Developer / Contributor Guide

We’re happy you’re interested in contributing to the Cilium project.

This guide will help you make sure you have an environment capable of testing changes to the Cilium source code, and that you understand the workflow of getting these changes reviewed and merged upstream.

If you’re interested in contributing, but don’t know where to start, then you should consider looking through the good-first-issue tag on the Cilium github issues page. Other small tasks are often tagged with the kind/microtask label.

Setting up a development environment

Developer requirements

You need to have the following tools available in order to effectively contribute to Cilium:

To run Cilium locally on VMs, you need:

Dependency Version / Commit ID Download Command
Vagrant >= 1.8.3 Vagrant Install Instructions
VirtualBox (if not using libvirt) >= 5.1.22 N/A (OS-specific)

Finally, in order to build the documentation, you should have Sphinx installed:

$ sudo pip install sphinx

You should start with the Getting Started Guides, which walks you through the set-up, such as installing Vagrant, getting the Cilium sources, and going through some Cilium basics.

Vagrant Setup

While the Getting Started Guides uses a Vagrantfile tuned for the basic walk through, the setup for the Vagrantfile in the root of the Cilium tree depends on a number of environment variables and network setup that are managed via contrib/vagrant/

Using the provided Vagrantfile

To bring up a Vagrant VM with Cilium plus dependencies installed, run:

$ contrib/vagrant/

This will create and run a vagrant VM based on the base box cilium/ubuntu-16.10. The box is currently available for the following providers:

  • libvirt
  • virtualbox


The following environment variables can be set to customize the VMs brought up by vagrant:

  • NWORKERS=n: Number of child nodes you want to start with the master, default 0.
  • RELOAD=1: Issue a vagrant reload instead of vagrant up
  • NFS=1: Use NFS for vagrant shared directories instead of rsync
  • K8S=1: Build & install kubernetes on the nodes
  • IPV4=1: Run Cilium with IPv4 enabled
  • VAGRANT_DEFAULT_PROVIDER={virtualbox | libvirt | …}

If you want to start the VM with cilium enabled with IPv4, with kubernetes installed and plus a worker, run:

$ IPV4=1 K8S=1 NWORKERS=1 contrib/vagrant/

If you have any issue with the provided vagrant box cilium/ubuntu-16.10 or need a different box format, you may build the box yourself using the packer scripts

Manual Installation

Alternatively you can import the vagrant box cilium/ubuntu-16.10 directly and manually install Cilium:

$ vagrant init cilium/ubuntu-16.10
$ vagrant up
$ vagrant ssh [...]
$ cd go/src/
$ make
$ sudo make install
$ sudo cp contrib/upstart/* /etc/init/
$ sudo usermod -a -G cilium vagrant
$ sudo service cilium restart


Your Cilium tree is mapped to the VM so that you do not need to keep copying files between your host and the VM. The default sync method is rsync, which only syncs when the VM is brought up, or when manually triggered (vagrant rsync command in the Cilium tree). You can also use NFS to access your Cilium tree from the VM by setting the environment variable NFS (mentioned above) before running the startup script (export NFS=1). Note that your host firewall have the NFS UDP ports open, the startup script will give the address and port details for this.


OSX file system is by default case insensitive, which can confuse git. At the writing of this Cilium repo has no file names that would be considered referring to the same file on a case insensitive file system. Regardless, it may be useful to create a disk image with a case sensitive file system for holding your git repos.


VirtualBox for OSX currently (version 5.1.22) always reports host-only networks’ prefix length as 64. Cilium needs this prefix to be 16, and the startup script will check for this. This check always fails when using VirtualBox on OSX, but it is safe to let the startup script to reset the prefix length to 16.

If for some reason, running of the provisioning script fails, you should bring the VM down before trying again:

$ vagrant halt

Unit Testing

Cilium uses the standard go test framework in combination with gocheck for richer testing functionality.

Running all tests

To run unit tests over the entire repository, run the following command in the project root directory:

$ make tests

Testing individual packages

It is possible to test individual packages by invoking go test directly. Before doing so, ensure that the kvstore dependency is met for testing. You can start a local etcd and consul instance by running:

$ make start-kvstores

You can then cd into the package subject to testing and invoke go test:

$ cd pkg/kvstore
$ go test

If you need more verbose output, you can pass in the -check.v and -check.vv arguments:

$ cd pkg/kvstore
$ go test -check.v -check.vv

Running individual tests

Due to the use of gocheck, the standard go test -run will not work, instead, the -check.f argument has to be specified:

$ go test -check.f TestParallelAllocation

Automatically run unit tests on code changes

The script contrib/shell/ contains some helpful bash functions to improve the feedback cycle between writing tests and seeing their results. If you’re writing unit tests in a particular package, the watchtest function will watch for changes in a directory and run the unit tests for that package any time the files change. For example, if writing unit tests in pkg/policy, run this in a terminal next to your editor:

$ . contrib/shell/
$ watchtest pkg/policy

This shell script depends on the inotify-tools package on Linux.

Development Cycle (Bash Script Framework)

The Vagrantfile in the Cilium repo root (hereon just Vagrantfile), always provisions Cilium build and install when the VM is started. After the initial build and install you can do further building and testing incrementally inside the VM. vagrant ssh takes you to the Cilium source tree directory (/home/vagrant/go/src/ by default, and the following commands assume that being your current directory.


Assuming you have synced (rsync) the source tree after you have made changes, or the tree is automatically in sync via NFS or guest additions folder sharing, you can issue a build as follows:

$ make

A successful build should be followed by running the unit tests:

$ make tests


After a successful build and test you can re-install Cilium by:

$ sudo -E make install

Restart Cilium service

To run the newly installed version of Cilium, restart the service:

$ sudo service cilium restart

You can verify the service and cilium-agent status by the following commands, respectively:

$ service cilium status
$ cilium status

Runtime Tests


Running the testsuite will modify the host environment. If you are using the default VM that might not be an issue, but if you are running bare-metal or a different VM the tests might fail or worst case remove possibly important configuration. Specifically, they are modifying the state and configuration of the system including, changes to iptables configuration, kernel configuration via sysctl, adding and removing networking devices, routes, etc. via iproute2. Please note this is not meant to be a complete summary, but a heads-up if you are planning to run the testsuite somewhere else than in the developer VM.

After the new version of Cilium is running, you should run the runtime tests:

$ sudo make runtime-tests

Development Cycle (Ginkgo Framework)


There is ongoing progress to move over to a more robust testing framework than a collection of Bash scripts for testing Cilium. Ginkgo has been chosen as this testing framework The tests in the test directory are built on top of Ginkgo. Ginkgo provides a rich framework for developing tests alongside the benefits of Golang (compilation-time checks, types, etc.). To get accustomsed to the basics of Ginkgo, we recommend reading the Ginkgo Getting-Started Guide , as well as running example tests to get a feel for the Ginkgo workflow.

These test scripts will invoke vagrant to create virtual machine(s) to run the tests. The tests make heavy use of the Ginkgo focus concept to determine which VMs are necessary to run particular tests. All test names must begin with one of the following prefixes:

  • Runtime: Test cilium in a runtime environment running on a single node.
  • K8s: Create a small multi-node kubernetes environment for testing features beyond a single host, and for testing kubernetes-specific features.
  • Nightly: sets up a multinode Kubernetes cluster to run scale, performance, and chaos testing for Cilium.

Running Tests

Running All Tests

Running all of the Ginkgo tests may take an hour or longer. To run all the ginkgo tests, invoke the make command as follows from the root of the cilium repository:

$ sudo make -C test/

The first time that this is invoked, the testsuite will pull the testing VMs and provision Cilium into them. This may take several minutes, depending on your internet connection speed. Subsequent runs of the test will reuse the image.

Running Runtime Tests

To run all of the runtime tests, execute the following command from the test directory:

ginkgo --focus="Runtime*" -noColor

Ginkgo searches for all tests in all subdirectories that are “named” beginning with the string “Runtime” and contain any characters after it. For instance, here is an example showing what tests will be ran using Ginkgo’s dryRun option:

$ ginkgo --focus="Runtime*" -noColor -dryRun
Running Suite: runtime
Random Seed: 1516125117
Will run 42 of 164 specs
RuntimePolicyEnforcement Policy Enforcement Always
  Always to Never with policy
RuntimePolicyEnforcement Policy Enforcement Always
  Always to Never without policy
RuntimePolicyEnforcement Policy Enforcement Never
  Container creation
RuntimePolicyEnforcement Policy Enforcement Never
  Never to default with policy
Ran 42 of 164 Specs in 0.002 seconds
SUCCESS! -- 0 Passed | 0 Failed | 0 Pending | 122 Skipped PASS

Ginkgo ran 1 suite in 1.830262168s
Test Suite Passed

The output has been truncated. For more information about this functionality, consult the aforementioned Ginkgo documentation.

Running Kubernetes Tests

To run all of the Kubernetes tests, run the following command from the test directory:

ginkgo --focus="K8s*" -noColor

Similar to the Runtime test suite, Ginkgo searches for all tests in all subdirectories that are “named” beginning with the string “K8s” and contain any characters after it.

The Kubernetes tests support the following Kubernetes versions:

  • 1.6
  • 1.7

By default, the Vagrant VMs are provisioned with Kubernetes 1.7. To run with any other supported version of Kubernetes, run the test suite with the following format:

K8S_VERSION=<version> ginkgo --focus="K8s*" -noColor

Running Nightly Tests

To run all of the Nightly tests, run the following command from the test directory:

ginkgo --focus="Nightly*"  -noColor

Similar to the other test suites, Ginkgo searches for all tests in all subdirectories that are “named” beginning with the string “Nightly” and contain any characters after it.

Nightly Testing Jenkins Setup

Nightly tests run once per day in the Cilium-Nightly-Tests Job. The configuration for this job is stored in Jenkinsfile.nightly.

To see the results of these tests, you can view the JUnit Report for an individual job:

  1. Click on the build number you wish to get test results from on the left hand side of the Cilium-Nightly-Tests Job.
  2. Click on ‘Test Results’ on the left side of the page to view the results from the build. This will give you a report of which tests passed and failed. You can click on each test to view its corresponding output created from Ginkgo.

Available CLI Options

For more advanced workflows, check the list of available custom options for the Cilium framework in the test/ directory and interact with ginkgo directly:

$ cd test/
$ ginkgo -- --help | grep -A 1 cilium
        On failure, hold the environment in its current state
        Provision Vagrant boxes and Cilium before running test (default true)
$ ginkgo --focus "Policies*" -- -cilium.holdEnvironment

For more information about other built-in options to Ginkgo, consult the Ginkgo documentation.

Running Specific Tests Within a Test Suite

If you want to run one specified test, there are a few options:

  • By modifying code: add the prefix “FIt” on the test you want to run; this marks the test as focused. Ginkgo will skip other tests and will only run the “focused” test. For more information, consult the Focused Specs documentation from Ginkgo.
It("Example test", func(){

FIt("Example focussed test", func(){
  • From the command line: specify a more granular focus if you want to focus on, say, L7 tests:
ginkgo --focus "Run*" --focus "L7 "

This will focus on tests prefixed with “Run*”, and within that focus, run any test that starts with “L7”.

Test Reports

The Cilium Ginkgo framework formulates JUnit reports for each test. The following files currently are generated depending upon the test suite that is ran:

  • runtime.xml
  • K8s.xml

Best Practices for Writing Tests

  • Provide informative output to console during a test using the By construct. This helps with debugging and gives those who did not write the test a good idea of what is going on. The lower the barrier of entry is for understanding tests, the better our tests will be!
  • Leave the testing environment in the same state that it was in when the test started by deleting resources, resetting configuration, etc.
  • Gather logs in the case that a test fails. If a test fails while running on Jenkins, a postmortem needs to be done to analyze why. So, dumping logs to a location where Jenkins can pick them up is of the highest imperative. Use the following code in an AfterEach for all tests:
if CurrentGinkgoTestDescription().Failed {


Ginkgo provides to us different ways of debugging. In case that you want to see all the logs messages in the console you can run the test in verbose mode using the option -v:

ginkgo --focus "Runtime*" -v

In case that the verbose mode is not enough, you can retrieve all run commands and their output in the report directory (./test/test-results). Each test creates a new folder, which contains a file called log where all information is saved, in case of a failing test an exhaustive data will be added.

$ head test/test_results/RuntimeKafkaKafkaPolicyIngress/logs
level=info msg=Starting testName=RuntimeKafka
level=info msg="Vagrant: running command \"vagrant ssh-config runtime\""
cmd: "sudo cilium status" exitCode: 0
 KVStore:            Ok         Consul:
ContainerRuntime:   Ok
Kubernetes:         Disabled
Kubernetes APIs:    [""]
Cilium:             Ok   OK
NodeMonitor:        Disabled
Allocated IPv4 addresses:

Further Assistance

Have a question about how the tests work or want to chat more about improving the testing infrastructure for Cilium? Hop on over to the testing channel on Slack.

Building Documentation

The documentation has several dependencies which can be installed using pip:

$ pip install -r Documentation/requirements.txt

Whenever making changes to Cilium documentation you should check that you did not introduce any new warnings or errors, and also check that your changes look as you intended. To do this you can build the docs:

$ make -C Documentation html

After this you can browse the updated docs as HTML starting at Documentation\_build\html\index.html.

Alternatively you can use a Docker container to build the pages:

$ make render-docs

This builds the docs in a container and builds and starts a web server with your document changes.

Now the documentation page should be browsable on http://localhost:8080.

Debugging datapath code


See also the user troubleshooting guide in the section Troubleshooting.

One of the most common issues when developing datapath code is that the BPF code cannot be loaded into the kernel. This frequently manifests as the endpoints appearing in the “not-ready” state and never switching out of it:

$ cilium endpoint list
ENDPOINT   POLICY        IDENTITY   LABELS (source:key[=value])   IPv6                     IPv4            STATUS
48896      Disabled      266        container:id.server           fd02::c0a8:210b:0:bf00     not-ready
60670      Disabled      267        container:id.client           fd02::c0a8:210b:0:ecfe   not-ready

Running cilium endpoint get for one of the endpoints will provide a description of known state about it, which includes BPF verification logs.

The files under /var/run/cilium/state provide context about how the BPF datapath is managed and set up. The .log files will describe the BPF requirements and features that Cilium detected and used to generate the BPF programs. The .h files describe specific configurations used for BPF program compilation. The numbered directories describe endpoint-specific state, including header configuration files and BPF binaries.

# for log in /var/run/cilium/state/*.log; do echo "cat $log"; cat $log; done
cat /var/run/cilium/state/bpf_features.log
BPF/probes: CONFIG_CGROUP_BPF=y is not in kernel configuration
BPF/probes: CONFIG_LWTUNNEL_BPF=y is not in kernel configuration
HAVE_LPM_MAP_TYPE: Your kernel doesn't support LPM trie maps for BPF, thus disabling CIDR policies. Recommendation is to run 4.11+ kernels.
HAVE_LRU_MAP_TYPE: Your kernel doesn't support LRU maps for BPF, thus switching back to using hash table for the cilium connection tracker. Recommendation is to run 4.10+ kernels.

Current BPF map state for particular programs is held under /sys/fs/bpf/, and the bpf-map utility can be useful for debugging what is going on inside them, for example:

# ls /sys/fs/bpf/tc/globals/
cilium_calls_15124  cilium_calls_48896        cilium_ct4_global       cilium_lb4_rr_seq       cilium_lb6_services  cilium_policy_25729  cilium_policy_60670       cilium_proxy6
cilium_calls_25729  cilium_calls_60670        cilium_ct6_global       cilium_lb4_services     cilium_lxc           cilium_policy_3978   cilium_policy_reserved_1  cilium_reserved_policy
cilium_calls_3978   cilium_calls_netdev_ns_1  cilium_events           cilium_lb6_reverse_nat  cilium_policy        cilium_policy_4314   cilium_policy_reserved_2  tunnel_endpoint_map
cilium_calls_4314   cilium_calls_overlay_2    cilium_lb4_reverse_nat  cilium_lb6_rr_seq       cilium_policy_15124  cilium_policy_48896  cilium_proxy4
# bpf-map info /sys/fs/bpf/tc/globals/cilium_policy_15124
Type:           Hash
Key size:       8
Value size:     24
Max entries:    1024
Flags:          0x0
# bpf-map dump /sys/fs/bpf/tc/globals/cilium_policy_15124
00000000  6a 01 00 00 82 23 06 00                           |j....#..|
00000000  01 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000010  00 00 00 00 00 00 00 00                           |........|

Submitting a pull request

Contributions may be submitted in the form of pull requests against the github repository at:

Before hitting the submit button, please make sure that the following requirements have been met:

  • The pull request and all corresponding commits have been equipped with a well written commit message which explains the reasoning and details of the change.
  • You have added unit and/or runtime tests where feasible.
  • You have tested the changes and checked for regressions by running the existing testsuite against your changes. See the Runtime Tests section for additional details.
  • You have signed off on your commits, see the section “Developer’s Certificate of Origin” for more details.

Triggering Pull-Request Builds With Jenkins

To ensure that build resources are used judiciously, builds on Jenkins are manually triggered via comments on each pull-request that contain “trigger-phrases”. Only members of the Cilium GitHub organization are allowed to trigger these jobs. Refer to the table below for information regarding which phrase triggers which build, which build is required for a pull-request to be merged, etc. Each linked job contains a description illustrating which subset of tests the job runs.

Jenkins Job Trigger Phrase Required To Merge?
Cilium-Bash-Tests test-me-please Yes
Cilium-Ginkgo-Tests test-me-please Yes
Cilium-Ginkgo-Tests-All test-all-ginkgo No
Cilium-Nightly-Tests-PR test-nightly No

CI / Testing environment

Logging into VM running tests

  1. If you have access to credentials for Jenkins, log into the Jenkins slave running the test workload
  2. Identify the vagrant box running the specific test
$ vagrant global-status
id       name                          provider   state   directory
6e68c6c  k8s1-build-PR-1588-6          virtualbox running /root/jenkins/workspace/cilium_cilium_PR-1588-CWL743UTZEF6CPEZCNXQVSZVEW32FR3CMGKGY6667CU7X43AAZ4Q/tests/k8s
ec5962a  cilium-master-build-PR-1588-6 virtualbox running /root/jenkins/workspace/cilium_cilium_PR-1588-CWL743UTZEF6CPEZCNXQVSZVEW32FR3CMGKGY6667CU7X43AAZ4Q
bfaffaa  k8s2-build-PR-1588-6          virtualbox running /root/jenkins/workspace/cilium_cilium_PR-1588-CWL743UTZEF6CPEZCNXQVSZVEW32FR3CMGKGY6667CU7X43AAZ4Q/tests/k8s
3fa346c  k8s1-build-PR-1588-7          virtualbox running /root/jenkins/workspace/cilium_cilium_PR-1588-CWL743UTZEF6CPEZCNXQVSZVEW32FR3CMGKGY6667CU7X43AAZ4Q@2/tests/k8s
b7ded3c  cilium-master-build-PR-1588-7 virtualbox running /root/jenkins/workspace/cilium_cilium_PR-1588-CWL743UTZEF6CPEZCNXQVSZVEW32FR3CMGKGY6667CU7X43AAZ4Q@2
  1. Log into the specific VM
$ JOB_BASE_NAME=PR-1588 BUILD_NUMBER=6 vagrant ssh 6e68c6c

Release Process

Cilium schedules a major release every 3 months. Each major release is performed by incrementing the Y in the version format X.Y.0. The group of committers can decide to increment X instead to mark major milestones in which case Y is reset to 0.

The following steps are performed to publish a release:

  1. The master branch is set to the version X.Y.90 at all times. This ensures that a development snapshot is considered more recent than a stable release at all times.
  2. The committers can agree on a series of release candidates which will be tagged vX.Y-rcN in the master branch.
  3. The committers declare the master branch ready for the release and fork the master branch into a release branch vX.Y+1.0.
  4. The first commit in the release branch is to change the version to X.Y+1.0.
  5. The next commit goes into the master branch and sets the version to X.Y+1.90 to ensure that the master branch will be considered more recent than any stable release of the major release that is about to be published.

Stable releases

The committers can nominate commits pushed to the master as stable release candidates in which case they will be backported to previous release branches. Upon necessity, stable releases are published with the version X.Y.Z+1.

Criteria for the inclusion into stable release branches are:

  • Security relevant fixes
  • Major bugfixes relevant to the correct operation of Cilium

Steps to release

  1. Create a new automated build for cilium/cilium container image tag with the full Cilium version on Point the automated build to the development branch of the to be released version. This will ensure that the to be released version always has a corresponding container image tag assigned.
  2. Update the AUTHORS file by running make update-authors
  3. Update the cilium_version and cilium_tag variables in examples/getting-started/Vagrantfile
  4. Review all merged PRs and add release-note/* labels as necessary. A useful query here is is:pr is:merged merged:>=2017-12-16
  5. Generate the release notes by running. git checkout master, cd contrib/release/, GITHUB_TOKEN=xxxx ./relnotes --markdown-file=~/NEWS.rst v1.0.0-rc2..
  6. Manually merge the generated file ~/NEWS.rst into NEWS.rst in the Cilium repository and add the title section with the corresponding release date.
  7. Create a pull request with all changes above, get it merged into the development branch of the to be released version.
  8. If the release is a new minor version which will receive backports, then create a git branch with the name vX.Y. Push this branch to GitHub and protect the branch so it can’t be pushed to directly to.
  9. Tag the release with the full version string vX.Y.Z and push the tag to the git repository.
  10. Build all binaries and push them to S3 using contrib/release/uploadrev. See the README in the contrib/release directory for more information.
  11. Create a GitHub release and include the release notes as well as links to the binaries.

Developer’s Certificate of Origin

To improve tracking of who did what, we’ve introduced a “sign-off” procedure.

The sign-off is a simple line at the end of the explanation for the commit, which certifies that you wrote it or otherwise have the right to pass it on as open-source work. The rules are pretty simple: if you can certify the below:

Developer Certificate of Origin
Version 1.1

Copyright (C) 2004, 2006 The Linux Foundation and its contributors.
1 Letterman Drive
Suite D4700
San Francisco, CA, 94129

Everyone is permitted to copy and distribute verbatim copies of this
license document, but changing it is not allowed.

Developer's Certificate of Origin 1.1

By making a contribution to this project, I certify that:

(a) The contribution was created in whole or in part by me and I
    have the right to submit it under the open source license
    indicated in the file; or

(b) The contribution is based upon previous work that, to the best
    of my knowledge, is covered under an appropriate open source
    license and I have the right under that license to submit that
    work with modifications, whether created in whole or in part
    by me, under the same open source license (unless I am
    permitted to submit under a different license), as indicated
    in the file; or

(c) The contribution was provided directly to me by some other
    person who certified (a), (b) or (c) and I have not modified

(d) I understand and agree that this project and the contribution
    are public and that a record of the contribution (including all
    personal information I submit with it, including my sign-off) is
    maintained indefinitely and may be redistributed consistent with
    this project or the open source license(s) involved.

then you just add a line saying:

Signed-off-by: Random J Developer <>

Use your real name (sorry, no pseudonyms or anonymous contributions.)