Added with_product(...) and with_user_agent_extra(...) public fun…

…ctions to improve telemetry for mid-stream libraries (#679)

## Changes

This PR solves three tracking challenges:
1. Adds consistent mechanism with Go SDK Public API. See
https://github.com/databricks/databricks-sdk-go/blob/00b1d09b24aa9fb971bcf23f3db3e80bf2bec6fe/useragent/user_agent.go#L20-L31
and
https://github.com/databricks/databricks-sdk-go/blob/00b1d09b24aa9fb971bcf23f3db3e80bf2bec6fe/useragent/user_agent.go#L49-L54

2. Some of our products, like UCX and Remorph, are used not only as
standalone CLI, but also as mid-stream libraries in other products,
where developers don't specify product name and product version within
the WorkspaceClient. This results in missing tracking information for
those integrations.
3. Mid-stream libraries, like blueprint, pytester, and lsql, do have
their own versions, but they don't create manage sdk.WorkspaceClient
and/or core.Config themselves, so we currently lack traffic attribution
for those libraries. Technically, Databricks Connect falls into the same
use-case.

## Tests
Moved unit tests that are relevant to User-Agent verification from
test_core.py to test_config.py to bring back consistency.

databricks/sdk/config.py

@@ -6,7 +6,7 @@
 import platform
 import sys
 import urllib.parse
-from typing import Dict, Iterable, Optional
+from typing import Dict, Iterable, List, Optional, Tuple
 
 import requests
 
@@ -44,6 +44,32 @@ def __repr__(self) -> str:
         return f"<ConfigAttribute '{self.name}' {self.transform.__name__}>"
 
 
+_DEFAULT_PRODUCT_NAME = 'unknown'
+_DEFAULT_PRODUCT_VERSION = '0.0.0'
+_STATIC_USER_AGENT: Tuple[str, str, List[str]] = (_DEFAULT_PRODUCT_NAME, _DEFAULT_PRODUCT_VERSION, [])
+
+
+def with_product(product: str, product_version: str):
+    """[INTERNAL API] Change the product name and version used in the User-Agent header."""
+    global _STATIC_USER_AGENT
+    prev_product, prev_version, prev_other_info = _STATIC_USER_AGENT
+    logger.debug(f'Changing product from {prev_product}/{prev_version} to {product}/{product_version}')
+    _STATIC_USER_AGENT = product, product_version, prev_other_info
+
+
+def with_user_agent_extra(key: str, value: str):
+    """[INTERNAL API] Add extra metadata to the User-Agent header when developing a library."""
+    global _STATIC_USER_AGENT
+    product_name, product_version, other_info = _STATIC_USER_AGENT
+    for item in other_info:
+        if item.startswith(f"{key}/"):
+            # ensure that we don't have duplicates
+            other_info.remove(item)
+            break
+    other_info.append(f"{key}/{value}")
+    _STATIC_USER_AGENT = product_name, product_version, other_info
+
+
 class Config:
     host: str = ConfigAttribute(env='DATABRICKS_HOST')
     account_id: str = ConfigAttribute(env='DATABRICKS_ACCOUNT_ID')
@@ -85,12 +111,21 @@ def __init__(self,
                  # Deprecated. Use credentials_strategy instead.
                  credentials_provider: CredentialsStrategy = None,
                  credentials_strategy: CredentialsStrategy = None,
-                 product="unknown",
-                 product_version="0.0.0",
+                 product=_DEFAULT_PRODUCT_NAME,
+                 product_version=_DEFAULT_PRODUCT_VERSION,
                  clock: Clock = None,
                  **kwargs):
         self._header_factory = None
         self._inner = {}
+        # as in SDK for Go, pull information from global static user agent context,
+        # so that we can track additional metadata for mid-stream libraries, as well
+        # as for cases, when the downstream product is used as a library and is not
+        # configured with a proper product name and version.
+        static_product, static_version, _ = _STATIC_USER_AGENT
+        if product == _DEFAULT_PRODUCT_NAME:
+            product = static_product
+        if product_version == _DEFAULT_PRODUCT_VERSION:
+            product_version = static_version
         self._user_agent_other_info = []
         if credentials_strategy and credentials_provider:
             raise ValueError(
@@ -234,6 +269,12 @@ def user_agent(self):
         ]
         if len(self._user_agent_other_info) > 0:
             ua.append(' '.join(self._user_agent_other_info))
+        # as in SDK for Go, pull information from global static user agent context,
+        # so that we can track additional metadata for mid-stream libraries. this value
+        # is shared across all instances of Config objects intentionally.
+        _, _, static_info = _STATIC_USER_AGENT
+        if len(static_info) > 0:
+            ua.append(' '.join(static_info))
         if len(self._upstream_user_agent) > 0:
             ua.append(self._upstream_user_agent)
         if 'DATABRICKS_RUNTIME_VERSION' in os.environ:

tests/test_config.py

@@ -1,4 +1,7 @@
-from databricks.sdk.config import Config
+import platform
+
+from databricks.sdk.config import Config, with_product, with_user_agent_extra
+from databricks.sdk.version import __version__
 
 from .conftest import noop_credentials
 
@@ -15,3 +18,51 @@ def test_config_supports_legacy_credentials_provider():
     c2 = c.copy()
     assert c2._product == 'foo'
     assert c2._product_version == '1.2.3'
+
+
+def test_extra_and_upstream_user_agent(monkeypatch):
+
+    class MockUname:
+
+        @property
+        def system(self):
+            return 'TestOS'
+
+    monkeypatch.setattr(platform, 'python_version', lambda: '3.0.0')
+    monkeypatch.setattr(platform, 'uname', MockUname)
+    monkeypatch.setenv('DATABRICKS_SDK_UPSTREAM', "upstream-product")
+    monkeypatch.setenv('DATABRICKS_SDK_UPSTREAM_VERSION', "0.0.1")
+    monkeypatch.setenv('DATABRICKS_RUNTIME_VERSION', "13.1 anything/else")
+
+    config = Config(host='http://localhost', username="something", password="something", product='test',
+                    product_version='0.0.0') \
+        .with_user_agent_extra('test-extra-1', '1') \
+        .with_user_agent_extra('test-extra-2', '2')
+
+    assert config.user_agent == (
+        f"test/0.0.0 databricks-sdk-py/{__version__} python/3.0.0 os/testos auth/basic"
+        f" test-extra-1/1 test-extra-2/2 upstream/upstream-product upstream-version/0.0.1"
+        " runtime/13.1-anything-else")
+
+    with_product('some-product', '0.32.1')
+    config2 = Config(host='http://localhost', token='...')
+    assert config2.user_agent.startswith('some-product/0.32.1')
+
+    config3 = Config(host='http://localhost', token='...', product='abc', product_version='1.2.3')
+    assert not config3.user_agent.startswith('some-product/0.32.1')
+
+
+def test_config_copy_deep_copies_user_agent_other_info(config):
+    config_copy = config.copy()
+
+    config.with_user_agent_extra("test", "test1")
+    assert "test/test1" not in config_copy.user_agent
+    assert "test/test1" in config.user_agent
+
+    config_copy.with_user_agent_extra("test", "test2")
+    assert "test/test2" in config_copy.user_agent
+    assert "test/test2" not in config.user_agent
+
+    with_user_agent_extra("blueprint", "0.4.6")
+    assert "blueprint/0.4.6" in config.user_agent
+    assert "blueprint/0.4.6" in config_copy.user_agent

tests/test_core.py

@@ -2,7 +2,6 @@
 import functools
 import os
 import pathlib
-import platform
 import random
 import string
 import typing
@@ -25,7 +24,6 @@
                                          DatabricksEnvironment)
 from databricks.sdk.service.catalog import PermissionsChange
 from databricks.sdk.service.iam import AccessControlRequest
-from databricks.sdk.version import __version__
 
 from .clock import FakeClock
 from .conftest import noop_credentials
@@ -181,31 +179,6 @@ def test_databricks_cli_credential_provider_installed_new(config, monkeypatch, t
     assert databricks_cli(config) is not None
 
 
-def test_extra_and_upstream_user_agent(monkeypatch):
-
-    class MockUname:
-
-        @property
-        def system(self):
-            return 'TestOS'
-
-    monkeypatch.setattr(platform, 'python_version', lambda: '3.0.0')
-    monkeypatch.setattr(platform, 'uname', MockUname)
-    monkeypatch.setenv('DATABRICKS_SDK_UPSTREAM', "upstream-product")
-    monkeypatch.setenv('DATABRICKS_SDK_UPSTREAM_VERSION', "0.0.1")
-    monkeypatch.setenv('DATABRICKS_RUNTIME_VERSION', "13.1 anything/else")
-
-    config = Config(host='http://localhost', username="something", password="something", product='test',
-                    product_version='0.0.0') \
-        .with_user_agent_extra('test-extra-1', '1') \
-        .with_user_agent_extra('test-extra-2', '2')
-
-    assert config.user_agent == (
-        f"test/0.0.0 databricks-sdk-py/{__version__} python/3.0.0 os/testos auth/basic"
-        f" test-extra-1/1 test-extra-2/2 upstream/upstream-product upstream-version/0.0.1"
-        " runtime/13.1-anything-else")
-
-
 def test_config_copy_shallow_copies_credential_provider():
 
     class TestCredentialsStrategy(CredentialsStrategy):
@@ -237,18 +210,6 @@ def refresh(self):
     assert config._credentials_strategy == config_copy._credentials_strategy
 
 
-def test_config_copy_deep_copies_user_agent_other_info(config):
-    config_copy = config.copy()
-
-    config.with_user_agent_extra("test", "test1")
-    assert "test/test1" not in config_copy.user_agent
-    assert "test/test1" in config.user_agent
-
-    config_copy.with_user_agent_extra("test", "test2")
-    assert "test/test2" in config_copy.user_agent
-    assert "test/test2" not in config.user_agent
-
-
 def test_config_accounts_aws_is_accounts_host(config):
     config.host = "https://accounts.cloud.databricks.com"
     assert config.is_account_client