PureLB - is a Service Load Balancer for Kubernetes

PureLB is a load-balancer orchestrator for Kubernetes clusters. It uses standard Linux networking and routing protocols, and works with the operating system to announce service addresses.

Documentation

https://purelb.gitlab.io/docs

Quick Start

Installation is easy. For production systems we recommend installing using either Helm or a CI-built manifest file. These approaches use versioned image tags so they are stable. Instructions are on our install page at https://purelb.gitlab.io/docs/install/ .

For development, you can install PureLB from the source tree. This isn't recommended for production because it will install PureLB using an unstable image tag that changes over time so you could have unintended upgrades.

1. Deploy the PureLB components
   kustomize build deployments/samples | kubectl apply -f -
   Now you can configure PureLB. PureLB's default node agent configuration usually "just works" so we loaded it above. PureLB's allocator manages IP addresses so it needs a configuration that matches the network on which it's running. The allocator is configured using "Service Group" resources which contain pools of IP addresses and their associated network configuration. The node agent configures the Linux OS to advertise them. The easiest way to get started is to create a Service Group that uses the same IPNET as the host interface, PureLB will add the allocated addresses to the same network interface.
2. Copy the default service group config to your custom version
   cp configs/default-servicegroup.yaml configs/my-servicegroup.yaml
3. Edit configs/my-servicegroup.yaml so the subnet and pool are appropriate for your network
4. Load your service group config
   kubectl apply -f configs/my-servicegroup.yaml

To test PureLB you can deploy a simple "echo" web application:

kubectl create deployment echoserver --image=k8s.gcr.io/echoserver:1.10

...and then expose the deployment using a LoadBalancer service:

kubectl expose deployment echoserver --name=echoserver-service --port=80 --target-port=8080 --type=LoadBalancer

The PureLB allocator will allocate an address and assign it to the service. The PureLB node agents then configure the underlying operating system to advertise the address.

Building

Run make help for Makefile documentation.

If you fork this project and want to build ARM images you'll need to set up a Gitlab CI ARM "runner" process for your fork. I use a Raspberry Pi 4 Model B running Raspbian GNU/Linux 10 (Buster).

Find your project's registration token from the project CI Settings - https://gitlab.com/{your_gitlab_name}/purelb/-/settings/ci_cd . Expand the "Runners" section and look for "Set up a specific Runner manually".

Install the runner client program - https://docs.gitlab.com/runner/install/linux-repository.html

Run gitlab-runner register. It will ask for the url (https://gitlab.com/) and registration token.

Stop the runner (systemctl stop gitlab-runner.service) and make a few edits to the /etc/gitlab-runner/config.toml runner config file:

• Set the privileged flag to true (it's false by default)
• Add "/certs/client" to the volumes list
• Increase wait_for_services_timeout to 300
• If you're running a Pi4 with 4GB of memory or more you can set concurrent to 2 so the allocator and lbnodeagent will build simultaneously

Start the runner systemctl start gitlab-runner.service and verify that it's running systemctl status gitlab-runner.service.

Verify that the runner is listed on your project's CI Settings page.

Code

• Commands - if you're a "top-down" learner then start here
• Internal Code - if you're a "bottom-up" learner then start here
• Docker Packaging
• Helm Packaging
• Sample Configurations
• K8s Deployment Files

Credits

PureLB wouldn't have been possible without MetalLB so we owe a huge debt of gratitude to Dave Anderson for almost single-handedly making MetalLB happen. Thank you Dave!