feat: Customizable Pip Installer (#5098)

Let you set "pip_installer": "pip" (or uv) to handle corner cases in install compatibilities

libs/cli/tests/unit_tests/test_config.py

@@ -1,3 +1,4 @@
+import copy
 import json
 import os
 import pathlib
@@ -40,6 +41,7 @@ def test_validate_config():
         "python_version": "3.11",
         "node_version": None,
         "pip_config_file": None,
+        "pip_installer": "auto",
         "image_distro": "debian",
         "dockerfile_lines": [],
         "env": {},
@@ -61,6 +63,7 @@ def test_validate_config():
         "python_version": "3.12",
         "node_version": None,
         "pip_config_file": "pipconfig.txt",
+        "pip_installer": "auto",
         "image_distro": "debian",
         "dockerfile_lines": ["ARG meow"],
         "dependencies": [".", "langchain"],
@@ -216,6 +219,74 @@ def test_validate_config_image_distro():
     assert config["image_distro"] == "debian"
 
 
+def test_validate_config_pip_installer():
+    """Test validation of pip_installer field."""
+    # Valid pip_installer values should work
+    config = validate_config(
+        {
+            "python_version": "3.11",
+            "dependencies": ["."],
+            "graphs": {"agent": "./agent.py:graph"},
+            "pip_installer": "auto",
+        }
+    )
+    assert config["pip_installer"] == "auto"
+
+    config = validate_config(
+        {
+            "python_version": "3.11",
+            "dependencies": ["."],
+            "graphs": {"agent": "./agent.py:graph"},
+            "pip_installer": "pip",
+        }
+    )
+    assert config["pip_installer"] == "pip"
+
+    config = validate_config(
+        {
+            "python_version": "3.11",
+            "dependencies": ["."],
+            "graphs": {"agent": "./agent.py:graph"},
+            "pip_installer": "uv",
+        }
+    )
+    assert config["pip_installer"] == "uv"
+
+    # Missing pip_installer should default to "auto"
+    config = validate_config(
+        {
+            "python_version": "3.11",
+            "dependencies": ["."],
+            "graphs": {"agent": "./agent.py:graph"},
+        }
+    )
+    assert config["pip_installer"] == "auto"
+
+    # Invalid pip_installer values should raise error
+    with pytest.raises(click.UsageError) as exc_info:
+        validate_config(
+            {
+                "python_version": "3.11",
+                "dependencies": ["."],
+                "graphs": {"agent": "./agent.py:graph"},
+                "pip_installer": "conda",
+            }
+        )
+    assert "Invalid pip_installer: 'conda'" in str(exc_info.value)
+    assert "Must be 'auto', 'pip', or 'uv'" in str(exc_info.value)
+
+    with pytest.raises(click.UsageError) as exc_info:
+        validate_config(
+            {
+                "python_version": "3.11",
+                "dependencies": ["."],
+                "graphs": {"agent": "./agent.py:graph"},
+                "pip_installer": "invalid",
+            }
+        )
+    assert "Invalid pip_installer: 'invalid'" in str(exc_info.value)
+
+
 def test_validate_config_file():
     with tempfile.TemporaryDirectory() as tmpdir:
         tmpdir_path = pathlib.Path(tmpdir)
@@ -799,6 +870,61 @@ WORKDIR /deps/__outer_unit_tests/unit_tests"""
     assert additional_contexts == {}
 
 
+def test_config_to_docker_pip_installer():
+    """Test that pip_installer setting affects the generated Dockerfile."""
+    graphs = {"agent": "./graphs/agent.py:graph"}
+    base_config = {
+        "python_version": "3.11",
+        "dependencies": ["."],
+        "graphs": graphs,
+    }
+
+    # Test default (auto) behavior with UV-supporting image
+    config_auto = validate_config(
+        {**copy.deepcopy(base_config), "pip_installer": "auto"}
+    )
+    docker_auto, _ = config_to_docker(
+        PATH_TO_CONFIG, config_auto, "langchain/langgraph-api:0.2.47"
+    )
+    assert "uv pip install --system" in docker_auto
+    assert "rm /usr/bin/uv /usr/bin/uvx" in docker_auto
+
+    # Test explicit pip setting
+    config_pip = validate_config({**copy.deepcopy(base_config), "pip_installer": "pip"})
+    docker_pip, _ = config_to_docker(
+        PATH_TO_CONFIG, config_pip, "langchain/langgraph-api:0.2.47"
+    )
+    assert "uv pip install --system" not in docker_pip
+    assert "pip install" in docker_pip
+    assert "rm /usr/bin/uv" not in docker_pip
+
+    # Test explicit uv setting
+    config_uv = validate_config({**copy.deepcopy(base_config), "pip_installer": "uv"})
+    docker_uv, _ = config_to_docker(
+        PATH_TO_CONFIG, config_uv, "langchain/langgraph-api:0.2.47"
+    )
+    assert "uv pip install --system" in docker_uv
+    assert "rm /usr/bin/uv /usr/bin/uvx" in docker_uv
+
+    # Test auto behavior with older image (should use pip)
+    config_auto_old = validate_config(
+        {**copy.deepcopy(base_config), "pip_installer": "auto"}
+    )
+    docker_auto_old, _ = config_to_docker(
+        PATH_TO_CONFIG, config_auto_old, "langchain/langgraph-api:0.2.46"
+    )
+    assert "uv pip install --system" not in docker_auto_old
+    assert "pip install" in docker_auto_old
+    assert "rm /usr/bin/uv" not in docker_auto_old
+
+    # Test that missing pip_installer defaults to auto behavior
+    config_default = validate_config(copy.deepcopy(base_config))
+    docker_default, _ = config_to_docker(
+        PATH_TO_CONFIG, config_default, "langchain/langgraph-api:0.2.47"
+    )
+    assert "uv pip install --system" in docker_default
+
+
 # config_to_compose
 def test_config_to_compose_simple_config():
     graphs = {"agent": "./agent.py:graph"}