feat(tools): adds an update scenario for all targets

This change adds a new function that describes the
main update scenario. It handles multiple hosts and
then runs an update on each of them.
Basically, it is the kind of function that can be
called directly from a CLI.

Signed-off-by: Olivier Hoareau <olivier.hoareau@vates.tech>

Author: olivierh-pro

lib/tools/tasks/update.py

@@ -2,13 +2,56 @@
 
 This module is intended for performing update actions on existing remote targets.
 """
+import sys
+from concurrent.futures import ThreadPoolExecutor
 
+from lib.common import HostAddress
 from lib.host import Host
+from lib.pool import Pool
 
 from .. import logger
 
 from typing import List
 
+def update_all(hosts: List[HostAddress], enablerepos: List[str]):
+    """Updates all targets scenario.
+
+    This function describes the update scenario for a set of remote targets. Those targets used for
+    running xcp-ng tests suite. See below.
+
+    The scenario
+    ------------
+
+    * Receives a list of master host, :py:class:`lib.common.HostAddress` (either hostname or ip address)
+
+        .. note:: Host must be a master
+
+            If provided hosts are not master (or main), an error :py:exc:`AssertionError` will be thrown
+            and then exits the program.
+
+    * Optionally receives a list of repositories to enabled (related to `yum`). *Repo(s) will be enabled for each host.*
+    * Creates a list of :py:class:`lib.pool.Pool`
+    * Updates are done using multithreading
+
+    :param :py:class:`List[lib.common.HostAddress]`: A list of host for the update scenario.
+    :param List[str] enablerepos: Enable one or more repo(s) when updating.
+    """
+    logger.debug(f"[{hosts}] enablerepos: {enablerepos}")
+    # init related pools
+    try:
+        pools = [Pool(h) for h in hosts]
+        logger.info("Preparing Pools...")
+    except AssertionError as ae:
+        logger.critical(ae)
+        sys.exit(1)
+
+    with ThreadPoolExecutor() as executor:
+        for p in pools:
+            executor.submit(update_host, p.master, enablerepos)
+
+    logger.info(pools)
+
+
 def update_host(host: Host, enablerepos: List[str] = []):
     """Updates the target.