Linkerd Conformance Validation

This repo contains the conformance tests for Linkerd2 as described by this RFC.

The conformance validation tool is primarily intended to be run on a specified version of Linkerd to verify the correctness of a Kubernetes cluster’s configuration with respect to Linkerd as well as validate non-trivial network communication (HTTP, gRPC, websocket) among stateless and stateful workloads in the Linkerd data plane.

The conformance tests exercise the following features:

• Validation of your Linkerd2 control plane
• Automatic proxy injection on workloads
• Functioning of linkerd tap, stat, routes and edges commands
• Verifying the functioning of the tap extension API server
• Retries and timeouts
• Data plane health checks
• Ingress configuration …and much more

If you are interested in helping to extend the test suites, see Adding new tests below.

Table of Contents

• Repository Structure
• Configuring your tests
  • Configuration Options
• Usage
  • Using the Sonobuoy CLI
  • Running the tests using Docker
  • Running the tests locally
• Adding new tests
  • Bootstrapping
  • Adding tests
  • Wiring up the newly added tests

Repository Structure

• specs contains the tests for each of the features organized into separate packages
• sonobuoy contains the items required to be able to run the tests as a Sonobuoy plugin
• utils contains helper functions that can be used while writing conformance tests
• bin contains useful helper scripts to build/push the Docker image and running the tests
• testdata contains the necessary files required by the tests, organized into subfolders

Configuring your tests

The conformance tests can be easily configured by specifying a config.yaml that holds the configuration values. This includes things like Linkerd version, Linkerd add-ons, test specific configuration, binary path, etc.

Run the command below to pull up a sample configuration file, config.yaml, and modify it according to your requirements. The tests shall read this YAML file during runtime and run accordingly.

CONFIG=https://raw.githubusercontent.com/linkerd/linkerd2-conformance/master/config.yaml

curl -sL $CONFIG > config.yaml

Configuration options

This section describes the various configuration options and its default values. Not providing a configuration file, or providing a partial configuration file will result in the tests running on default settings as described below

Option	Description	Default value
linkerdVersion	The linkerd2 binary version to use	Latest stable release
linkerdBinaryPath	If specified, the tests use the binary installed in the directory. It is recommended that this is left
unspecified while using Sonobuoy or if upgrade tests are enabled	$HOME/.linkerd2/bin/linkerd
clusterDomain	Use the specified cluster domain	"cluster.local"
K8sContext	Use the specified K8s context. Its is recommended that while running the tests with Sonobuoy (sonobuoy run), use the --context flag	""
controlPlane.namespace	Installs the control plane in the specified namespace	"l5d-conformance"
controlPlane.config.ha	Use a high-availability control plane for the tests	false
controlPlane.config.flags	Use the specified linkerd install CLI flag options while testing control plane installation	[]
controlPlane.config.addOns	Use the specified add-on configuration while testing control plane installation	nil
testCase.lifecycle.skip	Skip the pre-flight control plane installation tests	false
testCase.lifecycle.upgradeFromVersion	If specified, first install the CLI and control plane using the specified version, and test if they can be upgraded to linkerdVersion	""
testCase.lifecycle.reinstall	If true, install a new control plane for each test. Otherwise, use a single control plane throughout	false
testCase.lifecycle.uninstall	If using a single control plane, uninstall once the tests complete (whether they pass or fail)	false
testCase.inject.skip	Skip proxy injection tests	false
testCase.inject.clean	Delete the resources created for testing proxy injection	false
testCase.ingress.skip	If true, skips all ingress tests	false
testCase.ingress.config.controllers	List of ingress controllers to test. Currently only supports nginx	[]string

Usage

This section outlines the various methods that can be used to run the conformance tests against your Kubernetes cluster

Using the Sonobuoy CLI

Sonobuoy offers a reliable way to run diagnostic tests in a Kubernetes cluster. We leverage its plugin model to run conformance tests inside a Kubernetes pod.

The below commands assume that the user has the Sonobuoy CLI and kubectl (with a correctly configured kubeconfig) installed locally.

This repo provides a Sonobuoy plugin file that is intended to be plugged into the Sonobuoy CLI. Sonobuoy reads the plugin definition, and spins up a pod with the linkerd2-conformance Docker image.

# Create a ConfigMap from the `config.yaml` mentioned in the previous section
# This step allows the sonobuoy pod to read the test configurations.
$ kubectl create ns sonobuoy && \
  kubectl create cm l5d-config \
  -n sonobuoy \
  --from-file=config.yaml=/path/to/config.yaml

# Run the plugin
$ plugin=https://raw.githubusercontent.com/linkerd/linkerd2-conformance/master/sonobuoy/plugin.yaml

$ sonobuoy run \
  --plugin $plugin \
  --skip-preflight \
  --wait

# [Optional] Check the status of the pod
$ sonobuoy status

# Retrieve the test results
# This command downloads the tar ball containing the results
$ results=$(sonobuoy retrieve)

# Inspect the results
$ sonobuoy results $results --mode dump

# Clean up your cluster
$ sonobuoy delete --wait

Running the tests locally

These commands assume a working Go 1.14 environment along with the Linkerd2 CLI and kubectl (with a correctly configured kubeconfig) installed.

# clone this repository
$ git clone https://github.com/linkerd/linkerd2-conformance

# Navigate into project directory
$ cd linkerd2-conformance

$ go test -timeout 1h -ginkgo.v

# Optionally, you may also use the -ginkgo.reportFile flag to
# get a JUnit report

$ go test -timeout 1h -ginkgo.v -ginkgo.reportFile=path/to/report.xml

Adding new tests

This project makes use of Ginkgo paired with Gomega matcher library to describe tests and write assertions. Each of the tests can be found under the tests/ folder, in its respective packages.

Rather than having a separate test suite for each feature (and its associated _test.go files), this project provides a single test suite that runs tests for each of the features as an organized collection of specs. This was done to not only have greater control over the order in which the tests are run, but also to have a smooth and consistent contribution experience.

For the sake of understanding, we shall assume a feature called l5dFeature, for which we shall add a new test as shown below.

1. Bootstrapping

To add a new test for l5Feature, we first add a new package l5dFeature under the specs folder.

mkdir specs/l5dFeature

Our new package shall mainly require 2 new files

• spec.go - this file holds the description and structure of the test in the form of Describe, It, Context, etc. blocks.
• tests.go - this file shall contain assertions and testing logic for each of our specs as described in specs.go

touch specs/l5dFeature/tests.go
touch specs/l5dFeature/spec.go

2. Writing the tests

spec.go must contain a single (if required, more) exported function that returns a ginkgo.Describe block that holds the specs. This function must be named Runl5dFeatureTests.

For example

// spec.go

package l5dFeature

import (
    "github.com/onsi/ginkgo"
)

func Runl5dFeatureTests() bool {
  return ginkgo.Describe("l5d Feature", func() {
    ginkgo.It("can do something cool", testDoSomethingCool)
    ginkgo.It("can do something cooler", testDoSomethingCooler)

    ginkgo.It("should throw error", func() {
      ginkgo.When("this is unspecified", testThrowErrorUnspecified)
      ginkgo.When("something breaks", testThrowErrorWhenBroken)
    })
  })
}

tests.go must contain the functions that do the actual testing and assertions, which are used as callbacks as shown above.

For example

// tests.go

package l5dFeature

import (
    "github.com/onsi/ginkgo"
    "github.com/onsi/gomega"
)

func testSomethingCool() {
  // ...add testing logic here

  err := doSomethingCool()

  // sample assertion
  gomega.Expect(err).Should(gomega.BeNil(), "could not do something cool")
}

3. Wiring up the newly added test

Once the tests have been added, the newly written Runl5dFeatureTests must be brought to scope under the specs package. To do so, simply import the l5dFeature package under specs/specs.go, and call Runl5dFeatureTests in the function body of runPrimaryTests (or runLifecycleTests depending on what is being tested).

For example

func runPrimaryTests() bool {
    return ginkgo.Describe("", func() {
    // ...test initialisation logic here

    // Bring main tests into scope
    _ = inject.RunInjectTests()
    _ = l5dFeature.Runl5dFeatureTests() // call your test here

    // ...post testing logic
    })
}