Development Setup

This page provides an overview of different methods for efficient development on Cilium. Depending on your needs, you can choose the most suitable method.

Quick Start

If you’re in a hurry, here are the essential steps to get started:

On Linux:

make kind - Provisions a Kind cluster.
make kind-install-cilium-fast - Installs Cilium on the Kind cluster.
make kind-image-fast - Builds Cilium and deploys it.

On any OS:

make kind - Provisions a Kind cluster.
make kind-image - Builds Docker images.
make kind-install-cilium - Installs Cilium on the Kind cluster.

Detailed Instructions

Depending on your specific development environment and requirements, you can follow the detailed instructions below.

Verifying Your Development Setup

Assuming you have Go installed, you can quickly verify many elements of your development setup by running the following command:

$ make dev-doctor

Depending on your end-goal, not all dependencies listed are required to develop on Cilium. For example, “Ginkgo” is not required if you want to improve our documentation. Thus, do not consider that you need to have all tools installed.

Version Requirements

If using these tools, you need to have the following versions from them in order to effectively contribute to Cilium:

Dependency	Version / Commit ID	Download Command
git	latest	N/A (OS-specific)
clang	>= 10.0 (latest recommended)	N/A (OS-specific)
llvm	>= 10.0 (latest recommended)	N/A (OS-specific)
go	1.20	N/A (OS-specific)
ginkgo	>= 1.4.0 and < 2.0.0	`go install github.com/onsi/ginkgo/ginkgo@v1.16.5`
ginkgo	>= 1.4.0 and < 2.0.0	`go install github.com/onsi/ginkgo/ginkgo@v1.16.5`
golangci-lint	>= v1.27	N/A (OS-specific)
golangci-lint	>= v1.27	N/A (OS-specific)
cfssl	>= v1.6.0	`go install github.com/cloudflare/cfssl/cmd/cfssl@latest`
cfssl	>= v1.6.0	`go install github.com/cloudflare/cfssl/cmd/cfssl@latest`
cfssljson	>= v1.6.0	`go install github.com/cloudflare/cfssl/cmd/cfssljson@latest`
cfssljson	>= v1.6.0
Docker	OS-Dependent	N/A (OS-specific)
Docker	OS-Dependent	N/A (OS-specific)
Docker-Compose	OS-Dependent	N/A (OS-specific)
Docker-Compose	OS-Dependent	N/A (OS-specific)
python3-pip	latest	N/A (OS-specific)
python3-pip	latest	N/A (OS-specific)
helm	>= v3.6.0	N/A (OS-specific)
helm	>= v3.6.0	N/A (OS-specific)

For Integration Testing, you will need to run docker without privileges. You can usually achieve this by adding your current user to the docker group.

Finally, in order to run Cilium locally on VMs, you need:

Dependency	Version / Commit ID	Download Command
Vagrant	>= 2.0	Vagrant Install Instructions
VirtualBox	>= 5.2	N/A (OS-specific)

Kind-based Setup (preferred)

You can find the setup for a kind environment in contrib/scripts/kind.sh. This setup doesn’t require any VMs and/or VirtualBox on Linux, but does require Docker for Mac for Mac OS.

Makefile targets automate the task of spinning up an environment:

make kind: Creates a kind cluster based on the configuration passed in. For more information, see Configuration for clusters.
make kind-down: Tears down and deletes the cluster.

Depending on your environment you can build Cilium by using the following makefile targets:

For Linux and Mac OS

Makefile targets automate building Cilium images:

make kind-image: Builds all Cilium images and loads them into the cluster.
make kind-image-agent: Builds only the Cilium Agent image and loads it into the cluster.
make kind-image-operator: Builds only the Cilium Operator (generic) image and loads it into the cluster.
make kind-image-debug: Builds all Cilium images with optimizations disabled and dlv embedded for live debugging enabled and loads the images into the cluster.
make kind-install-cilium: Installs Cilium into the cluster using the Cilium CLI.

The preceding list includes the most used commands for convenience. For more targets, see the Makefile (or simply run make help).

For Linux only - with shorter development workflow time

On Linux environments, or on environments where you can compile and run Cilium, it is possible to use “fast” targets. These fast targets will build Cilium in the local environment and mount that binary, as well the bpf source code, in an pre-existing running Cilium container.

make kind-install-cilium-fast: Installs Cilium into the cluster using the Cilium CLI with the volume mounts defined.
make kind-image-fast: Builds all Cilium binaries and loads them into all kind clusters available in the host.

Configuration for clusters

make kind takes a few environment variables to modify the configuration of the clusters it creates. The following parameters are the most commonly used:

CONTROLPLANES: How many control-plane nodes are created.
WORKERS: How many worker nodes are created.
CLUSTER_NAME: The name of the Kubernetes cluster.
IMAGE: The image for kind, for example: kindest/node:v1.11.10.
KUBEPROXY_MODE: Pass directly as kubeProxyMode to the kind configuration Custom Resource Definition (CRD).

For more environment variables, see contrib/scripts/kind.sh.

Vagrant Setup

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/start.sh.

Option 1 - Using the Provided Vagrantfiles

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

$ contrib/vagrant/start.sh [vm_name]

This will create and run a vagrant VM based on the base box cilium/ubuntu. The vm_name argument is optional and allows you to add new nodes to an existing cluster. For example, to add a net-next VM to a one-node cluster:

$ K8S=1 NWORKERS=1 NETNEXT=1 ./contrib/vagrant/start.sh k8s2+

Cilium Vagrantfiles look for a file .devvmrc in the root of your Cilium repository. This file is ignored for Git, so it does not exist by default. If this file exists and is executable, it will be executed in the beginning of the VM bootstrap. This allows you to automatically customize the new VM, e.g., with your personal Git configuration. You may also want to add any local entries you need in /etc/hosts, etc.

For example, you could have something like this in your .devvmrc:

#!/usr/bin/env bash

git config --global user.name "Firstname Lastname"
git config --global user.email developer@company.com

sudo tee -a /etc/hosts <<EOF
192.168.99.99 nas
EOF

Remember to make the script executable (chmod +x .devvmrc). When successfully running, the VM bootstrap shows a message like this right after the shared folders have been set up:

runtime: ----------------------------------------------------------------
runtime: Executing .devvmrc

The box is currently available for the following providers:

virtualbox

Configuration Options

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, useful to resume halted VMs.
NO_PROVISION=1: Avoid provisioning Cilium inside the VM. Supports quick restart without recompiling all of Cilium.
K8S=1: Build & install kubernetes on the nodes. k8s1 is the master node, which contains both master components: etcd, kube-controller-manager, kube-scheduler, kube-apiserver, and node components: kubelet, kube-proxy, kubectl and Cilium. When used in combination with NWORKERS=1 a second node is created, where k8s2 will be a kubernetes node, which contains: kubelet, kube-proxy, kubectl and cilium.
NETNEXT=1: Run with net-next kernel.
SERVER_BOX and SERVER_VERSION: Run with a specified vagrant box. See: vagrant_box_defaults.rb for the supported versions.
IPV4=1: Run Cilium with IPv4 enabled.
RUNTIME=x: Sets up the container runtime to be used inside a kubernetes cluster. Valid options are: containerd and crio. If not set, it defaults to containerd.
VM_SET_PROXY=https://127.0.0.1:80/ Sets up VM’s https_proxy.
INSTALL=1: Restarts the installation of Cilium, Kubernetes, etc. Only useful when the installation was interrupted.
MAKECLEAN=1: Execute make clean before building cilium in the VM.
NO_BUILD=1: Does not run the “build” provision step in the VM. Assumes the developer had previously executed make build before provisioning the VM.
SHARE_PARENT: Share the parent of your Cilium directory instead. This requires your Cilium directory to be named cilium, but will also make all other files and folders in the parent directory available for the VM. This is useful to share all the cilium repos to the VM, for example.
USER_MOUNTS: Additional mounts for the VM in a comma-separated list of mount specifications. Each mount specification can be simply a directory name relative to the home directory, or include a ‘=’ character separating the destination mount point from the host directory. For example:
- USER_MOUNTS=foo
  - Mounts host directory ~/foo as /home/vagrant/foo
- USER_MOUNTS=foo,/tmp/bar=/tmp/bar
  - Mounts host directory ~/foo as /home/vagrant/foo in the VM, and host directory /tmp/bar as /tmp/bar in the VM.
VM_MEMORY: Memory in megabytes to configure for the VMs (default 4096).
VM_CPUS: Number of CPUs to configure for the VMs (default 2).

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

$ RUNTIME=containerd K8S=1 NWORKERS=1 contrib/vagrant/start.sh

If you want to get VM status, run:

$ RUNTIME=containerd K8S=1 NWORKERS=1 vagrant status

If you want to connect to the Kubernetes cluster running inside the developer VM via kubectl from your host machine, set KUBECONFIG environment variable to include new kubeconfig file:

$ export KUBECONFIG=$KUBECONFIG:${PATH_TO_CILIUM_REPO}/vagrant.kubeconfig

where PATH_TO_CILIUM_REPO is the path of your local clone of the Cilium git repository. Also add 127.0.0.1 k8s1 to your hosts file.

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

Launch CI VMs

The test directory also contains a Vagrantfile that can be used to bring up the CI VM images that will cache a Vagrant box locally (in test/.vagrant/ that prepulls all the docker images needed for the CI tests. Unfortunately some of the options are different from the main Vagrantfile, for example:

K8S_NODES determines the total number of k8s nodes, including the master. - NWORKERS is not supported.
USER_MOUNTS is not available.

To start a local k8s 1.18 cluster with one CI VM locally, run:

$ cd test
$ K8S_VERSION=1.18 K8S_NODES=1 ./vagrant-local-start.sh

This will first destroy any CI VMs you may have running on the current K8S_VERSION, and then create a local Vagrant box if not already created. This can take some time.

VM preloading can be turned off by exporting PRELOAD_VM=false. You can run make clean in test to delete the cached vagrant box.

To start the CI runtime VM locally, run:

$ cd test
$ ./vagrant-local-start-runtime.sh

The runtime VM is connected to the same private VirtualBox network as the local CI k8s nodes.

The runtime VM uses the same cached box as the k8s nodes, but does not start K8s, but runs Cilium as a systemd service.

Option 2 - Manual Installation

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

$ vagrant init cilium/ubuntu
$ vagrant up
$ vagrant ssh [...]
$ go get github.com/cilium/cilium
$ cd go/src/github.com/cilium/cilium/
$ make
$ sudo make install
$ sudo mkdir -p /etc/sysconfig/
$ sudo cp contrib/systemd/cilium.service /etc/systemd/system/
$ sudo cp contrib/systemd/cilium-docker.service /etc/systemd/system/
$ sudo cp contrib/systemd/cilium-consul.service /etc/systemd/system/
$ sudo cp contrib/systemd/cilium  /etc/sysconfig/cilium
$ sudo usermod -a -G cilium vagrant
$ sudo systemctl enable cilium-docker
$ sudo systemctl restart cilium-docker
$ sudo systemctl enable cilium-consul
$ sudo systemctl restart cilium-consul
$ sudo systemctl enable cilium
$ sudo systemctl restart cilium

Notes

Your Cilium tree is mapped to the VM so that you do not need to keep manually copying files between your host and the VM. Folders are by default synced automatically using VirtualBox Shared Folders with NFS. Note that your host firewall must have a variety of ports open. The Vagrantfile will inform you of the configuration of these addresses and ports to enable NFS.

Note

Although providing a Developer preview for macOS/arm64 (M1/M2) hosts, Oracle is not going to offer official support for ARM64 on Mac. As of VirtualBox 7.0.6 the developer preview is not working with the Cilium Vagrant Setup.

Note

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.

Note

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.

Note

Make sure your host NFS configuration is setup to use tcp:

# cat /etc/nfs.conf
...
[nfsd]
# grace-time=90
tcp=y
# vers2=n
# vers3=y
...

Note

Linux 5.18 on newer Intel CPUs which support Intel CET (11th and 12th gen) has a bug that prevents the VMs from starting. If you see a stacktrace with kernel BUG at arch/x86/kernel/traps.c and traps: Missing ENDBR messages in dmesg, that means you are affected. A workaround for now is to pass ibt=off to the kernel command line.

Note

VirtualBox for Ubuntu desktop might have network issues after suspending and resuming the host OS (typically by closing and re-opening the laptop lid). If the cilium status keeps showing unreachable from nodes but reachable from endpoints, you could hit this. Run the following code on each VM to rebuild routing and neighbor entries:

# assume we deployed the cluster with "NWORKERS=1" and "NETNEXT=1"

# fetch ipv6 addresses
$ ipv6_k8s1=$(vagrant ssh k8s1+ -c 'ip -6 --br a sh enp0s9 scope global' | awk '{print $3}')
$ ipv6_k8s2=$(vagrant ssh k8s2+ -c 'ip -6 --br a sh enp0s9 scope global' | awk '{print $3}')

# fetch mac addresses
$ mac_k8s1=$(vagrant ssh k8s1+ -c 'ip --br l sh enp0s9' | awk '{print $3}')
$ mac_k8s2=$(vagrant ssh k8s2+ -c 'ip --br l sh enp0s9' | awk '{print $3}')

# add route
$ vagrant ssh k8s1+ -c 'ip -6 r a fd00::/16 dev enp0s9'
$ vagrant ssh k8s2+ -c 'ip -6 r a fd00::/16 dev enp0s9'

# add neighbor
$ vagrant ssh k8s1+ -c "ip n r $ipv6_k8s2 dev enp0s9 lladdr $mac_k8s2 nud reachable"
$ vagrant ssh k8s2+ -c "ip n r $ipv6_k8s1 dev enp0s9 lladdr $mac_k8s1 nud reachable"

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

$ vagrant halt

Local Development in Vagrant Box

See Development Setup for information on how to setup the development environment.

When the development VM is provisioned, it builds and installs Cilium. 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/github.com/cilium/cilium) by default, and the following commands assume that you are working within that directory.

Build Cilium

When you make changes, the tree is automatically kept in sync via NFS. You can issue a build as follows:

$ make

Install to dev environment

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 systemctl restart cilium

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

$ sudo systemctl status cilium
$ cilium status

Simple smoke-test with HTTP policies

After Cilium daemon has been restarted, you may want to verify that it boots up properly and integration with Envoy still works. To do this, run this bash test script:

$ test/envoy/envoy-smoke-test.sh

This test launches three docker containers (one curl client, and two httpd servers) and tests various simple network policies with them. These containers should be automatically removed when the test finishes.

Making Changes

Make sure the main branch of your fork is up-to-date:
```
git fetch upstream main:main
```
Create a PR branch with a descriptive name, branching from main:
```
git switch -c pr/changes-to-something main
```
Make the changes you want.
Separate the changes into logical commits.
1. Describe the changes in the commit messages. Focus on answering the question why the change is required and document anything that might be unexpected.
2. If any description is required to understand your code changes, then those instructions should be code comments instead of statements in the commit description.
Note

For submitting PRs, all commits need be to signed off (git commit -s). See the section Developer’s Certificate of Origin.
Make sure your changes meet the following criteria:
1. New code is covered by Integration Testing.
2. End to end integration / runtime tests have been extended or added. If not required, mention in the commit message what existing test covers the new code.
3. Follow-up commits are squashed together nicely. Commits should separate logical chunks of code and not represent a chronological list of changes.
Run git diff --check to catch obvious white space violations
Run make to build your changes. This will also run make lint and error out on any golang linting errors. The rules are configured in .golangci.yaml
Run make -C bpf checkpatch to validate against your changes coding style and commit messages.
See Integration Testing on how to run integration tests.
See End-To-End Connectivity Testing for information how to run the end to end integration tests
If you are making documentation changes, you can generate documentation files and serve them locally on http://localhost:9081 by running make render-docs. This make target works both inside and outside the Vagrant VM, assuming that docker is running in the environment.

Add/update a golang dependency

Let’s assume we want to add github.com/containernetworking/cni version v0.5.2:

$ go get github.com/containernetworking/cni@v0.5.2
$ go mod tidy
$ go mod vendor
$ git add go.mod go.sum vendor/

For a first run, it can take a while as it will download all dependencies to your local cache but the remaining runs will be faster.

Updating k8s is a special case which requires updating k8s libraries in a single change:

$ # get the tag we are updating (for example ``v0.17.3`` corresponds to k8s ``v1.17.3``)
$ # open go.mod and search and replace all ``v0.17.3`` with the version
$ # that we are trying to upgrade with, for example: ``v0.17.4``.
$ # Close the file and run:
$ go mod tidy
$ go mod vendor
$ make generate-k8s-api
$ git add go.mod go.sum vendor/

Add/update a new Kubernetes version

Let’s assume we want to add a new Kubernetes version v1.19.0:

Follow the above instructions to update the Kubernetes libraries.
Follow the next instructions depending on if it is a minor update or a patch update.

Minor version

Check if it is possible to remove the last supported Kubernetes version from Kubernetes Compatibility, Requirements, Testing matrix, Running Kubernetes Tests, Integration with Istio and add the new Kubernetes version to that list.
If the minimal supported version changed, leave a note in the upgrade guide stating the minimal supported Kubernetes version.
If the minimal supported version changed, search over the code, more likely under pkg/k8s, if there is code that can be removed which specifically exists for the compatibility of the previous Kubernetes minimal version supported.
If the minimal supported version changed, update the field MinimalVersionConstraint in pkg/k8s/version/version.go
Sync all “slim” types by following the instructions in pkg/k8s/slim/README.md. The overall goal is to update changed fields or deprecated fields from the upstream code. New functions / fields / structs added in upstream that are not used in Cilium, can be removed.
Make sure the workflows used on all PRs are running with the new Kubernetes version by default. Make sure the files contributing/testing/{ci,e2e}.rst are up to date with these changes.
Update documentation files: - Documentation/contributing/testing/e2e.rst - Documentation/network/kubernetes/compatibility.rst - Documentation/network/kubernetes/requirements.rst
Update the Kubernetes version with the newer version in test/Vagrantfile, test/test_suite_test.go and test/vagrant-local-start.sh.
Add the new coredns files specific for the Kubernetes version, for 1.19 is test/provision/manifest/1.19. The coredns deployment files can be found upstream as mentioned in the previous k8s version coredns files. Perform a diff with the previous versions to check which changes are required for our CI and which changes were added upstream.
If necessary, update the coredns files from contrib/vagrant/deployments with newer the file versions from upstream.
Update the constraint in the function getK8sSupportedConstraints, that exists in the test/helpers/utils.go, with the new Kubernetes version that Cilium supports. It is possible that a new IsCiliumV1* var in that file is required as well.
Add the new version in test/provision/k8s_install.sh, if it is an RC install it using binaries.
Bump the kindest/node version in all of kind’s config files (for example, .github/kind-config*).
Bump the Kubernetes version in contrib/vagrant/scripts/helpers.bash and the etcd version to the latest version.
Run ./contrib/scripts/check-k8s-code-gen.sh
Run go mod vendor && go mod tidy
Run ./contrib/scripts/check-k8s-code-gen.sh (again)
Run make -C Documentation update-helm-values
Compile the code locally to make sure all the library updates didn’t removed any used code.
Provision a new dev VM to check if the provisioning scripts work correctly with the new k8s version.
Run git add vendor/ test/provision/manifest/ Documentation/ && git commit -sam "Update k8s tests and libraries to v1.28.0-rc.0"
Submit all your changes into a new PR.
Ensure that the target CI workflows are running and passing after updating the target k8s versions in the GitHub action workflows.
Once CI is green and PR has been merged, ping the CI team again so that they update the Cilium CI matrix, .github/maintainers-little-helper.yaml, and GitHub required PR checks accordingly.

Patch version

Bump the Kubernetes version in contrib/vagrant/scripts/helpers.bash.
Bump the Kubernetes version in test/provision/k8s_install.sh.
Submit all your changes into a new PR.

Making changes to the Helm chart

The Helm chart is located in the install/kubernetes directory. The values.yaml.tmpl file contains the values for the Helm chart which are being used into the values.yaml file.

To prepare your changes you need to run the make scripts for the chart:

$ make -C install/kubernetes

This does all needed steps in one command. Your change to the Helm chart is now ready to be submitted!

You can also run them one by one using the individual targets below.

When updating or adding a value they can be synced to the values.yaml file by running the following command:

$ make -C install/kubernetes cilium/values.yaml

Before submitting the changes the README.md file needs to be updated, this can be done using the docs target:

$ make -C install/kubernetes docs

At last you might want to check the chart using the lint target:

$ make -C install/kubernetes lint

Optional: Docker and IPv6

Note that these instructions are useful to you if you care about having IPv6 addresses for your Docker containers.

If you’d like IPv6 addresses, you will need to follow these steps:

Edit /etc/docker/daemon.json and set the ipv6 key to true.

{
  "ipv6": true
}

If that doesn’t work alone, try assigning a fixed range. Many people have reported trouble with IPv6 and Docker. Source here.

{
  "ipv6": true,
  "fixed-cidr-v6": "2001:db8:1::/64"
}

And then:

ip -6 route add 2001:db8:1::/64 dev docker0
sysctl net.ipv6.conf.default.forwarding=1
sysctl net.ipv6.conf.all.forwarding=1

Restart the docker daemon to pick up the new configuration.

The new command for creating a network managed by Cilium:

$ docker network create --ipv6 --driver cilium --ipam-driver cilium cilium-net

Now new containers will have an IPv6 address assigned to them.

Debugging

Datapath code

The tool cilium monitor can also be used to retrieve debugging information from the eBPF based datapath. To enable all log messages:

Start the cilium-agent with --debug-verbose=datapath, or
Run cilium config debug=true debugLB=true from an already running agent.

These options enable logging functions in the datapath: cilium_dbg(), cilium_dbg_lb() and printk().

Note

The printk() logging function is used by the developer to debug the datapath outside of the cilium monitor. In this case, bpftool prog tracelog can be used to retrieve debugging information from the eBPF based datapath. Both cilium_dbg() and printk() functions are available from the bpf/lib/dbg.h header file.

The image below shows the options that could be used as startup options by cilium-agent (see upper blue box) or could be changed at runtime by running cilium config <option(s)> for an already running agent (see lower blue box). Along with each option, there is one or more logging function associated with it: cilium_dbg() and printk(), for DEBUG and cilium_dbg_lb() for DEBUG_LB.

Note

If you need to enable the LB_DEBUG for an already running agent by running cilium config debugLB=true, you must pass the option debug=true along.

Debugging of an individual endpoint can be enabled by running cilium endpoint config ID debug=true. Running cilium monitor -v will print the normal form of monitor output along with debug messages:

$ cilium endpoint config 731 debug=true
Endpoint 731 configuration updated successfully
$ cilium monitor -v
Press Ctrl-C to quit
level=info msg="Initializing dissection cache..." subsys=monitor
<- endpoint 745 flow 0x6851276 identity 4->0 state new ifindex 0 orig-ip 0.0.0.0: 8e:3c:a3:67:cc:1e -> 16:f9:cd:dc:87:e5 ARP
-> lxc_health: 16:f9:cd:dc:87:e5 -> 8e:3c:a3:67:cc:1e ARP
CPU 00: MARK 0xbbe3d555 FROM 0 DEBUG: Inheriting identity=1 from stack
<- host flow 0xbbe3d555 identity 1->0 state new ifindex 0 orig-ip 0.0.0.0: 10.11.251.76:57896 -> 10.11.166.21:4240 tcp ACK
CPU 00: MARK 0xbbe3d555 FROM 0 DEBUG: Successfully mapped addr=10.11.251.76 to identity=1
CPU 00: MARK 0xbbe3d555 FROM 0 DEBUG: Attempting local delivery for container id 745 from seclabel 1
CPU 00: MARK 0xbbe3d555 FROM 745 DEBUG: Conntrack lookup 1/2: src=10.11.251.76:57896 dst=10.11.166.21:4240
CPU 00: MARK 0xbbe3d555 FROM 745 DEBUG: Conntrack lookup 2/2: nexthdr=6 flags=0
CPU 00: MARK 0xbbe3d555 FROM 745 DEBUG: CT entry found lifetime=21925, revnat=0
CPU 00: MARK 0xbbe3d555 FROM 745 DEBUG: CT verdict: Established, revnat=0
-> endpoint 745 flow 0xbbe3d555 identity 1->4 state established ifindex lxc_health orig-ip 10.11.251.76: 10.11.251.76:57896 -> 10.11.166.21:4240 tcp ACK

Passing -v -v supports deeper detail, for example:

$ cilium endpoint config 3978 debug=true
Endpoint 3978 configuration updated successfully
$ cilium monitor -v -v --hex
Listening for events on 2 CPUs with 64x4096 of shared memory
Press Ctrl-C to quit
------------------------------------------------------------------------------
CPU 00: MARK 0x1c56d86c FROM 3978 DEBUG: 70 bytes Incoming packet from container ifindex 85
00000000  33 33 00 00 00 02 ae 45  75 73 11 04 86 dd 60 00  |33.....Eus....`.|
00000010  00 00 00 10 3a ff fe 80  00 00 00 00 00 00 ac 45  |....:..........E|
00000020  75 ff fe 73 11 04 ff 02  00 00 00 00 00 00 00 00  |u..s............|
00000030  00 00 00 00 00 02 85 00  15 b4 00 00 00 00 01 01  |................|
00000040  ae 45 75 73 11 04 00 00  00 00 00 00              |.Eus........|
CPU 00: MARK 0x1c56d86c FROM 3978 DEBUG: Handling ICMPv6 type=133
------------------------------------------------------------------------------
CPU 00: MARK 0x1c56d86c FROM 3978 Packet dropped 131 (Invalid destination mac) 70 bytes ifindex=0 284->0
00000000  33 33 00 00 00 02 ae 45  75 73 11 04 86 dd 60 00  |33.....Eus....`.|
00000010  00 00 00 10 3a ff fe 80  00 00 00 00 00 00 ac 45  |....:..........E|
00000020  75 ff fe 73 11 04 ff 02  00 00 00 00 00 00 00 00  |u..s............|
00000030  00 00 00 00 00 02 85 00  15 b4 00 00 00 00 01 01  |................|
00000040  00 00 00 00                                       |....|
------------------------------------------------------------------------------
CPU 00: MARK 0x7dc2b704 FROM 3978 DEBUG: 86 bytes Incoming packet from container ifindex 85
00000000  33 33 ff 00 8a d6 ae 45  75 73 11 04 86 dd 60 00  |33.....Eus....`.|
00000010  00 00 00 20 3a ff fe 80  00 00 00 00 00 00 ac 45  |... :..........E|
00000020  75 ff fe 73 11 04 ff 02  00 00 00 00 00 00 00 00  |u..s............|
00000030  00 01 ff 00 8a d6 87 00  20 40 00 00 00 00 fd 02  |........ @......|
00000040  00 00 00 00 00 00 c0 a8  21 0b 00 00 8a d6 01 01  |........!.......|
00000050  ae 45 75 73 11 04 00 00  00 00 00 00              |.Eus........|
CPU 00: MARK 0x7dc2b704 FROM 3978 DEBUG: Handling ICMPv6 type=135
CPU 00: MARK 0x7dc2b704 FROM 3978 DEBUG: ICMPv6 neighbour soliciation for address b21a8c0:d68a0000

One of the most common issues when developing datapath code is that the eBPF 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
           ENFORCEMENT
48896      Disabled      266        container:id.server           fd02::c0a8:210b:0:bf00   10.11.13.37     not-ready
60670      Disabled      267        container:id.client           fd02::c0a8:210b:0:ecfe   10.11.167.158   not-ready

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

The files under /var/run/cilium/state provide context about how the eBPF datapath is managed and set up. The .h files describe specific configurations used for eBPF program compilation. The numbered directories describe endpoint-specific state, including header configuration files and eBPF binaries.

Current eBPF 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  cilium_tunnel_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
Key:
00000000  6a 01 00 00 82 23 06 00                           |j....#..|
Value:
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                           |........|