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https://github.com/lizrice/lb-from-scratch
A very basic eBPF Load Balancer in a few lines of C
https://github.com/lizrice/lb-from-scratch
Last synced: 22 days ago
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A very basic eBPF Load Balancer in a few lines of C
- Host: GitHub
- URL: https://github.com/lizrice/lb-from-scratch
- Owner: lizrice
- License: gpl-3.0
- Created: 2021-08-19T09:00:41.000Z (over 3 years ago)
- Default Branch: main
- Last Pushed: 2023-04-27T17:12:48.000Z (over 1 year ago)
- Last Synced: 2024-02-17T06:35:09.025Z (9 months ago)
- Language: C
- Size: 31.3 KB
- Stars: 263
- Watchers: 5
- Forks: 48
- Open Issues: 5
-
Metadata Files:
- Readme: README.MD
- License: LICENSE
Awesome Lists containing this project
README
# Network-related demos
* Load Balancer from Scratch
* Packetdrop
* Packet counting
## An eBPF Load Balancer from scratch
As seen at [eBPF Summit 2021](https://ebpf.io/summit-2021). This is not production ready :-)
This uses `libbpf` as a git submodule. If you clone this repo you'll need to run
`git submodule init` and `git submodule update` to get your copy of that repo.
## Load Balancer container
In my demo I'm running all the components as containers.
For the Load Balancer component itself you can build a Docker image from Dockerfile.lb, which starts from
an `ubuntu` container with additional dependencies so that it can compile the eBPF code.
```
docker buildx create --name mybuilder --bootstrap --use
docker buildx build --push --platform linux/arm64,linux/amd64 --tag lizrice/ubuntu-ebpf-lb -f Dockerfile.lb .
```
```bash
sudo apt install clang llvm libelf-dev libpcap-dev gcc-multilib build-essential make linux-tools-common
```
*Note: gcc-multilib is not currently available for ARM architectures on Ubuntu 22.04. I'm adding `/usr/include/$(shell uname -m)-linux-gnu` into the include path instead. See [this thread for more info](https://patchwork.ozlabs.org/project/netdev/patch/[email protected]/).*
My version of this container image is available at `lizrice/ubuntu-ebpf-lb`.
Running it as privileged gives it permissions to load eBPF programs:
```bash
docker run --rm -it -v ~/lb-from-scratch:/lb-from-scratch --privileged -h lb --name lb --env TERM=xterm-color lizrice/ubuntu-ebpf-lb
```
Exec into that container, `cd lb-from-scratch` and then `make` should build and
install the load balancer onto the eth0 interface for that container.
## Demo containers
Here's how I started the containers for the two backends and the client:
```bash
docker run -d --rm --name backend-A -h backend-A --env TERM=xterm-color nginxdemos/hello:plain-text
docker run -d --rm --name backend-B -h backend-B --env TERM=xterm-color nginxdemos/hello:plain-text
docker run --rm -it -h client --name client --env TERM=xterm-color ubuntu
```
Exec into one of the backends and install tcpdump with `apk add tcpdump` if you want to see incoming
traffic there.
Run something on the host that tails the output from BPF trace (for example, my [hello
world eBPF beginners examples](https://github.com/lizrice/libbpfgo-beginners))
or just `sudo cat /sys/kernel/debug/tracing/trace_pipe`
### IP addresses
The IP addresses for the client, load balancer and two backends are hard-coded at the top of the .c file. You'll likely need to change these to match the addresses assigned to the containers you run.
## Packet drop - ping demo
Install ping utils into the ubuntu-working container
```bash
apt install iputils-ping
```
Save off into an image called ubuntu-pingbox: `docker commit ubuntu-pingbox`
```bash
docker run --rm -it -v ~/ebpf-net-beginners:/ebpf-net-beginners --privileged -h pingbox --name pingbox --env TERM=xterm-color ubuntu-pingbox
```
Or use the version I pushed to Docker Hub
```bash
docker run --rm -it -v ~/lb-from-scratch:/lb-from-scratch --privileged -h pingbox --env TERM=xterm-color lizrice/ubuntu-pingbox
```
Find its ip address (`ip a` from inside, or `docker inspect pingbox`)
Check you can ping it from outside.
```bash
cd ebpf-net-beginners
```
Comment in the `packetdrop` target in the Makefile and then `make` to load the
program. Edit and make to drop or pass ICMP packets.
Tracing: `cat /sys/kernel/debug/tracing/trace_pipe` on host
Listen with `nc -l 80`
Curl from host with `curl -v 172.17.0.2` (use verbose to see the response even
if it's not valid HTML)
## xdp_liz
Counts packets!