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End-to-End Testing in Kubernetes

Updated: 5/3/2016

Table of Contents

Overview

End-to-end (e2e) tests for Kubernetes provide a mechanism to test end-to-end behavior of the system, and is the last signal to ensure end user operations match developer specifications. Although unit and integration tests provide a good signal, in a distributed system like Kubernetes it is not uncommon that a minor change may pass all unit and integration tests, but cause unforeseen changes at the system level.

The primary objectives of the e2e tests are to ensure a consistent and reliable behavior of the kubernetes code base, and to catch hard-to-test bugs before users do, when unit and integration tests are insufficient.

The e2e tests in kubernetes are built atop of Ginkgo and Gomega. There are a host of features that this Behavior-Driven Development (BDD) testing framework provides, and it is recommended that the developer read the documentation prior to diving into the tests.

The purpose of this document is to serve as a primer for developers who are looking to execute or add tests using a local development environment.

Before writing new tests or making substantive changes to existing tests, you should also read Writing Good e2e Tests

Building and Running the Tests

There are a variety of ways to run e2e tests, but we aim to decrease the number of ways to run e2e tests to a canonical way: hack/e2e.go.

You can run an end-to-end test which will bring up a master and nodes, perform some tests, and then tear everything down. Make sure you have followed the getting started steps for your chosen cloud platform (which might involve changing the KUBERNETES_PROVIDER environment variable to something other than "gce").

To build Kubernetes, up a cluster, run tests, and tear everything down, use:

go run hack/e2e.go -v --build --up --test --down

If you'd like to just perform one of these steps, here are some examples:

# Build binaries for testing
go run hack/e2e.go -v --build

# Create a fresh cluster.  Deletes a cluster first, if it exists
go run hack/e2e.go -v --up

# Run all tests
go run hack/e2e.go -v --test

# Run tests matching the regex "\[Feature:Performance\]"
go run hack/e2e.go -v --test --test_args="--ginkgo.focus=\[Feature:Performance\]"

# Conversely, exclude tests that match the regex "Pods.*env"
go run hack/e2e.go -v --test --test_args="--ginkgo.skip=Pods.*env"

# Run tests in parallel, skip any that must be run serially
GINKGO_PARALLEL=y go run hack/e2e.go --v --test --test_args="--ginkgo.skip=\[Serial\]"

# Run tests in parallel, skip any that must be run serially and keep the test namespace if test failed
GINKGO_PARALLEL=y go run hack/e2e.go --v --test --test_args="--ginkgo.skip=\[Serial\] --delete-namespace-on-falure=false"

# Flags can be combined, and their actions will take place in this order:
# --build, --up, --test, --down
#
# You can also specify an alternative provider, such as 'aws'
#
# e.g.:
KUBERNETES_PROVIDER=aws go run hack/e2e.go -v --build --up --test --down

# -ctl can be used to quickly call kubectl against your e2e cluster. Useful for
# cleaning up after a failed test or viewing logs. Use -v to avoid suppressing
# kubectl output.
go run hack/e2e.go -v -ctl='get events'
go run hack/e2e.go -v -ctl='delete pod foobar'

The tests are built into a single binary which can be run used to deploy a Kubernetes system or run tests against an already-deployed Kubernetes system. See go run hack/e2e.go --help (or the flag definitions in hack/e2e.go) for more options, such as reusing an existing cluster.

Cleaning up

During a run, pressing control-C should result in an orderly shutdown, but if something goes wrong and you still have some VMs running you can force a cleanup with this command:

go run hack/e2e.go -v --down

Advanced testing

Bringing up a cluster for testing

If you want, you may bring up a cluster in some other manner and run tests against it. To do so, or to do other non-standard test things, you can pass arguments into Ginkgo using --test_args (e.g. see above). For the purposes of brevity, we will look at a subset of the options, which are listed below:

--ginkgo.dryRun=false: If set, ginkgo will walk the test hierarchy without
actually running anything. Best paired with -v.

--ginkgo.failFast=false: If set, ginkgo will stop running a test suite after a
failure occurs.

--ginkgo.failOnPending=false: If set, ginkgo will mark the test suite as failed
if any specs are pending.

--ginkgo.focus="": If set, ginkgo will only run specs that match this regular
expression.

--ginkgo.skip="": If set, ginkgo will only run specs that do not match this
regular expression.

--ginkgo.trace=false: If set, default reporter prints out the full stack trace
when a failure occurs

--ginkgo.v=false: If set, default reporter print out all specs as they begin.

--host="": The host, or api-server, to connect to

--kubeconfig="": Path to kubeconfig containing embedded authinfo.

--prom-push-gateway="": The URL to prometheus gateway, so that metrics can be
pushed during e2es and scraped by prometheus. Typically something like
127.0.0.1:9091.

--provider="": The name of the Kubernetes provider (gce, gke, local, vagrant,
etc.)

--repo-root="../../": Root directory of kubernetes repository, for finding test
files.

Prior to running the tests, you may want to first create a simple auth file in your home directory, e.g. $HOME/.kube/config, with the following:

{
  "User": "root",
  "Password": ""
}

As mentioned earlier there are a host of other options that are available, but they are left to the developer.

NOTE: If you are running tests on a local cluster repeatedly, you may need to periodically perform some manual cleanup:

  • rm -rf /var/run/kubernetes, clear kube generated credentials, sometimes stale permissions can cause problems.

  • sudo iptables -F, clear ip tables rules left by the kube-proxy.

Federation e2e tests

By default, e2e.go provisions a single Kubernetes cluster, and any Feature:Federation ginkgo tests will be skipped.

Federation e2e testing involve bringing up multiple "underlying" Kubernetes clusters, and deploying the federation control plane as a Kubernetes application on the underlying clusters.

The federation e2e tests are still managed via e2e.go, but require some extra configuration items.

Configuring federation e2e tests

The following environment variables will enable federation e2e building, provisioning and testing.

$ export FEDERATION=true
$ export E2E_ZONES="us-central1-a us-central1-b us-central1-f"

A Kubernetes cluster will be provisioned in each zone listed in E2E_ZONES. A zone can only appear once in the E2E_ZONES list.

Image Push Repository

Next, specify the docker repository where your ci images will be pushed.

  • If KUBERNETES_PROVIDER=gce or KUBERNETES_PROVIDER=gke:

    If you use the same GCP project where you to run the e2e tests as the container image repository, FEDERATION_PUSH_REPO_BASE environment variable will be defaulted to "gcr.io/${DEFAULT_GCP_PROJECT_NAME}". You can skip ahead to the Build section.

    You can simply set your push repo base based on your project name, and the necessary repositories will be auto-created when you first push your container images.

     $ export FEDERATION_PUSH_REPO_BASE="gcr.io/${GCE_PROJECT_NAME}"

    Skip ahead to the Build section.

  • For all other providers:

    You'll be responsible for creating and managing access to the repositories manually.

     $ export FEDERATION_PUSH_REPO_BASE="quay.io/colin_hom"

    Given this example, the federation-apiserver container image will be pushed to the repository quay.io/colin_hom/federation-apiserver.

    The docker client on the machine running e2e.go must have push access for the following pre-existing repositories:

    • ${FEDERATION_PUSH_REPO_BASE}/federation-apiserver
    • ${FEDERATION_PUSH_REPO_BASE}/federation-controller-manager

    These repositories must allow public read access, as the e2e node docker daemons will not have any credentials. If you're using GCE/GKE as your provider, the repositories will have read-access by default.

Build

  • Compile the binaries and build container images:

    $ KUBE_RELEASE_RUN_TESTS=n KUBE_FASTBUILD=true go run hack/e2e.go -v -build

  • Push the federation container images

    $ build-tools/push-federation-images.sh

Deploy federation control plane

The following command will create the underlying Kubernetes clusters in each of E2E_ZONES, and then provision the federation control plane in the cluster occupying the last zone in the E2E_ZONES list.

$ go run hack/e2e.go -v --up

Run the Tests

This will run only the Feature:Federation e2e tests. You can omit the ginkgo.focus argument to run the entire e2e suite.

$ go run hack/e2e.go -v --test --test_args="--ginkgo.focus=\[Feature:Federation\]"

Teardown

$ go run hack/e2e.go -v --down

Shortcuts for test developers

  • To speed up e2e.go -up, provision a single-node kubernetes cluster in a single e2e zone:

    NUM_NODES=1 E2E_ZONES="us-central1-f"

    Keep in mind that some tests may require multiple underlying clusters and/or minimum compute resource availability.

  • You can quickly recompile the e2e testing framework via go install ./test/e2e. This will not do anything besides allow you to verify that the go code compiles.

  • If you want to run your e2e testing framework without re-provisioning the e2e setup, you can do so via make WHAT=test/e2e/e2e.test and then re-running the ginkgo tests.

  • If you're hacking around with the federation control plane deployment itself, you can quickly re-deploy the federation control plane Kubernetes manifests without tearing any resources down. To re-deploy the federation control plane after running -up for the first time:

    $ federation/cluster/federation-up.sh

Debugging clusters

If a cluster fails to initialize, or you'd like to better understand cluster state to debug a failed e2e test, you can use the cluster/log-dump.sh script to gather logs.

This script requires that the cluster provider supports ssh. Assuming it does, running:

cluster/log-dump.sh <directory>

will ssh to the master and all nodes and download a variety of useful logs to the provided directory (which should already exist).

The Google-run Jenkins builds automatically collected these logs for every build, saving them in the artifacts directory uploaded to GCS.

Local clusters

It can be much faster to iterate on a local cluster instead of a cloud-based one. To start a local cluster, you can run:

# The PATH construction is needed because PATH is one of the special-cased
# environment variables not passed by sudo -E
sudo PATH=$PATH hack/local-up-cluster.sh

This will start a single-node Kubernetes cluster than runs pods using the local docker daemon. Press Control-C to stop the cluster.

You can generate a valid kubeconfig file by following instructions printed at the end of aforementioned script.

Testing against local clusters

In order to run an E2E test against a locally running cluster, point the tests at a custom host directly:

export KUBECONFIG=/path/to/kubeconfig
export KUBE_MASTER_IP="http://127.0.0.1:<PORT>"
export KUBE_MASTER=local
go run hack/e2e.go -v --test

To control the tests that are run:

go run hack/e2e.go -v --test --test_args="--ginkgo.focus=\"Secrets\""

Version-skewed and upgrade testing

We run version-skewed tests to check that newer versions of Kubernetes work similarly enough to older versions. The general strategy is to cover the following cases:

  1. One version of kubectl with another version of the cluster and tests (e.g. that v1.2 and v1.4 kubectl doesn't break v1.3 tests running against a v1.3 cluster).
  2. A newer version of the Kubernetes master with older nodes and tests (e.g. that upgrading a master to v1.3 with nodes at v1.2 still passes v1.2 tests).
  3. A newer version of the whole cluster with older tests (e.g. that a cluster upgraded---master and nodes---to v1.3 still passes v1.2 tests).
  4. That an upgraded cluster functions the same as a brand-new cluster of the same version (e.g. a cluster upgraded to v1.3 passes the same v1.3 tests as a newly-created v1.3 cluster).

hack/e2e-runner.sh is the authoritative source on how to run version-skewed tests, but below is a quick-and-dirty tutorial.

# Assume you have two copies of the Kubernetes repository checked out, at
# ./kubernetes and ./kubernetes_old

# If using GKE:
export KUBERNETES_PROVIDER=gke
export CLUSTER_API_VERSION=${OLD_VERSION}

# Deploy a cluster at the old version; see above for more details
cd ./kubernetes_old
go run ./hack/e2e.go -v --up

# Upgrade the cluster to the new version
#
# If using GKE, add --upgrade-target=${NEW_VERSION}
#
# You can target Feature:MasterUpgrade or Feature:ClusterUpgrade
cd ../kubernetes
go run ./hack/e2e.go -v --test --check_version_skew=false --test_args="--ginkgo.focus=\[Feature:MasterUpgrade\]"

# Run old tests with new kubectl
cd ../kubernetes_old
go run ./hack/e2e.go -v --test --test_args="--kubectl-path=$(pwd)/../kubernetes/cluster/kubectl.sh"

If you are just testing version-skew, you may want to just deploy at one version and then test at another version, instead of going through the whole upgrade process:

# With the same setup as above

# Deploy a cluster at the new version
cd ./kubernetes
go run ./hack/e2e.go -v --up

# Run new tests with old kubectl
go run ./hack/e2e.go -v --test --test_args="--kubectl-path=$(pwd)/../kubernetes_old/cluster/kubectl.sh"

# Run old tests with new kubectl
cd ../kubernetes_old
go run ./hack/e2e.go -v --test --test_args="--kubectl-path=$(pwd)/../kubernetes/cluster/kubectl.sh"

Kinds of tests

We are working on implementing clearer partitioning of our e2e tests to make running a known set of tests easier (#10548). Tests can be labeled with any of the following labels, in order of increasing precedence (that is, each label listed below supersedes the previous ones):

  • If a test has no labels, it is expected to run fast (under five minutes), be able to be run in parallel, and be consistent.

  • [Slow]: If a test takes more than five minutes to run (by itself or in parallel with many other tests), it is labeled [Slow]. This partition allows us to run almost all of our tests quickly in parallel, without waiting for the stragglers to finish.

  • [Serial]: If a test cannot be run in parallel with other tests (e.g. it takes too many resources or restarts nodes), it is labeled [Serial], and should be run in serial as part of a separate suite.

  • [Disruptive]: If a test restarts components that might cause other tests to fail or break the cluster completely, it is labeled [Disruptive]. Any [Disruptive] test is also assumed to qualify for the [Serial] label, but need not be labeled as both. These tests are not run against soak clusters to avoid restarting components.

  • [Flaky]: If a test is found to be flaky and we have decided that it's too hard to fix in the short term (e.g. it's going to take a full engineer-week), it receives the [Flaky] label until it is fixed. The [Flaky] label should be used very sparingly, and should be accompanied with a reference to the issue for de-flaking the test, because while a test remains labeled [Flaky], it is not monitored closely in CI. [Flaky] tests are by default not run, unless a focus or skip argument is explicitly given.

  • [Feature:.+]: If a test has non-default requirements to run or targets some non-core functionality, and thus should not be run as part of the standard suite, it receives a [Feature:.+] label, e.g. [Feature:Performance] or [Feature:Ingress]. [Feature:.+] tests are not run in our core suites, instead running in custom suites. If a feature is experimental or alpha and is not enabled by default due to being incomplete or potentially subject to breaking changes, it does not block the merge-queue, and thus should run in some separate test suites owned by the feature owner(s) (see Continuous Integration below).

Viper configuration and hierarchichal test parameters.

The future of e2e test configuration idioms will be increasingly defined using viper, and decreasingly via flags.

Flags in general fall apart once tests become sufficiently complicated. So, even if we could use another flag library, it wouldn't be ideal.

To use viper, rather than flags, to configure your tests:

  • Just add "e2e.json" to the current directory you are in, and define parameters in it... i.e. "kubeconfig":"/tmp/x".

Note that advanced testing parameters, and hierarchichally defined parameters, are only defined in viper, to see what they are, you can dive into TestContextType.

In time, it is our intent to add or autogenerate a sample viper configuration that includes all e2e parameters, to ship with kubernetes.

Conformance tests

Finally, [Conformance] tests represent a subset of the e2e-tests we expect to pass on any Kubernetes cluster. The [Conformance] label does not supersede any other labels.

As each new release of Kubernetes providers new functionality, the subset of tests necessary to demonstrate conformance grows with each release. Conformance is thus considered versioned, with the same backwards compatibility guarantees as laid out in our versioning policy. Conformance tests for a given version should be run off of the release branch that corresponds to that version. Thus v1.2 conformance tests would be run from the head of the release-1.2 branch. eg:

  • A v1.3 development cluster should pass v1.1, v1.2 conformance tests

  • A v1.2 cluster should pass v1.1, v1.2 conformance tests

  • A v1.1 cluster should pass v1.0, v1.1 conformance tests, and fail v1.2 conformance tests

Conformance tests are designed to be run with no cloud provider configured. Conformance tests can be run against clusters that have not been created with hack/e2e.go, just provide a kubeconfig with the appropriate endpoint and credentials.

# setup for conformance tests
export KUBECONFIG=/path/to/kubeconfig
export KUBERNETES_CONFORMANCE_TEST=y
export KUBERNETES_PROVIDER=skeleton

# run all conformance tests
go run hack/e2e.go -v --test --test_args="--ginkgo.focus=\[Conformance\]"

# run all parallel-safe conformance tests in parallel
GINKGO_PARALLEL=y go run hack/e2e.go -v --test --test_args="--ginkgo.focus=\[Conformance\] --ginkgo.skip=\[Serial\]"

# ... and finish up with remaining tests in serial
go run hack/e2e.go -v --test --test_args="--ginkgo.focus=\[Serial\].*\[Conformance\]"

Defining Conformance Subset

It is impossible to define the entire space of Conformance tests without knowing the future, so instead, we define the compliment of conformance tests, below (Please update this with companion PRs as necessary):

  • A conformance test cannot test cloud provider specific features (i.e. GCE monitoring, S3 Bucketing, ...)

  • A conformance test cannot rely on any particular non-standard file system permissions granted to containers or users (i.e. sharing writable host /tmp with a container)

  • A conformance test cannot rely on any binaries that are not required for the linux kernel or for a kubelet to run (i.e. git)

  • A conformance test cannot test a feature which obviously cannot be supported on a broad range of platforms (i.e. testing of multiple disk mounts, GPUs, high density)

Continuous Integration

A quick overview of how we run e2e CI on Kubernetes.

What is CI?

We run a battery of e2e tests against HEAD of the master branch on a continuous basis, and block merges via the submit queue on a subset of those tests if they fail (the subset is defined in the [munger config] (https://github.com/kubernetes/contrib/blob/master/mungegithub/mungers/submit-queue.go) via the jenkins-jobs flag; note we also block on kubernetes-build and kubernetes-test-go jobs for build and unit and integration tests).

CI results can be found at ci-test.k8s.io, e.g. ci-test.k8s.io/kubernetes-e2e-gce/10594.

What runs in CI?

We run all default tests (those that aren't marked [Flaky] or [Feature:.+]) against GCE and GKE. To minimize the time from regression-to-green-run, we partition tests across different jobs:

  • kubernetes-e2e-<provider> runs all non-[Slow], non-[Serial], non-[Disruptive], non-[Flaky], non-[Feature:.+] tests in parallel.

  • kubernetes-e2e-<provider>-slow runs all [Slow], non-[Serial], non-[Disruptive], non-[Flaky], non-[Feature:.+] tests in parallel.

  • kubernetes-e2e-<provider>-serial runs all [Serial] and [Disruptive], non-[Flaky], non-[Feature:.+] tests in serial.

We also run non-default tests if the tests exercise general-availability ("GA") features that require a special environment to run in, e.g. kubernetes-e2e-gce-scalability and kubernetes-kubemark-gce, which test for Kubernetes performance.

Non-default tests

Many [Feature:.+] tests we don't run in CI. These tests are for features that are experimental (often in the experimental API), and aren't enabled by default.

The PR-builder

We also run a battery of tests against every PR before we merge it. These tests are equivalent to kubernetes-gce: it runs all non-[Slow], non-[Serial], non-[Disruptive], non-[Flaky], non-[Feature:.+] tests in parallel. These tests are considered "smoke tests" to give a decent signal that the PR doesn't break most functionality. Results for your PR can be found at pr-test.k8s.io, e.g. pr-test.k8s.io/20354 for #20354.

Adding a test to CI

As mentioned above, prior to adding a new test, it is a good idea to perform a -ginkgo.dryRun=true on the system, in order to see if a behavior is already being tested, or to determine if it may be possible to augment an existing set of tests for a specific use case.

If a behavior does not currently have coverage and a developer wishes to add a new e2e test, navigate to the ./test/e2e directory and create a new test using the existing suite as a guide.

TODO(#20357): Create a self-documented example which has been disabled, but can be copied to create new tests and outlines the capabilities and libraries used.

When writing a test, consult #kinds_of_tests above to determine how your test should be marked, (e.g. [Slow], [Serial]; remember, by default we assume a test can run in parallel with other tests!).

When first adding a test it should not go straight into CI, because failures block ordinary development. A test should only be added to CI after is has been running in some non-CI suite long enough to establish a track record showing that the test does not fail when run against working software. Note also that tests running in CI are generally running on a well-loaded cluster, so must contend for resources; see above about kinds of tests.

Generally, a feature starts as experimental, and will be run in some suite owned by the team developing the feature. If a feature is in beta or GA, it should block the merge-queue. In moving from experimental to beta or GA, tests that are expected to pass by default should simply remove the [Feature:.+] label, and will be incorporated into our core suites. If tests are not expected to pass by default, (e.g. they require a special environment such as added quota,) they should remain with the [Feature:.+] label, and the suites that run them should be incorporated into the munger config via the jenkins-jobs flag.

Occasionally, we'll want to add tests to better exercise features that are already GA. These tests also shouldn't go straight to CI. They should begin by being marked as [Flaky] to be run outside of CI, and once a track-record for them is established, they may be promoted out of [Flaky].

Moving a test out of CI

If we have determined that a test is known-flaky and cannot be fixed in the short-term, we may move it out of CI indefinitely. This move should be used sparingly, as it effectively means that we have no coverage of that test. When a test is demoted, it should be marked [Flaky] with a comment accompanying the label with a reference to an issue opened to fix the test.

Performance Evaluation

Another benefit of the e2e tests is the ability to create reproducible loads on the system, which can then be used to determine the responsiveness, or analyze other characteristics of the system. For example, the density tests load the system to 30,50,100 pods per/node and measures the different characteristics of the system, such as throughput, api-latency, etc.

For a good overview of how we analyze performance data, please read the following post

For developers who are interested in doing their own performance analysis, we recommend setting up prometheus for data collection, and using promdash to visualize the data. There also exists the option of pushing your own metrics in from the tests using a prom-push-gateway. Containers for all of these components can be found here.

For more accurate measurements, you may wish to set up prometheus external to kubernetes in an environment where it can access the major system components (api-server, controller-manager, scheduler). This is especially useful when attempting to gather metrics in a load-balanced api-server environment, because all api-servers can be analyzed independently as well as collectively. On startup, configuration file is passed to prometheus that specifies the endpoints that prometheus will scrape, as well as the sampling interval.

#prometheus.conf
job: {
  name: "kubernetes"
  scrape_interval: "1s"
  target_group: {
    # apiserver(s)
    target: "http://localhost:8080/metrics"
    # scheduler
    target: "http://localhost:10251/metrics"
    # controller-manager
    target: "http://localhost:10252/metrics"
  }
}

Once prometheus is scraping the kubernetes endpoints, that data can then be plotted using promdash, and alerts can be created against the assortment of metrics that kubernetes provides.

One More Thing

You should also know the testing conventions.

HAPPY TESTING!

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