kube-gen

kube-gen is a template rendering tool that generates files based on Kubernetes events and metadata. It is based on and inspired by Jason Wilder's excellent docker-gen.

Installation

Binary Download

See the Releases page

Docker Container

kube-gen can be run as a standalone container, or bundled in a container with other applications.

TODO: create official images

Usage

When run with no arguments (or with -h/-help), kube-gen prints the following usage message.

$ kube-gen
Usage: kube-gen [options] <template> [<output>]

Render templates using Kubernetes metadata and events

Options:
  -host string
    	 (default "http://localhost:8001")
  -interval int

  -log-cmd
    	log the output of the pre/post commands (default true)
  -overwrite
    	overwrite the output file if it exists (default true)
  -post-cmd string
    	command to run after template generation in complete
  -pre-cmd string
    	command to run before template generation
  -quiet
    	when set to true, nothing is logged
  -type value
    	types of resources to pull [pods, services, endpoints] - May be specified multiple times. If not specified, all types will be returned
  -version
    	display version information
  -wait string
    	<minimum>[:<maximum>] - the minimum and optional maximum time to wait after an event fires.E.g.: 500ms:5s
  -watch
    	watch for new events

Arguments:
  template: path or URL of the template file to render, or - to read from STDIN
  output: (Optional) path to write the rendered content. If not specified,
          rendered content is printed to STDOUT. By default, this file will
          be overwritten if it exists. Use -overwrite=false to return an
          error instead

Authentication / Connecting to the Kubernetes API

Currently, kube-gen does not support authentication, or reading the ~/.kube/config file. These features are forthcoming. In the mean time, the -host parameter should either be set to the value of kube-apiserver's --insecure-bind-address / --insecure-port values. Alternatively, as reflected by the default value, kube-gen can be run alongside kubectl proxy - which, by default, listens on 127.0.0.1:8001.

Watching for changes

The -watch flag configures kube-gen to watch the API for changes to Services, Pods, and Endpoints (support for other types is forthcoming). This mode is useul when combined with the -pre-cmd, -post-cmd, and -wait parameters.

Template Language

kube-gen supports templates written in Go`s text/template language. It supports all of the build in functions, as well as numerous custom functions described below. Many of the custom functions (and the documentation for those functions) have been borrowed from docker-gen. Those functions, along with the accompanying License and Copyright are located in the dockergen_template_functions.go source file.

aarondobbing/kube-gen