🐛 [CLI] Generate one --build-context argument for each dependency in the docker build command. (langchain-ai#4962)

* Generate one `--build-context` for each dependency in the `docker build` command.

* Try and fix test

---------

Co-authored-by: Nuno Campos <nuno@langchain.dev>

Author: fcourtial

libs/cli/langgraph_cli/cli.py

@@ -318,10 +318,8 @@ def _build(
     )
     # add additional_contexts
     if additional_contexts:
-        additional_contexts_str = ",".join(
-            f"{k}={v}" for k, v in additional_contexts.items()
-        )
-        args.extend(["--build-context", additional_contexts_str])
+        for k, v in additional_contexts.items():
+            args.extend(["--build-context", f"{k}={v}"])
     # run docker build
     runner.run(
         subp_exec(

libs/cli/tests/unit_tests/cli/test_cli.py

@@ -22,12 +22,14 @@
 
 
 @contextmanager
-def temporary_config_folder(config_content: dict):
+def temporary_config_folder(config_content: dict, levels: int = 0):
     # Create a temporary directory
     temp_dir = tempfile.mkdtemp()
     try:
         # Define the path for the config.json file
-        config_path = Path(temp_dir) / "config.json"
+        config_path = Path(temp_dir) / f"{'a/' * levels}config.json"
+        # Ensure the parent directory exists
+        config_path.parent.mkdir(parents=True, exist_ok=True)
 
         # Write the provided dictionary content to config.json
         with open(config_path, "w", encoding="utf-8") as config_file:
@@ -532,3 +534,38 @@ def test_build_command_shows_wolfi_warning() -> None:
         assert "Wolfi Linux" in result.output
         assert "image_distro" in result.output
         assert "wolfi" in result.output
+
+
+def test_build_generate_proper_build_context():
+    runner = CliRunner()
+    config_content = {
+        "python_version": "3.11",
+        "graphs": {"agent": "agent.py:graph"},
+        "dependencies": [".", "../../..", "../.."],
+        "image_distro": "wolfi",
+    }
+
+    with temporary_config_folder(config_content, levels=3) as temp_dir:
+        agent_path = temp_dir / "agent.py"
+        agent_path.touch()
+
+        # Mock docker command since we don't want to actually build
+        with runner.isolated_filesystem():
+            result = runner.invoke(
+                cli,
+                [
+                    "build",
+                    "--tag",
+                    "test-image",
+                    "--config",
+                    str(temp_dir / "config.json"),
+                ],
+                catch_exceptions=True,
+            )
+
+        build_context_pattern = re.compile(r"--build-context\s+(\w+)=([^\s]+)")
+
+        build_contexts = re.findall(build_context_pattern, result.output)
+        assert (
+            len(build_contexts) == 2
+        ), f"Expected 2 build contexts, but found {len(build_contexts)}"