[psuutil] Refactor to utilize sonic-platform package (sonic-net#1434)

#### What I did

Refactor psuutil to use sonic-platform package in lieu of old, deprecated platform plugins.

The psuutil utility is still useful, as psushow only reads and displays PSU data from State DB. However, this utility provides us the ability to read directly from the PSUs which is helpful for debugging.

#### How I did it

- Complete refactor to use sonic-platform package
- Add more output columns to display (Model, Serial, Voltage, Current, Power)
- Bump version to 2.0
- Add basic unit tests

psuutil/main.py

@@ -5,55 +5,46 @@
 # Command-line utility for interacting with PSU in SONiC
 #
 
-try:
-    import imp
-    import os
-    import sys
+import os
+import sys
 
-    import click
-    from sonic_py_common import device_info, logger
-    from tabulate import tabulate
-except ImportError as e:
-    raise ImportError("%s - required module not found" % str(e))
+import click
+import sonic_platform
+from sonic_py_common import logger
+from tabulate import tabulate
 
-VERSION = '1.0'
+
+VERSION = '2.0'
 
 SYSLOG_IDENTIFIER = "psuutil"
-PLATFORM_SPECIFIC_MODULE_NAME = "psuutil"
-PLATFORM_SPECIFIC_CLASS_NAME = "PsuUtil"
 
-# Global platform-specific psuutil class instance
-platform_psuutil = None
+ERROR_PERMISSIONS = 1
+ERROR_CHASSIS_LOAD = 2
+ERROR_NOT_IMPLEMENTED = 3
 
+# Global platform-specific Chassis class instance
+platform_chassis = None
 
 # Global logger instance
 log = logger.Logger(SYSLOG_IDENTIFIER)
 
 
 # ==================== Methods for initialization ====================
 
-# Loads platform specific psuutil module from source
-def load_platform_psuutil():
-    global platform_psuutil
-
-    # Load platform module from source
-    platform_path, _ = device_info.get_paths_to_platform_and_hwsku_dirs()
+# Instantiate platform-specific Chassis class
+def load_platform_chassis():
+    global platform_chassis
 
+    # Load new platform api class
     try:
-        module_file = os.path.join(platform_path, "plugins", PLATFORM_SPECIFIC_MODULE_NAME + ".py")
-        module = imp.load_source(PLATFORM_SPECIFIC_MODULE_NAME, module_file)
-    except IOError as e:
-        log.log_error("Failed to load platform module '%s': %s" % (PLATFORM_SPECIFIC_MODULE_NAME, str(e)), True)
-        return -1
+        platform_chassis = sonic_platform.platform.Platform().get_chassis()
+    except Exception as e:
+        log.log_error("Failed to instantiate Chassis due to {}".format(repr(e)))
 
-    try:
-        platform_psuutil_class = getattr(module, PLATFORM_SPECIFIC_CLASS_NAME)
-        platform_psuutil = platform_psuutil_class()
-    except AttributeError as e:
-        log.log_error("Failed to instantiate '%s' class: %s" % (PLATFORM_SPECIFIC_CLASS_NAME, str(e)), True)
-        return -2
+    if not platform_chassis:
+        return False
 
-    return 0
+    return True
 
 
 # ==================== CLI commands and groups ====================
@@ -66,63 +57,88 @@ def cli():
 
     if os.geteuid() != 0:
         click.echo("Root privileges are required for this operation")
-        sys.exit(1)
+        sys.exit(ERROR_PERMISSIONS)
 
-    # Load platform-specific psuutil class
-    err = load_platform_psuutil()
-    if err != 0:
-        sys.exit(2)
-
-# 'version' subcommand
+    # Load platform-specific Chassis class
+    if not load_platform_chassis():
+        sys.exit(ERROR_CHASSIS_LOAD)
 
 
+# 'version' subcommand
 @cli.command()
 def version():
     """Display version info"""
     click.echo("psuutil version {0}".format(VERSION))
 
-# 'numpsus' subcommand
-
 
+# 'numpsus' subcommand
 @cli.command()
 def numpsus():
     """Display number of supported PSUs on device"""
-    click.echo(str(platform_psuutil.get_num_psus()))
-
-# 'status' subcommand
+    num_psus = platform_chassis.get_num_psus()
+    click.echo(str(num_psus))
 
 
+# 'status' subcommand
 @cli.command()
-@click.option('-i', '--index', default=-1, type=int, help="the index of PSU")
+@click.option('-i', '--index', default=-1, type=int, help='Index of the PSU')
 def status(index):
     """Display PSU status"""
-    supported_psu = list(range(1, platform_psuutil.get_num_psus() + 1))
-    psu_ids = []
-    if (index < 0):
-        psu_ids = supported_psu
-    else:
-        psu_ids = [index]
-
-    header = ['PSU', 'Status']
+    header = ['PSU',  'Model', 'Serial', 'Voltage (V)', 'Current (A)', 'Power (W)', 'Status', 'LED']
     status_table = []
 
-    for psu in psu_ids:
-        msg = ""
-        psu_name = "PSU {}".format(psu)
-        if psu not in supported_psu:
-            click.echo("Error! The {} is not available on the platform.\n"
-                       "Number of supported PSU - {}.".format(psu_name, platform_psuutil.get_num_psus()))
-            continue
-        presence = platform_psuutil.get_psu_presence(psu)
-        if presence:
-            oper_status = platform_psuutil.get_psu_status(psu)
-            msg = 'OK' if oper_status else "NOT OK"
-        else:
-            msg = 'NOT PRESENT'
-        status_table.append([psu_name, msg])
+    psu_list = platform_chassis.get_all_psus()
+
+    for psu in psu_list:
+        psu_name = psu.get_name()
+        status = 'NOT PRESENT'
+        model = 'N/A'
+        serial = 'N/A'
+        voltage = 'N/A'
+        current = 'N/A'
+        power = 'N/A'
+        led_color = 'N/A'
+
+        if psu.get_presence():
+            try:
+                status = 'OK' if psu.get_powergood_status() else 'NOT OK'
+            except NotImplementedError:
+                status = 'UNKNOWN'
+
+            try:
+                model = psu.get_model()
+            except NotImplementedError:
+                pass
+
+            try:
+                serial = psu.get_serial()
+            except NotImplementedError:
+                pass
+
+            try:
+                voltage = psu.get_voltage()
+            except NotImplementedError:
+                pass
+
+            try:
+                current = psu.get_current()
+            except NotImplementedError:
+                pass
+
+            try:
+                power = psu.get_power()
+            except NotImplementedError:
+                pass
+
+            try:
+                led_color = psu.get_status_led()
+            except NotImplementedError:
+                pass
+
+        status_table.append([psu_name, model, serial, voltage, current, power, status, led_color])
 
     if status_table:
-        click.echo(tabulate(status_table, header, tablefmt="simple"))
+        click.echo(tabulate(status_table, header, tablefmt='simple', floatfmt='.2f'))
 
 
 if __name__ == '__main__':

tests/psuutil_test.py

@@ -0,0 +1,21 @@
+import sys
+import os
+from unittest import mock
+
+import pytest
+from click.testing import CliRunner
+
+test_path = os.path.dirname(os.path.abspath(__file__))
+modules_path = os.path.dirname(test_path)
+sys.path.insert(0, modules_path)
+
+sys.modules['sonic_platform'] = mock.MagicMock()
+import psuutil.main as psuutil
+
+
+class TestPsuutil(object):
+
+    def test_version(self):
+        runner = CliRunner()
+        result = runner.invoke(psuutil.cli.commands['version'], [])
+        assert result.output.rstrip() == 'psuutil version {}'.format(psuutil.VERSION)