feat: Add --no-install option to meltano add (meltano#6578)

* Add `--no-install` flag for `meltano add`

* Test `--no-install`

* Reference `--no-install` in `meltano add` docs

* Fix lint

* Update docs/src/_reference/command-line-interface.md

Co-authored-by: Taylor A. Murphy <taylor@meltano.com>

* Reset project context in test to avoid errors related to plugins having already been installed

Co-authored-by: Taylor A. Murphy <taylor@meltano.com>
Co-authored-by: Edgar R. M <edgarrm358@gmail.com>

docs/src/_reference/command-line-interface.md

@@ -20,7 +20,7 @@ Specifically, it will:
 3. Store the plugin definition in the `./plugins` directory (see [Lock Artifacts](/concepts/plugins#lock-artifacts))
 4. Assuming a valid `pip_url` is specified, install the new plugin using [`meltano install <type> <name>`](#install), which will:
    1. Create a dedicated [Python virtual environment](https://docs.python.org/3/glossary.html#term-virtual-environment) for the plugin inside the [`.meltano` directory](/concepts/project#meltano-directory) at `.meltano/<type>s/<name>/venv`, e.g. `.meltano/extractors/tap-gitlab/venv`
-   2. Install the plugin's [pip package](https://pip.pypa.io/en/stable/) into the virtual environment using `pip install <pip_url>`
+   2. Install the plugin's [pip package](https://pip.pypa.io/en/stable/) into the virtual environment using `pip install <pip_url>` (given `--no-install` is not provided)
 
 (Some plugin types have slightly different or additional behavior; refer to the [plugin type documentation](/concepts/plugins#types) for more details.)
 
@@ -80,6 +80,15 @@ meltano add <type> <name> --inherit-from <existing-name>
 meltano add extractor tap-ga--client-foo --inherit-from tap-google-analytics
 ```
 
+By default, `meltano add` will attempt to install the plugin after adding it. Use `--no-install` to skip this behavior:
+
+```bash
+meltano add <type> <name> --no-install
+
+# For example:
+meltano add extractor tap-spotify --no-install
+```
+
 #### Parameters
 
 - `--custom`: Add a [custom plugin](/concepts/plugins#custom-plugins). The command will prompt you for the package's [base plugin description](/concepts/plugins#project-plugins) metadata.
@@ -90,6 +99,8 @@ meltano add extractor tap-ga--client-foo --inherit-from tap-google-analytics
 
 - `--variant=<variant>`: Add a specific (non-default) [variant](/concepts/plugins#variants) of the identified [discoverable plugin](/concepts/plugins#discoverable-plugins).
 
+- `--no-install`: Do not install the plugin after adding it to the project.
+
 ## `config`
 
 Enables you to manage the [configuration](/guide/configuration) of Meltano itself or any of its plugins, as well as [plugin extras](#how-to-use-plugin-extras).

src/meltano/cli/add.py

@@ -55,6 +55,11 @@
     is_flag=True,
     help="Add a custom plugin. The command will prompt you for the package's base plugin description metadata.",
 )
+@click.option(
+    "--no-install",
+    is_flag=True,
+    help="Do not install the plugin after adding it to the project.",
+)
 @pass_project()
 @click.pass_context
 def add(
@@ -140,11 +145,12 @@ def add(
     )
     tracker.track_command_event(CliEvent.inflight)
 
-    success = install_plugins(project, plugins, reason=PluginInstallReason.ADD)
+    if not flags.get("no_install"):
+        success = install_plugins(project, plugins, reason=PluginInstallReason.ADD)
 
-    if not success:
-        tracker.track_command_event(CliEvent.failed)
-        raise CliError("Failed to install plugin(s)")
+        if not success:
+            tracker.track_command_event(CliEvent.failed)
+            raise CliError("Failed to install plugin(s)")
 
     _print_plugins(plugins)
     tracker.track_command_event(CliEvent.completed)

tests/meltano/cli/test_add.py

@@ -16,6 +16,8 @@
 from meltano.core.plugin.error import PluginNotFoundError
 from meltano.core.plugin.project_plugin import ProjectPlugin
 from meltano.core.plugin_install_service import PluginInstallReason
+from meltano.core.project import Project
+from meltano.core.project_init_service import ProjectInitService
 
 
 class TestCliAdd:
@@ -27,6 +29,13 @@ def patch_hub(self, meltano_hub_service: MeltanoHubService):
         ):
             yield
 
+    @pytest.fixture
+    def reset_project_context(
+        self, project: Project, project_init_service: ProjectInitService
+    ):
+        shutil.rmtree(".", ignore_errors=True)
+        project_init_service.create_files(project)
+
     @pytest.mark.parametrize(
         "plugin_type,plugin_name,default_variant,required_plugin_refs",
         [
@@ -521,3 +530,89 @@ def test_add_custom_variant(
             plugin_variant = plugin_def.variants[0]
 
             assert plugin.variant == plugin_variant.name == "personal"
+
+    @pytest.mark.parametrize(
+        "plugin_type,plugin_name,default_variant,required_plugin_refs",
+        [
+            (PluginType.EXTRACTORS, "tap-carbon-intensity", "meltano", []),
+            (PluginType.LOADERS, "target-sqlite", "meltanolabs", []),
+            (PluginType.TRANSFORMS, "tap-carbon-intensity", "meltano", []),
+            (
+                PluginType.ORCHESTRATORS,
+                "airflow",
+                Variant.ORIGINAL_NAME,
+                [PluginRef(PluginType.FILES, "airflow")],
+            ),
+        ],
+        ids=[
+            "single-extractor",
+            "single-loader",
+            "transform-and-related",
+            "orchestrator-and-required",
+        ],
+    )
+    def test_add_no_install(
+        self,
+        plugin_type,
+        plugin_name,
+        default_variant,
+        required_plugin_refs,
+        project,
+        cli_runner,
+        project_plugins_service,
+        reset_project_context,
+    ):
+        # ensure the plugin is not present
+        with pytest.raises(PluginNotFoundError):
+            project_plugins_service.find_plugin(plugin_name, plugin_type=plugin_type)
+
+        with mock.patch("meltano.cli.add.install_plugins") as install_plugin_mock:
+            install_plugin_mock.return_value = True
+            res = cli_runner.invoke(
+                cli, ["add", plugin_type.singular, plugin_name, "--no-install"]
+            )
+
+            if plugin_type is PluginType.TRANSFORMS:
+                assert res.exit_code == 1, res.stdout
+                assert isinstance(res.exception, CliError)
+                assert "Dependencies not met:" in str(res.exception)
+            else:
+                assert res.exit_code == 0, res.stdout
+                assert f"Added {plugin_type.descriptor} '{plugin_name}'" in res.stdout
+
+                plugin = project_plugins_service.find_plugin(plugin_name, plugin_type)
+                assert plugin
+                assert plugin.variant == default_variant
+
+                # check plugin lock file is added
+                plugins_dir = project.root_dir("plugins")
+                assert plugins_dir.joinpath(
+                    f"{plugin_type}/{plugin_name}--{default_variant}.lock"
+                ).exists()
+
+                for required_plugin_ref in required_plugin_refs:
+                    if (required_plugin_ref._type) == PluginType.FILES and (
+                        required_plugin_ref.name == "dbt"
+                    ):
+                        # file bundles with no managed files are added but do not appear in meltano.yml
+                        assert (
+                            f"Adding required file bundle '{required_plugin_ref.name}'"
+                            in res.stdout
+                        )
+                    else:
+                        plugin = project_plugins_service.get_plugin(required_plugin_ref)
+                        assert plugin
+
+                        assert (
+                            f"Added required {plugin.type.descriptor} '{plugin.name}'"
+                            in res.stdout
+                        )
+
+                    # check required plugin lock files are added
+                    assert list(
+                        plugins_dir.glob(
+                            f"{required_plugin_ref._type}/{required_plugin_ref.name}--*.lock"
+                        )
+                    )
+
+                install_plugin_mock.assert_not_called()