[components] Add --use-editable-dagster to dg generate code-location (#…

…26295)

## Summary & Motivation

Add an `--use-editable-dagster` flag to `dg generate code-location`.
This causes the command to read the `$DAGSTER_GIT_REPO_DIR` environment
variable and set up the code location to use editable installs from this
location. This is done by adding `tool.uv.sources` to the generated
pyproject.toml:

```
# If DAGSTER_GIT_REPO_DIR=/path/to/dagster

[tool.uv.sources]
dagster = { path = "/path/to/dagster/python_modules/dagster", editable=true }
dagster-webserver = { path="/path/to/dagster/python_modules/dagster-webserver", editable=true }
dagster-pipes = { path="/path/to/dagster/python_modules/dagster-pipes", editable=true }
dagster-components = { path = "/path/to/dagster/python_modules/libraries/dagster-components", editable=true }
```

We may also wish a path to be passable on the command line, or for this
to be somehow hidden from users since this is basically a dev tool.

## How I Tested These Changes

New unit test. Manual test generating a code location and loading it
with `dagster dev`.

python_modules/libraries/dagster-components/dagster_components/cli/generate.py

@@ -42,7 +42,8 @@ def generate_deployment_command(path: str) -> None:
 
 @generate_cli.command(name="code-location")
 @click.argument("name", type=str)
-def generate_code_location_command(name: str) -> None:
+@click.option("--use-editable-dagster", is_flag=True, default=False)
+def generate_code_location_command(name: str, use_editable_dagster: bool) -> None:
     """Generate a Dagster code location inside a component."""
     if not is_inside_deployment_project(Path(".")):
         click.echo(
@@ -55,8 +56,22 @@ def generate_code_location_command(name: str) -> None:
         click.echo(click.style(f"A code location named {name} already exists.", fg="red"))
         sys.exit(1)
 
+    if use_editable_dagster:
+        if "DAGSTER_GIT_REPO_DIR" not in os.environ:
+            click.echo(
+                click.style(
+                    "The `--use-editable-dagster` flag requires the `DAGSTER_GIT_REPO_DIR` environment variable to be set.",
+                    fg="red",
+                )
+            )
+            sys.exit(1)
+        editable_dagster_root = os.environ["DAGSTER_GIT_REPO_DIR"]
+    else:
+        editable_dagster_root = None
+
     code_location_path = os.path.join(context.code_location_root_path, name)
-    generate_code_location(code_location_path)
+
+    generate_code_location(code_location_path, editable_dagster_root)
 
 
 @generate_cli.command(name="component-type")

python_modules/libraries/dagster-components/dagster_components/generate.py

@@ -1,6 +1,7 @@
 import os
+import textwrap
 from pathlib import Path
-from typing import Any, Type
+from typing import Any, Optional, Type
 
 import click
 import yaml
@@ -30,15 +31,27 @@ def generate_deployment(path: str) -> None:
     )
 
 
-def generate_code_location(path: str) -> None:
+def generate_code_location(path: str, editable_dagster_root: Optional[str] = None) -> None:
     click.echo(f"Creating a Dagster code location at {path}.")
 
+    if editable_dagster_root:
+        uv_sources = textwrap.dedent(f"""
+        [tool.uv.sources]
+        dagster = {{ path = "{editable_dagster_root}/python_modules/dagster", editable = true }}
+        dagster-components = {{ path = "{editable_dagster_root}/python_modules/libraries/dagster-components", editable = true }}
+        dagster-pipes = {{ path = "{editable_dagster_root}/python_modules/dagster-pipes", editable = true }}
+        dagster-webserver = {{ path = "{editable_dagster_root}/python_modules/dagster-webserver", editable = true }}
+        """)
+    else:
+        uv_sources = ""
+
     generate_project(
         path=path,
         name_placeholder="CODE_LOCATION_NAME_PLACEHOLDER",
         templates_path=os.path.join(
             os.path.dirname(__file__), "templates", "CODE_LOCATION_NAME_PLACEHOLDER"
         ),
+        uv_sources=uv_sources,
     )
 
 

python_modules/libraries/dagster-components/dagster_components/templates/CODE_LOCATION_NAME_PLACEHOLDER/pyproject.toml.jinja

@@ -2,10 +2,14 @@
 name = "{{ project_name }}"
 requires-python = ">=3.9,<3.13"
 version = "0.1.0"
-dependencies = []
+dependencies = [
+    "dagster",
+]
 
 [project.optional-dependencies]
-dev = []
+dev = [
+    "dagster-webserver",
+]
 
 [build-system]
 requires = ["setuptools"]
@@ -17,3 +21,5 @@ project_name = "{{ project_name }}"
 
 [tool.setuptools.packages.find]
 exclude=["{{ project_name }}_tests"]
+
+{{ uv_sources }}

python_modules/libraries/dagster-components/dagster_components_tests/cli_tests/test_generate_commands.py

@@ -9,6 +9,7 @@
 from typing import Iterator
 
 import pytest
+import tomli
 from click.testing import CliRunner
 from dagster._utils import pushd
 from dagster_components.cli.generate import (
@@ -137,6 +138,49 @@ def test_generate_code_location_success() -> None:
         assert Path("code_locations/bar/bar_tests").exists()
         assert Path("code_locations/bar/pyproject.toml").exists()
 
+        with open("code_locations/bar/pyproject.toml") as f:
+            toml = tomli.loads(f.read())
+            # No tool.uv.sources added without --use-editable-dagster
+            assert "uv" not in toml["tool"]
+
+
+def _find_git_root():
+    current = Path.cwd()
+    while current != current.parent:
+        if (current / ".git").exists():
+            return current
+        current = current.parent
+    raise Exception("Could not find git root")
+
+
+def test_generate_code_location_editable_dagster_success(monkeypatch) -> None:
+    runner = CliRunner()
+    dagster_git_repo_dir = _find_git_root()
+    monkeypatch.setenv("DAGSTER_GIT_REPO_DIR", dagster_git_repo_dir)
+    with isolated_example_deployment_foo(runner):
+        result = runner.invoke(generate_code_location_command, ["--use-editable-dagster", "bar"])
+        assert result.exit_code == 0
+        assert Path("code_locations/bar").exists()
+        assert Path("code_locations/bar/pyproject.toml").exists()
+        with open("code_locations/bar/pyproject.toml") as f:
+            toml = tomli.loads(f.read())
+            assert toml["tool"]["uv"]["sources"]["dagster"] == {
+                "path": f"{dagster_git_repo_dir}/python_modules/dagster",
+                "editable": True,
+            }
+            assert toml["tool"]["uv"]["sources"]["dagster-pipes"] == {
+                "path": f"{dagster_git_repo_dir}/python_modules/dagster-pipes",
+                "editable": True,
+            }
+            assert toml["tool"]["uv"]["sources"]["dagster-webserver"] == {
+                "path": f"{dagster_git_repo_dir}/python_modules/dagster-webserver",
+                "editable": True,
+            }
+            assert toml["tool"]["uv"]["sources"]["dagster-components"] == {
+                "path": f"{dagster_git_repo_dir}/python_modules/libraries/dagster-components",
+                "editable": True,
+            }
+
 
 def test_generate_code_location_outside_deployment_fails() -> None:
     runner = CliRunner()

python_modules/libraries/dagster-components/setup.py

@@ -37,6 +37,7 @@ def get_version() -> str:
     packages=find_packages(exclude=["dagster_components_tests*", "examples*"]),
     install_requires=[
         f"dagster{pin}",
+        "tomli",
     ],
     zip_safe=False,
     entry_points={