diff --git a/examples/service/docker_s3_tutorial.ipynb b/examples/service/docker_s3_tutorial.ipynb
index 792a4f3d28..ee59f60ac4 100644
--- a/examples/service/docker_s3_tutorial.ipynb
+++ b/examples/service/docker_s3_tutorial.ipynb
@@ -257,6 +257,8 @@
     "\n",
     "> **Important Note on `ENDPOINT_URL`:**\n",
     "> - **Never** include a trailing slash (`/`) in the endpoint URL.\n",
+    "> - The same variables work with any S3-compatible storage (AWS S3, Backblaze B2, Cloudflare R2, MinIO): set `FSSPEC_S3_ENDPOINT_URL` to the S3 endpoint of your provider.\n",
+    "> - For AWS S3 you can leave `FSSPEC_S3_ENDPOINT_URL` unset, and the default AWS endpoint is used.\n",
     "\n",
     "#### **Verify the Setup**\n",
     "\n",
diff --git a/examples/service/postgres_config.yaml b/examples/service/postgres_config.yaml
index a1c5821cc9..e7ed0105b7 100644
--- a/examples/service/postgres_config.yaml
+++ b/examples/service/postgres_config.yaml
@@ -17,4 +17,6 @@ dataset_storage:
   # path: s3://<bucket>/workspace
   # or
   # path: gcs://<bucket>/workspace
+  # for s3, credentials and a custom endpoint come from the environment:
+  # FSSPEC_S3_KEY, FSSPEC_S3_SECRET, FSSPEC_S3_ENDPOINT_URL
   # list of supported FS: https://filesystem-spec.readthedocs.io/en/latest/api.html#built-in-implementations