Host stack test framework

Overview

The goal of the Host stack test framework (hs-test) is to ease writing and running end-to-end tests for VPP's Host Stack. End-to-end tests often want multiple VPP instances, network namespaces, different types of interfaces and to execute external tools or commands. With such requirements the existing VPP test framework is not sufficient. For this, Go was chosen as a high level language, allowing rapid development, with Docker and ip being the tools for creating required topology.

Ginkgo forms the base framework upon which the hs-test is built and run. All tests are technically in a single suite because we are only using package main. We simulate suite behavior by grouping tests by the topology they require. This allows us to run those mentioned groups in parallel, but not individual tests in parallel.

Anatomy of a test case

Prerequisites:

Install hs-test dependencies with make install-deps
Tests use hs-test's own docker image, so building it before starting tests is a prerequisite. Run make build[-debug] to do so
Docker has to be installed and Go has to be in path of both the running user and root
Root privileges are required to run tests as it uses Linux ip command for configuring topology

Action flow when running a test case:

It starts with running make test. Optional arguments are VERBOSE, PERSIST (topology configuration isn't cleaned up after test run, use make cleanup-hst to clean up), TEST=<test-name> to run a specific test and PARALLEL=[n-cpus]. If you want to run multiple specific tests, separate their names with a comma.
make list-tests (or make help) shows all tests.
Ginkgo looks for a spec suite in the current directory and then compiles it to a .test binary.
The Ginkgo test framework runs each function that was registered manually using Register[SuiteName]Test(). Each of these functions correspond to a suite.
Ginkgo's RunSpecs(t, "Suite description") function is the entry point and does the following:

Ginkgo compiles the spec, builds a spec tree

Describe container nodes in suite_*.go files are run (in series by default, or in parallel with the argument PARALLEL=[n-cpus])

Suite is initialized. The topology is loaded and configured in this step

Registered tests are run in generated It subject nodes

Execute tear-down functions, which currently consists of stopping running containers and clean-up of test topology

Adding a test case

This describes adding a new test case to an existing suite. For adding a new suite, please see Modifying the framework below.

To write a new test case, create a file whose name ends with _test.go or pick one that already exists
Declare method whose name ends with Test and specifies its parameter as a pointer to the suite's struct (defined in infra/suite_*.go)
Implement test behaviour inside the test method. This typically includes the following:
1. Import . "fd.io/hs-test/infra"
2. Retrieve a running container in which to run some action. Method GetContainerByName from HstSuite struct serves this purpose
3. Interact with VPP through the VppInstance struct embedded in container. It provides Vppctl method to access debug CLI
4. Run arbitrary commands inside the containers with Exec method
5. Run other external tool with one of the preexisting functions in the infra/utils.go file. For example, use wget with StartWget function
6. Use exechelper or just plain exec packages to run whatever else
7. Verify results of your tests using Assert methods provided by the test suite.
Create an init() function and register the test using Register[SuiteName]Tests(testCaseFunction)

Example test case

Assumed are two docker containers, each with its own VPP instance running. One VPP then pings the other. This can be put in file extras/hs-test/my_test.go and run with command make test TEST=MyTest.

package main

import (
        . "fd.io/hs-test/infra"
)

func init(){
        RegisterMySuiteTest(MyTest)
}

func MyTest(s *MySuite) {
        clientVpp := s.GetContainerByName("client-vpp").VppInstance

        serverVethAddress := s.NetInterfaces["server-iface"].Ip4AddressString()

        result := clientVpp.Vppctl("ping " + serverVethAddress)
        s.Log(result)
        s.AssertNotNil(result)
}

Filtering test cases

The framework allows us to filter test cases in a few different ways, using make test TEST=:

Suite name

File name

Test name

All of the above as long as they are ordered properly, e.g. make test TEST=VethsSuite.http_test.go.HeaderServerTest

Names are case sensitive!

Names don't have to be complete, as long as they are last: This is valid and will run all tests in every http file (if there is more than one):

make test TEST=VethsSuite.http

This is not valid:

make test TEST=Veths.http

They can also be left out:

make test TEST=http_test.go will run every test in http_test.go
make test TEST=Nginx will run everything that has 'Nginx' in its name - suites, files and tests.
make test TEST=HeaderServerTest will only run the header server test

Modifying the framework

Adding a test suite

To add a new suite, create a new file in the infra/ folder. Naming convention for the suite files is suite_[name].go.
Make a struct, in the suite file, with at least HstSuite struct as its member. HstSuite provides functionality that can be shared for all suites, like starting containers
Create a new map that will contain a file name where a test is located and test functions with a pointer to the suite's struct: var myTests = map[string][]func(s *MySuite){}
var myTests = map[string][]func(s *MySuite){} type MySuite struct { HstSuite }

Then create a new function that will add tests to that map:

func RegisterMyTests(tests ...func(s *MySuite)) {
        myTests[getTestFilename()] = tests
}

In suite file, implement SetupSuite method which Ginkgo runs once before starting any of the tests. It's important here to call ConfigureNetworkTopology() method, pass the topology name to the function in a form of file name of one of the yaml files in topo-network folder. Without the extension. In this example, myTopology corresponds to file extras/hs-test/topo-network/myTopology.yaml This will ensure network topology, such as network interfaces and namespaces, will be created. Another important method to call is LoadContainerTopology() which will load containers and shared volumes used by the suite. This time the name passed to method corresponds to file in extras/hs-test/topo-containers folder
func (s *MySuite) SetupSuite() { s.HstSuite.SetupSuite() // Add custom setup code here s.ConfigureNetworkTopology("myNetworkTopology") s.LoadContainerTopology("myContainerTopology") }

In suite file, implement SetupTest method which gets executed before each test. Starting containers and configuring VPP is usually placed here

func (s *MySuite) SetupTest() {
        s.HstSuite.setupTest()
        s.SetupVolumes()
        s.SetupContainers()
}

In order for Ginkgo to run this suite, we need to create a Describe container node with setup nodes and an It subject node. Place them at the end of the suite file

Declare a suite struct variable before anything else
To use BeforeAll() and AfterAll(), the container has to be marked as Ordered

Because the container is now marked as Ordered, if a test fails, all the subsequent tests are skipped. To override this behavior, decorate the container node with ContinueOnFailure

var _ = Describe("MySuite", Ordered, ContinueOnFailure, func() {
var s MySuite
BeforeAll(func() {
        s.SetupSuite()
})
BeforeEach(func() {
        s.SetupTest()
})
AfterAll(func() {
        s.TearDownSuite()
})
AfterEach(func() {
        s.TearDownTest()
})

for filename, tests := range myTests {
        for _, test := range tests {
                test := test
                pc := reflect.ValueOf(test).Pointer()
                funcValue := runtime.FuncForPC(pc)
                testName := filename + "/" + strings.Split(funcValue.Name(), ".")[2]
                It(testName, func(ctx SpecContext) {
                        s.Log(testName + ": BEGIN")
                        test(&s)
                }, SpecTimeout(TestTimeout))
        }
}
})

Notice the loop - it will generate multiple It nodes, each running a different test. test := test is necessary, otherwise only the last test in a suite will run. For a more detailed description, check Ginkgo's documentation: https://onsi.github.io/ginkgo/#dynamically-generating-specs.
testName contains the test name in the following format: [name]_test.go/MyTest.

To run certain tests solo, create a register function and a map that will only contain tests that have to run solo. Add a Serial decorator to the container node and Label("SOLO") to the It subject node:

var _ = Describe("MySuiteSolo", Ordered, ContinueOnFailure, Serial, func() {
        ...
        It(testName, Label("SOLO"), func(ctx SpecContext) {
                s.Log(testName + ": BEGIN")
                test(&s)
        }, SpecTimeout(TestTimeout))
})

Next step is to add test cases to the suite. For that, see section Adding a test case above

Adding a topology element

Topology configuration exists as yaml files in the extras/hs-test/topo-network and extras/hs-test/topo-containers folders. Processing of a network topology file for a particular test suite is started by the configureNetworkTopology method depending on which file's name is passed to it. Specified file is loaded and converted into internal data structures which represent various elements of the topology. After parsing the configuration, framework loops over the elements and configures them one by one on the host system.

These are currently supported types of network elements.

netns - network namespace
veth - veth network interface, optionally with target network namespace or IPv4 address
bridge - ethernet bridge to connect created interfaces, optionally with target network namespace
tap - tap network interface with IP address

Similarly, container topology is started by loadContainerTopology(), configuration file is processed so that test suite retains map of defined containers and uses that to start them at the beginning of each test case and stop containers after the test finishes. Container configuration can specify also volumes which allow to share data between containers or between host system and containers.

Supporting a new type of topology element requires adding code to recognize the new element type during loading. And adding code to set up the element in the host system with some Linux tool, such as ip. This should be implemented in netconfig.go for network and in container.go for containers and volumes.

Communicating between containers

When two VPP instances or other applications, each in its own Docker container, want to communicate there are typically two ways this can be done within hs-test.

Network interfaces. Containers are being created with -d --network host options, so they are connected with interfaces created in host system
Shared folders. Containers are being created with -v option to create shared volumes between host system and containers or just between containers

Host system connects to VPP instances running in containers using a shared folder where binary API socket is accessible by both sides.

Adding an external tool

If an external program should be executed as part of a test case, it might be useful to wrap its execution in its own function. These types of functions are placed in the utils.go file. If the external program is not available by default in Docker image, add its installation to extras/hs-test/Dockerfile.vpp in apt-get install command. Alternatively copy the executable from host system to the Docker image, similarly how the VPP executables and libraries are being copied.

Skipping tests

HstSuite provides several methods that can be called in tests for skipping it conditionally or unconditionally such as: skip(), SkipIfMultiWorker(), SkipUnlessExtendedTestsBuilt(). You can also use Ginkgo's Skip(). However the tests currently run under test suites which set up topology and containers before actual test is run. For the reason of saving test run time it is not advisable to use aforementioned skip methods and instead, just don't register the test.

External dependencies

Linux tools ip, brctl
Standalone programs wget, iperf3 - since these are downloaded when Docker image is made, they are reasonably up-to-date automatically
Programs in Docker images - envoyproxy/envoy-contrib and nginx
http_server - homegrown application that listens on specified port and sends a test file in response
Non-standard Go libraries - see extras/hs-test/go.mod

Generally, these will be updated on a per-need basis, for example when a bug is discovered or a new version incompatibility issue occurs.

Debugging a test

GDB

It is possible to debug VPP by attaching gdb before test execution by adding DEBUG=true like follows:

$ make test TEST=LDPreloadIperfVppTest DEBUG=true
...
run following command in different terminal:
docker exec -it server-vpp2456109 gdb -ex "attach $(docker exec server-vpp2456109 pidof vpp)"
Afterwards press CTRL+\ to continue

If a test consists of more VPP instances then this is done for each of them.

Utility methods

Packet Capture

It is possible to use VPP pcap trace to capture received and sent packets. You just need to add EnablePcapTrace to SetupTest method in test suite and CollectPcapTrace to TearDownTest. This way pcap trace is enabled on all interfaces and to capture maximum 10000 packets. Your pcap file will be located in the test execution directory.

Event Logger

clib_warning is a handy way to add debugging output, but in some cases it's not appropriate for per-packet use in data plane code. In this case VPP event logger is better option, for example you can enable it for TCP or session layer in build time. To collect traces when test ends you just need to add CollectEventLogs method to TearDownTest in the test suite. Your event logger file will be located in the test execution directory. To view events you can use G2 graphical event viewer or convert_evt tool, located in src/scripts/host-stack/, which convert event logs to human readable text.

Memory leak testing

It is possible to use VPP memory traces to diagnose if and where memory leaks happen by comparing of two traces at different point in time. You can do it by test like following:

func MemLeakTest(s *NoTopoSuite) {
    s.SkipUnlessLeakCheck()  // test is excluded from usual test run
    vpp := s.GetContainerByName("vpp").VppInstance
    /* do your configuration here */
    vpp.Disconnect()  // no goVPP less noise
    vpp.EnableMemoryTrace()  // enable memory traces
    traces1, err := vpp.GetMemoryTrace()  // get first sample
    s.AssertNil(err, fmt.Sprint(err))
    vpp.Vppctl("test mem-leak")  // execute some action
    traces2, err := vpp.GetMemoryTrace()  // get second sample
    s.AssertNil(err, fmt.Sprint(err))
    vpp.MemLeakCheck(traces1, traces2)  // compare samples and generate report
}

To get your memory leak report run following command:

$ make test-leak TEST=MemLeakTest
...
NoTopoSuiteSolo mem_leak_test.go/MemLeakTest [SOLO]
/home/matus/vpp/extras/hs-test/infra/suite_no_topo.go:113

  Report Entries >>

  SUMMARY: 112 byte(s) leaked in 1 allocation(s)
   - /home/matus/vpp/extras/hs-test/infra/vppinstance.go:624 @ 07/19/24 15:53:33.539

    leak of 112 byte(s) in 1 allocation(s) from:
        #0 clib_mem_heap_alloc_aligned + 0x31
        #1 _vec_alloc_internal + 0x113
        #2 _vec_validate + 0x81
        #3 leak_memory_fn + 0x4f
        #4 0x7fc167815ac3
        #5 0x7fc1678a7850
  << Report Entries
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