At Box, we use Kubernetes to empower our engineers to own the whole lifecycle of their microservices. When it comes to networking, our engineers use Tigera’s Project Calico to declaratively manage network policies for their apps running in our Kubernetes clusters. App owners define a Calico policy in order to enable their Pods to send/receive network traffic, which is instantiated as iptables rules.
There may be times, however, when such network policy is missing or declared incorrectly by app owners. In this situation, the iptables rules will cause network packet drops between the affected Pods, which get logged in a file that is inaccessible to app owners. We needed a mechanism to seamlessly deliver alerts about those iptables packet drops based on their network policies to help app owners quickly diagnose the corresponding issues.
To solve this, we developed a service called kube-iptables-tailer to detect packet drops from iptables logs and report them as Kubernetes events. We are proud to open-source kube-iptables-tailer for you to utilize in your own cluster, regardless of whether you use Calico or other network policy tools. App owners do not have to apply any additional changes to utilize kube-iptables-tailer.
They can simply run kubectl describe pods to check if any of their Pods’ traffic has been dropped due to iptables rules. All the results sent from kube-iptables-tailer will be shown under the Events section, which is a much better experience for developers when compared to reading through raw iptables logs.