffle(ranges)
         range_task = RangeGitLabLister()
-        group(range_task.s(minv, maxv, *args, **kwargs)
+        group(range_task.s(minv, maxv, lister_args=lister_args)
               for minv, maxv in ranges)()
 
 
-class IncrementalGitLabLister(ListerTaskBase):
+class IncrementalGitLabLister(GitLabListerTask):
     """Incremental GitLab lister (list only new available origins).
 
     """
     task_queue = 'swh_lister_gitlab_discover'
 
-    def new_lister(self, api_baseurl='https://gitlab.com/api/v4',
-                   instance='gitlab.com'):
-        # assuming going forward in desc order, page 1 through <x-total-pages>
-        return GitLabLister(instance=instance, api_baseurl=api_baseurl,
-                            sort='desc')
-
-    def run_task(self, *args, **kwargs):
-        lister = self.new_lister(*args, **kwargs)
+    def run_task(self, lister_args=None):
+        if lister_args is None:
+            lister_args = {}
+        lister_args['sort'] = 'desc'
+        lister = self.new_lister(**lister_args)
         _, total_pages, _ = lister.get_pages_information()
         # stopping as soon as existing origins for that instance are detected
         return lister.run(min_bound=1, max_bound=total_pages,