Getting Started with Cilium eBPF

Cilium is an open-source project that leverages the power of eBPF to provide advanced networking and security features for containerized…

Luis Soares

— 4 min read
Getting Started with Cilium eBPF

Cilium is an open-source project that leverages the power of eBPF to provide advanced networking and security features for containerized environments.

Note: If you’re unfamiliar with eBPF or want to get a quick review, I wrote an intro article about eBPF in this article. Read on!

Cilium enables API-aware network security, load balancing, and visibility for microservices, both on-premises and in the cloud, providing a transparent and efficient way to secure and manage network communication between containers, virtual machines, and bare-metal hosts without the need for complex, traditional networking components.

Some notable use cases include securing cloud-native applications, improving network performance, and simplifying network management.

With its programmable nature, Cilium eBPF can help reduce the complexity of managing containerized environments, making it easier for teams to deploy and manage their applications.

In this article, I’ll walk you through the process of getting started with Cilium eBPF, including installation, setup, and code samples in the Go language.

Let’s get started!

Prerequisites

Before you begin, ensure that you have the following prerequisites:

  • A Kubernetes cluster (version 1.9 or later) or a container runtime that supports the CNI (Container Network Interface) plugin, such as Docker.
  • Go language installed (version 1.15 or later) for code samples.
  • Helm, the Kubernetes package manager, to install Cilium (version 3.5 or later).

Installing Cilium

To install Cilium on your Kubernetes cluster, follow these steps:

Step 1: Add the Cilium Helm repository:

helm repo add cilium https://helm.cilium.io/

Step 2: Install Cilium using Helm:

helm install cilium cilium/cilium --version 1.10.0 --namespace kube-system --set kubeProxyReplacement=probe

Replace 1.10.0 with the desired Cilium version.

Configuring Cilium

By default, Cilium uses VXLAN for encapsulation. If you want to use a different encapsulation mode or configure other Cilium options, you can create a custom values file and pass it to Helm during installation. Here’s an example cilium-values.yaml file:

global: 
  kubeProxyReplacement: "probe" 
  tunnel: "disabled" 
  nativeRoutingCIDR: "10.0.0.0/8" 
  devices: "eth0" 
  encryption: 
    enabled: true

To apply the custom configuration, run the following:

helm install cilium cilium/cilium --version 1.10.0 --namespace kube-system -f cilium-values.yaml

Cilium eBPF Go Code Samples

To interact with Cilium eBPF from your Go application, you can use the Cilium eBPF library, which provides a high-level API to eBPF programs and maps.

Step 1: Install the Cilium eBPF Go library:

go get -u github.com/cilium/ebpf

Step 2: Load an eBPF program from a C file:

package main 
 
import ( 
    "github.com/cilium/ebpf" 
    "github.com/cilium/ebpf/link" 
) 
 
func main() { 
    // Load the eBPF program from a C file 
    spec, err := ebpf.LoadCollectionSpec("path/to/your/ebpf_program.c") 
    if err != nil { 
        panic(err) 
    } 
 
    // Compile the eBPF program 
    coll, err := ebpf.NewCollection(spec) 
    if err != nil { 
        panic(err) 
    } 
    defer coll.Close() 
}

Step 3: Attach the eBPF program to a network interface:

package main 
 
import ( 
    "github.com/cilium/ebpf" 
    "github.com/cilium/ebpf/link" 
) 
 
func main() { 
    // Load and compile the eBPF program (see previous step) 
 
    // Attach the eBPF program to a network interface 
    iface, err := net.InterfaceByName("eth0") 
    if err != nil { 
        panic(err) 
    } 
 
    xdp, opts := link.XDPAttachOptions{} 
    prog := coll.Programs["my_xdp_program"] // Replace "my_xdp_program" with the name of your eBPF program 
    if prog == nil { 
        panic("Failed to find eBPF program") 
    } 
 
    xdp, err := link.AttachXDP(*iface, prog, &opts) 
    if err != nil { 
        panic(err) 
    } 
    defer xdp.Remove() 
 
    // Use the eBPF program as needed 
}

Step 4: Interact with eBPF maps:

package main 
 
import ( 
    "github.com/cilium/ebpf" 
) 
 
func main() { 
    // Load and compile the eBPF program (see previous steps) 
 
    // Access eBPF maps from the compiled program 
    myMap := coll.Maps["my_map"] // Replace "my_map" with the name of your eBPF map 
    if myMap == nil { 
        panic("Failed to find eBPF map") 
    } 
 
    // Interact with the eBPF map (e.g., insert, delete, or lookup elements) 
    key := uint32(1) 
    value := uint64(42) 
 
    if err := myMap.Put(key, value); err != nil { 
        panic(err) 
    } 
 
    var retrievedValue uint64 
    if found, err := myMap.Lookup(key, &retrievedValue); err != nil { 
        panic(err) 
    } else if !found { 
        panic("Key not found in eBPF map") 
    } 
}

Monitoring and Troubleshooting

Cilium provides several tools for monitoring and troubleshooting your eBPF programs:

  • Cilium CLI: Use the cilium command-line tool to interact with the Cilium agent, check the status of your eBPF programs and manage network policies.
  • Hubble: Hubble is an observability platform built on Cilium that provides real-time visibility into the network, including flows, security policies, and performance metrics.

Advanced Use Cases

You may explore advanced use cases and applications as you become more proficient with Cilium eBPF.

Some of these include:

a. Load Balancing: Implement custom load balancing algorithms and strategies to distribute traffic evenly across your services, improving overall performance and reliability.

b. Network Policy Enforcement: Develop fine-grained, application-aware network policies to secure your services and control traffic flow within your environment.

c. Tracing and Profiling: Use eBPF’s tracing and profiling capabilities to gain deeper insights into your applications’ performance and identify potential bottlenecks or issues.

d. Custom Metrics Collection: Create eBPF programs to collect custom metrics from your applications and services, enabling more precise monitoring and observability.

Community and Resources

The Cilium project has a vibrant and active community that can provide support, advice, and inspiration as you explore the world of eBPF. Here are some resources to help you along your journey:

In this guide, we saw how to get started in Cilium eBPF, including installation, setup, code samples in the Go language, and advanced use cases.

As you continue exploring and experimenting with Cilium eBPF, don’t hesitate to engage with the community and seek additional resources.

Stay tuned, and happy coding!

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All the best,

Luis Soares

CTO | Head of Engineering | Golang & eBPF Enthusiast | Blockchain Engineer | Web3 | Cyber Security

#eBPF #linux #kernel #hooks #bytecode #virtualmachine #devops #helm #kubernetes #containers #k8s #LLVM #compiler #application #softwaredevelopment #softwareengineering #backend #development #softwaredesign #security #technology #networking

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