goping

goping is a command-line tool designed for Kubernetes environments to address the challenge of testing network connectivity to services when traditional ping is ineffective due to the nature of Kubernetes Services.

Table of Contents

• Background
• Installation
• Usage
  • Serve Command
  • Ping Command
• Technical Explanation

Background

In Kubernetes, using ping to test connectivity to services is ineffective due to the port requirement for Services to function. This tool addresses this limitation by providing an alternative method to test network connectivity to Kubernetes Services.

Why Regular Ping Fails in Kubernetes Services?

Kubernetes Services are stable networking endpoints in front of Pods, exposing a DNS name, virtual IP, and port. However, traditional ping does not utilize ports and thus cannot activate a Kubernetes Service.

Installation

To build the goping tool, ensure you have Go installed. Then run:

make build

This will generate the executable binary goping in the bin directory.

For building a Docker image:

make docker

This command will build a Docker image named goping-server.

Usage

Serve Command

The serve command starts the goping server.

goping serve --serve-addr=:8080 --log-level=info --production-mode

• --serve-addr specifies the address to serve on. Default is :8080.
• --log-level sets the log level (e.g., debug, info, warn, error, dpanic, panic, fatal). Default is info.
• --production-mode toggles production mode to disable debug logs.

Ping Command

The ping command tests the connectivity to the goping server.

goping ping <server-address> --packet-timeout=10ms --packets-count=4 --log-level=info --production-mode

• <server-address> is the address of the server to ping.
• --packet-timeout sets the timeout for each packet. Default is 10ms.
• --packets-count specifies the number of packets to send. Default is 4.
• --log-level sets the log level. Default is info.
• --production-mode toggles production mode.

Technical Explanation

In Kubernetes environments, the conventional ping command proves ineffective for testing connectivity to Services due to limitations in ICMP (Internet Control Message Protocol), which ping relies on and doesn't support port specifications. Kubernetes Services demand connections to arrive on specific ports to activate, a requirement ping fails to fulfill as it lacks port-specific functionality. To tackle this challenge, goping introduces a tailored solution. It simulates ping-like functionality, purpose-built for Kubernetes. goping utilizes UDP (User Datagram Protocol) to send packets targeted at Service endpoints on specified ports. This custom approach enables accurate connectivity testing to Kubernetes Services, circumventing the port-based constraints inherent in traditional ping commands.