diff --git a/swh/objstorage/replayer/cli.py b/swh/objstorage/replayer/cli.py
--- a/swh/objstorage/replayer/cli.py
+++ b/swh/objstorage/replayer/cli.py
@@ -1,4 +1,4 @@
-# Copyright (C) 2016-2020 The Software Heritage developers
+# Copyright (C) 2016-2022 The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
@@ -61,6 +61,40 @@
     ``--check-dst`` sets whether the replayer should check in the destination
     ObjStorage before copying an object. You can turn that off if you know
     you're copying to an empty ObjStorage.
+
+    The expected configuration file should have 3 sections:
+
+    - objstorage: the source object storage from which to retrieve objects to
+      copy; this objstorage can (and should) be a read-only objstorage,
+
+      https://docs.softwareheritage.org/devel/apidoc/swh.objstorage.html
+
+    - objstorage_dst: the destination objstorage in which objects will be
+      written into,
+
+    - journal_client: the configuration of the kafka journal from which the
+      `content` topic will be consumed to get the list of content objects to
+      copy from the source objstorage to the destination one.
+
+      https://docs.softwareheritage.org/devel/apidoc/swh.journal.client.html
+
+    In addition to these 3 mandatory sections, an optional 'replayer' section
+    can be provided with an 'error_reporter' config entry allowing to specify a
+    Redis connection parameter set that will be used to report objects that
+    could not be copied, eg.::
+
+      objstorage:
+        [...]
+      objstorage_dst:
+        [...]
+      journal_client:
+        [...]
+      replayer:
+        error_reporter:
+          host: redis.local
+          port: 6379
+          db: 1
+
     """
     import functools
     import mmap
@@ -100,12 +134,14 @@
     else:
         exclude_fn = None
 
-    journal_cfg = conf["journal_client"]
-    journal_cfg.setdefault("cls", "kafka")
-    if "error_reporter" in journal_cfg:
+    journal_cfg = conf.pop("journal_client")
+    replayer_cfg = conf.pop("replayer", {})
+    if "error_reporter" in replayer_cfg:
         from redis import Redis
+
         from swh.objstorage.replayer import replay
-        replay.REPORTER = Redis(**journal_cfg.pop("error_reporter")).set
+
+        replay.REPORTER = Redis(**replayer_cfg.get("error_reporter")).set
 
     client = get_journal_client(
         **journal_cfg, stop_after_objects=stop_after_objects, object_types=("content",),
diff --git a/swh/objstorage/replayer/tests/test_cli.py b/swh/objstorage/replayer/tests/test_cli.py
--- a/swh/objstorage/replayer/tests/test_cli.py
+++ b/swh/objstorage/replayer/tests/test_cli.py
@@ -1,4 +1,4 @@
-# Copyright (C) 2019-2020  The Software Heritage developers
+# Copyright (C) 2019-2022  The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
@@ -62,10 +62,9 @@
     return decorator
 
 
-def invoke(*args, env=None, journal_config=None):
+def invoke(*args, env=None, **kwargs):
     config = copy.deepcopy(CLI_CONFIG)
-    if journal_config:
-        config["journal_client"] = journal_config
+    config.update(kwargs)
 
     runner = CliRunner()
     with tempfile.NamedTemporaryFile("a", suffix=".yml") as config_fd:
@@ -132,7 +131,8 @@
         "replay",
         "--stop-after-objects",
         str(NUM_CONTENTS),
-        journal_config={
+        journal_client={
+            "cls": "kafka",
             "brokers": kafka_server,
             "group_id": kafka_consumer_group,
             "prefix": kafka_prefix,
@@ -170,7 +170,8 @@
         "replay",
         "--stop-after-objects",
         str(NUM_CONTENTS),
-        journal_config={
+        journal_client={
+            "cls": "kafka",
             "brokers": kafka_server,
             "group_id": kafka_consumer_group,
             "prefix": kafka_prefix,
@@ -216,7 +217,8 @@
         "--stop-after-objects",
         str(NUM_CONTENTS),
         env={"KAFKA_GROUP_INSTANCE_ID": "static-group-instance-id"},
-        journal_config={
+        journal_client={
+            "cls": "kafka",
             "brokers": kafka_server,
             "group_id": kafka_consumer_group,
             "prefix": kafka_prefix,
@@ -273,7 +275,8 @@
             str(NUM_CONTENTS),
             "--exclude-sha1-file",
             fd.name,
-            journal_config={
+            journal_client={
+                "cls": "kafka",
                 "brokers": kafka_server,
                 "group_id": kafka_consumer_group,
                 "prefix": kafka_prefix,
@@ -337,7 +340,8 @@
         "--stop-after-objects",
         str(NUM_CONTENTS),
         "--check-dst" if check_dst else "--no-check-dst",
-        journal_config={
+        journal_client={
+            "cls": "kafka",
             "brokers": kafka_server,
             "group_id": kafka_consumer_group,
             "prefix": kafka_prefix,
@@ -446,10 +450,13 @@
         "--check-dst",
         "--stop-after-objects",
         str(NUM_CONTENTS),
-        journal_config={
+        journal_client={
+            "cls": "kafka",
             "brokers": kafka_server,
             "group_id": kafka_consumer_group,
             "prefix": kafka_prefix,
+        },
+        replayer={
             "error_reporter": {"host": redis_proc.host, "port": redis_proc.port},
         },
     )
@@ -544,10 +551,13 @@
         "replay",
         "--stop-after-objects",
         str(NUM_CONTENTS),
-        journal_config={
+        journal_client={
+            "cls": "kafka",
             "brokers": kafka_server,
             "group_id": kafka_consumer_group,
             "prefix": kafka_prefix,
+        },
+        replayer={
             "error_reporter": {"host": redis_proc.host, "port": redis_proc.port},
         },
     )
@@ -628,7 +638,8 @@
         "replay",
         "--stop-after-objects",
         str(NUM_CONTENTS),
-        journal_config={
+        journal_client={
+            "cls": "kafka",
             "brokers": kafka_server,
             "group_id": kafka_consumer_group,
             "prefix": kafka_prefix,