Adding scripts to test sflow

[chitra-raghavan]

Description of PR

Summary:
Adding scripts to test sflow

Type of change

• [] Bug fix
• [] Testbed and Framework(new/improvement)
• Test case(new/improvement)

Approach

How did you do it?

• The test will run on the t0 testbed. The script is validated in sonic-vs image with vms-kvm-t0 topology loaded.
• 1 port from each port channel is used for sending traffic. Sflow is enabled on these 4 ports
• 2 ports from Vlan1000 are removed and assigned with ip address and used to reach sflow collector in ptf docker .
• Traffic is sent from ptf docker with different packet sizes to the port channel interfaces which are enabled with sflow .
• Collection is implemented using the sflowtool. Counter sampling output and flow sampling output are directed to a text file. The test script parses the text file and validates the data according to the polling/sampling rate configured and the interfaces enabled.
• For this test to run sflowtool to be installed in ptf docker Adding sflowtool to ptf docker to for sflow tests sonic-buildimage#4045

Test plan Document : sonic-net/SONiC#554

How did you verify/test it?

• The test will run on the t0 testbed. The script is validated in sonic-vs image with vms-kvm-t0 topology loaded.

Any platform specific information?

Supported testbed topology if it's a new test case?

Runs in t0 topology.

Script run :

root@e9a663910a81:/var/johnar/sonic-mgmt/tests# py.test --inventory=../ansible/lab --host-pattern=vlab-01  --module-path ../ansible/library/ --testbed=vms-kvm-t0  --testbed_file=vtestbed.csv    test_sflow.py  -vvv  --disable_loganalyzer -rab     --duration=0 --show-capture=stdout
================================================================================================================================================= test session starts =================================================================================================================================================
platform linux2 -- Python 2.7.12, pytest-4.6.6, py-1.8.0, pluggy-0.13.0 -- /usr/bin/python
cachedir: .pytest_cache
ansible: 2.0.0.2
rootdir: /var/johnar/sonic-mgmt/tests, inifile: pytest.ini
plugins: ansible-2.0.2
collected 15 items

test_sflow.py::TestSflowCollector::test_sflow_config PASSED                                     [  6%]
test_sflow.py::TestSflowCollector::test_collector_del_add PASSED                                [ 13%]
test_sflow.py::TestSflowCollector::test_two_collectors PASSED                                   [ 20%]
test_sflow.py::TestSflowPolling::testPolling PASSED                                             [ 26%]
test_sflow.py::TestSflowPolling::testDisablePolling PASSED                                      [ 33%]
test_sflow.py::TestSflowPolling::testDifferntPollingInt PASSED                                  [ 40%]
test_sflow.py::TestSflowInterface::testIntfRemoval PASSED                                       [ 46%]
test_sflow.py::TestSflowInterface::testIntfSamplingRate PASSED                                  [ 53%]
test_sflow.py::TestSflowInterface::testIntfChangeSamplingRate PASSED                            [ 60%]
test_sflow.py::TestAgentId::testNonDefaultAgent PASSED                                          [ 66%]
test_sflow.py::TestAgentId::testDelAgent PASSED                                                 [ 73%]
test_sflow.py::TestAgentId::testAddAgent PASSED                                                 [ 80%]
test_sflow.py::TestReboot::testRebootSflowEnable PASSED                                         [ 86%]
test_sflow.py::TestReboot::testRebootSflowDisable PASSED                                        [ 93%]
test_sflow.py::TestReboot::testFastreboot PASSED                                                [100%]

============================================== slowest test durations ==============================================
513.19s call     test_sflow.py::TestSflowCollector::test_two_collectors
419.81s call     test_sflow.py::TestReboot::testRebootSflowEnable
389.54s call     test_sflow.py::TestReboot::testRebootSflowDisable
356.24s call     test_sflow.py::TestReboot::testFastreboot
297.33s call     test_sflow.py::TestSflowCollector::test_collector_del_add
164.32s call     test_sflow.py::TestSflowCollector::test_sflow_config
133.97s call     test_sflow.py::TestSflowInterface::testIntfSamplingRate
132.87s call     test_sflow.py::TestSflowInterface::testIntfChangeSamplingRate
132.08s call     test_sflow.py::TestSflowInterface::testIntfRemoval
73.84s call     test_sflow.py::TestSflowPolling::testDifferntPollingInt
39.27s call     test_sflow.py::TestAgentId::testDelAgent
35.03s call     test_sflow.py::TestAgentId::testNonDefaultAgent
34.16s call     test_sflow.py::TestSflowPolling::testPolling
34.04s call     test_sflow.py::TestAgentId::testAddAgent
33.81s call     test_sflow.py::TestSflowPolling::testDisablePolling
22.66s setup    test_sflow.py::TestSflowInterface::testIntfRemoval
22.15s setup    test_sflow.py::TestSflowCollector::test_sflow_config
21.86s setup    test_sflow.py::TestReboot::testRebootSflowEnable
21.71s setup    test_sflow.py::TestSflowPolling::testPolling
20.90s setup    test_sflow.py::TestAgentId::testNonDefaultAgent
20.82s setup    test_sflow.py::TestSflowCollector::test_two_collectors
5.98s teardown test_sflow.py::TestReboot::testFastreboot
1.43s teardown test_sflow.py::TestReboot::testRebootSflowDisable
1.36s teardown test_sflow.py::TestSflowCollector::test_sflow_config
1.32s teardown test_sflow.py::TestReboot::testRebootSflowEnable
1.26s teardown test_sflow.py::TestSflowInterface::testIntfChangeSamplingRate
1.25s teardown test_sflow.py::TestSflowInterface::testIntfRemoval
1.24s teardown test_sflow.py::TestSflowCollector::test_collector_del_add
1.16s teardown test_sflow.py::TestSflowInterface::testIntfSamplingRate
1.15s setup    test_sflow.py::TestReboot::testFastreboot
1.08s setup    test_sflow.py::TestReboot::testRebootSflowDisable
1.02s teardown test_sflow.py::TestSflowCollector::test_two_collectors
1.01s teardown test_sflow.py::TestAgentId::testAddAgent
0.99s teardown test_sflow.py::TestSflowPolling::testPolling
0.99s setup    test_sflow.py::TestAgentId::testDelAgent
0.99s teardown test_sflow.py::TestAgentId::testDelAgent
0.96s teardown test_sflow.py::TestAgentId::testNonDefaultAgent
0.93s setup    test_sflow.py::TestSflowInterface::testIntfChangeSamplingRate
0.93s setup    test_sflow.py::TestSflowPolling::testDisablePolling
0.92s setup    test_sflow.py::TestSflowPolling::testDifferntPollingInt
0.92s teardown test_sflow.py::TestSflowPolling::testDisablePolling
0.90s teardown test_sflow.py::TestSflowPolling::testDifferntPollingInt
0.88s setup    test_sflow.py::TestSflowCollector::test_collector_del_add
0.81s setup    test_sflow.py::TestSflowInterface::testIntfSamplingRate
0.80s setup    test_sflow.py::TestAgentId::testAddAgent
============================================== 15 passed in 2950.05 seconds ===========================================
root@e9a663910a81:/var/johnar/sonic-mgmt/tests#

Known issue:
sonic-net/sonic-buildimage#3991 will be seen until sonic-net/sonic-linux-kernel#120 is merged in buildimage