vdk-core: ensure early logs are available

When vdk command is started logs do not really show up until click
command start getting executed. All logs before that (from plugin hooks)
seemed ignored.

I couldn't figure out for sure while click_log does that.

But this changes it so that early logs can be seen on console .
The log level of the early logs is controlled by LOG_LEVEL_VDK option
(which control the log level of VDK logs , since early logs are really
vdk logs it make sense)

By default LOG_LEVEL_VDK is WARNING, so if more verbose logs are set it
should be changed to INFO.

Testing Done:
```
export LOG_LEVEL_VDK=INFO
vdk run example
```
logs look like
https://gist.github.com/antoniivanov/bdd935927c1149b74944c58e96b50ee3

```
unset LOG_LEVEL_VDK
vdk run example
```
logs look like
https://gist.github.com/antoniivanov/afce585f8cd03ac4e09e9010dcdd2b9a

Tested also with vdk -v DEBUG ... to see debug logs show up correctly
(with bot set and unset LOG_LEVEL_VDK)

Tested other commands vdk deploy, login, info that logs look like before
(aka no unnecessary logs)

projects/vdk-core/src/vdk/internal/builtin_plugins/config/log_config.py

@@ -1,6 +1,7 @@
 # Copyright 2021-2023 VMware, Inc.
 # SPDX-License-Identifier: Apache-2.0
 import logging
+import os
 import re
 import socket
 import types
@@ -9,6 +10,7 @@
 
 from vdk.api.plugin.hook_markers import hookimpl
 from vdk.internal.builtin_plugins.config import vdk_config
+from vdk.internal.builtin_plugins.config.vdk_config import LOG_LEVEL_VDK
 from vdk.internal.builtin_plugins.run.job_context import JobContext
 from vdk.internal.core import errors
 from vdk.internal.core.config import ConfigurationBuilder
@@ -65,6 +67,30 @@ def _parse_log_level_module(log_level_module):
         )
 
 
+def configure_initial_logging_before_anything():
+    """
+    Configure logging at the start of the app.
+    At this point we do not know what user has configured so we use some sensible approach
+    All logs would be vdk only logs. User code will not have been executed yet so we will use log_level_vdk
+    to control the level.
+    We default to WARN since in most cases users would not care about internal vdk logs.
+
+    Logging lifecycle:
+    1. This function is executed at the entry point of the app and configures default logging format and level
+    2. After vdk_initialize hook is executed and CLI command starts then `vdk --verbosity` option is taken (if set)
+        and click logging configuration takes over
+    3. When initialize_job hook (applicable for vdk run only) is executed then below configure_loggers function
+        is run which adds more context to the logs and initializes syslog handler (if configured to do so)
+    """
+    log_level = "WARNING"
+    if os.environ.get("LOG_LEVEL_VDK", None):
+        log_level = os.environ.get("LOG_LEVEL_VDK")
+    elif os.environ.get("VDK_LOG_LEVEL_VDK", None):
+        log_level = os.environ.get("VDK_LOG_LEVEL_VDK")
+
+    logging.basicConfig(format="%(message)s", level=logging.getLevelName(log_level))
+
+
 def configure_loggers(
     job_name: str = "",
     attempt_id: str = "no-id",

projects/vdk-core/src/vdk/internal/builtin_plugins/config/vdk_config.py

@@ -68,11 +68,14 @@ def vdk_configure(self, config_builder: ConfigurationBuilder) -> None:
         )  # {LOCAL, CLOUD, NONE} To be overridden when executing in cloud
         config_builder.add(
             LOG_LEVEL_VDK,
-            None,
+            "INFO",
             True,
             "Logging verbosity of VDK code can be controlled from here. "
             "Allowed values: CRITICAL, ERROR, WARNING, INFO, DEBUG. "
-            "If not set python default or one set by vdk -v LEVEL is used. ",
+            "If not set python default is used. vdk -v <LEVEL> would take precedence over this variable."
+            "LOG_LEVEL_VDK environment variable is used when the CLI is starting as initial logging level "
+            "before any configuration is loaded. "
+            "Afterwards -v <LEVEL> is considered and vdk loaded configuration.",
         )
         config_builder.add(
             LOG_LEVEL_MODULE,

projects/vdk-core/src/vdk/internal/cli_entry.py

@@ -13,6 +13,9 @@
 from vdk.api.plugin.hook_markers import hookimpl
 from vdk.api.plugin.plugin_registry import IPluginRegistry
 from vdk.internal.builtin_plugins import builtin_hook_impl
+from vdk.internal.builtin_plugins.config.log_config import (
+    configure_initial_logging_before_anything,
+)
 from vdk.internal.builtin_plugins.internal_hookspecs import InternalHookSpecs
 from vdk.internal.core.config import Configuration
 from vdk.internal.core.config import ConfigurationBuilder
@@ -170,7 +173,7 @@ def main() -> None:
     This the starting point for the Python vdk console script.
     """
     # configure basic logging , it's expected that a plugin would override and set it up properly
-    click_log.basic_config(logging.getLogger())
+    configure_initial_logging_before_anything()
 
     log.debug("Setup plugin registry and call vdk_start hooks ...")
     plugin_registry = PluginRegistry()