Merge pull request #9 from anguslees/readme

Add a README.md

Author: anguslees

README.md

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+# kubecfg
+
+A tool for managing Kubernetes resources as code.
+
+`kubecfg` allows you to express the patterns across your
+infrastructure and reuse these powerful "templates" across many
+services, and then manage those templates as files in version control.
+The more complex your infrastructure is, the more you will gain from
+using kubecfg.
+
+Status: This is a golang-rewrite of
+https://github.com/anguslees/kubecfg.  The original version has a few
+additional features, but the golang version will feel more similar to
+`kubectl` and is the focus of future development.
+
+Yes, Google employees will recognise this as being very similar to a
+similarly-named internal tool ;)
+
+## Install
+
+To build from source:
+
+```console
+% PATH=$PATH:$GOPATH/bin
+% go install github.com/ksonnet/kubecfg
+```
+
+Requires golang >=1.7 and a functional cgo environment (C++ with libstdc++).
+
+## Quickstart
+
+```console
+# This example uses ksonnet-lib
+% git clone https://github.com/ksonnet/ksonnet-lib.git
+
+# Set kubecfg/jsonnet library search path.  Can also use `-J` args everywhere.
+% export KUBECFG_JPATH=$PWD/ksonnet-lib
+
+# Hello-world ksonnet-lib example
+% cd ksonnet-lib/examples/hello-world
+
+# Show generated YAML
+% kubecfg show -o yaml hello.v1.jsonnet
+
+# Create resources
+% kubecfg update hello.v1.jsonnet
+
+# Modify configuration
+% sed -ie 's/nginx:1.7.9/nginx:1.13.0/' hello.v1.jsonnet
+# Update to new config
+% kubecfg update hello.v1.jsonnet
+```
+
+## Features
+
+- Supports JSON, YAML or jsonnet files (by file suffix).
+- Best-effort sorts objects before updating, so that dependencies are
+  pushed to the server before objects that refer to them.
+
+## Infrastructure-as-code Philosophy
+
+The idea is to describe *as much as possible* about your configuration
+as files in version control (eg: git).
+
+Changes to the configuration follow a regular review, approve, merge,
+etc code change workflow (github pull-requests, phabricator diffs,
+etc).  At any point, the config in version control captures the entire
+desired-state, so the system can be easily recreated in a QA cluster
+or to recover from disaster.
+
+### Jsonnet
+
+Kubecfg relies heavily on [jsonnet](http://jsonnet.org/) to describe
+Kubernetes resources, and is really just a thin Kubernetes-specific
+wrapper around jsonnet evaluation.  You should read the jsonnet
+tutorial, and skim the functions available in the jsonnet `std`
+library.