feat: allow extending bentoml with extra commands (bentoml#5064)

* feat: allow extending bentoml with extra commands

Signed-off-by: Frost Ming <me@frostming.com>

* fix: ensure newline at EOF

Signed-off-by: Frost Ming <me@frostming.com>

src/bentoml/_internal/cloud/deployment.py

@@ -1465,7 +1465,7 @@ def _build_requirements_txt(bento_dir: str) -> bytes:
     content = b""
     if filename and os.path.exists(fullpath := os.path.join(bento_dir, filename)):
         with open(fullpath, "rb") as f:
-            content = f.read()
+            content = f.read().rstrip(b"\n") + b"\n"
     for package in config.python.packages or []:
         content += f"{package}\n".encode()
     bentoml_requirement = get_bentoml_requirement()

src/bentoml_cli/cli.py

@@ -19,6 +19,7 @@ def create_bentoml_cli() -> click.Command:
     from bentoml_cli.serve import serve_command
     from bentoml_cli.start import start_command
     from bentoml_cli.utils import BentoMLCommandGroup
+    from bentoml_cli.utils import get_entry_points
 
     server_context.service_type = "cli"
 
@@ -49,6 +50,9 @@ def bentoml_cli():
     bentoml_cli.add_command(develop_command)
     bentoml_cli.add_command(deployment_command)
     bentoml_cli.add_command(secret_command)
+    # Load commands from extensions
+    for ep in get_entry_points("bentoml.commands"):
+        bentoml_cli.add_command(ep.load())
 
     if psutil.WINDOWS:
         import sys

src/bentoml_cli/utils.py

@@ -7,13 +7,16 @@
 import re
 import time
 import typing as t
+from importlib.metadata import entry_points
 
 import click
 import click_option_group as cog
 from click import ClickException
 from click.exceptions import UsageError
 
 if t.TYPE_CHECKING:
+    from importlib.metadata import EntryPoint
+
     from click import Command
     from click import Context
     from click import HelpFormatter
@@ -474,3 +477,12 @@ def is_valid_bento_tag(value: str) -> bool:
 
 def is_valid_bento_name(value: str) -> bool:
     return re.match(r"^[A-Za-z_0-9]*$", value) is not None
+
+
+def get_entry_points(group: str) -> t.Iterable[EntryPoint]:
+    """A compatible version of importlib.metadata.entry_points for Python < 3.10"""
+    try:
+        return entry_points(group=group)
+    except TypeError:
+        # For Python < 3.10, entry_points() does not accept group argument
+        return entry_points().get(group, [])