CSIT-1450: PAPI executor

Change-Id: I4c756cc4b29901184594a728f6184c30cadd9c1a
Signed-off-by: Vratko Polak <vrpolak@cisco.com>

6 files changed, 334 insertions, 340 deletions

diff --git a/resources/libraries/python/IPsecUtil.py b/resources/libraries/python/IPsecUtil.py
index 2479ec1822..5c9a08fc31 100644
--- a/resources/libraries/python/IPsecUtil.py
+++ b/resources/libraries/python/IPsecUtil.py
@@ -20,7 +20,6 @@ from enum import Enum, IntEnum
 from robot.api import logger
 
 from resources.libraries.python.PapiExecutor import PapiExecutor
-from resources.libraries.python.PapiErrors import PapiError
 from resources.libraries.python.topology import Topology
 from resources.libraries.python.VatExecutor import VatExecutor
 from resources.libraries.python.VatJsonUtil import VatJsonUtil
@@ -252,36 +251,21 @@ class IPsecUtil(object):
         :type node: dict
         :type protocol: IPsecProto
         :type index: int
+        :raises RuntimeError: If failed to select IPsec backend or if no API
+            reply received.
         """
-        # TODO: move composition of api data to separate method
-        api_data = list()
-        api = dict(api_name='ipsec_select_backend')
-        api_args = dict(protocol=protocol)
-        api_args['index'] = index
-        api['api_args'] = api_args
-        api_data.append(api)
-
-        api_reply = None
-        with PapiExecutor(node) as papi_executor:
-            papi_executor.execute_papi(api_data)
-            try:
-                papi_executor.papi_should_have_passed()
-            except AssertionError:
-                raise PapiError('Failed to select IPsec backend on host {host}'.
-                                format(host=node['host']))
-            api_reply = papi_executor.get_papi_reply()
-
-        if api_reply is not None:
-            api_r = api_reply[0]['api_reply']['ipsec_select_backend_reply']
-            if api_r['retval'] == 0:
-                logger.trace('IPsec backend successfully selected on host '
-                             '{host}'.format(host=node['host']))
-            else:
-                raise PapiError('Failed to select IPsec backend on host {host}'.
-                                format(host=node['host']))
-        else:
-            raise PapiError('No reply received for ipsec_select_backend API '
-                            'command on host {host}'.format(host=node['host']))
+
+        cmd = 'ipsec_select_backend'
+        cmd_reply = 'ipsec_select_backend_reply'
+        err_msg = 'Failed to select IPsec backend on host {host}'.format(
+            host=node['host'])
+        args = dict(protocol=protocol, index=index)
+        with PapiExecutor(node) as papi_exec:
+            papi_resp = papi_exec.add(cmd, **args).execute_should_pass(err_msg)
+        data = papi_resp.reply[0]['api_reply'][cmd_reply]
+        if data['retval'] != 0:
+            raise RuntimeError('Failed to select IPsec backend on host {host}'.
+                               format(host=node['host']))
 
     @staticmethod
     def vpp_ipsec_backend_dump(node):
@@ -290,34 +274,20 @@ class IPsecUtil(object):
         :param node: VPP node to dump IPsec backend on.
         :type node: dict
         """
-        # TODO: move composition of api data to separate method
-        api_data = list()
-        api = dict(api_name='ipsec_backend_dump')
-        api_args = dict()
-        api['api_args'] = api_args
-        api_data.append(api)
-
-        api_reply = None
-        with PapiExecutor(node) as papi_executor:
-            papi_executor.execute_papi(api_data)
-            try:
-                papi_executor.papi_should_have_passed()
-            except AssertionError:
-                raise PapiError('Failed to dump IPsec backends on host {host}'.
-                                format(host=node['host']))
-            # After API change there is returned VPP internal enum object
-            # representing VPP IPSEC protocol instead of integer representation
-            # so JSON fails to decode it - we need to check if it is Python API
-            # bug or we need to adapt vpp_papi_provider to correctly encode
-            # such object into JSON
-            # api_reply = papi_executor.get_papi_reply()
-            api_reply = papi_executor.get_papi_stdout()
-
-        if api_reply is not None:
-            logger.trace('IPsec backend dump\n{dump}'.format(dump=api_reply))
-        else:
-            raise PapiError('No reply received for ipsec_select_backend API '
-                            'command on host {host}'.format(host=node['host']))
+
+        err_msg = 'Failed to dump IPsec backends on host {host}'.format(
+            host=node['host'])
+        with PapiExecutor(node) as papi_exec:
+            papi_resp = papi_exec.add('ipsec_backend_dump').execute_should_pass(
+                err_msg, process_reply=False)
+        # After API change there is returned VPP internal enum object
+        # representing VPP IPSEC protocol instead of integer representation
+        # so JSON fails to decode it - we need to check if it is Python API
+        # bug or we need to adapt vpp_papi_provider to correctly encode
+        # such object into JSON
+        # logger.trace('IPsec backend dump\n{dump}'.
+        # format(dump=papi_resp.reply))
+        logger.trace('IPsec backend dump\n{dump}'.format(dump=papi_resp.stdout))
 
     @staticmethod
     def vpp_ipsec_add_sad_entry(node, sad_id, spi, crypto_alg, crypto_key,
diff --git a/resources/libraries/python/InterfaceUtil.py b/resources/libraries/python/InterfaceUtil.py
index a73b6df8f3..939d8083dc 100644
--- a/resources/libraries/python/InterfaceUtil.py
+++ b/resources/libraries/python/InterfaceUtil.py
@@ -20,7 +20,6 @@ from robot.api import logger
 from resources.libraries.python.CpuUtils import CpuUtils
 from resources.libraries.python.DUTSetup import DUTSetup
 from resources.libraries.python.PapiExecutor import PapiExecutor
-from resources.libraries.python.PapiErrors import PapiError
 from resources.libraries.python.IPUtil import convert_ipv4_netmask_prefix
 from resources.libraries.python.IPUtil import IPUtil
 from resources.libraries.python.parsers.JsonParser import JsonParser
@@ -1637,33 +1636,19 @@ class InterfaceUtil(object):
         :type node: dict
         :returns: Thread mapping information as a list of dictionaries.
         :rtype: list
-        :raises RuntimeError: If failed to run command on host.
-        :raises PapiError: If no API reply received.
         """
-        api_data = list()
-        for ifc in node['interfaces'].values():
-            if ifc['vpp_sw_index'] is not None:
-                api = dict(api_name='sw_interface_rx_placement_dump')
-                api_args = dict(sw_if_index=ifc['vpp_sw_index'])
-                api['api_args'] = api_args
-                api_data.append(api)
-
-        with PapiExecutor(node) as papi_executor:
-            papi_executor.execute_papi(api_data)
-            try:
-                papi_executor.papi_should_have_passed()
-                api_reply = papi_executor.get_papi_reply()
-            except AssertionError:
-                raise RuntimeError('Failed to run {api_name} on host '
-                                   '{host}!'.format(host=node['host'], **api))
-
-        if api_reply:
-            thr_mapping = [s['sw_interface_rx_placement_details'] \
-                for r in api_reply for s in r['api_reply']]
-            return sorted(thr_mapping, key=lambda k: k['sw_if_index'])
-        else:
-            raise PapiError('No reply received for {api_name} on host {host}!'.
-                            format(host=node['host'], **api))
+
+        cmd = 'sw_interface_rx_placement_dump'
+        cmd_reply = 'sw_interface_rx_placement_details'
+        err_msg = "Failed to run '{cmd}' PAPI command on host {host}!".format(
+            cmd=cmd, host=node['host'])
+        with PapiExecutor(node) as papi_exec:
+            for ifc in node['interfaces'].values():
+                papi_exec.add(cmd, sw_if_index=ifc['vpp_sw_index'])
+            papi_resp = papi_exec.execute_should_pass(err_msg)
+        thr_mapping = [s[cmd_reply] for r in papi_resp.reply
+                       for s in r['api_reply']]
+        return sorted(thr_mapping, key=lambda k: k['sw_if_index'])
 
     @staticmethod
     def vpp_sw_interface_set_rx_placement(node, sw_if_index, queue_id,
@@ -1678,28 +1663,23 @@ class InterfaceUtil(object):
         :type sw_if_index: int
         :type queue_id: int
         :type worker_id: int
-        :raises RuntimeError: If failed to run command on host.
-        :raises PapiError: If no API reply received.
+        :raises RuntimeError: If failed to run command on host or if no API
+            reply received.
         """
-        api_data = list()
-        api = dict(api_name='sw_interface_set_rx_placement')
-        api_args = dict(sw_if_index=sw_if_index, queue_id=queue_id,
-                        worker_id=worker_id)
-        api['api_args'] = api_args
-        api_data.append(api)
-
-        with PapiExecutor(node) as papi_executor:
-            papi_executor.execute_papi(api_data)
-            try:
-                papi_executor.papi_should_have_passed()
-                api_reply = papi_executor.get_papi_reply()
-            except AssertionError:
-                raise RuntimeError('Failed to run {api_name} on host '
-                                   '{host}!'.format(host=node['host'], **api))
-
-        if not api_reply:
-            raise PapiError('No reply received for {api_name} on host {host}!'.
-                            format(host=node['host'], **api))
+
+        cmd = 'sw_interface_set_rx_placement'
+        cmd_reply = 'sw_interface_set_rx_placement_reply'
+        err_msg = "Failed to run '{cmd}' PAPI command on host {host}!".format(
+            host=node['host'], cmd=cmd)
+        args = dict(sw_if_index=sw_if_index, queue_id=queue_id,
+                    worker_id=worker_id)
+        with PapiExecutor(node) as papi_exec:
+            papi_resp = papi_exec.add(cmd, **args).execute_should_pass(err_msg)
+        data = papi_resp.reply[0]['api_reply'][cmd_reply]
+        if data['retval'] != 0:
+            raise RuntimeError("Failed to set interface RX placement "
+                               "to worker on host {host}".
+                               format(host=node['host']))
 
     @staticmethod
     def vpp_round_robin_rx_placement(node, prefix):
diff --git a/resources/libraries/python/PapiErrors.py b/resources/libraries/python/PapiErrors.py
deleted file mode 100644
index 5afebbf2ce..0000000000
--- a/resources/libraries/python/PapiErrors.py
+++ /dev/null
@@ -1,42 +0,0 @@
-# Copyright (c) 2018 Cisco and/or its affiliates.
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at:
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-"""PAPI Errors class file."""
-
-__all__ = ['PapiError', 'PapiInitError', 'PapiJsonFileError',
-           'PapiCommandError', 'PapiCommandInputError']
-
-
-class PapiError(Exception):
-    """Python API error."""
-    pass
-
-
-class PapiInitError(PapiError):
-    """This exception is raised when construction of VPP instance failed."""
-    pass
-
-
-class PapiJsonFileError(PapiError):
-    """This exception is raised in case of JSON API file error."""
-    pass
-
-
-class PapiCommandError(PapiError):
-    """This exception is raised when PAPI command(s) execution failed."""
-    pass
-
-
-class PapiCommandInputError(PapiCommandError):
-    """This exception is raised when incorrect input of Python API is used."""
-    pass
diff --git a/resources/libraries/python/PapiExecutor.py b/resources/libraries/python/PapiExecutor.py
index ad0de27b82..0313284405 100644
--- a/resources/libraries/python/PapiExecutor.py
+++ b/resources/libraries/python/PapiExecutor.py
@@ -1,4 +1,4 @@
-# Copyright (c) 2018 Cisco and/or its affiliates.
+# Copyright (c) 2019 Cisco and/or its affiliates.
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
 # You may obtain a copy of the License at:
@@ -16,43 +16,248 @@
 import binascii
 import json
 
-from paramiko.ssh_exception import SSHException
 from robot.api import logger
 
 from resources.libraries.python.Constants import Constants
-from resources.libraries.python.PapiErrors import PapiInitError, \
-    PapiJsonFileError, PapiCommandError, PapiCommandInputError
-# TODO: from resources.libraries.python.PapiHistory import PapiHistory
 from resources.libraries.python.ssh import SSH, SSHTimeout
 
-__all__ = ['PapiExecutor']
+__all__ = ["PapiExecutor", "PapiResponse"]
+
+# TODO: Implement Papi History
+# from resources.libraries.python.PapiHistory import PapiHistory
+
+
+class PapiResponse(object):
+    """Class for metadata specifying the Papi reply, stdout, stderr and return
+    code.
+    """
+
+    def __init__(self, papi_reply=None, stdout="", stderr="", ret_code=None):
+        """Construct the Papi response by setting the values needed.
+
+        :param papi_reply: API reply from last executed PAPI command(s).
+        :param stdout: stdout from last executed PAPI command(s).
+        :param stderr: stderr from last executed PAPI command(s).
+        :param ret_code: ret_code from last executed PAPI command(s).
+        :type papi_reply: list
+        :type stdout: str
+        :type stderr: str
+        :type ret_code: int
+        """
+
+        # API reply from last executed PAPI command(s)
+        self.reply = papi_reply
+
+        # stdout from last executed PAPI command(s)
+        self.stdout = stdout
+
+        # stderr from last executed PAPI command(s).
+        self.stderr = stderr
+
+        # return code from last executed PAPI command(s)
+        self.ret_code = ret_code
+
+    def __str__(self):
+        """Return string with human readable description of the group.
+
+        :returns: Readable description.
+        :rtype: str
+        """
+        return ("papi_reply={papi_reply} "
+                "stdout={stdout} "
+                "stderr={stderr} "
+                "ret_code={ret_code}".
+                format(papi_reply=self.reply,
+                       stdout=self.stdout,
+                       stderr=self.stderr,
+                       ret_code=self.ret_code))
+
+    def __repr__(self):
+        """Return string executable as Python constructor call.
+
+        :returns: Executable constructor call.
+        :rtype: str
+        """
+        return ("PapiResponse(papi_reply={papi_reply} "
+                "stdout={stdout} "
+                "stderr={stderr} "
+                "ret_code={ret_code})".
+                format(papi_reply=self.reply,
+                       stdout=self.stdout,
+                       stderr=self.stderr,
+                       ret_code=self.ret_code))
 
 
 class PapiExecutor(object):
-    """Contains methods for executing Python API commands on DUTs."""
+    """Contains methods for executing Python API commands on DUTs.
+
+    Use only with "with" statement, e.g.:
+
+    with PapiExecutor(node) as papi_exec:
+        papi_resp = papi_exec.add('show_version').execute_should_pass(err_msg)
+    """
 
     def __init__(self, node):
-        self._stdout = None
-        self._stderr = None
-        self._ret_code = None
+        """Initialization.
+
+        :param node: Node to run command(s) on.
+        :type node: dict
+        """
+
+        # Node to run command(s) on.
         self._node = node
-        self._json_data = None
-        self._api_reply = list()
-        self._api_data = None
+
+        # The list of PAPI commands to be executed on the node.
+        self._api_command_list = list()
+
+        # The response on the PAPI commands.
+        self.response = PapiResponse()
 
         self._ssh = SSH()
-        try:
-            self._ssh.connect(node)
-        except:
-            raise SSHException('Cannot open SSH connection to host {host} to '
-                               'execute PAPI command(s)'.
-                               format(host=self._node['host']))
 
     def __enter__(self):
+        try:
+            self._ssh.connect(self._node)
+        except IOError:
+            raise RuntimeError("Cannot open SSH connection to host {host} to "
+                               "execute PAPI command(s)".
+                               format(host=self._node["host"]))
         return self
 
     def __exit__(self, exc_type, exc_val, exc_tb):
-        pass
+        self._ssh.disconnect(self._node)
+
+    def clear(self):
+        """Empty the internal command list; return self.
+
+        Use when not sure whether previous usage has left something in the list.
+
+        :returns: self, so that method chaining is possible.
+        :rtype: PapiExecutor
+        """
+        self._api_command_list = list()
+        return self
+
+    def add(self, command, **kwargs):
+        """Add next command to internal command list; return self.
+
+        :param command: VPP API command.
+        :param kwargs: Optional key-value arguments.
+        :type command: str
+        :type kwargs: dict
+        :returns: self, so that method chaining is possible.
+        :rtype: PapiExecutor
+        """
+        self._api_command_list.append(dict(api_name=command, api_args=kwargs))
+        return self
+
+    def execute(self, process_reply=True, ignore_errors=False, timeout=120):
+        """Turn internal command list into proper data and execute; return
+        PAPI response.
+
+        This method also clears the internal command list.
+
+        :param process_reply: Process PAPI reply if True.
+        :param ignore_errors: If true, the errors in the reply are ignored.
+        :param timeout: Timeout in seconds.
+        :type process_reply: bool
+        :type ignore_errors: bool
+        :type timeout: int
+        :returns: Papi response including: papi reply, stdout, stderr and
+            return code.
+        :rtype: PapiResponse
+        :raises KeyError: If the reply is not correct.
+        """
+
+        local_list = self._api_command_list
+
+        # Clear first as execution may fail.
+        self.clear()
+
+        ret_code, stdout, stderr = self._execute_papi(local_list, timeout)
+
+        papi_reply = list()
+        if process_reply:
+            json_data = json.loads(stdout)
+            for data in json_data:
+                try:
+                    api_reply_processed = dict(
+                        api_name=data["api_name"],
+                        api_reply=self._process_reply(data["api_reply"]))
+                except KeyError:
+                    if ignore_errors:
+                        continue
+                    else:
+                        raise
+                papi_reply.append(api_reply_processed)
+
+        return PapiResponse(papi_reply=papi_reply,
+                            stdout=stdout,
+                            stderr=stderr,
+                            ret_code=ret_code)
+
+    def execute_should_pass(self, err_msg="Failed to execute PAPI command.",
+                            process_reply=True, ignore_errors=False,
+                            timeout=120):
+        """Execute the PAPI commands and check the return code.
+        Raise exception if the PAPI command(s) failed.
+
+        Note: There are two exceptions raised to distinguish two situations. If
+        not needed, re-implement using only RuntimeError.
+
+        :param err_msg: The message used if the PAPI command(s) execution fails.
+        :param process_reply: Indicate whether or not to process PAPI reply.
+        :param ignore_errors: If true, the errors in the reply are ignored.
+        :param timeout: Timeout in seconds.
+        :type err_msg: str
+        :type process_reply: bool
+        :type ignore_errors: bool
+        :type timeout: int
+        :returns: Papi response including: papi reply, stdout, stderr and
+            return code.
+        :rtype: PapiResponse
+        :raises RuntimeError: If no PAPI command(s) executed.
+        :raises AssertionError: If PAPI command(s) execution passed.
+        """
+
+        response = self.execute(process_reply=process_reply,
+                                ignore_errors=ignore_errors,
+                                timeout=timeout)
+
+        if response.ret_code != 0:
+            raise AssertionError(err_msg)
+        return response
+
+    def execute_should_fail(self,
+                            err_msg="Execution of PAPI command did not fail.",
+                            process_reply=False, ignore_errors=False,
+                            timeout=120):
+        """Execute the PAPI commands and check the return code.
+        Raise exception if the PAPI command(s) did not fail.
+
+        It does not return anything as we expect it fails.
+
+        Note: There are two exceptions raised to distinguish two situations. If
+        not needed, re-implement using only RuntimeError.
+
+        :param err_msg: The message used if the PAPI command(s) execution fails.
+        :param process_reply: Indicate whether or not to process PAPI reply.
+        :param ignore_errors: If true, the errors in the reply are ignored.
+        :param timeout: Timeout in seconds.
+        :type err_msg: str
+        :type process_reply: bool
+        :type ignore_errors: bool
+        :type timeout: int
+        :raises RuntimeError: If no PAPI command(s) executed.
+        :raises AssertionError: If PAPI command(s) execution passed.
+        """
+
+        response = self.execute(process_reply=process_reply,
+                                ignore_errors=ignore_errors,
+                                timeout=timeout)
+
+        if response.ret_code == 0:
+            raise AssertionError(err_msg)
 
     @staticmethod
     def _process_api_data(api_d):
@@ -68,15 +273,12 @@ class PapiExecutor(object):
 
         api_data_processed = list()
         for api in api_d:
-            api_name = api['api_name']
-            api_args = api['api_args']
-            api_processed = dict(api_name=api_name)
             api_args_processed = dict()
-            for a_k, a_v in api_args.iteritems():
+            for a_k, a_v in api["api_args"].iteritems():
                 value = binascii.hexlify(a_v) if isinstance(a_v, str) else a_v
                 api_args_processed[str(a_k)] = value
-            api_processed['api_args'] = api_args_processed
-            api_data_processed.append(api_processed)
+            api_data_processed.append(dict(api_name=api["api_name"],
+                                           api_args=api_args_processed))
         return api_data_processed
 
     @staticmethod
@@ -85,6 +287,8 @@ class PapiExecutor(object):
 
         Apply binascii.unhexlify() method for unicode values.
 
+        TODO: Remove the disabled code when definitely not needed.
+
         :param api_r: API reply.
         :type api_r: dict
         :returns: Processed API reply / a part of API reply.
@@ -112,39 +316,25 @@ class PapiExecutor(object):
         """
 
         if isinstance(api_reply, list):
-            reverted_reply = list()
-            for a_r in api_reply:
-                reverted_reply.append(self._revert_api_reply(a_r))
+            reverted_reply = [self._revert_api_reply(a_r) for a_r in api_reply]
         else:
             reverted_reply = self._revert_api_reply(api_reply)
         return reverted_reply
 
-    def _process_json_data(self):
-        """Process received JSON data."""
-
-        for data in self._json_data:
-            api_name = data['api_name']
-            api_reply = data['api_reply']
-            api_reply_processed = dict(
-                api_name=api_name, api_reply=self._process_reply(api_reply))
-            self._api_reply.append(api_reply_processed)
-
-    def execute_papi(self, api_data, timeout=120):
+    def _execute_papi(self, api_data, timeout=120):
         """Execute PAPI command(s) on remote node and store the result.
 
         :param api_data: List of APIs with their arguments.
         :param timeout: Timeout in seconds.
         :type api_data: list
         :type timeout: int
-        :raises SSHTimeout: If PAPI command(s) execution is timed out.
-        :raises PapiInitError: If PAPI initialization failed.
-        :raises PapiJsonFileError: If no api.json file found.
-        :raises PapiCommandError: If PAPI command(s) execution failed.
-        :raises PapiCommandInputError: If invalid attribute name or invalid
-            value is used in API call.
+        :raises SSHTimeout: If PAPI command(s) execution has timed out.
         :raises RuntimeError: If PAPI executor failed due to another reason.
         """
-        self._api_data = api_data
+
+        if not api_data:
+            RuntimeError("No API data provided.")
+
         api_data_processed = self._process_api_data(api_data)
         json_data = json.dumps(api_data_processed)
 
@@ -157,68 +347,12 @@ class PapiExecutor(object):
             ret_code, stdout, stderr = self._ssh.exec_command_sudo(
                 cmd=cmd, timeout=timeout)
         except SSHTimeout:
-            logger.error('PAPI command(s) execution timeout on host {host}:'
-                         '\n{apis}'.format(host=self._node['host'],
-                                           apis=self._api_data))
-            raise
-        except (PapiInitError, PapiJsonFileError, PapiCommandError,
-                PapiCommandInputError):
-            logger.error('PAPI command(s) execution failed on host {host}'.
-                         format(host=self._node['host']))
+            logger.error("PAPI command(s) execution timeout on host {host}:"
+                         "\n{apis}".format(host=self._node["host"],
+                                           apis=api_data))
             raise
-        except:
-            raise RuntimeError('PAPI command(s) execution on host {host} '
-                               'failed: {apis}'.format(host=self._node['host'],
-                                                       apis=self._api_data))
-
-        self._ret_code = ret_code
-        self._stdout = stdout
-        self._stderr = stderr
-
-    def papi_should_have_failed(self):
-        """Read return code from last executed script and raise exception if the
-        PAPI command(s) didn't fail.
-
-        :raises RuntimeError: When no PAPI command executed.
-        :raises AssertionError: If PAPI command(s) execution passed.
-        """
-
-        if self._ret_code is None:
-            raise RuntimeError("First execute the PAPI command(s)!")
-        if self._ret_code == 0:
-            raise AssertionError(
-                "PAPI command(s) execution passed, but failure was expected: "
-                "{apis}".format(apis=self._api_data))
-
-    def papi_should_have_passed(self):
-        """Read return code from last executed script and raise exception if the
-        PAPI command(s) failed.
-
-        :raises RuntimeError: When no PAPI command executed.
-        :raises AssertionError: If PAPI command(s) execution failed.
-        """
-
-        if self._ret_code is None:
-            raise RuntimeError("First execute the PAPI command(s)!")
-        if self._ret_code != 0:
-            raise AssertionError(
-                "PAPI command(s) execution failed, but success was expected: "
-                "{apis}".format(apis=self._api_data))
-
-    def get_papi_stdout(self):
-        """Returns value of stdout from last executed PAPI command(s)."""
-
-        return self._stdout
-
-    def get_papi_stderr(self):
-        """Returns value of stderr from last executed PAPI command(s)."""
-
-        return self._stderr
-
-    def get_papi_reply(self):
-        """Returns api reply from last executed PAPI command(s)."""
-
-        self._json_data = json.loads(self._stdout)
-        self._process_json_data()
-
-        return self._api_reply
+        except Exception:
+            raise RuntimeError("PAPI command(s) execution on host {host} "
+                               "failed: {apis}".format(host=self._node["host"],
+                                                       apis=api_data))
+        return ret_code, stdout, stderr
diff --git a/resources/libraries/python/VPPUtil.py b/resources/libraries/python/VPPUtil.py
index b3f471a33d..1bc1b4358e 100644
--- a/resources/libraries/python/VPPUtil.py
+++ b/resources/libraries/python/VPPUtil.py
@@ -20,7 +20,6 @@ from robot.api import logger
 from resources.libraries.python.Constants import Constants
 from resources.libraries.python.DUTSetup import DUTSetup
 from resources.libraries.python.PapiExecutor import PapiExecutor
-from resources.libraries.python.PapiErrors import PapiError
 from resources.libraries.python.ssh import exec_cmd, exec_cmd_no_error
 from resources.libraries.python.topology import NodeType
 from resources.libraries.python.VatExecutor import VatExecutor
@@ -140,49 +139,26 @@ class VPPUtil(object):
 
     @staticmethod
     def vpp_show_version(node, verbose=False):
-        """Run "show_version" API command.
+        """Run "show_version" PAPI command.
 
         :param node: Node to run command on.
         :param verbose: Show version, compile date and compile location if True
             otherwise show only version.
         :type node: dict
         :type verbose: bool
-        :raises PapiError: If no reply received for show_version API command.
         """
-        # TODO: move composition of api data to separate method
-        api_data = list()
-        api = dict(api_name='show_version')
-        api_args = dict()
-        api['api_args'] = api_args
-        api_data.append(api)
-
-        api_reply = None
-        with PapiExecutor(node) as papi_executor:
-            papi_executor.execute_papi(api_data)
-            try:
-                papi_executor.papi_should_have_passed()
-            except AssertionError:
-                raise RuntimeError('Failed to get VPP version on host: {host}'.
-                                   format(host=node['host']))
-            api_reply = papi_executor.get_papi_reply()
-
-        if api_reply is not None:
-            version_data = api_reply[0]['api_reply']['show_version_reply']
-            ver = version_data['version'].rstrip('\0x00')
-            if verbose:
-                date = version_data['build_date'].rstrip('\0x00')
-                loc = version_data['build_directory'].rstrip('\0x00')
-                version = \
-                    'VPP Version:        {ver}\n' \
-                    'Compile date:       {date}\n' \
-                    'Compile location:   {loc}\n '\
-                    .format(ver=ver, date=date, loc=loc)
-            else:
-                version = 'VPP version:{ver}'.format(ver=ver)
-            logger.info(version)
-        else:
-            raise PapiError('No reply received for show_version API command on '
-                            'host {host}'.format(host=node['host']))
+
+        with PapiExecutor(node) as papi_exec:
+            papi_resp = papi_exec.add('show_version').execute_should_pass()
+        data = papi_resp.reply[0]['api_reply']['show_version_reply']
+        version = ('VPP version:      {ver}\n'.
+                   format(ver=data['version'].rstrip('\0x00')))
+        if verbose:
+            version += ('Compile date:     {date}\n'
+                        'Compile location: {loc}\n '.
+                        format(date=data['build_date'].rstrip('\0x00'),
+                               loc=data['build_directory'].rstrip('\0x00')))
+        logger.info(version)
 
     @staticmethod
     def vpp_show_version_verbose(node):
@@ -326,27 +302,8 @@ class VPPUtil(object):
         :type node: dict
         :returns: VPP thread data.
         :rtype: list
-        :raises RuntimeError: If failed to run command on host.
-        :raises PapiError: If no API reply received.
         """
-        api_data = list()
-        api = dict(api_name='show_threads')
-        api_args = dict()
-        api['api_args'] = api_args
-        api_data.append(api)
-
-        with PapiExecutor(node) as papi_executor:
-            papi_executor.execute_papi(api_data)
-            try:
-                papi_executor.papi_should_have_passed()
-                api_reply = papi_executor.get_papi_reply()
-            except AssertionError:
-                raise RuntimeError('Failed to run {api_name} on host '
-                                   '{host}!'.format(host=node['host'], **api))
-
-        if api_reply:
-            return \
-                api_reply[0]['api_reply']['show_threads_reply']['thread_data']
-        else:
-            raise PapiError('No reply received for {api_name} on host {host}!'.
-                            format(host=node['host'], **api))
+
+        with PapiExecutor(node) as papi_exec:
+            resp = papi_exec.add('show_threads').execute_should_pass()
+        return resp.reply[0]['api_reply']['show_threads_reply']['thread_data']
diff --git a/resources/tools/papi/vpp_papi_provider.py b/resources/tools/papi/vpp_papi_provider.py
index 845cc932ca..e5e030c6ab 100644
--- a/resources/tools/papi/vpp_papi_provider.py
+++ b/resources/tools/papi/vpp_papi_provider.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python
 
-# Copyright (c) 2018 Cisco and/or its affiliates.
+# Copyright (c) 2019 Cisco and/or its affiliates.
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
 # You may obtain a copy of the License at:
@@ -18,17 +18,10 @@
 
 import argparse
 import binascii
-import fnmatch
 import json
 import os
 import sys
 
-sys.path.append('/tmp/openvpp-testing')
-try:
-    from resources.libraries.python.PapiErrors import *
-except:
-    raise
-
 # Sphinx creates auto-generated documentation by importing the python source
 # files and collecting the docstrings from them. The NO_VPP_PAPI flag allows
 # the vpp_papi_provider.py file to be importable without having to build
@@ -54,7 +47,7 @@ if do_import:
         sys.path.append(modules_path)
         from vpp_papi import VPP
     else:
-        raise PapiInitError('vpp_papi module not found')
+        raise RuntimeError('vpp_papi module not found')
 
 # client name
 CLIENT_NAME = 'csit_papi'
@@ -75,7 +68,7 @@ def papi_init():
         vpp = VPP()
         return vpp
     except Exception as err:
-        raise PapiInitError('PAPI init failed:\n{exc}'.format(exc=repr(err)))
+        raise RuntimeError('PAPI init failed:\n{err}'.format(err=repr(err)))
 
 
 def papi_connect(vpp_client, name='vpp_api'):
@@ -101,7 +94,7 @@ def papi_disconnect(vpp_client):
 
 
 def papi_run(vpp_client, api_name, api_args):
-    """api_name
+    """Run PAPI.
 
     :param vpp_client: VPP instance.
     :param api_name: VPP API name.
@@ -120,7 +113,8 @@ def convert_reply(api_r):
     """Process API reply / a part of API reply for smooth converting to
     JSON string.
 
-    # Apply binascii.hexlify() method for string values.
+    Apply binascii.hexlify() method for string values.
+
     :param api_r: API reply.
     :type api_r: Vpp_serializer reply object (named tuple)
     :returns: Processed API reply / a part of API reply.
@@ -164,9 +158,8 @@ def process_reply(api_reply):
 def main():
     """Main function for the Python API provider.
 
-    :raises PapiCommandInputError: If invalid attribute name or invalid value is
-        used in API call.
-    :raises PapiCommandError: If PAPI command(s) execution failed.
+    :raises RuntimeError: If invalid attribute name or invalid value is
+        used in API call or if PAPI command(s) execution failed.
     """
 
     parser = argparse.ArgumentParser()
@@ -201,14 +194,16 @@ def main():
             reply.append(api_reply)
         except (AttributeError, ValueError) as err:
             papi_disconnect(vpp)
-            raise PapiCommandInputError(
-                'PAPI command {api}({args}) input error:\n{exc}'.format(
-                    api=api_name, args=api_args), exc=repr(err))
+            raise RuntimeError('PAPI command {api}({args}) input error:\n{err}'.
+                               format(api=api_name,
+                                      args=api_args,
+                                      err=repr(err)))
         except Exception as err:
             papi_disconnect(vpp)
-            raise PapiCommandError(
-                'PAPI command {api}({args}) error:\n{exc}'.format(
-                    api=api_name, args=api_args), exc=repr(err))
+            raise RuntimeError('PAPI command {api}({args}) error:\n{exc}'.
+                               format(api=api_name,
+                                      args=api_args,
+                                      exc=repr(err)))
     papi_disconnect(vpp)
 
     return json.dumps(reply)